EOS Imaging - Carpeta de Producto by deleccientifica

CONTENIDO EOS IMAGING EOS, DE EOS IMAGING DELEC CIENTÍFICA

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A B O C A D O S A L A I N N O VA C I Ó N

C O N S U LT O R Í A E S P E C I A L I Z A D A

S E RV I C I O T ÉC N I CO E X P E RTO

¿ P O R Q U É E L EG I R LO ?

SOBRE EOS

SISTEMA EOS

SterEOS 21 EOS APPS

C A R A C T E R Í S T I C A S P R I N C I PA L E S D E E O S 2 4 BENEFICIOS 25 C ATÁ L O G O 2 7 BIBLIOGRAFÍA 29 ESPECIFICACIONES TÉCNICAS

F O L L E TO S 3 8

Esta carpeta fue generada por el equipo de consultores de DeLeC Científica. Buenos Aires, Argentina. 2019. DeLeC Científica Uruguaya - Representante Regional Exclusivo Fco. García Corina 2357 – Piso 1. Montevideo - Uruguay DeLeC Científica Argentina – Agente Comercial Local Aráoz 821 -C1414DPQ - Buenos Aires – Argentina. Tel: (+54-11) 4775 5844

l sistema EOS permite obtener imágenes 3D de cuerpo completo en un tiempo récord entre los sistemas actuales. Al simplificar el proceso, EOS consigue disminuir los tiempos del paciente frente a la radiación

y acelerar el trabajo en las salas de rayos. Con EOS se obtienen dos imágenes del paciente, una lateral y una anteroposterior de alta definición que permiten a los profesionales trabajar con seguridad en sus diagnósticos. En tan sólo 20 segundos o menos, se obtienen dos imágenes radiográficas digitales de cuerpo completo del paciente. Sin “stitching” de imágenes (discontinuidades en la composición) y sin la necesidad de utilizar CDs o sistemas físicos de almacenamiento, EOS reduce el tiempo de espera del paciente y los tiempos de trabajo logrando realizar el examen completo en 4 minutos, incluso para estudios de columna complejos.

EOS IMAGING

EOS, DE EOS IMAGING

¿Qué es el sistema EOS?

EOS es un sistema de adquisición de imágenes innovador con una estación de trabajo 3D para el diagnóstico y seguimiento ortopédico avanzado. Basado en una invención ganadora de un Premio Nobel en física en el campo de la detección de partículas, es capaz de capturar simultáneamente imágenes de rayos X biplanares de todo el cuerpo con el peso en bipedestación, utilizando dosis de radiación baja y ultrabaja (Micro Dose).

DELEC CIENTÍFICA

¿Quiénes somos?

ABOCADOS A LA

DeLeC Científica es una empresa exitosa, en constante crecimiento, líder en innovación tecnológica aplicada a la medicina que fue fundada en el año 2003 por un grupo empresario de capitales nacionales, con vocación de servicio y alto grado de Responsabilidad Social.

“Si en el futuro somos lo que proyectamos, en el presente somos lo que hacemos en virtud de aquella decisión y proyecto”. José Ortega y Gasset

Nuestra misión es impulsar la mejora continua de nuestro sistema de salud regional, ofreciendo para ello los mejores productos de la revolución tecnológica del siglo XXI. A tal fin, nos hemos propuesto hacer foco en lo especial y proveer soluciones a problemas de los que nadie se ha ocupado, teniendo en cuenta que hay muchas empresas de electromedicina, de todo tipo y tamaño, que se dedican a atender el mercado de volumen con soluciones estandarizadas que dejan afuera a mucha gente.

¿A quiénes servimos y con qué tipo de productos? Servimos a las comunidades científicas y médicas proveyéndoles productos y servicios de última generación y alto valor agregado. Nos concentramos exclusivamente en aquellos que son seguros y están debidamente certificados y aprobados por los organismos internacionales de control - FDA y CE - y también los nacionales - ANMAT y ARN –; todo en el marco de un soporte pre y post venta de excelencia.

¿En qué nos especializamos? Somos consultores altamente especializados en el desarrollo e implementación de programas médicos de excelencia soportados por equipos y sistemas de real innovación tecnológica.

INNOVACIÓN

¿Cómo estamos organizados? La firma cuenta con seis áreas de trabajo con roles bien definidos. • División de Sistemas Médicos: Se distingue por proveer la mejor tecnología de punta disponible, a partir de la revolución tecnológica del siglo XXI, para cubrir necesidades de equipamiento de diagnóstico y también de tratamiento. Busca optimizar resultados clínicos y al mismo tiempo mejorar la calidad de la experiencia vivida por los pacientes antes, durante y después del proceso de tratamiento. • División de Cirugía Robótica y Simulación: pone a disposición de la comunidad médica la posibilidad inigualable de asistencia robótica a la cirugía mínimamente invasiva y también los únicos simuladores quirúrgicos verdaderamente realísticos; considerados los mejores del mundo en cirugía virtual. • División de Radioterapia y Radiocirugía: Ofrece la trilogía ideal de equipos para tratamiento de tumores malignos y benignos. • División de Ingeniería, Soporte Técnico y Aplicaciones Clínicas: Asegura el correcto funcionamiento de la base de equipos de innovación tecnológica instalada, incluyendo su actualización continua, y brinda servicio docente a los usuarios para asegurar su correcta utilización y las buenas prácticas. • División de Comunicación y Marketing: Área en constante crecimiento que busca llegar estratégicamente a los públicos de relevancia para la empresa y trasmitir un mensaje claro sobre su misión y objetivos. Para que “las cosas sean” es necesario comunicar que existen. “No se desea lo que no se conoce”. • División de Administración, Personal y Finanzas: Optimiza los resultados económicos de la empresa, cuidando que haya una distribución equitativa de los recursos entre los seis grupos de interés: proveedores, clientes, personal, accionistas, bancos/inversores y el fisco. Su objetivo principal es velar por una gestión eficiente y ecuánime al momento de crear valor económico produciendo, al mismo tiempo, valor social.

Precisión submilimétrica e innovación en tratamientos de radioterapia y radiocirugía.

Radioterapia intraoperatoria, Pequeño, ligero, móvil, autoblindado y efectivo.

Tomógrafo de mamas con imágenes 3D realmente isotrópicas.

Hospitales móviles diseñados a la necesidad del cliente.

Tomógrafos móviles autoblindados de uso en clínicas y ambulancias.

Adquisición continua de imagen en bipedestación 2D y 3D con baja dosis.

Simuladores de alta y mediana fidelidad y sistema audiovisual con herramientas de gestión.

Cabezas para intubación, torso para trauma y monitor multiparamétrico simulado.

Tecnología no invasiva que ayuda a visualizar venas no visibles a simple vista.

Sistema de adquisición de señales biológicas y software para educación e investigación.

¿Cuál es nuestra filosofía? Nuestro lema es ganar cuando el cliente también gana, cumplir con lo prometido y hacerlo a tiempo.

¿Qué nos diferencia del resto de las empresas del rubro? Nuestro diferencial es que no sólo proveemos equipos, sino que desarrollamos programas médicos de excelencia, acompañando al cliente desde la etapa embrionaria del proyecto hasta su optimización operativa. • Seleccionamos el equipamiento necesario y lo instalamos. • Brindamos soporte técnico con garantía oficial. • Nos encargamos del entrenamiento de los médicos y del personal de la institución local. • Una vez que llegamos a una institución, nunca nos vamos.

¿Cuál es nuestra modalidad de trabajo? Trabajamos en equipo con proveedores y clientes a través de una continua actividad de docencia. No tenemos vendedores, pero nos atenemos al perfil y la descripción habitual de las tareas de un vendedor técnico. Nuestro equipo se compone de profesionales universitarios, frecuentemente con posgrado que, a poco de ingresar a la compañía, son enviados a las distintas fábricas representadas para capacitarse de la mejor forma para ofrecer cada producto con solvencia técnica y científica.

¿Contra quiénes competimos? No poseemos competidores, ya que vamos en una dirección distinta al resto, usualmente: cambiando paradigmas.

¿Dónde comercializamos y soportamos nuestros productos? La firma comercializa la mayoría de sus productos en Argentina, Uruguay, Paraguay y Bolivia. Sin embargo, muchas veces, a pedido de distintos fabricantes, extendemos nuestro radio de acción llegando a otros países de América del Sur. En el 2010 introdujimos la cirugía robótica en Colombia, preparando el terreno para que luego se nombrara un distribuidor local. Antes, en el 2008, habíamos instalado las dos primeras unidades da Vinci que hubo en Brasil. Lo hicimos en el Hospital Albert Einstein y en el Sirio Libanes, ambos de Sao Paulo. Cabe destacar que también en este país existe actualmente un distribuidor local para esta tecnología.

¿Cuál es nuestra visión de futuro? En el mediano plazo esperamos ser líderes regionales y referentes indiscutidos en innovación tecnológica aplicada a la medicina. Esto lo lograremos gracias a nuestro comportamiento empresarial, calidad de relaciones que establezcamos, eficiencia y efectividad de nuestros productos y servicios. Apostamos a ser una organización de renombre y prestigio regional, comprometiéndonos con la comunidad y ayudando para la construcción de un mundo mejor a través de la mejora continua del servicio de salud.

Oficinas de DeLeC Científica

C O N S U LT O R Í A

Nuestra experiencia en el ámbito de la innovación tecnológica en salud nos dice

ESPECIALIZADA

que el mejor equipo de radiocirugía no hace una intervención de calidad por sí mismo. Tan importante como la herramienta son la formación, la comprensión de la tecnología, el buen uso, el asesoramiento y los objetivos que orientan la práctica. Por eso en DeLeC Científica acompañamos a las instituciones desde el desarrollo de los proyectos, el diseño de nuevas áreas o servicios de salud, el asesoramiento en la adquisición de nuevas tecnologías, los requerimientos normativos y legales, la diagramación logística, el mantenimiento y el monitoreo del uso. Un asesoramiento adecuado es clave para: - obtener planificaciones que permitan optimizar el tiempo de los proyectos, - prever los riesgos potenciales para garantizar la viabilidad en el mediano y largo plazo, - identificar todos los stakeholders alrededor del proyecto y prever cuál será el impacto en ellos, - conseguir una mirada profunda sobre la inversión, el retorno y reconocer oportunidades que no están a la vista. Con el fin de asesorar tomando como referencia los máximos estándares de calidad, los consultores de DeLeC nos actualizamos de acuerdo a los programas de formación de las firmas que representamos y participamos de forma activa en la agenda más relevante de la innovación tecnológica médica en Occidente.

Ofrecer un servicio técnico de alta performance, alineado tanto a las exigencias y

SERVICIO TÉCNICO

estándares de las marcas con las que trabajamos, como a los requerimientos de

EXPERTO

nuestros clientes es un punto destacado en nuestra empresa. El equipo técnico asiste en la interpretación de los requerimientos previos (condiciones eléctricas, infraestructura, etc.), se ocupa de la instalación, cuando el equipo lo requiere, y luego monitorea el funcionamiento y el uso para garantizar el desempeño óptimo de la tecnología. El servicio de instalación de DeLeC Científica para el equipo Radixact cumple con todos los procesos recomendados por la fábrica. Nuestros técnicos deben cumplir con un cronograma de formación y capacitación anual, en las casas matrices de las firmas que representamos. Por lo tanto, desde DeLeC Científica ofrecemos una asistencia de instalación y posventa certificada por fábrica.

¿POR QUÉ ELEGIRLO?

EOS está desafiando el status quo en el área de imágenes ortopédicas, ofreciendo precisión en 2D y 3D a una baja dosis y posicionando un nuevo estándar de cuidado del paciente. EOS es una empresa de dispositivos médicos que se originó a partir de la investigación científica en el método de detección de la radiación que ganó el Premio Nobel de Física en el año 1992. Desde ese entonces, un equipo multidisciplinario de profesionales trabaja para transformar ciencia en tecnología, desarrollando y comercializando soluciones avanzadas basadas en la adquisición y procesamiento de imágenes para el diagnóstico, tratamiento y monitoreo de las patologías musculoesqueléticas. EOS tiene un alto compromiso con la calidad del servicio en términos de la dosis absorbida por el paciente, el flujo de trabajo y los parámetros médicos obtenidos automáticamente; lo que aumenta la eficiencia de toda la institución. Los principales beneficios del equipo radican en la posibilidad de utilizar dos niveles de emisión de radiación manteniendo una excelente calidad de imagen, la generación automática de más de 100 parámetros clínicos de interés para el diagnóstico y tratamiento de distintas patologías; y la generación automática de un informe médico que facilita y agiliza el flujo de trabajo. En el año 2008 fue instalado el primer sistema EOS en Europa y Norteamérica. Hoy en día la plataforma EOS está presente en 51 países, incluyendo EE.UU., Japón, China y en la Unión Europea. La empresa está situada en París y tiene 5 sedes en Besançon (Francia), Cambridge (USA), Montreal (Canadá), Frankfurt (Alemania) y Singapur.

SOBRE EOS

SISTEMA EOS El sistema de adquisición de imágenes frontal y lateral espacialmente calibradas permite realizar una reconstrucción superficial tridimensional (3D) del sistema esquelético, en escala 1: 1 verdadera, en la estación de trabajo sterEOS. El software ofrece una vista superior (“bird’s-eye view”) para analizar la rotación de las extremidades inferiores, articulaciones y deformidades de la columna en el plano horizontal, proporcionando nuevas posibilidades revolucionarias en la cirugía ortopédica.

Sistema de adquisición EOS

SterEOS La estación de trabajo sterEOS está dedicada a analizar las imágenes EOS del plano frontal y lateral -ya sea a baja dosis o micro dosis- para generar un modelo 3D preciso y específico de la columna y/o de los miembros inferiores del paciente en posición funcional. Una vez que los modelos son generados, los parámetros clínicos relevantes son automáticamente calculados. Los modelos 3D y las mediciones precisas de los parámetros están libres de las desviaciones asociadas a las mediciones manuales y a los efectos de la magnificación en las imágenes 2D. Esto permite tomar decisiones clínicas correctamente fundamentadas desde el diagnóstico hasta el planeamiento de la cirugía y durante el control post-operatorio. Automáticamente se generan fichas personalizadas de los pacientes en formato DICOM, las cuales pueden ser compartidas con el equipo médico y ser utilizadas para el plan de tratamiento.

EOS APPS

Las EOSapps son soluciones online, 3D para ser utilizadas en el planeamiento de cirugías, basadas en imágenes EOS precisas, sin desviaciones y en posición funcional. Las EOSapps permiten seleccionar y posicionar automáticamente los implantes más adecuados según la anatomía 3D de cada paciente y permiten simular en 3D los resultados post-operatorios en tiempo real, incluyendo el impacto que tiene la cirugía sobre algunos parámetros clínicos de importancia. SpineEOS Debido a la complejidad de la columna, las cirugías son particularmente difíciles y necesitan una preparación cuidadosa para tener mejores resultados. El software online spineEOS genera una visualización 3D de la columna del paciente en el estado real y otra con la corrección óptima que debería realizarse, basada en la literatura (valores de referencia para adultos y pediátricos). Esta corrección puede ser modificada por el cirujano incluyendo la simulación de osteotomías, seleccionar y posicionar celdas inter-somáticas y planear precisamente el largo, ancho y la forma de las guías para la columna en 3D. Todos los parámetros clínicos de importancia (ángulo de Cobb, lordosis/cifosis, SVA) se muestran en tiempo real para tomar decisiones sobre la cirugía más fácilmente. KneeEOS Debido a una población añosa, el número de artroplastias de rodilla sigue aumentando. A pesar de grandes esfuerzos, se sigue necesitando el progreso para mejorar los resultados del 20% de pacientes que estadísticamente no están satisfechos con los resultados quirúrgicos. El software online kneeEOS es utilizado para diagramar artroplastias de rodilla seleccionando y posicionando implantes en 3D automáticamente. El cirujano puede modificar el plan con un inmediato feedback del cambio de los parámetros clínicos relevantes. Gracias a las imágenes de cuerpo entero de EOS 2D/3D en posición de bipedestación, kneeEOS puede ser utilizado para anticipar las consecuencias del alineamiento de la prótesis con la pierna (HKA) y la rotación de la rodilla (varus/valgus, flexión/extensión, rotación interna/externa) (1) (2); dos criterios importantes para lograr una artroplastia total de rodilla exitosa.

1. Measuring femoral and rotational alignment: EOSsystem versus computed tomography. D. Folinaisa, P. Thelen, C. Delin, C. Radier, Y. Catonne, J.Y. Lazennec. Hôpital de La Pitié-Salpêtrière, 2012. 2. Reliability of a new method for lower-extremity measurements based on stereoradiographic three-dimensional reconstruction. Guenoun B, Zadegan F, Aim F, Hannouche D, Nizard R. Orthop Traumatol Surg Res 2012 Jul 31.

HipEOS La artroplastia total de cadera es un procedimiento usual que sigue siendo un desafío. Es crucial identificar los riesgos pre-operatorios y minimizar las complicaciones post-operatorias para mejorar los resultados. La simulación quirúrgica en hipEOS 3D y su software de planeamiento son utilizados para diagramar THA. Comienza con una propuesta automática para el tamaño y la posición del vástago y el acetábulo basados en el implante que prefiera el cirujano y en la anatomía del paciente. Luego este plan personalizado del paciente puede ser ajustado por el médico con un inmediato feedback de cómo esos cambios van afectando los parámetros clínicos relevantes. Gracias a las imágenes de cuerpo entero de EOS 2D/3D en posición de bipedestación y sentado, hipEOS puede ser utilizado para anticipar los resultados de la cirugía, como son el rango de movilidad, las discrepancias en el largo de las piernas, el offset femoral y la torsión, que son criterios relevantes para lograr una artroplastia total de cadera exitosa.

CARACTERÍSTICAS PRINCIPALES DE EOS El Sistema de Imágenes EOS consiste en: Gantry EOS Un brazo vertical que soporta dos sistemas de adquisición de imágenes montados en ángulo recto. Cada sistema de adquisición está compuesto por un tubo de rayos X y un detector lineal. Una zona de adquisición de hasta 44,8 cm de ancho y 175 cm de alto. Elementos de estabilización del paciente. EOS Workstation Computadora para selección de parámetros de adquisición y operación de EOS. Sistema de posicionamiento láser Define los límites superior e inferior del área de exploración utilizando dos haces láser independientes proyectados sobre el paciente. Micro Dose (opcional).

BENEFICIOS Beneficios de EOS Posición funcional • Las imágenes son adquiridas con el peso en bipedestación, brindando una evaluación global del paciente en una posición funcional. EOS proporciona imágenes 2D precisas, sin sesgos por magnificación o stitching, y valiosa información anatómica 3D en todas las etapas de evaluación, aún con la opción Micro Dose. • Es posible comprender los mecanismos de compensación entre la columna vertebral, las caderas y las rodillas gracias a la adquisición de cuerpo completo contemplando peso en bipedestación. Reducción de Dosis suministrada • La dosis de radiación se reduce en un 50% en comparación con un sistema DR3, 85% en comparación con un sistema CR4. • Sustitución de exámenes TC específicos por un examen EOS para reducir la dosis de radiación del paciente en un 95%5. • Protocolo Micro Dose para un examen completo de la columna (AP y L) a una dosis que es equivalente a sólo una semana de radiación natural (entre 10 y 90 μGy), lo que cobra importancia en el seguimiento de pacientes pediátricos de acuerdo al principio de ALARA (tan bajo como razonablemente posible) más si requieren exploraciones frecuentes sobre el curso de su tratamiento (escoliosis). Eficiencia en toda la instalación • Captura imágenes de cuerpo completo frontal y lateral en menos de 20 segundos para los adultos y 15 segundos para los niños. • Completa un examen en menos de 4 minutos, incluso para la columna vertebral o cuerpo completo3.

3. Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. Dietrich TJ et al. Skeletal Radiol. 2013. 4. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Deschenes S et al. Spine (Phila Pa 1976)2010 Apr. 5. Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography. Delin C et al. Eur J Radiol. 2014.

Beneficios de sterEOS Mejora de los resultados clínicos • Permite visualizar y comprender la posición, rotación y orientación de los huesos en 3D dentro del sistema esquelético global desde una posición de bipedestación. • Posibilita la mejora del diagnóstico y las capacidades de investigación clínica con más de 100 mediciones 2D y 3D automáticamente calculadas, a escala 1:1, libres de sesgo y tomadas en una posición funcional. • Es posible realizar una evaluación post-operatoria de un reemplazo total de cadera a través de un flujo de trabajo dedicado y preciso que calcula automáticamente la posición de los componentes protésicos. • Los modelos 3D y la medición de parámetros clínicos 2D / 3D está disponible incluso en los estudios pediátricos de Micro Dose y los realizados con la silla EOS radiolúcida. Eficiencia en todos los procesos • Flujos de trabajo 3D simples y sencillos dedicados a la evaluación postural, la columna vertebral, los miembros inferiores y la artroplastia total de cadera (THA). • Potente base de datos de pacientes con gestión de acceso de usuarios y con la posibilidad de compartir datos con médicos internos y externos. • Enrutamiento automático a PACS y webPACS de imágenes, informes de pacientes y modelos 3D.

C ATÁ LO G O El núcleo del sistema EOS está compuesto por el Sistema de adquisición EOS (gantry), la Workstation para adquisición, el Sistema sterEOS (Workstation 3D), un Software para la columna vertebral y las extremidades inferiores, un Sistema de posicionamiento láser, entrenamiento inicial EOS y sterEOS brindado por un Especialista Clínico y garantía completa por un año. De manera opcional, se pueden incluir los siguientes ítems: • Micro Dose. • Sistema sterEOS adicional. • EOS Chair: Silla radiolúcida para posicionamiento de paciente pediátrico. • EOS Chair - Cobertor lavable. • EOS Chair - Kit de elementos para aseguramiento de la posición del paciente. • Curso de formación in situ que cubre instalación, operación y mantenimiento de EOS y sterEOS. Los usuarios serán instruidos en el funcionamiento del sistema, procedimientos, utilización de software y equipos auxiliares.

ESPECIFICACIONES TÃ&#x2030;CNICAS

EOS

- low dose 2D|3D imaging system

EOS is an imaging device which combines the use of a Nobel Prize-winning particle detector and an innovative linear scanning technique. With these two technologies, EOS enables whole body frontal and lateral images to be acquired simultaneously for a standing or seated patient, with a reduction in the dose of 50% compared to a DR system1 and up to 85% compared to a CR system2, with equal or superior image quality. In less than 20 seconds, two full-body digital radiographs are taken, without image stitching or any cassette to handle: EOS is a real time-saver for patients and operators. •

Significant exposure dose reduction1,2 compared to Computed Radiography or Digital Radiography

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Micro Dose option, for follow-up measurements in pediatrics, with dose equivalent to a week’s natural radiation exposure3

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Exceptional image quality

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Simultaneous acquisition of frontal and lateral images

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Continuous image (no “stitching”) and true size (no magnification)

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Acquisition of full body or localized images of a seated or standing patient

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Total exam cycle time of around 4 minutes for a complete frontal and lateral spine examination1

Specifications 2D imaging

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Acquisition software

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Images are obtained by vertical scanning

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Patient is in a standing or seated position

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Patient information management compatible with DICOM 3.0 standard (Modality Worklist SCU)

Two simultaneous frontal and lateral acquisitions. Single plane acquisitions are also possible.

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Selection of area of interest (height and width) and acquisition mode (biplane, frontal or lateral)

The user-defined acquisition zone may cover the full body or a specific zone (spine, lower limbs, etc.) up to 44.8 cm wide and 175 cm high

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Selection of morphotype and anatomical region

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Adjustment of kV, mA and acquisition speed (auto/manual)

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Display of radiation exposure dose (mGy.cm²)

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Image display and processing tools (windowing, zoom, measurements, secondary captures, annotations)

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Contrast enhancement (smooth, standard, strong) and specific processing if there is a prosthesis present, available at acquisition or during post-processing. The types of default processing and contrast enhancement are set up during applications training

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Image print SCU and print true size

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Archive on DICOM 3.0 PACS (Verification service and Image Storage SCU & SCP, Query Retrieve SCU, storage commitment SCU)

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Statistical tool for analyzing the number of rejected or repeated images (RRA)

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Automatic generation and sending of reports on the dose accumulated during the examination:

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Image file size: between 2 MB and 70 MB depending on the acquisition area

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Acquisition is 5 to 10 seconds for a spine, less than 20 seconds for a whole body

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Automatic detector gain adjustment ensures maximum image contrast, regardless of kV being applied

Detectors •

2 linear detectors, Nobel prize-winning AGD technology (Adjustable Gain Detector)

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Number of pixels/line: 1764/line, Pixel size: 254 µm

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Pixel depth: 16 bits (> 65 000 grey levels)

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Typical Dynamic Range: > 90dB

» RDSR (Radiation Dose Structured Report) » MPPS (Modality Performed Procedure Step)

Tubes • • •

Two X-ray tubes, maximum power 42 kW Small or large focal spot (0.4 x 0.7mm / 0.6 x 1.3mm) Aluminum (1 mm) or Copper (0.1 mm) filtration

Dimensions •

External dimensions: 2 m (l) x 2 m (w) x 2.7 m (h)

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Internal dimensions: 76 cm (l) x 76 cm (w) x 254 cm (h)/ 29.9 in (l) x 29.9 in (w) x 100 in (h)

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Width of patient access: 46 cm / 18.1 in

6.6 ft (l) x 6.6 ft (w) x 8.9 ft (h)

DON’T GUESS. SEE.

www.eos-imaging.com

Accessories delivered with EOS system

Options

Platform with footstep

Micro Dose

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Removable platform including fixation support, a platform and a footstep

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Indicated for pediatrics imaging with patient entrance dose of 10 to 90 µGy

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Patient raised by: 30 cm / 11.8 in

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For the purpose of follow-up patient measurements in pediatrics (lower limb deformities, scoliosis angle trending…)

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Available for 3 anatomical regions: full spine, lower limbs, full body

Patient stabilization •

Stabilization bar: enables the stabilization of the patient for acquisitions of the lower limbs in AP

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Posture stabilization device: enables the stabilization of the patient using a pressure pad applied to the head for AP and PA examinations of the spine and the full body

Laser positioning system •

A laser positioning system4 is available as an option on customer request in order to expedite the definition of top and bottom limits of the scanning area by using two independent laser lines projected on a patient’s skin

•

This option comes in addition to the external metric scale and preview scan setting tools offered in the EOS system for the definition of the scanning area

Quality control accessories •

Equipment used for the Quality Control procedure provided by EOS imaging in accordance with the regulations in force

Microphone •

Microphone and loudspeaker to communicate with the patient in the cabin

EC conformity assessment: LNE/G-MED CE0459, Class IIb . For USA - Caution : Federal law restricts this device to sale by or on the order of a physician 1 Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. Dietrich TJ et al. Skeletal Radiol. 2013. 2

Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Deschenes S et al. Spine (Phila Pa 1976)2010 Apr 20;35(9):989-94.

EOS microdose protocol for the radiological follow-up of adolescent idiopathic scoliosis. Ilharreborde B. et al. Eur Spine J. 2015 Apr 24.

EOS imaging SA. 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60

www.eos-imaging.com

EOS imaging Inc. 185 Alewife Brook Parkway #410 | Cambridge, MA 02138 USA | +1 (678) 564 5400

May 2015

3.5 version R22-BRO-094-A-EN

sterEOS - 2D|3D Workstation The first weight-bearing 3D modeling solution that automatically calculates over 100 clinically relevant parameters*.

Introduction Designed specifically for orthopaedic applications, the sterEOS workstation offers a state-of-the-art 2D viewer (sterEOS 2D) while also enabling 3D measurements and 3D weight bearing modeling of the bone surface using the EOS simultaneously acquired AP and Lateral biplanar images (sterEOS 3D).

sterEOS 2D sterEOS 2D provides specialized tools dedicated to the analysis of paired images taken with EOS. sterEOS 2D provides state-of-the-art features for the management of DICOM images acquired from EOS or other modalities**.

sterEOS 3D Without any additional radiation, sterEOS 3D allows for three-dimensional clinical measurements and modeling of the spine, lower limbs (femur and tibia) and hip prothesis (cup and stem post-operatively). From this 3D modeling, sterEOS automaticaly calculates diverse clinical parameters allowing for global analysis of the patient, as well as Postural Assessment.

sterEOS workstation

Specifications Workstation: •

PC Windows 7

•

Dedicated graphics board

•

Medical LCD monitor 21 inch colour / 2 million pixels (1600x1200)

•

Microsoft Word and Excel

•

Reader/Writer CD 16X DVD +/- RW

Communications Interface: •

Transfer of images to the PACS in DICOM format

•

Sending images to DICOM printers (Print True Size available)

•

Generation of a patient report in DICOM and RTF (Rich Text Format) including selected EOS X-Ray images, 3D images, clinical data and users comments. Example of a patient report sterEOS 3D Final output

EC conformity assessment: LNE/G-MED CE0459, Class I (measuring). For USA - Caution : Federal law restricts this device to sale by or on the order of a physician. * for the spine, pelvis, femur and tibia. ** except mammography and angiography.

DON’T GUESS. SEE.

www.eos-imaging.com

3 D Modeling The process of 3D modeling starts by the identification of anatomical landmarks on the frontal and lateral EOS X-rays. These landmarks combined with large statistical databases and contour detection algorithms (spine and lower limb) allow a 3D model that is adjusted to match the bone contours on the EOS X-rays. 3D clinical parameters are then automatically calculated from the model. Hence full-size 3D modeling can be performed from two low-dose EOS X-rays without any additional radiation. The combination of whole body, lowdose X-ray images and 3D weight-bearing modeling with associated calculations gives various medical specialties, particularly orthopedics, access to new clinical information to aid in the analysis of spine, hip & knee deformities and therapies.

3D Lower Limb Alignment The fast 3D lower limb alignment process provides reliable leg length and postural angles, independent of the leg orientation or patient position in the EOS system.

3D orientation of the acetabular cup and femoral stem2,3 sterEOS 3D provides the clinician with 3D tools allowing postoperative assessment of acetabular cup orientation and femoral stem position and orientation.

Lower limb alignment clinical parameters and display Acetabular cup and femoral stem clinical parameters and display Femoral Axis Length

Lengths

Tibial Axis Length Anatomical length Functional Length

Hip parameters

Knee parameters

Acetabular Cup

Anatomical Anteversion and Inclination Functional Anteversion and Inclination

Femoral Head Diameter Femoral Length

HKS Varus/Valgus

Femoral Stem

Knee Flexion / Extension

Femoral Offset Femoral Antetorsion Neck Shaft Angle

3D Lower Limb Modeling1 It is possible to complete the lower limb alignment process to obtain a 3D lower limb model . The visualization of the 3D model can be made from any point of view (top & bottom views, frontal & lateral views). 3D lower limb modeling allows for calculation of further clinical parameters, including femoral and tibial torsions. Lower limb modeling clinical parameters and display

Lengths

Femoral Axis Length Tibial Axis Length Anatomical Length Functional Length

Hip parameters

Femoral Head Diameter Femoral Offset Neck Shaft Angle Neck Length

Knee Parameters

Torsional Parameters

3D Tool Box Due to the perfect relationship between the two orthogonal images acquired simultaneously with EOS, the 3D toolbox enables the clinician to obtain, in a few clicks, real three-dimensional measurements**, eliminating typical errors linked to X-ray projection and magnification.

3D Tool Box and 3D neck shaft angle measurements

HKS Varus / Valgus Knee Flexion / Extension Femoral Mechanical Angle Tibial Mechanical Angle

Femoral Torsion Tibial Torsion Femoral-Tibial Rotation

**Provided the reference plan is well positioned 3D Lower Limb modeling is unable to highlight bone alterations such as fractures, osteophytes or fibrocartilage calluses and is not adapted for pediatric use. It may not be used in the presence of implants or congenital deformities and when bone structures are not visible in the X-rays. Approved for patients over 15 years old. Â˛ 3D measurements of femoral stem may not be used when the femoral head and neck of the stem are not clearly visible in the X-rays. 3 The 3D envelops of the pelvis and cut femur do not represent precisely the shape of the bone. Their only purpose is to situate the prosthesis in the space. 1

version 1.6

R22-BRO-075-EN-A

3D Spine Modeling1

Postural Assessment

The 3D spine modeling process may aid in the analysis of scoliosis and related spinal disorders and deformities. Modeling may be carried out from T1 to L5 and allows for the selection of the apex and junctional vertebrae of the scoliosis and an automatic calculation of clinical parameters. sterEOS allows the user different viewing angles of the global spine (including “birds-eye view” or view from above).

sterEOS 3D contains a streamlined application which may aid in the analysis of the degenerative spine and related postural disorders. The software provides access to the clinical parameters of the spine, pelvis and lower limb, allowing for quantification of a patient’s sagittal balance. Postural assessment clinical parameters and display

3D spine modeling clinical parameters and display Pelvic Version

Full modeling

Fast and full modeling

Scoliosis Parameters Sagittal Balance Parameters

Cobb Angle Axial rotation of the apical vertebrae

Pelvic Incidence

Pelvic

Sacral Slope

Parameters

Pelvic Obliquity

T1-T12 Kyphosis T4-T12 Kyphosis L1-L5 Lordosis L1-S1 Lordosis

Pelvic Parameters

Pelvic Version Pelvic Incidence Sacral Slope Pelvic Obliquity Pelvic Rotation

Vertebral & Intervertebral Rotations

Frontal Lateral Axial

Pelvic Rotation

Sagittal Balance Parameters

Kyphosis/Lordosis SVA (Sagittal Vertical Axis) CAM plumb line Spino-Sacral Angle T1 tilt T9 tilt Full Body Index Roussouly’s classification

Lower limbs

Knee flexion

Scoliosis Parameters

Cobb Angle

The application provides the comparison of the calculated clinical parameters with reference values specific to each patient2. In order to aid the user with analysis of the results, a graphical representation of the reference values is provided, highlighting the differences between the measured clinical parameters and reference values. This graphical representation is included to the patient report. Graphical representation of reference values

Fast 3D modeling: sterEOS 3D provides a fast workflow of spine modeling. It optimizes the processing time by modeling only the vertebrae related to the calculation of the clinical parameters. Fast spine modeling may be carried out from T1 to L5 and allows: • The identification of the apical and junctional vertebrae of the scoliosis as well as the automatic calculation of the scoliosis parameters: Cobb angles (3 max) and axial rotations of the apical vertebrae. • The automatic calculation of the sagittal clinical parameters: Kyphosis T1-T12 and T4-T12, Lordosis L1-L5 and L1-S1. Full 3D modeling: sterEOS 3D spine modeling allows the 3D detailed modeling of all thoracic and lumbar vertebrae. In addition to the clinical parameters computed from the fast 3D modeling of the spine, the system gives access to the calculation of all vertebrae orientations and inter-vertebral rotations (frontal, lateral, axial) of the spine 3D model. 3D Spine modeling may not be used when the bone structures are not visible in the X-rays, in the presence of implants and in the following pathologies: supernumerary vertebrae, congenital deformities, spondylolisthesis, and other local bone deformities. It is unable to highlight bone alterations such as fractures and local deformation of the bone. Approved for patients over 7 years old. Reference values are defined for the adult asymptomatic Caucasian population (age > 18 years)

version 1.6

R22-BRO-075-EN-A

Patient report example

8_A_Postural_Assessment1 (Sex: F-Birth date: 22/10/1942)

NOT FOR CLINICAL USE Acquisition date: 26/11/2012

Postural assessment Sagittal balance

SVA (1)

104 mm

T1 Tilt (1)

-4°

Spino Sacral Angle (1)

102°

CAM plumb line (1)

140 mm

T9 Tilt (1)

6°

Full Body Index (1)

15°

Knee flexion (Right) (2)

11°

Lordosis L1/S1

46°

Kyphosis/Lordosis (2)

Kyphosis T1/T12

52°

(1) Parameters calculated in the patient frame (based on a vertical plane passing through the center of the acetabula), which corrects the effect of a potential axial rotation of the pelvis during acquisition. (2) Parameters calculated in the radio frame. - 1.6.3.7890 - created: 07/03/2014 - 3D Lateral 05/03/2014 20:46:38 - NO CLINICAL USE

-1/4-

Headquarters 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60 EOS imaging Inc. 185 Alewife Brook Parkway #410 | Cambridge, MA 02138 USA | +1 (678) 564 5400

www.eos-imaging.com

version 1.6

R22-BRO-075-EN-A Feb 2014

FOLLETOS

EOS Micro Dose

VENTAJAS

&ster

R22-BRO-012-F-EN / May 2016

Innovative imaging system and 3D workstation for advanced orthopedic care

CONNECTING IMAGING TO CARE

What is EOS? EOS is a dedicated modality that specifically addresses the unique needs of the orthopedic industry. The EOS system simultaneously captures full-body, frontal and lateral images. The X-rays are weight-bearing, giving radiologists and surgeons a global assessment of their patient in a functional position. Low dose EOS exams provide accurate 2D images and valuable anatomical 3D information throughout the patient care pathway. The Micro Dose option further reduces radiation exposure without compromising the ability to generate 3D models. Using Micro Dose for follow-up, pediatric exams is another important step towards the ALARA principle (As Low As Reasonably Achievable) and is particularly important for patients with conditions that require frequent scans over the course of their treatment.

BENEFITS OF THE EOS SYSTEM Low dose imaging ¤

Radiation dose reduced by 50% compared to a DR system1, 85% compared to a CR system2 and 95% less than basic CT scans3 The Micro Dose option captures a frontal and lateral full spine at a dose equivalent to only a week’s worth of natural radiation4

Improved clinical outcome ¤

¤ ¤

Full body, weight bearing images for improved diagnosis and global view of patient’s skeleton No magnification and no stitching for accurate measurements Excellent contrast with over 65,000 grey levels for high image quality

High patient throughput ¤

Fast, full-body image acquisitions of less than 20 seconds for adults and 15 seconds for children Efficient exam cycle of about 4 minutes, even for complex spine or full body1

ster What is sterEOS?

OS ing

The sterEOS workstation enables you to create patient-specific, 3D models of the spine and/or lower limbs from weight-bearing low dose or Micro Dose EOS exams. Once the models are generated, you have access to over 100 automatically calculated clinical parameters. A DICOM patient report featuring the 2D images, 3D model and relevant clinical data can then be produced and shared with the patient and medical team.

the the tep ith

The 3D information generated by sterEOS workstation is used by surgeons throughout the patient care pathway from diagnosis to follow-up. Whether you’re interested in understanding your patient’s condition by visualizing the anatomy from numerous perspectives, comparing 3D measurements to reference values, planning a surgery in 3D, evaluating outcomes or monitoring your patients progression over time; the sterEOS workstation provides the 3D information you need.

BENEFITS OF THE sterEOS WORKSTATION Improved clinical outcomes ¤

s3 ¤

Patient-specific, 3D data set and model (in a functional position) for a global assessment of the skeletal system Automatically calculated 3D clinical parameters for accurate treatment and surgical planning

Facility-wide efficiency ¤

Seamless push of images, patient report and 3D models to PACS archives Fast and straightforward 3D modeling workflows dedicated to postural assessment, spine, pelvis, lower limbs and Total Hip Arthroplasty (THA) Direct link to EOS 3DServices and EOSapps cloud-based, 3D surgical planning platform*

Valuable 3D information at a low dose ¤

Improved understanding of the position, rotation and orientation of a patient’s bones Patient-specific, 3D data sets enable surgeons to plan their procedures by selecting and positioning implants in 3D with EOSapps 3D modeling capabilities from Micro Dose, pediatric follow-up exams

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

About EOS imaging EOS imaging is a med-tech company based in Paris, France that designs, develops and markets EOS, an innovative medical imaging system dedicated to orthopaedics and osteoarticular pathologies. A low dose or Micro Dose EOS exam provides full body, stereo-radiographic images in weight-bearing positions. The frontal and lateral images are acquired simultaneously in less than 20 seconds without magnification.

The accompanying sterEOS workstation enables you to create patient-specific 3D models, calculate over 100 clinical parameters automatically and generate customizable patient reports. EOS imaging also offers online 3DServices and EOSapps* cloudbased, 3D surgical planning software solutions. The EOS platform adds value throughout the patient care pathway and truly connects imaging to care.

1. Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. Dietrich TJ et al. Skeletal Radiol. 2013. 2. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Deschenes S et al. Spine (Phila Pa 1976)2010 Apr. 3. Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography. Delin C et al. Eur J Radiol. 2014 4. EOS microdose protocol for the radiological follow-up of adolescent idiopathic scoliosis. Ilharreborde B. et al. Eur Spine J. 2015

R22-BRO-012-F-EN / May 2016

Please read carefully the labeling provided with the device. For USA - Caution: Federal law restricts this device to sale by or on the order of a physician. *Check with your local EOS imaging representative for availability in your region.

Micro Dose Only a weekâ&#x20AC;&#x2122;s worth of natural radiation for each spinal exam

Innovative solutions for public health concerns

Every day, people are exposed to low levels of naturally occurring background radiation from their surroundings. Unfortunately, the levels of radiation exposure from artificial sources, such as medical imaging, has increased over the last two decades1. This means that the average person’s exposure and risks are also increasing.

Children are particularly susceptible to the adverse effects from medical radiation2. Patients who require multiple diagnostic radiographic examinations during their childhood and adolescence may have an increased risk of radiation-induced cancers later in life3.

EOS imaging addresses this growing concern through a unique, low dose imaging modality called EOS®. With a standard low dose EOS exam, the radiation dose is already reduced by 50% to 85% compared to Digital Radiography without compromising image quality 4, 5. With our Micro Dose feature, patient exposure is even further minimized in accordance with ALARA principle (As Low As Reasonably Achievable).

REFERENCES 1. Use of Diagnostic Imaging Studies and Associated Radiation Exposure for Patients Enrolled in Large Integrated Health Care Systems, 1996-2010, American Medical Association. 2012. 2. Characterization of Radiation Exposure in Early-Onset Scoliosis Patients Treated With the Vertical Expandable Prosthetic Titanium Rib. Nelson A. et al. J Pediatr Orthop. 2014 3. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Pearce MS et al. Lancet. 2012 4. Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. Dietrich TJ et al. Skeletal Radiol. 2013 5. Diagnostic imaging of spinal deformities: reducing patient’s radiation dose with a new slot-scanning X-ray imager. Deschenes S et al. Spine. 2010

A new step towards the ALARA principle

One day 9 Sv 6

One week

Micro Dose

63 Sv 7

Only a week’s worth of natural radiation for each child’s AP + LAT spine exam

The Micro Dose feature can be used to monitor spine and lower limb disease progression in pediatric patients, particularly for pathologies which require frequent monitoring such as scoliosis. When using the Micro Dose option for an exam, you can model your patient’s spine and lower limbs in 3D either with your sterEOS® workstation or with our convenient 3DServices. www.EOS3DServices.com Micro Dose 2D images

3D model from Micro Dose images

With Micro Dose, the resulting radiation exposure was 5.5 times less than with a typical EOS exam protocol, corresponding to a 45-fold dose reduction compared to conventional radiographs, and could almost be considered negligible. Brice Ilharreborde, MD, PhD, Department of Pediatric Orthopedic Surgery, Robert Debré Hospital, Paris, France

6. NCRP Report No 160 - Ionizing Radiation Exposure of the population of the United States. 7. EOS microdose protocol for the radiological follow-up of adolescent idiopathic scoliosis. Ilharreborde B. et al. Eur Spine J. 2015

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

The accompanying sterEOS workstation enables you to create patient-specific 3D models, calculate over 100 clinical parameters automatically and generate customizable patient reports. EOS imaging also offers online 3DServices* and EOSapps*, cloudbased, 3D surgical planning software solutions. The EOS platform adds value throughout the patient care pathway and truly connects imaging to care.

R22-BRO-083-G-EN / July 2016

Please read carefully the labeling provided with these devices. For USA - Caution: Federal law restricts this device to sale by or on the order of a physician. * Check with your local EOS imaging representative for availability in your region. EOS imaging SA | 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60 EOS imaging, Inc. | 185 Alewife Brook Parkway #205 | Cambridge, MA 02138 USA | +1 (678) 564 5400

spine Add a 3rd dimension to your surgical planning

EOSapps

Software for surgical planning has been available for some time now, but there are limitations associated with 2D imaging and concerns about CT radiation dose for 3D. EOS imaging has now expanded beyond a low dose imaging system to provide additional solutions for each step of the patient care pathway including 3D surgical planning. EOSapps are online, 3D surgical planning solutions* based on unbiased, weight-bearing

EOS images. Now, with a traditional low dose EOS exam, you are able to reconstruct your patientâ&#x20AC;&#x2122;s anatomy in 3D and use the accurate 2D/3D data to select and position implants. By planning your procedure in 3D, you are able to take into account important clinical parameters such as torsion and rotation which are not available with 2D planning. EOSapps enable surgeons to make better informed clinical decisions and enter the operating room with more confidence.

WORKFLOW

spineEOS Due to the complex nature of the spine, surgeries may be particularly difficult and call for careful preparation for better outcomes. The spineEOS online software provides a 3D visualization of the patient’s spine in its current state as well as a literature-based, optimal correction of their anatomy in 3D. The correction can be modified by the surgeon including simulating osteotomies, selecting and positioning cages and accurately planning the length, width and shape of the spinal rods in 3D. All key clinical parameters are displayed in real time to efficiently determine the best surgical strategy. Thanks to the full body, weight-bearing 2D/3D EOS images, spineEOS displays the anticipated spine after correction and a restoration of a deformative or degenerative spine patient’s global balance pre-operatively.

BENEFITS Improved clinical outcomes ¤

Immediate visualization of 3D frontal and sagittal alignment planning based on different adult and pediatric reference values, including pelvis and knee compensatory mechanisms Real-time 3D simulation of osteotomies and generic intersomatic cage positioning Optimization of the surgical strategy by analyzing the automatically calculated, post-operative 3D parameters (Cobb angles, lordosis/kyphosis, SVA) 3D visualization of the rod shape, diameter and length

Facility-wide efficiency ¤

Improved understanding of the surgical plan and patient’s anatomy for more efficiency in the OR Selection and pre-bending of rods based on 3D planning Online access from any computer through a compliant server Customizable, patient-specific planning reports

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

The accompanying sterEOS workstation enables you to create patient-specific 3D models, calculate over 100 clinical parameters automatically and generate customizable patient reports. EOS imaging also offers online 3DServices and EOSapps* cloud-based, 3D surgical planning software solutions. The EOS platform adds value throughout the patient care pathway and truly connects imaging to care.

R22-BRO-114-B-EN / Nov 2016

Please read carefully the labeling provided with the device. Caution: US Federal law restricts this device to sale by or on the order of a physician. *Check with your local EOS imaging representative for availability in your region. Manufacturer: oneFIT medical EOS imaging SA | 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60 EOS imaging, Inc. | 185 Alewife Brook Parkway #205 | Cambridge, MA 02138 USA | +1 (678) 564 5400

hip Add a 3rd dimension to your surgical planning

EOSapps Software for surgical planning has been available for some time now, but there are limitations associated with 2D imaging and concerns about CT radiation dose for 3D. EOS imaging has now expanded beyond a low dose imaging system to provide additional solutions for each step of the patient care pathway including 3D surgical planning. EOSapps are online, 3D surgical planning solutions* based on unbiased, weight-bearing

WORKFLOW

hipEOS The scope of Total Hip Arthroplasty (THA) has expanded considerably in recent years to include younger, more active patients. The surgical objectives have evolved from merely relieving pain to restoring full function1. hipEOS is used to plan a primary, total hip arthroplasty starting with an automatic selection and position of the two implant components in 3D based on the patient’s anatomy. The plan can be adjusted by the physician with immediate feedback on how changes affect relevant clinical parameters. Thanks to the full body, weight-bearing 2D/3D EOS images, hipEOS can be used to anticipate the consequences of the surgical strategy on leg length discrepancies, femoral offset and femoral torsion; three key criteria for successful total hip arthroplasties. .

BENEFITS Improved clinical outcomes ¤

Patient-matched implant size selection2 without complex radiological calibration protocols Patient-specific, 3D planning for cup inclination/ anteversion, stem torsion and localization of the femoral neck resection plane, without the need for additional CT exams3 Real-time, 3D simulation of the leg restoration: automatic calculation and display of key clinical parameters including lower limb discrepancy and femoral offset variation

Facility-wide efficiency ¤

Automatic proposal of implant size and position according to 2D/3D patient data set Online database of 3D implants from multiple manufacturers Online access from any computer through a compliant server Customizable, patient-specific planning reports

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

About EOS imaging EOS imaging is a med-tech company based in Paris, France that designs, develops and markets EOS, an innovative medical imaging system dedicated to orthopedics and osteoarticular pathologies. A low dose or Micro Dose EOS exam provides full body, stereo-radiographic images in weight-bearing positions. The frontal and lateral images are acquired simultaneously in less than 20 seconds without magnification.

The accompanying sterEOS workstation enables you to create patient-specific 3D models, calculate over 100 clinical parameters automatically and generate customizable patient reports. EOS imaging also offers online 3DServices and EOSapps*, cloud-based 3D surgical planning software solutions. The EOS platform adds value throughout the patient care pathway and truly connects imaging to care.

R22-BRO-087-C-EN / Nov 2016

1.Accuracy of Digital Preoperative Templating in 100 Consecutive Uncemented Total Hip Arthroplasties, Journal of Arthroplasty, 2013-02-01, R.Shaarani & al . 2.Pre-operative three-dimensional planning of total hip arthroplasty based on biplanar low dose radiographs: accuracy and reproducibility for a set of 31 patients. D. Mainard et al.. The Bone and Joint Journal. 2016 3.Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography. C.Delin et al. Eur J Radiol. 2013 Please read carefully the labeling provided with the device. Caution: US Federal law restricts this device to sale by or on the order of a physician. *Check with your local EOS imaging representative for availability in your region.

knee Add a 3rd dimension to your surgical planning

EOS apps

WORKFLOW

kneeEOS Due to our aging population, the number of Total Knee Arthroplasties (TKA) keeps increasing. Despite significant efforts, progress is still needed to improve the surgical outcome as 20% of patients are unsatisfied with their results1. The kneeEOS online software is used to plan a primary, total knee arthroplasty by automatically selecting and positioning implants in 3D. The surgeon can modify the plan with immediate feedback on how changes to the plan affect relevant clinical parameters in 3D. Thanks to the full body, weight-bearing 3D EOS images, kneeEOS can be used to anticipate the consequences of the prosthesis placement on leg alignment and knee rotation; two key criteria for successful total knee arthroplasties.

BENEFITS Improved clinical outcomes ¤

Patient-matched implant size selection without complex radiological calibration protocols Unique 3D planning for implant positioning, including the resection levels on the femur and the tibia, without the need for additional CT exams2 Real-time 3D surgical simulations of the impact on leg alignment (HKA) and knee rotations (varus/valgus, flexion/extension, internal/external rotation) in a functional position

Facility-wide efficiency ¤

Automatic proposal of implant size and position according to the 2D/3D patient data set Online database of 3D implants from multiple manufacturers Online access from any computer through a compliant server Customizable patient-specific planning reports

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

The accompanying sterEOS workstation enables you to create patient-specific 3D models, calculate over 100 clinical parameters automatically and generate customizable patient reports. EOS imaging also offers online 3DServices and EOSapps*, cloud-based 3D surgical planning software solutions. The EOS platform adds value throughout the patient care pathway and truly connects imaging to care.

1.«What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients.» Beswick, A. D., V. Wylde, R. Gooberman-Hill, A. Blom and P. Dieppe (2012). BMJ Open. 2.Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography. Delin C et al. Eur J Radiol. 2013

R22-BRO-115-B-EN / Nov 2016

Radiolucent Chair

It can be difficult to image non-ambulatory patients whose conditions, such as neuromuscular scoliosis, may need to be monitored frequently. Thanks to the EOS radiolucent chair, these patients may still benefit from a low dose EOS exam! With the EOS chair, you can acquire frontal and lateral EOS images of your patient’s spine and pelvis in their natural, seated position. Once your patient is securely fastened in the chair, the wheels allow you to roll him or her smoothly into your EOS cabin. What’s more

important is that the resulting image quality is uncompromised due to the radiolucent materials. From the biplanar images you can even create 3D models of your patient using the sterEOS workstation or EOS 3DServices. The resulting model is accompanied by over 100 automatically calculated 3D clinical parameters. This 3D information helps surgeons to make accurate diagnoses, plan their surgeries in 3D with EOSapps, assess the results of the intervention post-operatively and follow-up with their patients’ over time.

The EOS system combined with EOS chair was useful for assessing preoperative trunk collapse, pelvic obliquity and postoperative corrections in all planes. This specific device changed our daily practice for the assessment of spinal deformities in non-ambulatory patients.* Pr. Raphaël Vialle, MD, Department of Pediatric Orthopedic Surgery, Armand-Trousseau Hospital, Paris, France.

*A radiolucent chair for sitting-posture radiographs in non-ambulatory children: use in biplanar digital slot-scanning. Vialle R. et al. Pediatr Radiol. 2015

SPECIFICATIONS Patient capacity ¤

Patient’s weight from 20kg to 100kg (45lb to 220lb) Patient’s height from 80cm to 165cm (30’’ to 65’’)

Chair components ¤

Removable foams to fit patient morphology

Chin strap

Headrest

Breast plate

Pelvis strap

Feet stabilization straps

Disposable, protective covers

4 wheels with brakes

Materials

Seat: ABS (Acrylonitrile Butadiene Styrene)

Removable, washable covers

Why choose

Full-body, weight-bearing exams Low dose & Micro Dose imaging

Fast exam time 3D models & clinical parameters High image quality

Online 3D surgical planning solutions

R22-BRO-112-C-EN / Feb 2017

Please read carefully the labeling provided with these devices. Caution: US Federal law restricts these devices to sale by or on the order of a physician. *Check with your local EOS imaging representative for availability in your region. EOS imaging SA | 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60 EOS imaging, Inc. | 185 Alewife Brook Parkway #205 | Cambridge, MA 02138 USA | +1 (678) 564 5400

BIBLIOGRAFÍA

D. FOLINAISA, P. THELEN, C. DELIN, C. RADIER, Y. CATONNE, J.Y. LAZENNEC. HÔPITAL DE LA PITIÉ-SALPÊTRIÈRE (2012) Measuring femoral and rotational alignment: EOSsystem versus computed tomography. GUENOUN B, ZADEGAN F, AIM F, HANNOUCHE D, NIZARD R. ORTHOP TRAUMATOL SURG RES (2012 Jul 31) Reliability of a new method for lower-extremity measurements based on stereoradiographic three-dimensional reconstruction. DIETRICH TJ ET AL. SKELETAL RADIOL (2013) Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. DESCHENES S ET AL. SPINE (Phila Pa 1976) (2010 Apr) Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. DELIN C ET AL. EUR J RADIOL (2014) Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography.

CONTENIDO CASOS CLÍNICOS

POTENTIAL APPLICATIONS OF A LOW-DOSE S TA N D I N G W H O L E B O D Y R A D I O G R A P H Y SYSTEM

I M AG E Q UA L I T Y

M E D I A L F E M O R OT I B I A L O S T E O A R T H R I T I S A N D G E N U - VA LG U M : W H E R E I S T H E PROBLEM?

3D EVALUATION OF SURGICAL CORRECTION O F I D I O PAT H I C S C O L I O S I S B Y V E R T E B R A L C O L U M N M A N I P U L AT I O N 19 PA P E R S

M E A S U R I N G F E M O R A L A N D R O TAT I O N A L A L I G N M E N T: E O S S Y S T E M V E R S U S CO M P U T E D TO M O G R A P H Y 22 RELIABILITY OF A NEW METHOD FOR LO W E R - E X T R E M I T Y M E A S U R E M E N T S B A S E D O N S T E R EO R A D I O G R A P H I C T H R E E DIMENSIONAL RECONTRUCTION

C O M P A R I S O N O F R A D I AT I O N D O S E , W O R K F L O W, P AT I E N T C O M F O R T A N D F I N A N C I A L B R E A K - E V E N O F S TA N D A R D D I G I TA L R A D I O G R A P H Y A N D A N O V E L B I P L A N A R L O W - D O S E X - R AY S Y S T E M O F U P R I G H T F U L L- L E N G T H LO W E R L I M B A N D HOLE SPINE RADIOGRAPHY

DIAGNOSTIC IMAGING OF SPINAL DEFORMITIES

I O N I Z I N G R A D I AT I O N D O S E S D U R I N G LO W E R L I M B TO R S I O N TO R S I O N A N D ANTEVERSION MEASUREMENTS BY EOS STEREORADIOGRAPHY AND COMPUTED TO M O G R A P H Y

ANEXO

A continuación se pone a disposición una selección de publicaciones científicas que avalan las características y beneficios del sistema EOS. En la selección de estos papers se dio prioridad a los contenidos más recientes y pertinentes, teniendo en cuenta la presentación que se ofrece en la carpeta EOS confeccionada por DeLeC Científica. Si el lector desea ampliar la información científica sobre los usos del EOS puede consultar a los sitios www.delec.com.ar, o bien al correo: comunicaciones@delec.com.ar.

CASOS CLÍNICOS

Potential applications of a low-dose standing whole body radiography system

Potential applications of a low-dose standing whole body radiography system M. DE LA SIMONE, C. GOMES, R. NIZARD

EOS is an imaging system that permits the simultaneous acquisition of frontal and lateral X-rays of the whole body or a local anatomical area - at the same time as it reduces the X-ray dose by around 90% compared with a conventional system [1]. . Based on work for which Georges Charpak won the Nobel Prize for physics in 1992, the EOS system has been available since 2007 from EOS imaging (formerly Biospace Med), headquartered in Paris, France. Figure 1. EOS system and principle of scanning acquisition

General system description 2D radiological imaging The EOS system is designed around a C-shaped vertically traveling arm supporting two image acquisition systems mounted at right angles. Each is composed of an X-ray tube and a linear detector (Figure 1). Each X-ray beam is first collimated as it exits the tube, and reaches the patient as a fan-shaped beam half a millimeter thick. A few seconds of scanning are sufficient to simultaneously acquire AP and lateral images of either the whole body or a selected anatomical area (Figure 2).

Figure 2. Examples of EOS whole-body and local images

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M. DE LA SIMONE, C. GOMES, R. NIZARD

Three phenomena account for the significant dose reduction compared with conventional systems: – Elimination of most of the scattered radiation, which is responsible for a substantial portion of the dose received by patients in conventional systems. This large reduction of scattered radiation is due principally to the fan-shaped beam geometry produced by the collimation slits (at the tube exit and then at the detector inlet) (Figure 1). – Amplification of the signal by the detectors, using the principle of the multiwire proportional chamber, based on the work of Georges Charpak. The interaction of the photons with pressurized xenon in the detector produces an electron cloud that is amplified to obtain an electron avalanche. The very small quantity of photons passing through the patient can thus be amplified to produce a strong signal. – The adjustable internal gain of the detectors makes it possible to adapt their response to the patient’s morphology and to the area to be radiographed, and therefore to obtain very high contrast images in 30 000 gray levels. Dechênes et al. compared spinal AP and lateral x-rays of 50 young adults, acquired simultaneously with EOS and a computed radiography (CR) system. They observed dose reduction by a factor of up to nine with EOS [1]. They also judged the overall image quality to be equivalent or better with EOS in 97.2% of the cases.

The principle of direct acquisition by scanning (approximately 5 seconds for a pelvis, 20 seconds for the whole body) considerably reduces the time usually spent on conventional imaging (either CR or DR, direct radiography) of the main axes. Both CR and DR, usually obtained by the computerized “stitching” of several local images, require much more time and entail the risk of diagnostic error should the images be poorly aligned. 3D modeling The sterEOS software that comes with the device uses the simultaneity and orthogonality of the frontal and lateral images to generate a three-dimensional model of the patient’s bone envelope. The modeling process is the same regardless of the body area concerned. The operator begins by identifying several anatomical structures on the image (Figure 3a). The software uses the position of these landmarks to provide an initial model (Figure 3b). The contours of this first model are projected on the radiograph and fitted, both manually and, depending on the area concerned, by automatic detection of the bone contours on the images. When the contours projected on the 3D model correspond to the radiologic bone edges, the modeling process is complete (Figure 3c). This model also calculates numerous 3D clinical parameters automatically. Today, the software can be used to model the (thoracic and lumbar) spine and the lower limbs (femur and tibia). Research is underway to extend the use of this modeling method to other anatomical structures.

Figure 3. Method for 3D modeling: example of the femur

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Potential applications of a low-dose standing whole body radiography system

Clinical applications Lower limbs Spine The minimally irradiating character of the machine naturally guided the initial development of software toward the management of idiopathic scoliosis, which requires repeated radiography <and most often affects children and teens> [2]. Spinal deformities can now be studied in a standing, weight-bearing position, on radiographic images that are of equal quality over the entire spine, thereby strongly reducing the problems of over- and under-exposure, especially for profiles (Figure 4). Moreover, 3D models (Figure 4) automatically calculate not only the standard frontal and sagittal balance parameters but also the axial rotation of each vertebral level, in a weight-bearing position.

The management of hip and knee replacement surgery is a major public health issue today. In 2008 in France, there were 120 000 total hip replacements and 66 000 knee replacements (Source: PMSI 2008). In 2005 in the United States, there were 235 000 hip replacements and 534 000 knee replacements, and Kurtz et al. [3] project that by 2030 the annual figures will be 572 000 hip and 3 400 000 knee replacements. Conventional radiography of the legs, however, presents the risk of the measurement errors inherent in the projection of a volume onto a plane. Computed tomography, while it does furnish 3D information, is limited by its high level of irradiation and its inability to examine a weight-bearing patient. In this complex clinical and medico-economic context, the EOS system offers new tools to compensate for these defects.

Figure 4. 2D/3D EOS examination of the entire spine (courtesy of Dr Obeid, Orthopedic Surgery department (Pr. Vital), Hospital Pellegrin, Bordeaux).

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M. DE LA SIMONE, C. GOMES, R. NIZARD

Unequal leg length Unequal leg length after total hip arthroplasty is the second most cited source of medical malptractice litigation amoung AAHKS surgeons [4]. Classically, unequal leg length is assessed by measuring the difference in height between the femoral heads on a frontal pelvic image or by measuring radiographic images of the entire legs. The magnification factor applied to images by conventional radiography systems is a source of error. The EOS system, on the other hand, provides full-scale images. Moreover, standard complete hip/knee/ankle (HKA) images do not allow a valid comparison of the length of lower limbs in patients with genu flexum (knee that cannot be fully extended) or genu recurvatum (back-

knee). Figure 5 shows an EOS image of the legs: the posttraumatic unequal length, assessed by a frontal HKA image at 10 mm, is actually 26 mm. The difference between the standard measurement and the 3D sterEOS measurement is explained by the flexion of the left leg. Only a 3D measurement allows an exact assessment of bone length in these cases. Hip The natural anteversion of the femoral heads complicates the interpretation of measurements taken from frontal pelvic radiographs or from images centered on the hips. The planning of total hip arthroplasties is based on such images and is significantly affected by measurement errors associated with the phenomenon of radiographic projection.

Figure 5. 2D/3D EOS examination of the legs (courtesy of Pr Hauger, Pellegrin Hospital, Bordeaux).

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Potential applications of a low-dose standing whole body radiography system

Femoral offset, for example, is described in recent literature as an important parameter for planning hip arthroplasty [5,6]. Comparing the standard 2D offset measurements to CT measurements for 223 patients, Sariali et al. [7] assessed at 8% the error for femoral offset on frontal radiographs. 3D modeling of the proximal femur, routinely performed from low-dose EOS images, allows automatic calculation of the clinical parameters of the hip in three dimensions. These parameters are totally independent of the spatial orientation of the femoral neck (Figure 6).

The sterEOS software, however, uses the 3D envelopes of the femur and tibia to compute all the femorotibial parameters required for the knee. The HKA angle can be calculated secondarily in the true posterior bicondylar plane, even if it was not perfectly placed during acquisition. Figure 7, for example, shows a patient with an excess internal femoral rotation associated with bilateral genu flexum. On a conventional HKA image, the combination of these two particularities creates the impression of genu valgus, measurable at 10Â° on the left, although the valgus calculated by the sterEOS software is actually less than 1Â°.

Knees The mechanical femorotibial angle, or HKA, is an essential parameter for surgical treatment of gonarthritis [8,9]. It is conventionally measured by radiography of the entire leg (hip-knee-ankle image). The result is correct only if both knees remain in a frontal position, and there is no guarantee that the position will be maintained as the images are taken.

Torsion of the lower limbs The 3D envelope created from the EOS images can also measure femoral and tibial torsion by a method similar to the superposition of CT slices (Figure 8), but with much less irradiation delivered to the patient.

Figure 6. Standard measurement of femoral offset (courtesy of Pr Nizard, Hospital LariboisiĂ¨re, Paris): a) Standard measurement distorted by anteversion of the femoral neck b) 3D sterEOS measurements

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M. DE LA SIMONE, C. GOMES, R. NIZARD

Figure 7 (courtesy of the Pediatric Orthopedics Department - Motor skills analysis laboratory, Timone Children’s University Hospital Center, Marseille):

Figure 8. From the same patient (courtesy of Pr Hauger, Pellegrin Hospital, Bordeaux):

a) EOS radiography of the legs as a whole and standard measurement of the valgus b) 3D Modeling of the lower limbs visualized as positioned during acquisition c) 3D Modeling of the lower limbs with the knee seen frontally. The valgus calculated on the front of the knee is nearly 0°.

a) EOS examination and 3D modeling b) CT measurement of torsion

Assessment of the position of acetabular implants The orientation of some types of acetabular implants can also be measured from the EOS frontal/lateral images. Its orientation in space can be defined with precision by placing a 3D ring that symbolizes the edge of the cup (figure 9) on the radiograph. The anteversion of the implant can then be calculated in a horizontal plane. This real “functional anteversion”, as described by Lazennec et al. [10], varies according to pelvic version and therefore also as a function of the patient’s position.

In Figure 9, anteversion of the acetabulum was thus assessed by sterEOS at 19° in a standing position, while it increased to 30° in a seated position, because of the pelvic retroversion resulting from the change of position. The possibility of performing EOS examinations in different positions (seated, standing, or crouched) should improve our understanding of postoperative prosthetic conflict and dislocation phenomena.

Potential applications of a low-dose standing whole body radiography system

Standing position

Seated position

Figure 9. Measurement of acetabular anteversion from the EOS images. Anteversion here is measured in a strict horizontal plane (in red). (courtesy of Pr Sautet, Hospital Saint-Antoine, Paris)

Whole-body examination The procurement of whole-body images in different positions has revised the way we understand the interactions between diseases in different anatomical areas. As early as 1991, Itoi et al. [11] (Figure 10) insisted on the importance of studying postural balance as a whole, especially in degenerative diseases. Contrary to the pelvic-spinal relation, widely described in the literature [12], the interactions between the spine and lower limbs, like those between the hips and knees, are on the whole little known.

The EOS system appears particularly suitable for studying these interactions, as shown by the radiographs in Figure 11: we can observe compensation for anterior spinal imbalance in this 72-yearold patient by pelvic retroversion and by flexion of the lower limbs.

M. DE LA SIMONE, C. GOMES, R. NIZARD

Figure 10. Classification of spinal deformities according to Itoi et al. [12]

Conclusion EOS is a large-format imaging system with minimally irradiating X-rays. It is capable of taking life-size radiographs and modeling the weight-bearing skeleton in three dimension, with optional automatic calculation of different 3D clinical parameters. Since its initial development, these characteristics have made it an especially appropriate tool for studying spinal deformities but also for assessing postural balance, especially in degenerative diseases. Recent developments in 3D modeling of the lower limbs offer new perspectives, especially for total arthroplasties of the hip and knee. A complete 3D evaluation of the weight-bearing legs is now possible on a routine basis and with very low radiation doses.

Figure 11. Whole-body EOS examination. Anterior spinal imbalance compensated by pelvic retroversion and genu flexum. (courtesy of Dr Obeid, Orthopedic Surgery Department (Pr. Vital), Hospital Pellegrin, Bordeaux)

Potential applications of a low-dose standing whole body radiography system

References

[1] Deschênes S, Charron G, Beaudoin G, Labelle H, Dubois J, Miron M-C, Parent S. Diagnostic imaging of spinal deformities : Reducing patients radiation dose with a new slot-scanning X-ray imager. Spine (in press). [2] Dubousset J, Charpak G, Skalli W, de Guise J, Kalifa G, Wicart P. Skeletal and spinal imaging with EOS system. Arch Pediatr. 2008 Jun;15(5):665-6. [3] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007 Apr;89(4):780-5. [4] Konyves A, Bannister GC. The importance of leg length discrepancy after total hip arthroplasty. J Bone Joint Surg Br. 2005 Feb;87(2):155-7. [5] Sakalkale DP, Sharkey PF, Eng K, Hozack WJ, Rothman RH. Effect of femoral component offset on polyethylene wear in total hip arthroplasty. Clin Orthop Relat Res. 2001 Jul;(388):125-34. [6] Patel AB, Wagle RR, Usrey MM, Thompson MT, Incavo SJ, Noble PC. Guidelines for Implant Placement to Minimize Impingement During Activities of Daily Living After Total Hip Arthroplasty. J Arthroplasty. 2009 Dec 17.

[7] Sariali E, Mouttet A, Pasquier G, Durante E. Three-dimensional hip anatomy in osteoarthritis. Analysis of the femoral offset. J Arthroplasty. 2009 Sep 24(6):990-7. [8] Desmé D, Galand-Desmé S, Besse JL, Henner J, Moyen B, Lerat JL. Axial lower limb alignment and knee geometry in patients with osteoarthritis of the knee. Rev Chir Orthop Reparatrice Appar Mot. 2006 Nov;92(7):673-9. [9] Cerejo R, Dunlop DD, Cahue S, Channin D, Song J, Sharma L. The influence of alignment on risk of knee osteoarthritis progression according to baseline stage of disease Arthritis Rheum. 2002 Oct;46(10):2632-6. [10] Lazennec JY, Riwan A, Gravez F, Rousseau MA, Mora N, Gorin M, Lasne A, Catonne Y, Saillant G. Hip spine relationships: application to total hip arthroplasty. Hip Int. 2007 Special Issue on DDH from child to adult age;17:91104. [11] Itoi E. Roentgenographic analysis of posture in spinal osteoporotics. Spine (Phila Pa 1976). 1991 Jul;16(7):750-6. [12] Legaye J, Duval-Beaupère G, Hecquet J, Marty C. Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J. 1998;7(2):99-103.

EOS

- ultra low dose 2D|3D imaging system Image Quality

Clinical Case: Image Quality Emory University Orthopedic and Spine Center, Atlanta, Georgia* 1.2.2 Image Quality

Introduction EOS has the unique advantage of offering a significantly reduced radiation

dose while maintaining the high image quality and information content required for diagnostic radiology. The technological characteristics behind EOS’s low dose capabilities are the scanning method and the unique detector. The thin fan-beam geometry and the slot scanning technique results in X-ray scatter suppression. The unique EOS detector technology provides a very high signal-to-noise ratio and optimal dynamic range management [3]. Clinical studies have been performed to compare radiation dose and resulting image quality between EOS and other X-ray modalities. The objective of this paper is to outline a study comparing the conventional radiography system (film) with EOS in terms of image quality (Emory University) and dose (Entrance Surface Air Kerma, ESAK).

Clinical study

1.1 Materials and method

A comparative study, performed at Erasmus Hospital, Brussels and St. Vincent de Paul, Paris, on 64 scoliosis patients, compared radiation dose between EOS and conventional screen-film systems for both AP and lateral spine images. An individual informed consent was obtained from all patients enrolled. 64 patients, 41 females and 23 males (mean age= 14.7± 4.8 y – BMI= 19.8± 4.6 kg/m²) admitted for scoliosis detection or follow-up, underwent full spine radiographs. For all patients, a PosteroAnterior (PA) and a lateral projection (LAT) were prescribed, except for 7 patients who had a single PA radiograph and for 2 patients who had a single LAT radiograph. Regardless of the medical prescription, each patient underwent examination with the EOS system under similar technical conditions of those used with a conventional screen-film device. Acquisition parameters, X-ray tube output dose rates, and patient morphologic data were registered during acquisition on both modalities. This data allowed for the calculation of Entrance Surface Air Kerma (ESAK), which corresponds to the dose at the entrance of the patient without backscatter radiation.

1.2 Results 1.2.1 Dosimetry

The following are the dose results obtained during this study. Full Spine PA

Full Spine LAT

EOS (ESAK)

0.12 mGy

0.19 mGy

Screen-Film Modality (ESAK)

0.81 mGy

1.67 mGy

Average % Decrease of Dose

85%

89%

EOS dose measurements for both PA and LAT spine images were 85% to

89% below those obtained using conventional screen-film modality.

In addition, the images were evaluated based on the European guideline quality criteria for diagnostic radiographic images [1]. These guidelines consist of 8 criteria for both PA and LAT images including both reproduction and inclusion criteria. Scores yielded a significantly higher score for EOS than for screen-film images for 4 quality criteria in the PA view and 5 in LAT view. More importantly, the observers reported a global image quality score significantly higher for PA and LAT radiographs obtained with EOS than with screen-film. For additional image quality testing, a random sampling of these images was read by U.S. Board Certified Radiologists from the Emory University Orthopedic and Spine Center. For each reading, images were randomized, in a non-paired manner, and scored by three independent radiologists who were blinded as to the origin of the modality. To evaluate the image quality, the criteria were based on the European Guidelines on Quality Criteria for Diagnostic Radiographic Images[1] and were finalized by the Chief of Musculoskeletal Imaging at Emory University. The quality of the images was scored on a 1-4 scale for feature conspicuity. Understanding that conspicuity is a subjective assessment of several features which include spatial and contrast resolution, these measures were not quantified for this study. The following scale was used: 1: Not seen. 2: Poor but usable, characteristic features are detectable but details are not fully reproduced; features just visible. 3: Good: allows an adequate assessment, details of anatomical structures are visible but not necessarily clearly defined; details emerging. 4: Very good: allows an excellent assessment, anatomical details are clearly defined; details clear. The following tables show the image quality comparison results from the Emory University Radiologist for both PA and LAT exams.

PA View EOS AP n=10

Film AP n=10

EOS – Film

Vertebral Bodies

3.7

2.8

0.9

Pedicles

3.7

2.7

1.0

Facet Joints

2.0

0.0

Spinous Process

3.2

2.5

0.7

Transverse Processes

3.1

2.7

0.4

Ribs

3.7

2.1

1.6

Lateral View EOS Lat n=11

Film Lat n=11

Cervical Spine

3.6

1.9

1.7

Thoracic Spine

2.7

1.6

1.1

EOS – Film

Lumbar Spine

3.5

2.8

0.7

C7-T1 Endplates

2.8

1.5

1.3

T12-L1 Endplates

3.1

2.4

0.7

L5-S1 Endplates

3.5

2.5

1.0

DON’T GUESS. SEE.

www.eos-imaging.com

A sample of the image quality comparison between radiographs provided by both EOS and screen-film for the same subject is shown below: a) EOS image of a whole spine, PA view; b) corresponding screen-film image; c) EOS image of a whole spine, LAT view; d) corresponding screen-film image.

1.3 Discussion and conclusion

1.4 References

Scoliosis patients often require repeated X-ray exposure, which is why this population deserves particular attention and became the focus of this initial dose reduction study. Obtaining good quality diagnostic images with a significantly lower dose of radiation is an important public health goal, especially for these patients. This study shows that with EOS, dose reduction by more than 85% is possible without compromising image quality, and in fact providing an improvement in most of the quality criteria evaluated. In addition, other systems (CR) make it possible to deliver a smaller dose, but often by compromising image quality for certain criteria [2]. Through this study, EOS has proven itself as a great diagnostic imaging tool for addressing dose reduction issues in pediatric scoliosis patients. A study of greater depth, currently being finalized at several sites in Montreal, Canada (phantom and in vivo, 30 to 40 patients), will be published soon. These studies target the lung, pelvis and the spine by comparing EOS with both DR and CR systems. All initial findings of these Montreal trials seem to confirm the result of the above study.

1. European Commission (1996) European guidelines on quality criteria for diagnostic radiographic images in paediatrics. Report EUR 16261EN 2. Hansen J, Jurik AG, Fiirgaard B, Egund N (2003) Optimisation of scoliosis examinations in children. Pediatr Radiol 33:752-65 3. Dubousset J, Charpak G, Dorion I, Skalli W, Lavaste F, Deguise J, Kalifa G, Ferey S. [A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position : the EOS system]. Bulletin de l’Académie Nationale de Médecine 2005 ; 189(2):287-297 ; discussion 297-300.

* Three American Board of Radiology Certified physician radiologists from the Emory Orthopedic and Spine Center in Atlanta, GA served as independent observers for image evaluation. They included Michael Terk, MD, Chief of Musculoskeletal Radiology, Walt Carpenter, MD, and Terry Hudson, MD.

EOS imaging SA. 10 rue Mercoeur | 75011 Paris France | +33 (0) 155 25 60 60

www.eos-imaging.com

EOS imaging Inc. 185 Alewife Brook Parkway #410 | Cambridge, MA 02138 USA | 678.564.5400

R22-BRO-007-EN-C

EOS

- ultra low dose 2D|3D imaging system

Clinical Case : Medial femorotibial osteoarthritis and genu-valgum: Where is Medial femorotibial osteoarthritis and genuthe problem? valgum: Where is the problem? Dr Dominique Folinais, Dr Philippe Thelen, RIM Maussins - Nollet, Paris, France Pr Yves Catonné, La Pitié Salpêtrière, Paris, France

Introduction Frontal malalignment of the lower limbs has been shown to be closely linked to the onset and progression of knee osteoarthritis. Restoration of a satisfactory alignment after total knee arthroplasty has a positive impact on implant durability and functional result. An angle measurement commonly used to assess this alignment is the HKA angle (Hip-Knee-Ankle). It is measured on a full length AP radiograph of the lower limbs between the femoral mechanical axis and the tibial mechanical axis (1). However, various authors have demonstrated that this measurement, although widely used, could be very inaccurate in case of poor patient positioning during radiographic acquisition. This is especially true when flexion is associated with a rotation of the lower limb(2). In this context, the EOS system (EOS imaging, Paris, France) allows, on the basis of a biplane X-ray acquisition, for the construction of a 3D model of the lower limbs in a weight-bearing position. This 3D model provides various clinical parameters, including the HKA angle, which, calculated in the knee frontal plane, remains independent of patient positioning during the X-ray acquisition(3).

Clinical case 1.1 Patient History We report the case of a 51-year old patient who came for a radiographic evaluation of knee alignment. A standard knee radiograph performed previously showed tibiofemoral osteoarthritis on the right side. This osteoarthritis was predominantly medial, with moderate joint space narrowing but significant osteophytosis. Clinically, the patient presented irreducible bilateral knee-flexion, which did not allow for the taking of X-rays with the legs fully extended.

Figure 1: Conventional measurement of the 2D HKA angle

1.2 Diagnostic A biplane AP and LAT EOS examination of the lower limbs was performed with the EOS system (EOS imaging, Paris France). The frontal EOS radiograph was used to perform a conventional 2D measurement of the HKA angle. The latter was measured between the femoral shaft that connects the center of the femoral head at point I, and the tibial axis joining the same point I and point C, C being the center of the talocrural space(1). On the other hand, based on the biplane acquisition, a 3D model was generated using dedicated software (sterEOS, EOS imaging, Paris, France) (Figure 2). From this modeling, the software application automatically calculated the HKA angle as the angle between the FM and TM axes, projected on the frontal plane of the knee, itself defined as passing through the center of the medial and lateral condyles and the center of the femoral head (3). The standard 2D measurement found a right valgus of 5.4°, in contradiction with the predominantly medial tibiofemoral knee osteoarthritis. On the contralateral side, a 1.4° varus was measured.

Figure 2: EOS Three-dimensional modeling (¾ view)

DON’T GUESS. SEE.

www.eos-imaging.com

The 3D examination, meanwhile, found a 3.8° varus on the right side, this time in agreement with the observations from the centered X-rays, and a varus of 2.1° on the left side. The flexion of the right and left knees were 33° and 20° respectively. The 3D review also found an increased anteversion of the femoral necks, especially on the right side (28 °, against 22° on the left). Finally, while the 2D examination concluded to a leg length discrepancy of 18mm, 3D modeling showed a left leg only 2mm longer than the right leg.

1.3 Discussion The limitations of plane radiology for measuring the frontal alignment of the knees have been widely demonstrated in literature(2). Routine clinical practice today is based on the optimization of patient positioning, intended to limit 2D measurement errors. Radiographers generally try to position the patient in a way that both knees face the Xray beam, in order to avoid measurement errors. However, in the case of major deformities, this positioning can prove to be a difficult task for the radiographer. On the case we report here , the patient had bilateral knee flexion and also presented an internal rotation of the knees, especially on the right side, probably favored by high anteversion of her femoral neck (28°). This created at the right side a « false valgus » (5.4°) on the frontal radiograph, in contradiction with the fact that the tibiofemoral osteoarthritis was predominantly medial. With the 3D technique, when visualizing the modeling in the right knee AP plane, it becomes clear that the deformity is actually a genu-varum (measured at 3.8° with the 3D software) (Figure 3). 2D measurement not only provoked a major measurement error of 9.2° of the HKA angle, but also a reversal in the orientation of the deformity (valgus in 2D, varus in 3D). On the contralateral side, the knee had less flexion and showed a minor rotation relative to the acquisition plane and the measurement was

therefore relatively accurate in 2D (1.4° of varus in 2D against 2.1° varus in 3D). This case demonstrates the importance of taking into account rotational anomalies of the lower limb when assessing the frontal alignment of the knee. Isolated sagittal deviation, whether in extension or, as is more usual, in flexion, does not lead to errors on the 2D measurement of frontal knee alignment. The combination of rotational deviation of the lower limb and either flexion or extension, is a source of errors in 2D measurements. These errors are all the more important as the flexion and rotation deviation are higher, as can be seen in this case (Figure 4), where the 2D measurement error is more important on the right than on the left. Regarding the assessment of limb length discrepancy, the right limb showed a bigger flexion, and therefore seemed 18 mm shorter than the left side. In fact, the two lower limbs were almost identical in length.

Figure 4: Axial view “from above”. The origin of the 2D projection error is confirmed. There is a combination of a knee flexion together with an internal rotation, particularly on the right side.

1.4 Conclusion The measurement of the coronal alignment of the knee plays a major role in the planning of total knee arthroplasty or osteotomy realignment. The case we report here illustrates the limitations of conventional 2D measurement. It also shows the interest of 3D modeling performed with the EOS system, especially in the case of complex lower limb deformities. The EOS system allows one to avoid a possible error in surgical planning, which can have serious consequences on the functional level after surgery.

References 1. Duparc J, Massare C. [Radiological measurement of the angular deviation of the knee in the frontal plane]. Ann Radiol (Paris). 1967;10(9):635-56. Epub 1967/01/01. PubMed PMID: 5597355. 2. Brouwer RW, Jakma TS, Brouwer KH, Verhaar JA. Pitfalls in determining knee alignment: a radiographic cadaver study. J Knee Surg. 2007;20(3): 210-5. Epub 2007/08/02. PubMed PMID: 17665783. 3. Chaibi Y, Cresson T, Aubert B, Hausselle J, Neyret P, Hauger O, et al. Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays. Comput Methods Biomech Biomed Engin. 2011:1. Figure 3: The EOS model displaying a frontal view of the right knee (A) and a frontal view of the left knee (B). The 2D projection error is confirmed. When one limb is in frontal view, the other one is in strong internal rotation and appears to be in valgus.

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EOS

3D evaluation of surgical correction of idiopathic scoliosis by vertebral column manipulation

- ultra low dose 2D|3D imaging system

The EOS is intended for use in general radiographic examinations and applications and, when used with sterEOS, allows the images to aid in the analysis of scoliosis and related disorders and deformities in adult patients as well as pediatric patients 7 years and older. The following is an example of the use of the system in clinical practice.

Clinical Case: 3D evaluation of surgical correction of idiopathic scoliosis by vertebral column manipulation Dr. Ibrahim Obeid, Pellegrin Hospital, Bordeaux, France

Introduction

Scoliotic patients are exposed to multiple diagnostic X-rays during childhood and adolescence, which makes them particularly vulnerable to the well-known and harmful effects of ionizing radiation. Because EOS is 5 to 10 times less irradiating than currently used radiologic systems, EOS is an obvious choice as the appropriate tool to diagnose and monitor scoliosis. Furthermore, because EOS is able to perform full body, weight bearing examinations, physicians also have access to evidence of a potential lower limb compensation for spine imbalance. As AP and LAT X-rays of the spine are acquired simultaneously, sterEOS software enables a 3D reconstruction of the bony envelope, which can be observed from various views, and an automatic calculation of several spinal and pelvic clinical parameters, including the axial rotation of each vertebra.

Clinical Study 1.1 Patient History

The patient is a 14-year-old female with a known history of right thoracic idiopathic scoliosis. At the time of the surgical intervention, the patient’s sterEOS 3D reconstruction revealed a 54° Cobb angle and a 12° apical rotation, resulting in a significant rib hump.

Prior to this surgery, the patient had been undergoing treatment for the scoliosis via orthopedic bracing for four years. Her Risser sign was 2. The decision to perform surgery was made in order to stop the progression of this scoliosis and to reduce the rib hump.

1.2 Therapy Planning and Outcome The patient had preop EOS examination (Figure 1) with an associated 3D reconstruction (Figure 3). The mobility of her spine was evaluated with lateral bending X-rays. The physician chose the vertebral column manipulation (VMC) method with intentions of performing an axial rotation correction and to avoid gibbectomy. The superior fusion level was chosen at T2, in order to prevent a shoulder imbalance which could result from the curvature correction. For the inferior fusion, L1 was chosen because the L1-L2 disc had good mobility in both directions and also because L1 had minimal axial rotation. There were no postoperative complications. The patient was able to stand the day after surgery and was sent home after one week. Postop EOS X-rays were obtained (Figure 4), and because anatomic landmarks were visible, a postop sterEOS 3D reconstruction was performed as well. This analysis showed a significant correction of the deformity in all three directions. The Cobb angle was reduced from 54° to 17°.

Figure 1: Preoperative X-rays

DON’T GUESS. SEE.

Figure 2: Postoperative

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Figure 3: Preoperative 3D Preoperative 3D Reconstruction Figure 3:

Reconstruction

Figure 4: Figure 4:

Postoperative 3D Postoperative 3D Reconstruction Reconstruction

The patient’s sagittal balance was kept at a satisfying level (48° Lordosis and 22° kyphosis) while the axial rotation of the most rotated vertebrae (apical rotation) was considerably reduced from 12° to 2° (Figure 5).

Figure 5: Vertebrae Axial rotations

1.3 Conclusion EOS and sterEOS allowed both a 2D and a 3D evaluation of the correction of this idiopathic scoliosis using the vertebral column manipulation (VCM) method. sterEOS 3D reconstruction enabled the physician to highlight the correction of the scoliosis in the three directions. The surgical outcome was quantified through the automated calculation of the pelvic and spinal clinical parameters. More particularly, the vertebral axial rotations correction could be assessed in the weight bearing position.

1.4 References 1. Dubousset J, Charpak G, Dorion I, Skalli W, Lavaste F, Deguise J, Kalifa G, Ferey S (2005) A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position : the EOS system. Bulletin de l’Académie Nationale de Médecine 2005 ; 189(2):287-297 ; discussion 297-300 2. Lenke, LG (2008) Scoliosis and Chest Wall Derotation Utilizing Pedicle Screws and the Vertebral Column Manipulator Device (VCM). Spine Volume 33 (10): 1-2

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PAPERS

Orthopaedics & Traumatology: Surgery & Research (2013) 99, 509—516

Available online at

www.sciencedirect.com

ORIGINAL ARTICLE

Measuring femoral and rotational alignment: EOS system versus computed tomography D. Folinais a,∗, P. Thelen a, C. Delin a, C. Radier a, Y. Catonne b, J.Y. Lazennec b a b

Measuring femoral and rotational alignment: EOS system versus computed tomography RIM Maussins-Nollet, 114, rue Nollet, 75017 Paris, France Service d’orthopédie, hôpital de La Pitié-Salpêtrière, 47-83, boulevard de l’Hôpital, 75013 Paris, France

Accepted: 17 December 2012

KEYWORDS Computed tomography; EOS system; Lower limb; Femoral torsion; Tibial torsion; Rotational alignment

Summary Introduction: Computed tomography (CT) is currently the reference standard for measuring femoral and tibial rotational alignment. The EOS System is a new biplanar low-dose radiographic device that allows 3-dimensional lower-limb modelling with automated measurements of femoral and tibial rotational alignment (torsion). Hypothesis: Femoral and tibial torsion measurements provided by the EOS System are equivalent to those obtained using CT. Materials and methods: In a retrospective analysis of 43 lower limbs in 30 patients, three senior radiologists measured femoral and tibial torsion on both CT and EOS images. Agreement between CT and EOS values was assessed by computing Pearson’s correlation coefﬁcient and interobserver reproducibility by computing the intraclass correlation coefﬁcient (ICC). Results: Femoral torsion was 13.4◦ by EOS vs. 13.7◦ by CT (P = 0.5) and tibial torsion was 30.8◦ by EOS vs. 30.3◦ by CT (P = 0.4). Strong associations were found between EOS and CT values for both femoral torsion (P = 0.93) and tibial torsion (P = 0.89). With EOS, the ICC was 0.93 for femoral torsion and 0.86 for tibial torsion; corresponding values with CT were 0.90 and 0.92. Discussion: The EOS system is a valid alternative to CT for lower-limb torsion measurement. EOS imaging allows a comprehensive evaluation in all three planes while substantially decreasing patient radiation exposure. Level of evidence: Level III, case-control. © 2013 Published by Elsevier Masson SAS.

Introduction

∗

Corresponding author. Tel.: +33 4 42 26 49 00. E-mail address: dfolinais@gmail.com (D. Folinais).

Rotational malalignment of the lower limbs is frequently idiopathic [1,2] and less often related to injury [3] or to disorders such as cerebral palsy [4]. Many studies have established that these axial-plane deformities of the lower limbs, regardless of their cause, can affect the development of

510 various knee disorders such as patello-femoral instability [5,6], knee osteoarthritis [7—9], and hip osteoarthritis [10]. Rotational osteotomies may therefore be indicated to correct the deformity [2,11]. Consequently, the optimal management of lower-limb rotational malalignment requires accurate and reproducible measurements of femoral and tibial torsion. Several clinical [12], sonographic [13], fluoroscopic [14], and magnetic-resonance-imaging (MRI) [15] methods for measuring lower-limb torsion have been described but none has gained predominance in everyday practice. The accuracy of clinical methods has been challenged [12]. The sonographic and fluoroscopic methods follow a variety of protocols and are difficult to use [13,14]. Finally, although MRI-based methods have been proven accurate [15], their use is hampered by the limited availability of MRI machines. Computed tomography (CT) measurement of lower-limb torsion has been well validated and is widely used as the current reference standard [16]. CT measurement of tibial torsion is generally reported to be both accurate and reproducible [17,18]. The measurements are classically taken on superimposed axial slices between the tangent to the posterior tibial-plateau rim and the bimalleolar axis. The best CT method for measuring femoral torsion remains debated. The main difficulty is determination of the femoral neck axis [19,20]. Although several reported methods use axial slices to assess femoral neck orientation, slice selection strongly influences the measured value [20,21]. The biplanar low-dose EOS system (EOS imaging, Paris, France) [22—24] has been used to develop a new method for clinical lower-limb analysis [25]. In the EOS system, two perpendicular X-ray beams are mounted on a C-arm, which moves vertically. The patient stands or sits in the middle of the scanning booth. All or part of the body is scanned, simultaneously producing projections in two perpendicular planes. The radiation dose to the patient is substantially lower than with conventional radiographs [23,26]. Dedicated software (ster EOS, EOS imaging, Paris, France) can be used to alter generic models of the femur, tibia, and fibula, thereby producing a 3D model of the patient’s lower-limb skeleton. From this model, the software automatically computes a set of 3D clinical lower-limb parameters, including femoral torsion and tibial torsion [25,27]. Here, our objective was to compare femoral and tibial torsion values measured using the new EOS-based method and the reference CT method.

D. Folinais et al. study). EOS imaging as part of the preoperative work-up for total hip or knee arthroplasty provides information on overall body alignment and, more speciﬁcally, on alignment of the lumbar spine and pelvis, whose assessment is considered crucial prior to joint replacement surgery [24,28].

Computed tomography (CT) measurements

Material and methods

A helical CT machine was used (Somatom, Siemens, Definition AS 40-slice, Erlangen, Germany). Three acquisition zones (hip, knee, and ankle) were defined on an anteroposterior scout view. In each zone, 1.25-mm slices were acquired as recommended by the manufacturer. The lower limbs were extended, fixed in neutral rotation, and strapped to the table to prevent movements during acquisition. Measurements were performed using OSIRIX MD software (Osirix Foundation, Geneva, Switzerland) by three senior radiologists who had extensive experience in osteoarticular radiology. All measurements in a given patient were made using the same CT acquisition. Femoral torsion was measured as described by Reikeras et al. [29] (Fig. 1). After recovery of the native images from our institution’s Picture archiving and communication system (PACS), each radiologist selected the slices to be used for the measurements. The femoral neck axis was determined by superimposing two slices, one through the centre of the femoral head and the other through the middle of the femoral neck (on which the anterior and posterior cortices were parallel to each other). Each radiologist created a superimposition then used it to determine the femoral neck axis as the line through the femoral head centre and the middle of the neck diameter. To determine the axis of the femoral condyles, each radiologist selected a slice through the most prominent point of the condyles. This point can often be identified based on the fabella, when present, or on the roman-arch shape of the intercondylar notch. The degree of femoral torsion was measured as the angle subtended by the femoral neck axis and the posterior bicondylar axis. This angle was given a positive value in case of anteversion and a negative value in case of retroversion. Tibial torsion was measured as described by Reikeras and Hoiseth [18] and validated by Liodakis et al. [30] (Fig. 1). Each radiologist selected two reference slices, one through the middle of the proximal tibial epiphysis above the proximal end of the fibula and the other tangent to the talar dome. Tibial torsion was measured as the angle between the line tangent to the posterior tibial plateau rim and the bimalleolar axis through the centres of the anteroposterior diameters of the medial and lateral malleoli.

Population

EOS measurements

We retrospectively included all patients who underwent both CT measurement of lower-limb torsion and EOS imaging including at least the entire lower limbs, between November 2009 and March 2011. The imaging studies were performed as part of standard care, either for the preoperative work-up before total hip arthroplasty (in patients requiring an evaluation in the axial plane) or for an evaluation of implant position combined with an assessment of lower-limb alignment (with only the non-operated side being included in the

At the beginning of the study, the radiologists had been using the EOS system and its modelling software on a regular basis for 18 months. The native images were recovered from the PACS, and a single EOS acquisition per patient was used by all three radiologists. Each radiologist produced a 3D model of the lower limb using sterEOS software. On the model of the femur, the femoral neck axis (from the centre of the femoral head to the base of the neck) and the axis tangent to the posterior condyles were determined automatically. Femoral

Running head: lower-limb torsion measurement: EOS vs. CT

Figure 1

a: computed tomography measurement of femoral torsion; b: computed tomography measurement of tibial torsion.

neck anteversion was computed as the angle between the projections of these two axes on the transverse femoral plane (defined as the line perpendicular to the mechanical axis of the femur) (Fig. 2). On the model of the tibia, the axis tangent to the posterior tibial plateau rim and the bimalleolar axis were determined automatically. Tibial torsion was computed as the angle between the projections of these two axes in the transverse tibial plane (defined as the line perpendicular to the mechanical axis of the tibia) (Fig. 2). Therefore, in our study the EOS and CT measurements were obtained using the same anatomical landmarks. Biplanar acquisition with the patient in the strict anteroposterior/lateral position would result in superimposition of the anatomical landmarks on the lateral view, precluding the production of a 3D model by the sterEOS software [25]. Therefore, as part of standard care, the patients underwent the following imaging procedures: • either simultaneous anteroposterior and lateral imaging in the bipodal standing position with the entire body rotated 15◦ relative to the acquisition system (Fig. 3); • or anteroposterior and lateral imaging in the unipodal standing position with the limb to be studied in the strict anteroposterior/lateral position and the contralateral limb on a support and flexed 70◦ to 90◦ (Fig. 3).

511

Between April and September 2011, the three study radiologists reviewed all EOS and CT measurements recovered from our PACS, speciﬁcally for our study, working independently from one another, and without knowledge of the measurements obtained during patient management.

Radiation dose The radiation dose delivered by the EOS system was recorded directly from the device. The EOS doses were compared to published data on doses delivered by CT with the equipment and acquisition protocols used in the patients included in our study [31].

Statistical analysis SPSS version 15.0 (IBM, Armonk, NY, USA) was used for all statistical tests. Descriptive data were computed on the overall dataset. Student’s t test was performed to determine whether the measured values differed significantly between EOS and CT. Agreement between these two methods was assessed by computing Pearson’s correlation coefficient. Interobserver reproducibility of each method was evaluated based on the intraclass coefficient (ICC) [32]. Mean

512

D. Folinais et al. Table 2 Interobserver reproducibility (intraclass coefﬁcient, ICC) of torsion measurements using the EOS system and computed tomography (CT). ICC

EOS

Femoral torsion Tibial torsion

Unipodal

Bipodal

Overall

0.90 0.88

0.94 0.84

0.93 0.86

0.90 0.92

was 0.93 for femoral torsion and 0.86 for tibial torsion; corresponding values by CT were 0.90 and 0.92, respectively. Table 2 reports the ICC values for interobserver reproducibility and Table 3 the interobserver measurement error values. Time needed to assess torsion, including image acquisition and processing, was 10 to 15 minutes by CT and 15 to 20 minutes by EOS. By EOS, mean radiation dose measured as air kerma was 0.18 ± 0.05 mGy for the anteroposterior view and 0.45 ± 0.08 mGy for the lateral view. The CT protocol used in our study has been reported to deliver 8.4 to 15.6 mGy to the skin, depending on the anatomic region being imaged [31]. Figure 2 a: EOS measurement of femoral torsion; b: EOS measurement of tibial torsion.

interobserver error with the corresponding standard deviation (SD) was computed.

Results Population CT and EOS studies of 43 lower limbs in 30 patients (25 females and 15 males; mean age, 53.2 ± 20.4 years) meeting our inclusion criteria were retrieved from our PACS and included in the study. EOS studies were obtained in the bipodal stance for 25 lower limbs in 17 patients and in the unipodal stance for 18 lower limbs in 13 patients.

Measured femoral and tibial torsion values Table 1 reports the femoral and tibial torsion values obtained using EOS and CT. Torsion values differed between the right and left sides in the 16 patients with data on both lower limbs. Mean side-to-side difference in femoral torsion was 6.3◦ by EOS and 6.8◦ by CT (P = 0.6); tibial torsion showed a mean side-to-side difference of 3.9◦ with both imaging modalities. By EOS, the ICC for interobserver reproducibility

Table 1

Discussion In this study, we describe a new 3D method for measuring femoral and tibial torsion on EOS images and we provide a comparison of this method to the current reference standard CT method. Femoral torsion values are heavily dependent on the level of the selected CT slices [21] (Fig. 4). Inaccuracies in the identiﬁcation of femoral neck landmarks can lead to major measurement differences. In studies comparing several CT methods, Sugano et al. [19] and Liodakis et al. [30] found that the most accurate was that described by Reikeras et al. [29], which was therefore chosen for our study. For tibial torsion measurements, we chose the method of Reikeras et al. [18] based on evidence of its greater reproducibility compared to other methods [30]. The EOS and CT methods used in our study used identical anatomical landmarks for the measurements. In our study of 43 lower limbs, mean femoral torsion in the overall sample was between 13◦ and 14◦ and mean tibial torsion was between 30◦ and 31◦ . Tibial torsion was slightly less than in previous studies conducted in asymptomatic individuals [17,34], whereas femoral torsion was within the reported normal range [29]. These data are difﬁcult to interpret, however, given the heterogeneity of the diagnoses in our study

Measurement of femoral and tibial torsion using the EOS system and computed tomography (CT).

Femoral torsion Tibial torsion

EOS

P value

EOS/CT Pearson’s correlation coefﬁcient

13.4◦ ± 9.1◦ 30.8◦ ± 8.8◦

13.7◦ ± 9.4◦ 30.3◦ ± 9.6◦

0.5 0.4

0.93 0.89

Running head: lower-limb torsion measurement: EOS vs. CT

Figure 3

513

a: bipodal EOS acquisition; b: unipodal EOS acquisition.

reproducibility seemed slightly better by CT, with an ICC of 0.92 compared to 0.86 by EOS. However, the ICC values for the two modalities remained very similar, with the ICC by EOS being at the high end of the range indicating a strong correlation (0.7—0.89) and the ICC by CT being at the low end of the range indicating a very strong correlation (0.9—1) [37]. The 3D modelling method used by the EOS system requires visibility on the lateral view of the landmarks of each lower limb. Chaibi et al. [25] described a position with shifted feet to meet this requirement. In our study, we evaluated two other positions, both used in everyday practice at

population. The high prevalence of side-to-side asymmetry of about 6◦ for femoral torsion and 4◦ for tibial torsion was also consistent with earlier studies [18,29,34—36]. We found very close correlations between CT and EOS values for both femoral torsion ( = 0.93) and tibial torsion ( = 0.89). No signiﬁcant bias was detected between the measurements obtained using these two imaging modalities. Reproducibility of femoral torsion measurement seemed slightly better with EOS than with CT. However, with both modalities the ICC values were equal to or greater than 0.9, indicating a very strong correlation [37]. For tibial torsion,

Table 3

Interobserver measurement error with the EOS system and with computed tomography (CT).

Interobserver error

EOS

Unipodal Femoral torsion Tibial torsion

Bipodal

2.7 ± 4.5 2.9◦ ± 2.3◦ ◦

◦

Overall

2.7 ± 4.5 4.1◦ ± 3.5◦ ◦

◦

2.7◦ ± 4.5◦ 3.4◦ ± 3.0◦

3.4◦ ± 7.2◦ 2.7◦ ± 5.4◦

514

Figure 4 Importance of slice selection level for computed tomography measurement. Depending on the level of the slices, femoral anteversion varied by 8◦ . a: identiﬁcation of the femoral head centres; b: superimposition of maximum intensity projection slices down to the middle of the femoral neck: methoddescribed by Riekeras et al. [29]; c: superimposition of maximum intensity projection slices down to the base of the femoral neck: method described Murphy et al. [33]. Femoral torsion is greater by 8◦ using level c) compared to level b).

our institution. In our experience, these positions are associated with greater ease in differentiating the anatomical landmarks on the lateral view. Importantly, the 3D measurements obtained by the EOS system are independent from patient position during acquisition. Our data suggest better interobserver reproducibility with the bipodal stance for femoral torsion and with the unipodal stance for tibial torsion. However, sample sizes were too small for meaningful statistical comparisons. In our study, both EOS and CT measurements were performed by senior radiologists who were specialised in osteoarticular radiology. The influence of experience on measurement quality, although not evaluated in our study, probably deserves consideration. With CT measurements, for instance, great care is needed to identify the femoral neck landmarks. With EOS, automatic determination of the axes is influenced by the quality of bone contouring, which in turn is influenced by the degree to which superimposition of bone landmarks on the lateral view is avoided. The EOS system is not appropriate for all patients. For biplanar X-ray acquisition of the lower limbs, the patient must stand without moving for about 10 s to avoid motion artefacts. Therefore, patients who are unable to stand and

D. Folinais et al. those who are unsteady in the standing position are not candidates for EOS imaging of the lower limbs. Furthermore, the 3D modelling software relies on generic 3D models of the femur and tibia and therefore cannot be used after total hip or knee replace mentor for modelling the native acetabulum. Marked deformities of the femoral head or knee may create specific challenges. Some of the anatomic landmarks may be difficult to identify in patients who have advanced hip osteoarthritis with femoral head deformity and florid osteophyte formation. This limitation similarly affects torsion measurement by EOS and by CT. Comparable challenges arise in patients with residual abnormalities due to major dysplasia, slipped capital femoral epiphysis, massive avascular necrosis of the femoral head, or hip luxation or subluxation. Finally, the simultaneous acquisition by the EOS system of an anteroposterior view and a lateral view ensures very easy 3D modelling, which is useful for morphological analyses. However, the 3D model thus obtained is of limited relevance to the structural diagnosis, since it is based on generic models of the femur and tibia. Conventional 2D goniometry also has a number of limitations. Only deviations in the coronal plane can be measured using this technique. Conventional 2D methods, even those involving digitisation, deliver larger radiation doses [26,38,39]. Isolated analysis of rotational malalignment is only very rarely performed. Until now, 2D goniometry had to be completed by CT, and vice versa, which considerably increased the radiation dose to the patient. The EOS system can be used for single-plane imaging to perform conventional 2D goniometry. However, we believe that 3D imaging is crucial in patients with major lower-limb deformities, particularly when several abnormalities exist in combination (e.g., rotational malalignment, fixed flexion, and lower-limb length discrepancy) (Fig. 5) [40]. EOS has been demonstrated to deliver far lower radiation doses than conventional radiological techniques. This advantage is ascribable to the use of the multiwire chamber developed by Charpak (Nobel Prize in Physics, 1992). A 6- to 9-fold radiation dose decrease versus conventional radiographs has been reported for full-spine EOS imaging [26]. In a study involving an Alderson-Rando phantom (trunk and lower limbs) and lithium fluoride thermoluminescent dosimetry, Delin et al. [31] established that the radiation dose delivered to the patient during lower-limb torsion measurement was 4- to 23-fold higher with CT than with EOS. A major advantage of the EOS system compared to CT is the collection of 3D data during a single scan. Thus, EOS images immediately provide a 3D analysis instead of a single-plane analysis. We demonstrated that torsion values measured using the EOS system correlated closely with CT values, without bias and with comparably satisfactory interobserver reproducibility. The EOS system may therefore constitute a valid alternative to CT for evaluating lower-limb torsion. The use of the EOS system substantially decreases overall radiation exposure, a major advantage in patients who often require extensive orthopaedic investigations involving multiple imaging studies over time.

Running head: lower-limb torsion measurement: EOS vs. CT

515

Figure 5 EOS image acquisition and 3D modelling. Major complex lower-limb deformity with length discrepancy, ﬁxed ﬂexion, and asymmetrical femoral and tibial torsion.

Disclosure of interest The authors declare that they have no conﬂicts of interest concerning this article.

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measurements calculation from biplanar X-rays. Comput Methods Biomech Biomed Engin 2012;15:457—66. Deschenes S, Charron G, Beaudoin G, Labelle H, Dubois J, Miron MC, et al. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine (PhilaPa 1976) 2010;35:989—94. Than P, Szuper K, Somoskeoy S, Warta V, Illes T. Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop 2012;36:1291—7. Lazennec JY, Brusson A, Rousseau MA. Hip-spine relations and sagittal balance clinical consequences. Eur Spine J 2011;20(Suppl. 5):686—98. Reikeras O, Bjerkreim I, Kolbenstvedt A. Anteversion of the acetabulum and femoral neck in normals and in patients with osteoarthritis of the hip. Acta Orthop Scand 1983;54:18—23. Liodakis E, Doxastaki I, Chu K, Krettek C, Gaulke R, Citak M, et al. Reliability of the assessment of lower limb torsion using computed tomography: analysis of ﬁve different techniques. Skeletal Radiol 2012;41(3):305—11. Delin C, Silvera S, Radier C, Bassinet C, Rehel JL. Dosimétrie des mesures de torsion et d’antéversion des membres inférieurs utilisant l’EOS et le scanner. Rev Chir Orthop 2011;97(7S):S298 [In French]. Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater reliability. Psychol Bull 1979;86:420—8. Murphy SB, Simon SR, Kijewski PK, Wilkinson RH, Griscom NT. Femoral anteversion. J Bone Joint Surg Am 1987;69:1169—76. Strecker W, Keppler P, Gebhard F, Kinzl L. Length and torsion of the lower limb. J Bone Joint Surg Br 1997;79:1019—23. Clementz BG. Tibial torsion measured in normal adults. Acta Orthop Scand 1988;59:441—2. Braten M, Terjesen T, Rossvoll I. Femoral anteversion in normal adults. Ultrasound measurements in 50 men and 50 women. Acta Orthop Scand 1992;63:29—32. Munro BH. Statistical methods for health care research. 3rd ed. Philadelphia: Lippincott; 1997. Vano E, Fernandez JM, Ten JI, Prieto C, Gonzalez L, Rodriguez R, et al. Transition from screen-ﬁlm to digital radiography: evolution of patient radiation doses at projection radiography. Radiology 2007;243:461—6. Dubousset J, Charpak G, Skalli W, de Guise J, Kalifa G, Wicart P. Skeletal and spinal imaging with EOS system. Arch Pediatr 2008;15:665—6 [In French]. Thelen P, Delin C, Folinais D, Radier C. Evaluation of a new lowdose biplanar system to assess lower-limb alignment in 3D: a phantom study. Skeletal Radiol 2012;41:1287—93.

Orthopaedics & Traumatology: Surgery & Research (2012) 98, 506—513

Available online at

www.sciencedirect.com

ORIGINAL ARTICLE

Reliability of a new method for lower-extremity measurements based on stereoradiographic three-dimensional reconstruction B. Guenoun a,∗, F. Zadegan b, F. Aim b, D. Hannouche b, R. Nizard b a

Department of Orthopedic and traumatology Surgery ‘‘A’’, Cochin, Port-Royal Hospital Group (AP—HP), 27, rue du Faubourg-Saint-Jacques, 75679 Paris, France b Department of Orthopedic and traumatology Surgery, Lariboisiere, Fernand-Widal-Saint Louis Hospital Group (AP—HP), 2, rue Ambroisé-Paré, 75475 Paris cedex 10, France Accepted: 12 March 2012

KEYWORDS Radiographic image interpretation; Computer-assisted orthopaedics; Skeletal imaging; Three-dimensional; Radiation dosage; Leg length measurements

∗

Reliability of a new method for lower-extremity measurements based on stereoradiographic threedimensional recontruction

Summary Introduction: Several clinical and radiological techniques have been described to assess lower limb length and angle measurements. None of them has yet met the ideal criteria for a reliable, reproducible, safe, and inexpensive system. In this context, a new biplanar X-ray system (EOSTM , EOS imaging, Paris, France) makes it possible to obtain a 3D reconstruction of the lower extremities from two 2D orthogonal radiographic images, with associated calculation of 3D measurements. The reliability of this technique has never been documented on adults. Hypothesis: Lower limb measurements produced by the 3D EOSTM reconstruction system are reproducible regarding inter- and intraobserver assessment and more reliable with this 3D technique than when they are obtained from 2D measurements. Materials and methods: This study included 25 patients awaiting total hip arthroplasty (50 lower limbs). Two independent observers made all measurements twice, both on the 2D frontal radiograph and using 3D reconstructions (femoral measurements of length, offset, neck shaft angle, neck length, and head diameter, as well as the tibia length, limb length, HKA and HKS). Reproducibility was estimated by intraclass correlation coefﬁcients. Results: Both the inter- and intraobserver reproducibility of the EOSTM measurements was excellent; more speciﬁcally inter- and intraobserver reproducibility was 0.997 and 0.997 for femoral length, 0.996 and 0.995 for tibial length, 0.999 and 0.999 for limb length, 0.894 and 0.891 for HKS, 0.993 and 0.994 for HKA, 0.870 and 0.845 for femoral offset, and 0.765 and 0.851 for neck shaft angle. For most of the variables, the interobserver correlations were statistically better with the EOSTM 3D reconstruction.

Corresponding author. Tel.: +33 1 58 41 30 82; fax: +33 1 58 41 30 87. E-mail address: B.Guenoun@Free.fr (B. Guenoun).

Reliability of EOS biplanar X-ray in lower-extremity measurements

507

Discussion: Our results show that the EOSTM systems allow reproducible lower limb measurements. Furthermore, 3D EOSTM reconstructions offer better reproducible measures for most of the parameters than radiographic 2D projection. Its use before deciding on surgery and during planning for lower limb arthroplasty appears essential to us. Level of evidence: Level III: diagnostic prospective study on consecutive patients. © 2012 Elsevier Masson SAS. All rights reserved.

Introduction Since the era of arthroplasty began, orthopedic surgeons have needed to take meticulous lower limb measurements to optimize preoperative planning. Currently, plain radiographs are used in clinical practice and research for most of these measurements. Even with digitization, however, these measurements remain limited to only two dimensions, and they may well be insufficiently accurate to allow diagnosis or preoperative planning [1,2]. The ability to measure the different relevant lengths and angles of the lower limb in 3D space is essential in the analysis of lower limb anatomy and biomechanics. The choice of imaging technique requires consideration of accuracy, reliability, magnification, radiation dose, cost, need for special equipment, convenience, and the ability to image the entire limb. A technique’s accuracy is defined as the variation of the measurement when using the imaging method compared with its variation with the reference technique or gold standard, whereas its reliability is the interobserver and intraobserver variation in measurements. Besides standard clinical techniques [3], the currently available methods for lower limb measurements are conventional and digital radiography [4], computed tomography (CT) [5], and magnetic resonance imaging (MRI) [6]. Most of these radiologic techniques, however, have specific limitations, and the specific protocols required do not appear to be routinely employed. A new imaging method, the low-dose digital stereoradiography, was recently developed [7,8]. This technique is based on the multiwire proportion chamber for particle detectors, for which G. Charpak won a Nobel Prize in physics. A partnership between a team of biomedical engineers, orthopedic surgeons, and radiologists has transformed it into the low-dose system named EOSTM (EOSTM Imaging, Paris, France). The system consists of a C-shaped vertically travelling arm supporting two image acquisition systems, placed orthogonally, each composed of an X-ray tube and a linear detector. The source and detector thus move together, with the beam always horizontal to the patient. The system produces full-length, weight-bearing images with minimal irradiation [7—9]. Specially designed software included in the workstation allows three-dimensional (3D) modelling of the bone envelope and automatic calculation of specific clinical variables (Fig. 1). Biplanar stereoradiography and personalized modelling of the skeleton have been extensively developed for various anatomic regions including the lumbar spine [10], cervical spine [11], ribs [12], pelvis [13]. In a recent study, the use of this technique on lower extremities was validated on children [14]. The goal of our study

was to investigate intraobserver and interobserver reproducibility of these EOSTM 3D reconstruction measurements in vivo. As a secondary aim, we compared these results with 2D measurements.

Materials and methods Patients This study included 25 patients scheduled for total hip arthroplasty (50 lower limbs). Patients consented in writing to inclusion in the study after receiving comprehensive information about the study protocol and other details. Inclusion criteria for this study included need for a primary total hip replacement and provision of informed consent. This study received an institutional review board approval (Comité de Protection des Personnes Île-de-France X, Number: 2011-0403). Patients were excluded if they had previously had any kind of bone surgery (osteosynthesis or arthroplasty) for the lower limbs. Each patient underwent biplanar EOSTM long-leg radiography in a weight-bearing position. Dose received by the patient (entrance ‘‘air kerma’’), given by the acquisition system, was recorded for each patient.

2D measurement For each patient, the EOSTM frontal 2D X-ray was used to perform 2D measurements with a dedicated software (SterEOS 2D, EOSTM Imaging, Paris). Measurements were done as follows (Fig. 2): • Femur length: between the center of the femoral head and the center of the femoral notch. • Tibia length: between the center of the tibial plateau and the center of the tibial plafond. • Total length: between the center of the femoral head and the center of the tibial plafond. • HKA angle: between the femoral mechanical axis and the tibial mechanical axis. The femoral mechanical axis was deﬁned as that connecting the center of the femoral head to the center of the femoral notch, and the tibial mechanical axis as the line from the center of the tibial plateau extending distally to the center of the tibial plafond. • HKS angle: between the femoral mechanical axis and the femoral anatomical axis. • Femoral head diameter: diameter of a circle ﬁtting the femoral head.

508

Figure 1

B. Guenoun et al.

EOSTM 3D modelling process. a: simultaneous radiographic acquisition; b: radiographic images; c: 3D modelling.

• Femoral neck length: length of the neck axis between the center of the femoral neck and the point joining the neck axis and the diaphysis axis. • Neck-shaft angle: angle between the femoral neck axis and the axis of the diaphysis. • Femoral offset: distance between the center of the femoral head and the axis of the diaphysis. Two independent observers did each 2D measurement twice.

3D measurement With the dedicated 3D software (SterEOS 3D, EOSTM Imaging, Paris), the same operators reconstructed each lower extremity in 3D. The reconstruction process begins by the selection of anatomical landmarks: center of the femoral head, femoral condyles, and tibial extremities (proximal and distal). The application creates the lower limb envelope; the operators then adjust the reconstruction manually to match the model better. Finally, the clinical measurements are automatically extracted from the ﬁnal envelope. The available lower limb measurements were: femur length, tibial length, lower limb length, HKS angle, HKA angle, femoral offset, neck shaft angle, femoral head diameter, femoral neck length, femoral anteversion, femoro-tibial rotation, tibial torsion, and presence of ﬂexion contracture or recurvatum (Fig. 2). Landmarks used to do the 2D measurements were equivalent to those used by the 3D software for the automated calculations. Two independent observers did each 3D measurement twice.

Statistical analysis

Figure 2 graph.

3D lower limb reconstruction and long-leg radio-

These data enabled us to calculate intraclass correlation coefficients [15] to determine the intra- and interobserver reliability for each technique. The means, SD, and 95% confidence intervals were calculated for the variables above (two observers by two times by 100 lower limbs). We investigated intra- and interobserver reproducibility of each variable with multivariate four-way analysis of variance. Means for the quantitative variables were compared with Student’s ttest or the nonparametric Mann-Whitney test for comparing paired means. Significance was defined as a P value of 0.05. Completed data were analyzed with use of the Statistical

Reliability of EOS biplanar X-ray in lower-extremity measurements Table 1

509

Results of lower limb measurements by 3D EOSTM and the 2D EOSTM radiograph.

Variable

Femur length (cm) Tibia length (cm) Lower limb length (cm) HKS angle (◦ ) HKA angle (◦ ) Femoral offset (cm) Neck shaft angle (◦ ) Femoral head diameter (cm) Femoro-tibial rotation (◦ ) Tibial torsion (◦ ) Femoral neck length (cm) Flessum/Recurvatum (◦ ) Femoral anteversion (◦ )

Difference

Mean (Min; Max)

41.66 (48.16; 36.75) 36.29 (41.48; 30.54) 78.15 (88.47; 67.87) 6.02 (9.23; 2.07) 1.10 (−20.83; 14.32) 4.27 (5.84; 3.11) 122.69 (139.56; 108.87) 4.47 (5.16; 3.70) 7.16 (27.61; 0.23) 28.91 (43.93; 9.76) 5.01 (6.51; 4.04) 6.67 (18.24; −14.72) 10.27 (35.03; −6.28)

2.42 2.59 4.80 1.48 5.36 0.54 5.96 0.29 5.52 7.13 0.50 6.11 8.65

41.15 (36.40; 47.70) 35.54 (29.40; 40.60) 77.29 (66.70; 88.60) 5.59 (1.30; 9.00) 0.71 (−23.10; 16.70) 3.60 (2.30; 6.00) 130.73 (110.30; 146.20) 4.55 (3.50; 5.80)

0.47 0.55 0.84 0.36 0.71 0.68 0.96 0.47

0.51 0.75 0.86 0.43 0.38 0.67 −8.04 −0.08

< 0.05 < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 < 0.05

0.68

0.25

< 0.05

Package for the Social Sciences, version 17.0 (SPSS, Chicago, Illinois).

Results Values of each lower limb variable extracted from the 2D measurement and 3D EOSTM reconstruction are reported in Table 1 and did not differ from the value of the literature [4,16—18]. We found a statistical difference for all the lower limb variables between the 2D and the 3D techniques (P < 0.05). The intraobserver correlations of the 3D technique were excellent as they were for the 2D technique. This was the case conﬁrmed for all the variables. On the other hand, correlations were somewhat lower for some of the variables for the 2D technique: neck shaft angle, and femoral head diameter. The intraobserver correlations were statistically better with the 3D technique than the 2D technique for most of the variables (Table 2). The interobserver correlations of the 3D EOSTM technique were also excellent, as for the 2D technique. Again, this result was conﬁrmed for all variables in the 3D reconstructions, while for the 2D technique, some variables were less well correlated (HKS angle, neck shaft angle, femoral head diameter, and femoral neck length). For most of the variables, the interobserver correlations were statistically better with the 3D reconstruction (Table 2). The mean difference between the two observers is shown in Table 3. For all lower limb measurements, 3D technique SD was systematically slightly inferior to 2D measurement (P ≤ 0.005). The average dose delivered for the stereoradiographic examination (AP + LAT) was 0.54 mGy (SD = 0.05 mGy).

Discussion The ideal method for measuring lower limb variables should be readily available, accurate, reliable, inexpensive, allow visualization of the entire limb, minimize radiation exposure, and have no magniﬁcation error. Review of the

4.78 (3.50; 6.90)

literature shows that, until now, no single imaging method could be considered ideal. Until now, the EOSTM system has been available only in a few medical centers in France and a few major cities in Europe and North America. The literature about this technique is thus sparse. In this study, we aimed to evaluate the interest of a new 3D modelling technique for the assessment of lower limb lengths and angles in terms of measurement reliability. Overall, we found the 3D technique to have similar or better intra- and inter-operator reliability than 2D radiography. We compared these to the results reported for various other tools for assessing lower limb variables so that we could discuss its potential advantages and pitfalls. The main limitation of our study is the use of lower limbs from a hospital-based population of patients requiring total hip arthroplasty. This inclusion criterion meant that most of the proximal limbs viewed had major coxarthrosis. Coxarthrosis causes significant anatomical changes in the proximal extremities of the femur and may cause difficulty at the time of reconstruction when the anatomical model is used. Similarly, it may distort measurements on 2D radiography; we found 2D reproducibility slightly worse than rates reported in the literature for equivalent measurements [20,21]. It would probably have been better to use healthy bones to test the reproducibility of the EOSTM system, but it would have been difficult from an ethical point of view to expose subjects to radiation without any clinical purpose. Besides, the differences in shape of repeated lower limb reconstructions, the high intraobserver and interobserver reproducibility in the 3D reconstruction showed the stability of the reconstructions. The promising results of the current in vivo study demonstrate that it should be possible to use EOSTM stereoradiography for lower limb measurements in clinics, despite the pitfalls related to the superposition of multiple soft tissue and bony structures. In addition, the absence of significant differences between subjects showed that the method was both feasible and reproducible for most subjects. Secondly, we did not compare measurement of the 3D reconstruction with conventional full-length radiographs or the CT-scan, principally in order to avoid an additional exposure for the patients. Even if these techniques are the

0.618 (0.133—0.814)

To compare the coefﬁcient correlations, we use the Fisher transformation [19] to create the Z variable then we compare it to the normal distribution (Z = 1.96 for an alpha error risk of 0.05 and a bilateral hypothesis). Signiﬁcant differences are labeled by * .

2.88 4.26

0.828 (0.754—0.881)

0.997 (0.995—0.998) 0.995 (0.985—0.998) 0.999 (0.998—1.000)* 0.891 (0.843—0.926) 0.994 (0.991—0.996) 0.915 (0.876—0.942)* 0.851 (0.786—0.897) 0.886 (0.834—0.922)* 0.719 (0.609—0.802) 0.826 (0.751—0.880) 0.921 (0.885—0.946)* 0.996 (0.994—0.997) 0.912 (0.872—0.940) 0.994 (0.991—0.996) 0.995 (0.993—0.997) 0.998 (0.996—0.998) 0.876 (0.821—0.915) 0.994 (0.991—0.996) 0.845 (0.777—0.893) 0.794 (0.709—0.857) 0.793 (0.706—0.855) 2.96 1.95 2.42 5.29 0.47 0.99 2.33 1.88 0.993 (0.990—0.995) 0.993 (0.990—0.995) 0.998 (0.997—0.999) 0.593 (0.347—0.743) 0.992 (0.988—0.995) 0.831 (0.756—0.884) 0.587 (0.023—0.811) 0.565 (0.029—0.793)

3D (95% CI)

0.997 (0.995—0.998) 0.995 (0.995—0.998) 0.999 (0.999—1.000)* 0.894 (0.847—0.928)* 0.993 (0.989—0.995) 0.870 (0.812—0.911) 0.765 (0.673—0.835)* 0.721 (0.443—0.846) 0.652 (0.523—0.751) 0.730 (0.621—0.811) 0.870 (0.785—0.919)* 0.991 (0.987—0.994) 0.821 (0.728—0.882)

2D (95% CI) 2D (95% CI)

Intraobserver Interobserver

Femur length Tibia length Lower limb length HKS angle HKA angle Femoral offset Neck shaft angle Femoral head diameter Femoro-tibial rotation Tibia torsion Femoral neck length Flessum/Recurvatum Femoral anteversion

Table 2

Interobserver and intraobserver correlations (95% CI) of the clinical variables according to the 2D and the 3D techniques.

3D (95% CI)

2.42 0 2.42 0.48 0 2.22 1.24 2.27

B. Guenoun et al.

510

Table 3 Mean interobserver differences in clinical variables with the EOSTM 2D and 3D techniques.

Femur length (cm) Tibia length (cm) Lower limb length (cm) HKS angle (◦ ) HKA angle (◦ ) Femoral offset (cm) Neck shaft angle (◦ ) Femoral head diameter (cm) Femoral neck length (cm)

0.206 0.218 0.224 0.868 0.519 0.312 4.685 0.359 0.466

0.132* 0.159* 0.127* 0.519* 0.497* 0.269* 2.937* 0.252* 0.265*

Signiﬁcant differences are labeled by * .

clinical routine practice or the most reproducible techniques used to measure lower limb variables. However, a recent study [22] suggests that orthopedic measurements done on EOSTM 2D images are comparable with those performed on conventional 2D X-rays. We chose instead to compare it with EOSTM 2D frontal X-rays, to optimize the usefulness of our study for the everyday practice of orthopedic surgeons. The third major limitation of this study is that all the measurements were performed by two experienced operators. For this study alone, each operator did 100 EOSTM reconstructions and the same number of measurements of EOSTM 2D frontal X-rays. Obviously, in everyday practice, these reconstructions must be performed by an experienced operator. The data processing requires specific staff training and the image takes about 5 minutes for each reconstruction for a training user. Unlike other studies, we did not assess here the impact of operator experience on the reproducibility of measurements. In our study, radiation doses delivered by the biplane system were slightly higher than what was reported on spine examination on adolescents with the same system [23], but far from the doses classically reported for a single AP pelvis conventional X-ray or CT-scan [24] and from European diagnostic reference levels [25]. Despite rapidly advancing technology, it is important to bear in mind that the accuracy and ease of obtaining measurements with any imaging modality is not a substitute for a thorough clinical assessment. Clinical evaluation of patients with long-standing limb shortening, especially with associated muscle weakness, can use blocks under the short limb to estimate the amount of correction that feels optimal; a goniometer can also be used to measure angular deformities. It is nonetheless generally agreed now that radiographs are more accurate and reliable than a clinical exam for analyzing the lower limb variables [26,27]. Accuracy has increased with digitization of radiography: digital total-leg radiography is a reliable method that produces no significant angle differences compared to conventional radiography systems and requires significantly less evaluation time [4], its simplicity of implementation and interpretation distinguishes it from all other techniques. Although standard long-leg radiography remains the reference technique for the evaluation of the clinical variables of the lower limb, numerous studies have demonstrated its limitations in terms of accuracy and

Reliability of EOS biplanar X-ray in lower-extremity measurements Table 4 Interobserver and intraobserver correlation for clinical lower limb discrepancy with a variety of imaging techniques. Interobserver

Intraobserver

Clinical Jonson and Gross [3]

0.970

0.650

Standing AP radiograph Sabharwal et al. [32] Leitzes et al. [6]

0.968 0.980

0.978 0.990

Slit scanograms Terry et al. [27]

0.990

CT scanograms Aitken et al. [20] Sabharwal et al. [32]

0.995 NA

NA 0.979

MRI Leitzes et al. [6]

0.990

0.999

3D EOS

NA: non applicable.

reproducibility. These studies have reported measurements of these variables, and most specifically lower limb discrepancies, with a variety of other imaging techniques, including orthoroentgenograms [28,29], CR-based teleoroentgenograms [30], Slit scanograms [31], CT scanograms [20,21,32], or MRI [6]. Many factors can modify the interpretation of measurements calculated from standard radiographs, despite the standardization of theoretical angles: source position and motion, the direction of the incident rays, the extent of their penetration, and the patient’s position (position and rotation of the hip, knee and ankle). The technical characteristics of the EOSTM system control for most of these factors. Only a one-way scan is needed to record both the frontal and lateral views, unlike most other techniques. The full process time is around a 20-second scanning process. This shorter acquisition time reduces the number of movements during the process, compared, for example, with techniques such as orthoroentgenograms or scanograms, which are prone to errors due to patients moving between exposures. EOSTM , unlike CT scanograms and MRI, has the advantage of displaying the entire length of the lower limb, without any magnification error: the source of irradiation moves during the procedure, with the structure to be measured always centered in the gantry [33]. Our study provided excellent inter- and intraobserver reproducibility for the 2D measurements and the 3D modelling values. Comparison of our data with the literature shows that the reproducibility of the assessment of lower limb lengths using EOSTM 3D modelling [3] is better than clinical assessment [3] and better than or at least equivalent to methods using plain X-rays [19,28,34—36], computed radiography teleoroentgenograms [30], CT scanograms [20], or MRI [6] (Table 4). All the techniques had satisfactory inter- and intraobserver correlation coefficients (high to excellent). However, there are disadvantages to most of these techniques as well, including the need for special radiographic equipment such as grids,

511

filters, and processors along with the need for long radiographic cassettes, which may not be readily available given the recent advances in digital imaging and which can be difficult to store. The CT-scan was presented as a solution that both improves reproducibility and reduces 2D projection error phenomena. It has, however, several important limitations: the dose required to perform the examination is higher than that needed for conventional radiography, patients cannot be examined in a weight-bearing position, and the measurements, which depend too highly on the decision markers, lack reproducibility. Reproducibility of this 3D technique had been previously evaluated on a pediatric population [14]. The reliability of the assessment of femur length, tibia length, HKA angle, and neck shaft angle was evaluated on children with the same conclusion of excellent interobserver correlation for femoral and tibial length and HKA angle. Interobserver ICC for the neck-shaft angle was found to be 0.66 on children and 0.76 in our study, suggesting that this parameter is probably less reliable than the others. The mean values of each lower limb variable extracted from the 3D reconstruction did not differ from the values reported in the literature [4,16—18,37]. In addition to the significant difference for all lower limbs parameters between the 2D and 3D measurements, we saw remarkable differences for certain variables: total length, HKA angle, femoral offset, and neck-shaft angle. Various studies have demonstrated the negative impact of some deflections [20,29] or positions [38] of the lower limb on the accuracy of radiology measurements. A recent study on dry bones confirmed that the bias between 2D and 3D measurement is due to projection errors in 2D, by validating the accuracy of EOSTM 3D parameters against CT-scan on dry bones [14]. In the presence of axial rotation of the lower limb during acquisition, the measurement of frontal knee alignments may be biased [39], just as femoral neck anteversion can distort the assessment of 2D parameters of the hip [18]. Indeed, it is for the hip variables, especially the femoral offset and neck-shaft angle, that we see the largest differences between 2D and 3D measurements. Sariali et al. [18] measured femoral offset in a series of 223 hips in both 2D frontal projection and 3D acquisition by a CT-scan and found a mean offset of 38.7 mm in 2D and 42.2 mm in 3D. Similarly, Pasquier et al. [37] found in a series of 61 patients that the 2D femoral offset was undervalued by 3.3 mm. Our study found an offset of 36.0 mm in 2D and of 43.0 mm in 3D, for a difference of 7 mm. We also found a difference of 8◦ between 2D and 3D for the neck-shaft angle in our population, consistent with the findings by Kay et al. [40], which highlighted the effect of femoral rotation on the neck-shaft angle measurement. The low dose system provides spectacular dose reduction, consistent with international recommendations on radiation protection [7] and ranging from six to 18 [23,25] times lower than for a standard long-leg X-ray [8]: 5 mrads. The irradiation dose is an important factor for consideration, not only in their young patients, but also in ours, often old, with multiple comorbid conditions and both requiring a thorough assessment for arthroplasty and likely to require many more imaging procedures with ionizing radiation. Our study could overcome most of the limitations in the available articles about different findings in the assessment of lower limb measurements as retrospective case series

512 with multiple confounding variables not clearly stated by the investigators, such as image size, presence of angular deformities and contractures of the lower limbs. The precision and accuracy of our measurements is quite remarkable, and especially useful for orthopedic surgery research. We can wonder, in any case, whether daily orthopedics practice requires measurements as precise and as accurate as EOSTM provides. Certainly, the standard surgery that will result from these measurements does not. The final problem is not yet completely resolved: the difficulty of developing reconstruction models that take the prosthetic implant into account. Schlatterer et al. [41] were the first to test positioning 3D models of total knee arthroplasties for non-prosthetic reconstruction and found some difficulties, specifically related to the definition of the landmarks. We plan to follow this initial phase of evaluation with further development of this imaging tool, to create a protocol for complete preoperative planning, using this 3D reconstruction.

Conclusion In our study, the EOSTM 3D modelling technique showed excellent inter- and intraobserver reproducibility, better than for 2D measurements. This technique appears to be a reliable tool for lower limb measurements, providing greatly reduced irradiation and satisfactory inter- and intraobserver reproducibility, high accuracy, and a low exam cost. This imaging system is a useful tool for preoperative assessment of the lower limbs (arthroplasty, tumor) and should be the second-line technique for the evaluation of lower limbs (in cases of massive long-leg discrepancy or frontal deformation) for planning surgery, to supplement standard radiography. For now, the major ﬂaw of the EOSTM system is its lack of availability for everyday practice. All the radiologic methods, found in the literature, were reported to have similar and very high reliability for lower limb measurements. The standing AP radiograph of the lower limbs, including extremities, should be the method of choice for the ﬁrst evaluation. Our department will continue to study the lower limb measurements obtained with the EOSTM system after total hip arthroplasty to evaluate the value of its use in orthopedics practice.

Disclosure of interest The authors declare that they have no conﬂicts of interest concerning this article.

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[32] Sabharwal S, Zhao C, McKeon JJ, McClemens E, Edgar M, Behrens F. Computed radiographic measurement of limb-length discrepancy. Full-length standing anteroposterior radiograph compared with scanogram. J Bone Joint Surg Am 2006;88:2243—51. [33] Horsﬁeld D, Jones SN. Assessment of inequality in length of the lower limb. Radiography 1986;52:223—7. [34] Machen MS, Stevens PM. Should full-length standing anteroposterior radiographs replace the scanogram for measurement of limb length discrepancy? J Pediatr Orthop B 2005;14: 30—7. [35] Temme JB, Chu WK, Anderson JC. CT scanograms compared with conventional orthoroentgenograms in long bone measurement. Radiol Technol 1987;59:65—8. [36] Helms CA, McCarthy S. CT scanograms for measuring leg length discrepancy. Radiology 1984;151:802. [37] Pasquier G, Ducharne G, Ali ES, Giraud F, Mouttet A, Durante E. Total hip arthroplasty offset measurement: is CT scan the most accurate option? Orthop Traumatol Surg Res 2010;96:367—75. [38] Swanson KE, Stocks GW, Warren PD, Hazel MR, Janssen HF. Does axial limb rotation affect the alignment measurements in deformed limbs? Clin Orthop Relat Res 2000;371:246—52. [39] Brouwer RW, Jakma TS, Brouwer KH, Verhaar JA. Pitfalls in determining knee alignment: a radiographic cadaver study. J Knee Surg 2007;20:210—5. [40] Kay RM, Jaki KA, Skaggs DL. The effect of femoral rotation on the projected femoral neck-shaft angle. J Pediatr Orthop 2000;20:736—9. [41] Schlatterer B, Suedhoff I, Bonnet X, Catonne Y, Maestro M, Skalli W. Skeletal landmarks for TKR implantations: evaluation of their accuracy using EOSTM imaging acquisition system. Orthop Traumatol Surg Res 2009;95:2—11.

Skeletal Radiol (2013) 42:959–967 DOI 10.1007/s00256-013-1600-0

SCIENTIFIC ARTICLE

Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography Tobias J. Dietrich & Christian W. A. Pfirrmann & Alexander Schwab & Katja Pankalla & Florian M. Buck

Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system of upright fulllength lower limb and hole spine radiography

Received: 7 November 2012 / Revised: 1 February 2013 / Accepted: 4 March 2013 / Published online: 28 March 2013 # ISS 2013

Abstract Objective To compare the radiation dose, workflow, patient comfort, and financial break-even of a standard digital radiography and a biplanar low-dose X-ray system. Materials and methods A standard digital radiography system (Ysio, Siemens Healthcare, Erlangen, Germany) was compared with a biplanar X-ray unit (EOS, EOS imaging, Paris, France) consisting of two X-ray tubes and slotscanning detectors, arranged at an angle of 90° allowing simultaneous vertical biplanar linear scanning in the upright patient position. We compared data of standing full-length lower limb radiographs and whole spine radiographs of both X-ray systems. Results Dose–area product was significantly lower for radiographs of the biplanar X-ray system than for the standard digital radiography system (e.g. whole spine radiographs; standard digital radiography system: 392.2±231.7 cGy*cm2 Electronic supplementary material The online version of this article (doi:10.1007/s00256-013-1600-0) contains supplementary material, which is available to authorized users T. J. Dietrich (*) : C. W. A. Pfirrmann : K. Pankalla : F. M. Buck Department of Radiology, Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland e-mail: tobiasjdietrich@gmail.com T. J. Dietrich : C. W. A. Pfirrmann : A. Schwab : K. Pankalla : F. M. Buck University of Zurich, Zurich, Switzerland A. Schwab Department of Finances, Orthopedic University Hospital Balgrist, 8008 Zurich, Switzerland

versus biplanar X-ray system: 158.4±103.8 cGy*cm2). The mean examination time was significantly shorter for biplanar radiographs compared with standard digital radiographs (e.g. whole spine radiographs: 449 s vs 248 s). Patients’ comfort regarding noise was significantly higher for the standard digital radiography system. The financial break-even point was 2,602 radiographs/year for the standard digital radiography system compared with 4,077 radiographs/year for the biplanar X-ray unit. Conclusion The biplanar X-ray unit reduces radiation exposure and increases subjective noise exposure to patients. The biplanar X-ray unit demands a higher number of examinations per year for the financial break-even point, despite the lower labour cost per examination due to the shorter examination time. Keywords Digital radiography . Radiation dosage . Workflow . Financial management

Introduction Standard digital radiography systems with X-ray area detectors are widely installed and used. Another imaging solution for evaluation of patients with particular musculoskeletal deformities is a novel biplanar X-ray unit with a vertical biplanar slot-scanning X-ray technique (EOS scanner; EOS Imaging, Paris, France). The first reports about this technique were published in 2005 [1, 2]. Although the financial investment needed to purchase, install, run and depreciate such a scanner is substantially higher compared with standard digital

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radiography systems, these biplanar X-ray systems offer radiographs without distortions and enable secondary 3D reconstruction [2–4]. Because of these advantages an increasing number of biplanar X-ray systems are being installed with a total of 50 biplanar X-ray systems installed worldwide as of November 2012. Thirty-two units were installed in Europe, 15 in North America and 3 in the remaining continents. So far, no technological assessment addressing workflow and patient comfort parameters of standard digital radiography systems compared with biplanar X-ray systems has been published in the peer-reviewed literature. Thus, the purpose of our study was to compare the radiation dose, workflow, patient comfort and financial parameters of a standard digital radiography system and a biplanar X-ray system.

Materials and methods The institutional review board issued a waiver for this study. All the patients included gave written permission for anonymised use of their data before the imaging examination. Radiographs Full-length lower limb radiographs and whole spine radiographs of a standard digital radiography system were compared with radiographs of a biplanar X-ray system (Figs. 1, 2). In total, 68 consecutive anteroposterior full-length lower limb radiographs and 47 consecutive anteroposterior and lateral whole spine radiographs were obtained using the standard digital radiography system during a 2-month period from May until June 2011. These examinations were compared with 198 anteroposterior full-length lower limb radiographs and 134 anteroposterior and lateral whole spine radiographs of a biplanar X-ray system acquired during a 2-month period from March to April 2011. Patients All patients referred for the respective examinations in the time periods mentioned above were included in the study. Mentally disabled patients were not included. The average patient’s height and weight were within the same range for the digital radiography groups compared with the biplanar radiograph study groups. The average patient’s height and weight for full-length lower limb radiographs was slightly lower for the digital radiography group (mean patients’ height and weight: 168.5±9.1 cm, 77.3±17.7 kg) than in patients imaged in the biplanar X-ray system (mean patient’s height and weight: 169.2±10.5 cm, 81.1±21.6 kg) and vice versa for total spine radiographs (digital radiography group mean patient’s height and weight 166.6±10.7 cm, 62.1±

Fig. 1 A 65-year-old female patient. a Anteroposterior full-length lower limb radiograph of the standard digital radiography system for planning of a total knee arthroplasty on the right side and b postoperative radiograph of the biplanar X-ray system. The patient also underwent posterior interbody fusion of L4 to S1

13.0 kg; biplanar X-ray group mean patient’s height and weight 163.6±10.9 cm, 57.7±16.7 kg). X-ray systems Both the standard digital radiography system and biplanar X-ray system are commercially available and were evaluated under daily clinical conditions at an University orthopaedic hospital in Switzerland. All radiographs were obtained in an upright standing position. Standard digital radiography system The standard digital radiography system (Ysio; Siemens Healthcare, Erlangen, Germany) is equipped with an indirect digital radiography image detector consisting of a X-ray scintillator layer of caesium iodide. Based on auto-tracking movements of the X-ray tube and detector, it enables automated acquisition of a craniocaudal image series consisting of up to four separate digital radiographs (digital detector area: 43 × 43 cm) in a single acquisition process in a

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Fig. 2 An 18-year-old male patient with levoscoliosis at the thoracolumbar level after posterior spinal fusion of the vertebral bodies T4–T12. a, b Standard digital radiographs and c, d biplanar

radiographs of the whole spine in the anteroposterior and lateral views at the 6-month follow-up. The technical image quality of both whole spine radiographs is very good

monoplanar imaging technique. The images of these series are then semi-automatically stitched together by radiographic technicians at a post-processing workplace (Syngo®, Siemens Healthcare, Erlangen, Germany). The isotropic image resolution at the detector is 139 μm.

–

– Biplanar X-ray system

Standard digital radiography system: tube voltage, 75–90 kVp for the anteroposterior and 77–90 kVp for the lateral view; tube current by automatic exposure control; detector-to-tube distance, 300 cm; maximum craniocaudal field of view, 180 cm. Biplanar X-ray system: tube voltage, 90 kVp for the anteroposterior and 110 kVp for the lateral view; the tube current was selected manually and the exposure stayed constant from the top to the bottom of the acquisition without automatic exposure control, 250 mAs for the anteroposterior and 320 mAs for the lateral view; detector-to-tube distance, 130 cm; object to tube distance approximately 100 cm for both sources in the standing position; maximum craniocaudal field of view, 175 cm [6]. The scanning time was approximately 13 s for adult full-length lower limb and 10 s for whole spine radiographs.

The biplanar X-ray system (EOS; EOS imaging, Paris, France) consists of two coupled X-ray tubes and slotscanning detectors, arranged at an angle of 90° allowing simultaneous vertical biplanar linear scanning by two slitlike, fan-shaped X-ray beams. The linear detectors rely on gaseous micromesh structure technology promoting primary signal amplification through electronic avalanche in the xenon gas [5]. This system allows imaging at low radiation levels [6]. The detector technology has undergone several evolutions since the publication by Després et al. [5] including hardware modification of the detector and output signal processing. These improvements in particular reduce the ripple artefacts. Isotropic image resolution at the detector is 254 μm [6].

Data acquisition

Imaging parameters

Radiation exposure to patients

The following imaging parameters were used for a mediumsized patient habitus and were adapted depending on the patient’s weight and size:

Both X-ray units are equipped with an integrated dosimeter and the dose–area product (DAP) is shown automatically on the control panel [7].

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Table 1 Likert-type item rating of patients’ comfort parameters Questions relating to patients’ comfort

Patients’ answers according to a four point Likert-type item rating 1

What was your overall impression of the examination in this X-ray unit? Did you feel claustrophobic in this unit?

Very good

Rather good

Rather poor

Very poor

Not at all claustrophobic

Not really claustrophobic

Rather claustrophobic

Very claustrophobic

Was it easy to step inside and outside the unit?

Very easy

Rather easy

Rather difficult

Very difficult

How safe did you feel during the examination? How did you assess the examination time in this unit?

Very safe Very quick

Rather safe Rather quick

Rather unsafe Rather slow

Very unsafe Very slow

Would you take another examination in this unit? How did you rate the noise during the examination?

Yes Very quiet

Wouldn’t mind Rather quiet

Would rather not Rather loud

No Very loud

A questionnaire was used for evaluation of patients’ comfort consisting of the questions listed above by applying a four point Likert type item

Radiography technicians’ workflow

Financial analysis

Technicians were trained for at least for 6 weeks to use the systems. The examination time was measured and defined as the time period between the moment when the patient stepped inside the examination room and the moment the patient stepped outside the examination room plus the time needed for processing the examination data in the radiology information system and transferring the images to the picture archiving and communications system (PACS). Using a four-point Likert-type item (answers: very easy, rather easy, rather difficult, very difficult), one question evaluated the workflow as experienced by the radiography technician: was it easy to position the patient? [8]. In addition, the radiography technicians’ workflow parameters were assessed by a two-item questionnaire, with the following questions:

The cost effectiveness was evaluated by the calculation of the break-even point based on a maximum number of examinations per annum of each X-ray system. The maximum number of examinations per annum was calculated by recording the time period of standard digital radiographs and biplanar radiographs for 3 days by three different technicians in our department. These time period measurements included the time from picking up the patient in the waiting room, changing patients’ clothes, acquisition of the radiograph, time needed for electronic documentation and bringing the patient back to the waiting room. The cost effectiveness analysis in the present study assumed a theoretical maximum utilization per annum (250 workdays per year) as well as a theoretical maximum reimbursement of both X-ray systems with an equal ratio of whole spine radiographs in anteroposterior/lateral views and anteroposterior full-length lower limb radiographs. Calculations of financial reimbursement, fixed costs and variable costs revealed the financial break-even point and the corresponding number of examinations per annum. Our financial calculations were based on the preconditions with the following parameters: financial reimbursement with an equal ratio by health insurances and accident/disability insurances was CHF 182 per examination (TARMED version 1.07.01). The annual interest and

& &

Was it necessary to repeat the examination? Were there any delays or problems?

Patients’ comfort A questionnaire was used for evaluation of patients’ comfort consisting of the following questions using a four-point Likert-type item (Table 1) [8]. Table 2 Dose–area product of full-length lower limb radiographs and whole spine radiographs

Dose–area product

Full-length lower limb radiographs anteroposterior (cGy*cm2) Whole spine radiographs anteroposterior/lateral (cGy*cm2)

Standard digital radiographs

Biplanar X-rays

(n=66) 170.9±104.2 (n=47) 392.2±231.7

(n=198) 92.1±45.5 (n=134) 158.4±103.8

P value (Student’s t test)

<0.001 <0.001

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Table 3 Examination time of full-length lower limb radiographs and whole spine radiographs Examination time Standard digital radiographs Full-length lower limb radiographs anteroposterior Whole spine radiographs anteroposterior/lateral

P value

Biplanar X-rays

(n=68)

(n=185)

309±95 s

226±74 s

(n=47)

(n=133)

449±122 s

248±77 s

digital radiography system and the biplanar X-ray system. A computer software package (SPSS, version 17.0, SPSS) was used for statistical calculations.

Results Radiation exposure to patients <0.001 <0.001

depreciation period was 8 years for both the standard digital radiography system and biplanar X-ray system. Indirect cost was 7.63 % and included mainly back-office tasks and infrastructure provided by the hospital for the radiology department such as real estate service, information technology, energy and air conditioning, human resources management, telephone switchboard, laundry, cleaning service, technical service, pharmacy, restaurant for employees and centralised purchasing department. Fixed costs included these indirect costs as well as annual interest and depreciation of fixed assets. Variable costs were 46.2 % and included labour costs (76.3 % of the variable costs), picture archiving and communication system including labour costs (4.5 % of variable costs), maintenance expense (9.6 % of variable costs) and consumption of materials (9.6 % of variable costs). Overall costs was the sum of the fixed costs and variable costs. Statistical analysis The Student’s t test and Mann–Whitney U test served for statistics. A P value less than 0.05 was considered sufficient to indicate statistical significance between the standard

The dose–area product (Table 2) of anteroposterior standing full-length lower limb radiographs as well as the dose–area product of the whole spine radiographs including anteroposterior and lateral views was significantly lower for radiographs of the biplanar X-ray system compared with the standard digital radiography system (e.g. spine; standard digital radiography system: 392.2 ± 231.7 cGy*cm2 vs biplanar X-ray system: 158.4±103.8 cGy*cm2, P=<0.001 [Student’s t test]). Radiography technicians’ workflow The mean examination time (Table 3) was significantly shorter for biplanar radiographs compared with standard digital radiographs (e.g. whole spine radiographs; standard digital radiography system: 449 s vs biplanar X-ray system: 248 s). The remaining workflow parameters (Table 4) did not reveal any significant difference. Patients’ comfort In contrast to the examination time measured, patients undergoing full-length lower limb radiographs subjectively assessed the examination time significantly longer in the biplanar X-ray system, whereas there was no significant difference for whole spine radiographs (Table 5). The biplanar

Table 4 Radiography technicians’ workflow parameters

Was it easy to position the patient? Was it necessary to repeat the examination? (Yes) Were there any delays or problems? (Yes)

Full-length lower limb radiographs anteroposterior

Whole spine radiographs anteroposterior/ lateral

Std DR system Mean

Std DR system

Biplanar system

Mean

P value

Mean

P value

1.2 0 % (0/68)

1.2 2.6 % (5/190)

0. 22 0.18

1.3 4.3 % (2/47)

1.2 6.7 % (9/134)

0.201 0.55

4.4 % (3/68)

10.5 % (20/190)

0.13

27.7 % (13/47)

22.4 % (30/134)

0.47

Biplanar system

Values for the question “Was it easy to position the patient?” are expressed as mean. We used a four-point Likert- type Item (answers: 1=very easy, 2=rather easy, 3=rather difficult, 4=very difficult) Two radiography technicians’ workflow parameters were binary as yes or no The Mann–Whitney U test served for statistics Std DR system standard digital radiography system

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Table 5 Patients’ comfort parameters Full-length lower limb radiographs anteroposterior

Whole spine radiographs anteroposterior/lateral

Std DR system Mean

Biplanar system Mean

Std DR system Mean

Biplanar system Mean

P value

What was your overall impression of the examination in this X-ray unit? Did you feel claustrophobic in this unit?

1.3

0.61

1.3

0.55

1.0

1.1

0.058

1.1

0.71

Was it easy to step inside and outside the unit?

1.4

0.98

1.1

0.49

How safe did you feel during the examination?

1.2

0.99

1.2

1.3

0.35

How did you assess the examination time in this unit? Would you take another examination in this unit?

1.2 1.1

1.4 1.1

0.015 0.834

1.3 1.1

1.4 1.1

0.80 0.11

How did you rate the noise during the examination?

1.2

1.7

<0.001

1.4

1.8

<0.01

P value

Values are expressed as mean. A questionnaire was used for evaluation of patients’ comfort consisting of the questions listed above by applying a four-point Likert-type Item, e.g. “What was your overall impression of the examination in this X-ray unit?” (Answers: 1=very good, 2=rather good, 3=rather poor, 4=very poor) The Mann–Whitney U test served for statistics Std DR system standard digital radiography system

X-ray system was significantly noisier compared with the standard digital radiography system (Table 5, P < 0.01 [Mann–Whitney U test]). No other parameters relating to the patients’ comfort showed significant differences between the standard digital radiography system and the biplanar X-ray system. However, patients undergoing full-length lower limb radiography felt considerably more (P=0.058) claustrophobic in the biplanar X-ray system than in the standard digital radiography system. Patients undergoing whole spine radiographs, on the other hand, did not feel significantly more claustrophobic in the biplanar X-ray system (P=0.714).

Financial analysis

Fig. 3 The calculation of the financial break-even point (BE) based on cost and financial reimbursement by health insurance is shown as a graphical illustration. The total fixed costs are lower owing to the smaller financial investment for a the standard

digital radiography systems compared with b the biplanar X-ray system. Therefore, the biplanar X-ray system demands a higher number of examinations per annum to reach the financial breakeven point

The theoretical maximum number of examinations per annum was 12,000 radiographs (48 radiographs per day) for the standard digital radiography system compared with 17,250 radiographs (69 radiographs per day) for the biplanar X-ray system. Financial investment was higher for the biplanar X-ray system compared with the standard digital radiography system; therefore, the annual interest and depreciation of fixed assets was lower for the standard digital radiography system (CHF 88,700) than for the

Skeletal Radiol (2013) 42:959–967

biplanar X-ray system (CHF 160,500). The higher theoretical maximum utilization per annum was associated with higher indirect costs for the biplanar X-ray system (CHF 239,011) compared with the standard digital radiography system (CHF 166,269). The break-even point was 2,602 examinations/year for the standard digital radiography system and 4,077 examinations/year for the biplanar X-ray system (Fig. 3, Table 6). In particular, the significantly shorter examination time in the biplanar X-ray system with a higher patient throughput partly outweighed the difference in the break-even analysis.

Discussion The biplanar X-ray system reduced radiation exposure to patients in comparison to the standard digital radiography system. Deschênes et al. compared radiation doses of a biplanar X-ray system and a computed radiography system in 50 patients with spinal deformities. They stated a 6 to 9 times reduction of the average skin dose in the thoracoabdominal region when using a biplanar X-ray system instead of computed radiography with phosphor imaging plates [6]. In the present study, we have observed a dose–area product reduction of approximately 50 % in patients examined with the biplanar X-ray system compared with a digital radiography system with

Table 6 Cost-effective analysis of a theoretical maximum utilization of the standard digital radiography system and biplanar X-ray system per annum (equal ratio of whole spine radiographs in anteroposterior/ lateral views and anteroposterior full-length lower limb radiographs,

Productivity Maximum numbers of examinations per annum (day) Reimbursement per examination Cost composition Annual interest and depreciation of fixed assets Indirect cost Total fixed cost (sum of annual interest and indirect cost) Variable cost Overall cost Theoretical maximum Reimbursement Calculation of break-even-point

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an indirect digital image detector consisting of a X-ray scintillator layer of caesium iodide. Detective quantum efficiency (DQE) refers to the efficiency of a detector in converting Xray energy into an image signal [9, 10]. It is known that a computed radiography system with phosphor imaging plates has a DQE comparable to that of conventional analogue X-ray imaging systems (screen-film systems), whereas indirect CsIbased flat-panel detector technology as used in the present study has a better DQE [9, 10]. The improved DQE of the indirect CsI-based flat-panel detector in our study compared with the DQE of a computed radiography detector may explain in part the lower dose reduction with the biplanar X-ray system in the present study compared with the study by Deschênes et al. Dose–area product served for measurement of skin entrance exposure in the present study. Parry et al. [7] stated that their measurements obtained with a dose–area product meter strongly correlated with those obtained with the thermoluminescent dosimeters. DAP measurement is not the most accurate technique for comparing radiation dose. Luminescence dosimeters also measure radiation due to backscatter, which may increase the entrance surface dose by about 30 % [7, 11]. However, Martin stated that the DAP can audit and compare radiation doses from a wide variety of radiological examinations [11]. So far, there have been no reports about biplanar X-ray systems dealing with examination time, workflow and patients’ comfort analysis available in the literature. Overall,

assumption of 250 workdays per year). CHF Swiss Francs. Costs underwent rounding according to the system of our department of finances Standard digital radiography system

Biplanar X-ray system

12,000 (48) CHF 182

17,250 (69) CHF 182

CHF CHF CHF CHF CHF CHF

88,700 166,269 255,000 1,007,134 1,262,100 2,178,200

160,500 239,011 399,500 1,447,755 1,847,300 3,131,200

Number of examinations per annum Percentage of maximum numbers of examinations Reimbursement and overall cost break-even point Total fixed cost

2,602 21.7 % CHF 473,600 CHF 255,000

4,077 23.6 % CHF 742,000 CHF 399,500

Variable cost

CHF 218,600

CHF 342,500

Financial reimbursement by health insurance; fixed and variable costs were included. Fixed costs included annual interest and depreciation of fixed assets as well as back-office tasks provided by the hospital for the radiology department. Variable costs included labour costs for radiologists, radiography technicians and cost of materials per examination

966

patients’ comfort with the biplanar X-ray system in comparison to the standard digital radiography system was equal. Exclusively one comfort parameter revealed significant differences: noise exposure from the standard digital radiography system was significantly lower compared with the biplanar X-ray system. Studies addressing patients’ comfort in the field of diagnostic radiology are rare in the peer-reviewed literature, e.g. breast imaging, CT colonography preparation, dental radiography or invasive procedures such as MR hysterosalpingography and retrograde urethrography [12–16]. One may speculate that patients’ comfort in imaging could influence patients’ compliance and thus indirectly image quality. The examination time of the biplanar X-ray system in our study was significantly shorter than that of the standard digital radiography system implying lower labour costs for radiography technicians per examination and a higher patient throughput per time period. On the other hand the biplanar X-ray system demands a much higher financial investment than standard digital radiography systems. Given the fact that financial reimbursement for radiographs in Switzerland is the same for standard digital radiographs and biplanar radiographs, the shorter examination time and higher financial investment of the biplanar X-ray system requires a higher number of examinations to reach financial break-even. With the biplanar X-ray system it is not possible to obtain radiographs of patients in the prone or supine position. Therefore, the biplanar X-ray system cannot replace a standard digital radiography system. This drawback limits applicability in a general hospital setting. McKenna et al. [17] carried out a systematic review and economic evaluation of the biplanar X-ray system. The authors suggested that the biplanar X-ray system is not cost-effective [17]. They stated that a patient throughput of 7,530 examinations per year for computed radiography compared with a range of 15,100 to 26,500 examinations per year for the biplanar X-ray system is required to achieve an incremental cost-effectiveness ratio of £30,000 per quality-adjusted life year [17]. The authors also found that the number of examinations for the financial break-even has to be doubled for the biplanar X-ray system compared with computed radiography [17], which is similar to our analysis for a digital radiography system. Our financial analysis is different to that of McKenna et al., who assessed the costeffectiveness of the biplanar X-ray system without practical assessment in daily practice as in the present study. The theoretical maximum number of examinations per annum is a key parameter for our cost analysis. The higher patient throughput due to the significantly shorter examination time of the biplanar X-ray system partly outweighed the difference in the present break-even analysis. The latter issue was not considered in the study by McKenna et al. Finally, the financial data of McKenna et al. [17] were based on the National Health Service (NHS) of the United Kingdom

Skeletal Radiol (2013) 42:959–967

whereas our data were based on the healthcare system of Switzerland. A biplanar X-ray system may be operated cost-effectively in addition to a standard digital radiography system in institutions with a high number of examinations. Institutions with a standard digital radiography system and an additional biplanar X-ray system have the advantage of choosing between both units for each patient individually. In our department, the predominant types of examinations performed in the biplanar X-ray system were whole spine radiographs and full-length lower limb radiographs. Whole body radiographs and whole femur radiographs were rarely performed. Children and teenagers in our department were preferably examined in the biplanar X-ray unit taking into consideration the special radiation protection issues of young patients. Advantages of the biplanar X-ray system are radiographs without distortions and the possibility of additional secondary 3D reconstructions with measurement of both internal and external surfaces without acquisition of multiple tomographic images [1, 3, 18–23]. Femur antetorsion can be measured based on the images of the biplanar X-ray system as an alternative to computed tomography [19]. Nevertheless, additional secondary 3D reconstruction is a time-intensive procedure consuming between 15 and 30 min for radiologists or radiography technicians to image the entire spine [2]. Our study has limitations. In this study we did not investigate image quality. The quality of the biplanar X-ray system has already been validated for the measurement of skeletal deformities [4, 24–26]. The significantly better image quality of biplanar X-ray systems compared with computed radiography has been reported for spine radiographs in the frontal view and lateral view in a previous study [6]. The cost analysis reflects the financial situation of one specific orthopaedic hospital in a single country and may apply for other hospitals in various national health systems. In summary, the biplanar X-ray system reduces radiation exposure and increases subjective noise exposure to patients. The biplanar X-ray unit demands a higher number of examinations per year for the financial break-even point despite the lower labour costs per examination owing to the shorter examination time. Thus, the biplanar X-ray system may be suitable for institutions with a high number of radiographs in the standing or sitting position. Conflict of interests The authors declare that they have no conflict of interest.

References 1. Dumas R, Aissaoui R, Mitton D, Skalli W, de Guise JA. Personalized body segment parameters from biplanar low-dose radiography. IEEE Trans Biomed Eng. 2005;52:1756–63.

Skeletal Radiol (2013) 42:959–967 2. Dubousset J, Charpak G, Dorion I, et al. A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system. Bull Acad Natl Med. 2005;189:287–300. 3. Illés T, Tunyogi-Csapó M, Somoskeöy S. Breakthrough in threedimensional scoliosis diagnosis: significance of horizontal plane view and vertebra vectors. Eur Spine J. 2011;20:135–43. 4. Labelle H, Aubin CE, Jackson R, Lenke L, Newton P, Parent S. Seeing the spine in 3D: how will it change what we do? J Pediatr Orthop. 2011;31:S37–45. 5. Després P, Beaudoin G, Gravel P, de Guise JA. Physical characteristics of a low-dose gas microstrip detector for orthopedic x-ray imaging. Med Phys. 2005;32:1193–204. 6. Deschênes S, Charron G, Beaudoin G, et al. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine. 2010;35:989–94. 7. Parry CK, Chu RY, Eaton BG, Chen CY. Measurement of skin entrance exposure with a dose-area-product meter at chest radiography. Radiology. 1996;201:574–5. 8. Uebersax JS. Likert scales: dispelling the confusion. Statistical Methods for Rater Agreement website. 2006. Available via http://john-uebersax.com/stat/likert.htm. Accessed 6 November 2012. 9. Illers H, Buhr E, Hoeschen C. Measurement of the detective quantum efficiency (DQE) of digital X-ray detectors according to the novel standard IEC 62220–1. Radiat Prot Dosim. 2005;114:39–44. 10. Korner M, Weber CH, Wirth S, Pfeifer KJ, Reiser MF, Treitl M. Advances in digital radiography: physical principles and system overview. Radiographics. 2007;27:675–86. 11. Martin CJ. Radiation dosimetry for diagnostic medical exposures. Radiat Prot Dosim. 2008;128:389–412. 12. Svane G, Azavedo E, Lindman K, et al. Clinical experience of photon counting breast tomosynthesis: comparison with traditional mammography. Acta Radiol. 2011;52:134–42. 13. Liedenbaum MH, Denters MJ, de Vries AH, et al. Low-fiber diet in limited bowel preparation for CT colonography: influence on image quality and patient acceptance. Am J Roentgenol. 2010;195:W31–7. 14. Gonçalves A, Wiezel VG, Gonçalves M, Hebling J, Sannomiya EK. Patient comfort in periapical examination using digital receptors. Dentomaxillofac Radiol. 2009;38:484–8.

967 15. Winter L, Glücker T, Steimann S, et al. Feasibility of dynamic MRhysterosalpingography for the diagnostic work-up of infertile women. Acta Radiol. 2010;51:693–701. 16. Berná-Mestre JD, Berná-Serna JD, Aparicio-Mesón M, CanterasJordana M. Urethrography in men: conventional technique versus clamp method. Radiology. 2009;252:240–6. 17. McKenna C, Wade R, Faria R, et al. EOS 2D/3D X-ray imaging system: a systematic review and economic evaluation. Health Technol Assess. 2012;16:1–188. 18. Morvan G, Mathieu P, Vuillemin V, et al. Standardized way for imaging of the sagittal spinal balance. Eur Spine J. 2011;20:602–8. 19. Than P, Szuper K, Somoskeöy S, Warta V, Illés T. Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop. 2012;36:1291–7. 20. Sabourin M, Jolivet E, Miladi L, Wicart P, Rampal V, Skalli W. Three-dimensional stereoradiographic modeling of rib cage before and after spinal growing rod procedures in early-onset scoliosis. Clin Biomech. 2010;25:284–91. 21. Ohl X, Stanchina C, Billuart F, Skalli W. Shoulder bony landmarks location using the EOS® low-dose stereoradiography system: a reproducibility study. Surg Radiol Anat. 2009;32:153–8. 22. Schlatterer B, Suedhoff I, Bonnet X, Catonne Y, Maestro M, Skalli W. Skeletal landmarks for TKR implantations: evaluation of their accuracy using EOS imaging acquisition system. Orthop Traumatol Surg Res. 2009;95:2–11. 23. Lazennec JY, Rousseau MA, Rangel A, et al. Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: measurements reproducibility with EOS imaging system versus conventional radiographies. Orthop Traumatol Surg Res. 2011;97:373–80. 24. Buck FM, Guggenberger R, Koch PP, Pfirrmann CW. Femoral and tibial torsion measurements with 3D models based on low-dose biplanar radiographs in comparison with standard CT measurements. Am J Roentgenol. 2012;199:W607–12. 25. Thelen P, Delin C, Folinais D, Radier C. Evaluation of a new lowdose biplanar system to assess lower-limb alignment in 3D: a phantom study. Skeletal Radiol. 2012;41:1287–93. 26. Sutter R, Pfirrmann CW, Espinosa N, Buck FM. Threedimensional hindfoot alignment measurements based on biplanar radiographs: comparison with standard radiographic measurements. Skeletal Radiol. 2013;42:493–98. .

Diagnostic Imaging of Spinal Deformities

Reducing Patients Radiation Dose With a New Slot-Scanning X-ray Imager Sylvain Deschênes, PhD,* Guy Charron, MSc,† Gilles Beaudoin, PhD,† Hubert Labelle, MD,* Josée Dubois, MD, MSc,* Marie-Claude Miron, MD,* and Stefan Parent, MD, PhD*

Study Design. Clinical trial comparing image quality and entrance dose between Biospace EOS system, a new slot-scanning radiographic device, and a Fuji FCR 7501S computed radiography (CR) system for 50 patients followed for spinal deformities. Objective. Based on their physical properties, slotscanners show the potential to produce image quality comparable to CR systems using less radiation. This article validates this assertion by comparing a new slot-scanner to a CR system through a wide-ranging evaluation of dose and image quality for scoliosis examinations. Summary of Background Data. For each patient included in this study, lateral and posteroanterior images were acquired with both systems. For each system, entrance dose was measured for different anatomic locations. Methods. Dose and image quality being directly related, comparable images were obtained using the same radiograph tube voltage on both systems while tube currents were selected to match signal-to-noise ratios on a phantom. Different techniques were defined with respect to patient’s thickness about the iliac crests. Given dose amplitudes expected for scoliosis examinations, optically stimulated luminescence dosimeters were chosen as optimal sensors. Two radiologists and 2 orthopedists evaluated the images in a randomized order using a questionnaire targeting anatomic landmarks. Visibility of the structures was rated on a 4 level scale. Image quality assessment was analyzed using a Wilcoxon signed-rank tests.

From the *Department of Medical Imaging, Centre Hospitalier Universitaire Sainte-Justine, Montreal, Quebec, Canada; and †Department of Radiology, Centre Hospitalier de l’Université de Montréal, Notre-Dame Hospital, Montreal, Quebec, Canada. Acknowledgment date: February 24, 2009. Revision date: July 14, 2009. Acceptance date: July 20, 2009. The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication. Corporate/industry and other funds were received in support of this work. One or more of the author(s) has/have received or will receive benefits for subject of this manuscript: e.g. honoraria, gifts, consultancies. Supported by This study obtained CHU Sainte-Justine’s ethic committee approval. Informed consent was obtained from the patients, if over 18 years old. For minors, informed consent was obtained from the parent or guardian. The slot-scanning system evaluated in this paper was obtained through a grant from the Canadian Foundation for Innovation. The evaluation was supported through research funds by Biospace Med, the company producing the new slot-scanning device that is the subject of this manuscript. At the end of the study, Gilles Beaudoin and Sylvain Deschênes, the physicists working on this project, have come to a consulting agreement with Biospace Med. Address correspondence and reprint requests to Sylvain Deschênes, PhD, Department of Medical Imaging, Centre Hospitalier Universitaire Sainte-Justine, 3175 Côte-Sainte-Catherine, Montreal, Quebec, Canada, H3T 1C5; E-mail: sylvain.deschenes@recherche-ste-justine.qc.ca

Results. Average skin dose was reduced from 6 to 9 times in the thoracoabdominal region when using the slot-scanner instead of CR. Moreover, image quality was significantly better with EOS for all structures in the frontal view (P 0.006) and lateral view (P 0.04), except for lumbar spinous processes, better seen on the CR (P 0.003). Conclusion. We established that the EOS system offers overall enhanced image quality while reducing drastically the entrance dose for the patient. Key words: spine radiographs, scoliosis, radiation dose, image quality. Spine 2010;35:989 –994

Follow-up of spinal deformities, such as scoliosis, typically involves many radiographs of the patient throughout childhood and adolescence. In the last 20 years, these multiple radiograph exposures have become a source of concern with several studies showing that harmful effects can be linked to ionizing radiation, especially for younger patients.1–3 Highly irradiant methods, like computed tomography (CT)-scans and image-guided interventions, are the primary targets of these publications. However, some other findings conclude that radioinduced harmful outcomes, like breast cancer, can also be linked to standard radiographs follow-up examinations used for evaluation of scoliosis progression.4 – 6 These results triggered a widespread campaign in the medical imaging community to reduce dose, especially in centers providing pediatric care. On the other hand, dose reduction should not be conducted at the expense of valuable diagnostic information. Since dose-free imaging methods, like magnetic resonance imaging and ultrasound, fall short in producing high resolution images of bony structures, the practical solution resides in minimizing the dose while preserving or even enhancing image quality. This is what the EOS system (Biospace, Paris, France) claims to do. This new slot-scanning radiograph imager allows the acquisition of radiograph images while the patient is in weightbearing position. Physical properties of slot-scanners suggest high-quality images with less irradiation than standard imagers. Collimation of both the beams and detectors minimizes the scattered radiation, potentially enhancing effective detective quantum efficiency, and increasing the detected signal-to-noise ratio (SNR). This improvement should translate into the desired combination of high image quality and reduced dose.7,8 This article intends to further investigate this assertion by means of a thorough clinical study on patients fol989

990 Spine • Volume 35 • Number 9 • 2010

lowed up for scoliosis. Dose assessment of the EOS system is conducted through a combined image quality and entrance skin dose comparison with the CR system formerly dedicated to scoliosis radiograph examinations at our site. Weighing both aspects concurrently is essential since dose can be arbitrarily decreased, but at the cost of lower image quality. Our results will also be compared with dose measurements that were obtained for scoliosis examinations from other pediatric centers.9 –12 Materials and Methods Scoliosis Radiologic Follow-up Examination This study respects the standard radiological examination designed for spinal deformity follow-up developed through a collaboration of the orthopedic and medical imaging departments. The clinical setup combines the acquisition of posteroanterior (PA) and sagittal views of the spine. A setup was designed to avoid any major alteration to the natural posture. Patient must be in weight-bearing position, arms folded at 45° in order to avoid superposition with the spine in the radiograph image. Images were taken, so at least the last cervical vertebra and the pelvis were visible.

Radiographic Systems The EOS system, shown in Figure 1, is a new slot-scanning radiologic device that allows the acquisition of 2 x-ray images simultaneously. It is composed of 2 x-ray sources, shaped as fan beams through collimation slits. The sources are coupled to linear detectors built using the micromesh gaseous structure technology.13 Distance between sources and detectors is 1.3 m, with the patient standing at approximately 1 m of both sources. The 2 source-detector pairs are positioned orthogonally, so the patient’s face and profile images are generated line-by-line while the whole system is vertically translated. The system also offers the possibility to activate only one source for single view image acquisition.

The user determines the start and finish heights of the vertical scan. This way, irradiation to body parts outside the region of interest is minimized. The result is a pair of digital images, with height depending on the vertical course’s length while each line contains 1764 pixels. Image resolution at the detector is isotropic at 254 m, but a numerical rescaling reconstructs the images in the patient’s plane. Default settings assume the patient is standing at the intersection of the beams. In this case, effective resolution is brought down to 193 m by 185 m for the frontal view and to 179 m by 185 m in the lateral view. Horizontal resolutions differ due to a slight variation in distance between patient and detector for the 2 incidences. Image’s dynamic is particularly wide, spreading over 30,000 gray levels. For a spine examination, scan time lasts from 8 to 15 seconds, depending on the patient’s height. Patients are asked to hold their breath during the scan. Since images are taken simultaneously, there is no movement of the patient between each radiograph. This characteristic benefits techniques such as 3-dimensional reconstruction of bony structures from 2 radiographic views since their accuracy depends strongly on the spatial correspondence of the structures from one view to the other.14,15 Comparison was conducted with a Fuji Computed Radiography FCR 7501S system. It consists of a standard radiograph source and 3 embedded photostimulable phosphor imaging plates. Each image is generated by exposing one of these plates. The plate is then read and images are digitized and stored. A new plate is brought forward and the system is ready for a new acquisition. Distance between source and imaging plates is 1.83 m, with the patient standing approximately 30 cm from the plate. Frontal and lateral views are acquired separately, one after the other. During the examination, the patient is positioned on a rotating platform to minimize variation of the posture between acquisitions. This setup was developed in part to reach adequate accuracy when performing 3-dimensional reconstruction from stereoscopic techniques. Images spatial resolution is 400 400 m. Intensity information is stored on a standard 4096 gray levels dynamic range.

Radiographic Parameters

Figure 1. EOS slot-scanning radiologic device.

Clinical radiologic parameters for the CR system have been chosen by the medical imaging team in order to generate diagnostic images with the lowest possible irradiation dose. So as to conduct a fair comparison of the systems, we fixed the technical parameter of the slot-scanner to match the CR image quality. This was achieved by keeping the same tube voltage for both systems while varying the tube currents. This way, the x-ray penetration in tissues is kept constant while the dose is adjusted. On the CR, dose is increased with respect to patient’s thickness at the iliac crests. For the same patient, we computed the dose required to generate image quality on the slot-scanner that would be similar to the one observed on the CR. This is achieved by acquiring images of a step phantom, made of lucite and aluminum stairs for several tube currents on EOS and CR. These images depict signal intensities with respect to x-ray attenuation through different lucite and aluminum thicknesses. A second acquisition sequence was carried out with a block of lucite added behind the phantom to reach thicknesses comparable to clinical examinations for the scoliosis study of larger patients.

Spine X-ray Low-Dose System • Deschênes et al 991 stance, thermoluminescent dosimeter dose readings imply lengthy and burdensome annealing processes while the same reading can be obtained in 10 seconds by simply turning a knob on the OSLD reader. Thirteen locations, easily spotted on patients of different shapes, were chosen to assess the main radiosensitive regions of the body. Figure 2 shows their positions on a RANDO phantom (Phantom Laboratory, Salem, NY). Two radiological technicians were thoroughly trained to correctly install the dosimeters.

Clinical Study and Image Quality Evaluation Figure 2. Dosimeters’ positions for the study, shown on a RANDO anthropomorphic phantom. Image quality is characterized using the SNR computed for regions of various attenuations in the phantom image. Matching images with comparable SNR in both methods leads to the definition of equivalent techniques on the EOS system.

Dose Evaluation We chose Optically Stimulated Luminescence Dosimeters (OSLD) (Landauer, Glenwood, IL) to evaluate the entrance skin dose. These sensors, composed of aluminum oxide crystals (Al2O3:C), are invisible on the radiographs. After being exposed to ionizing radiation, dose can be measured by stimulating the crystal with green light. As a result, the crystal emits blue light proportionally to the amount of radiation exposure. These dosimeters are sensitive to doses as low as 10 Gy and up to 100 Gy. This range largely covers the exposure values expected in this study. Besides, OSLD are very easy to read and manipulate, unlike thermoluminescent dosimeters. For in-

A total of 50 patients (39 female, 11 males) needing spine radiographs, were recruited for this study. The patients (age, 14.8 3.6 years) underwent examinations on both CR and EOS, 15 minutes apart. For each patient, a dosimeter set was installed and the first radiograph examination conducted. The complete set of dosimeters was then changed and stored for later analysis. The same steps were followed for the second examination. Images were anonymized and saved for later reading while dose values were read and stored in a database. An example of images obtained from this study is shown in Figure 3. One patient’s radiographs had to be rejected due to a technical problem during image acquisition. Proficient dose comparison must be correlated with an evaluation of image quality. Quantitatively assessing image quality was conducted using a questionnaire based on the “European Guidelines for Quality Criteria for Diagnostic Radiographic Images in Pediatrics”16 and adapted by medical experts to fit the clinical and research needs for scoliosis. Namely, the focus was placed on structures used to either define anatomical landmarks involved in the computation of clinical parameters, such as Cobb angles and vertebral rotations, or to generate a 3-di-

Figure 3. A, Posteroanterior and lateral view of a patient taken with the CR system and (B) radiographs of the same patient acquired by the slot-scanner.

992 Spine • Volume 35 • Number 9 • 2010

Table 1. Anatomical Structure Evaluated by Experts T1–T7 vertebrae Vertebral body Pedicles Transverse process Spinous process T8–T12 vertebrae Vertebral body Pedicles Transverse process Spinous process L1–L5 vertebrae Vertebral body Pedicles Transverse process Spinous process Pelvis Iliac crest Femoral heads Other structures Craniocervical junction Clavicles Rib cage Cervicothoracic junction Lumbosacral junction

mensional surface model from stereoradiographic reconstruction methods. Table 1 lists the structures retained for the purpose of this study. A blind evaluation of image quality was conducted on all images by 2 orthopedists and 2 radiologists. They randomly examined 196 images using the questionnaire mentioned above. The visibility of each structure was evaluated on a 4 level scale: (1) Structure not detectable; (2) Structure visible but features not perceptible; (3) Features discernible but not clearly defined; and (4) Features clearly defined. At first, a simple assessment of the comparative paired scores was performed. Statistical analysis of the questionnaire results followed, using all paired visibility scoring to perform a Wilcoxon test. This test is a nonparametric alternative to the paired Student t test. An interobserver agreement evaluation is then obtained using an analysis of variance on the results from the 4 experts who filled the questionnaires. All statistical results were computed using the SPSS software.

Results Based on their position relative to the beam, 7 of the 13 dosimeters’ locations were selected to evaluate entrance skin dose. Each of the points was facing the beam for at least 1 of the 2 incidences. As seen in Table 2, average radiation dose measured with EOS was consistently lower at all points, reducing dose as much as 9.2 times compared to the CR system. Entrance skin dose is decreased from 6 to 9 times with EOS for the thoracoabdominal region while 3 times less radiation hits the nape of the neck. The dose reduction at this point is inferior due to each system’s geometry. CR produces conic projection, whereas an EOS scan produces a cylindrical projection. In the slot-scanner’s configuration, the x-rays travel less distance to reach the neck compared to the source of the CR, which is centered near the thoracolumbar junction.

Table 2. Average Dose Measured With Dosimeters Directly Facing at Least 1 of the X-ray Sources Number 2 5 6 7 9 11 12

Anatomic Entrance Point Nape of the neck Center of the back Proximal lateral point Outer side of the proximal breast Proximal anterosuperior iliac spine Proximal iliac crest Distal iliac crest

EOS Dose

Fuji Dose

Ratio

0.20 mGy 0.18 mGy 0.27 mGy 0.11 mGy

0.59 mGy 1.04 mGy 2.38 mGy 0.83 mGy

2.9 5.9 8.8 7.6

0.16 mGy

1.47 mGy

9.2

0.30 mGy 0.11 mGy

2.47 mGy 0.73 mGy

8.2 6.5

Image quality results are shown in Table 3. As expected from our radiographic parameter optimization, a majority (51% and 62%) of the comparison criteria shows equal scores for both systems. However, in the case where a bias toward a system arises, results show that the EOS system is favored in a large proportion. These observations are supported by a Wilcoxon statistical analysis of all visibility scoring. Results show that visibility on EOS images is significantly better (P 0.006) for all structures in the PA view. EOS is also significantly better (P 0.037) for all structures in sagittal view with one exception: the lumbar spinous process for which Fuji has better visibility (P 0.003). Interobserver agreement was assessed using an analysis of variance test. It showed that the experts agree on the visibility all structures in PA views, except for one reader at odds regarding the lumbar transverse process. In the sagittal view, the experts agree for all structures above the lumbar region. Results are less consistent for the lumbar region. This can be explained by the fact that the scanning technique delivers a uniform dose across the vertical span of the examination. Technical parameters were set to reach equivalent image quality, but since the amount of radiation varies with the geometry of the xray beam, a trade-off had to be made. In our case, the CR’s tube is aligned with the lumbar region, where the patient’s thickness is maximal. Conic projection leads to reduced irradiation for more distant anatomy like the cervical spine. This is fortunate since patient’s thickness is lesser in this region. In contrast, slot-scanning gives equivalent dose throughout the translation of the sourcedetector couple. Therefore, we decided on setting the technical parameters to match image quality around the thoracic spine. This way, dose reduction is less and image quality is maximal around the cervical region while

Table 3. Image Quality Comparison Between SlotScanner and Computed Radiography System

Global image quality Structures visibility

EOS CR

CR EOS

50.5% 61.9%

46.7% 32.4%

2.8% 5.7%

Spine X-ray Low-Dose System • Deschênes et al 993

Figure 4. Image formation using a system with conic projection.

dose reduction is maximal in the lower lumbar part of the spine, at the cost of image quality. Lastly, we compared the slot-scanner’s entrance skin dose with other studies measuring the entrance air kerma for scoliosis examinations. These results were weighed against entrance dose found at point 5 for the PA view and point 6 for the lateral view. For patients of age groups similar to our study, the lowest entrance dose, obtained on a CR system using air-gap and no antiscatter grid, was still 18% higher than with the slot-scanner.9 However, no image quality assessment was presented with this technique. Other studies, using both CR and digital radiography systems, show average entrance doses varying from 0.5 mGy to 3.1 mGy in PA view and 0.89 mGy and 3.9 mGy in lateral view.10 –12 This corresponds to 3 to 18 times more dose than what is given by the slot-scanner. Discussion The slot-scanning technology offers dose reduction benefits while considerably enhancing image quality. The main drawback resides in the fact that uniform dose is delivered across the entire area of the body. This translates in a similar irradiation along the scan even though patients’ thickness varies. It also leads to compromises during the choice of the optimal parameters. We opted for a technique that would match image quality from both systems for a region around the thoracolumbar junction. That choice could explain the poorer results encountered for the lumbar region. On the other hand, the fact that the slot-scanner’s beams are always aligned with the detectors can also improve visual representations of anatomy. As shown in Figure 4, usual CR system will project information on the image plane through a conic perspective. This causes distortion from the center to the edges of the radiograph, leading to increasing errors in scale for structures far from the central region. Due to the fan-beam geometry, slot-scanning only encounters this distortion along the horizontal axis, as can be seen in Figure 5. However, this cylindrical projection’s deformation of the image is corrected by the numerical rescaling performed by the system’s visu-

Figure 5. Image formation using a slot-scanner with cylindrical projection geometry.

alization interface. This way, the image is reconstructed as if it was acquired in the patient’s reference plane and limits the distortion to the patient’s thickness instead of the whole distance between source and detector. With standard CR, radiographs are attenuated by the patient’s body following trajectories more or less tilted with respect to the center line. Therefore, structures that are close to be aligned with the horizontal plane, like intervertebral discs and vertebral endplates, will partly overlap far from the source. The result is a lower contrast between these tissues. Slot-scanner’s projection geometry therefore enhances contrast for structures lying in the horizontal plane. An example of this behavior can be seen in Figure 6, where higher delineation between the disc and vertebral endplates is observed in the upper thoracic spine imaged with the slot-scanner. Projection geometry also shows a faster occlusion of the cervical spine by the patient’s head. Studies are presently underway to evaluate the effect of the EOS projection on clinical parameters. Overall, the EOS system shows better image quality while substantially reducing patient’s dose exposure. The dose reduction could further be improved by including an automatic exposure control similar to what is found in modern CT-scanners. This way, an optimal amount of dose could be delivered with respect to the patient’s morphology. Evaluations of organ dose and effective dose are presently being finalized. A comparison between EOS and a digital radiography system for chest radiographs is also underway. From a clinical perspective, one of the most interesting features of the slot-scanner is the possibility to simultaneously acquire 2 orthogonal images. This considerably facilitates the 3-dimensional surface reconstruction of vertebrae and pelvis using stereoscopic algorithms. New clinical parameters can then be computed, potentially offering information more appropriate than the 2D indexes normally used to assess the deformity. It is inter-

994 Spine • Volume 35 • Number 9 • 2010

Figure 6. Delineation of the intervertebral spaces in (A) a CR system with conic projection and (B) a slot-scanner with cylindrical projection geometry.

esting to note that this 3-dimensional representation is obtained using hundreds of times less irradiation than what is required by a CT-scan image reconstruction. Key Points ●

●

This work presents a dosimetry study of radiograph examinations for spinal deformities follow-ups. The evaluation is based on a thorough comparison of doses and images obtained from a slotscanner and a CR system. Dose evaluation shows that the slot-scanner delivers 6 to 9 times less entrance dose than the CR system. Four experts agree that image quality is significantly better for slot scanner.

Acknowledgments The authors thank the team of nurses, research associates, and radiologic technologists from both departments of medical imaging and orthopedics in CHU Sainte-Justine for their participation in this project. References 1. International Commission on Radiological Protection. Recommendations of the International Commission on Radiological Protection. Oxford: Pergamon Press; 1991. Publication 60, Annals of the ICRP, vol 21(1–3). 2. Brenner DJ, Hall EJ. Computed tomography—an increasing source of radiation exposure. N Engl J Med 2007;357:2277– 84.

3. Brenner DJ. Estimating cancer risks from pediatric CT: going from the qualitative to the quantitative. Pediatr Radiol 2002;32:228 –31. 4. Bone CM, Gordon H. The risk of carcinogenesis from radiographs to paediatric orthopaedic patients. J Pediatr Orthop 2000;20:251– 4. 5. Hoffman DA, Lonstein JE, Morin MM. Breast cancer in women with scoliosis exposed to multiple diagnostic x-rays. J Natl Cancer Inst 1989; 81:1307–12. 6. Doody M, Lonstein J, Stovall M, et al. Breast cancer mortality after diagnostic radiography. Spine 2000;25:2052– 63. 7. Samei E, Saunders R, Lo JY, et al. Fundamental imaging characteristics of a slot-scan digital chest radiographic system. Med Phys 2004;31:2687–98. 8. Samei E, Lo JY, Yoshizumi T, et al. Comparative scatter and dose performance of slot-scan and full-field digital chest radiography systems. Radiology 2005;235:940 –9. 9. Hansen J, Joric AG, Fiirgaard B, et al. Optimisations of scoliosis examination in children. Pediatr Radiol 2003;33:752– 65. 10. Geijer H, Beckman KW, Jonsson B, et al. Digital radiography of scoliosis with a scanning method: initial evaluation. Radiology 2001;28:402–10. 11. Gogos K, Yakoumakis E, Tsalafoutas I, et al. Radiation dose considerations in common paediatric x-ray examinations. Pediatr Radiol 2003; 33:236 – 40. 12. Gialousis G, Yiakoumakis EN, Makri TK, et al. Comparison of dose from radiological examination for scoliosis in children among two pediatric hospitals. Health Phys 2008;94:471– 8 13. Després P, Beaudoin G, Gravel P, et al. Physical characteristics of a low-dose gas microstrip detector for orthopedic x-ray imaging. Med Phys 2005;32: 1193–204. 14. Deschenes S, Pomero V, Godbout B, et al. Vertebral pose estimation using edge-based pattern matching and stereoradiographic 3D reconstruction of the spine. In: International Research Society of Spinal Deformities Meeting; 2004:187–90. 15. Cresson T, Godbout B, Branchaud D, et al. Surface reconstruction from planar x-ray images using moving least squares. Conf Proc IEEE Eng Med Biol Soc 2008;2008:3967–70. 16. European Commission. European guidelines on quality criteria for diagnostic radiographic images in pediatrics. Luxembourg, Europe: Office for Official Publications of the European Communities; 1964:15– 64. Report EUR 16261EN.

European Journal of Radiology 83 (2014) 371–377

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European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad

Ionizing radiation doses during lower limb torsion torsion and anteversion measurements by EOS stereoradiography and computed tomography

Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography Cyrille Delin a,∗,1 , Stéphane Silvera b,2 , Céline Bassinet c,3 , Philippe Thelen a,1 , Jean-Luc Rehel c,3 , Paul Legmann b,2 , Dominique Folinais a,1 a

Réseau d’Imagerie Médicale Maussins-Nollet, 114 rue Nollet, 75017 Paris, France Service de Radiologie A, Hôpital Cochin, 27 rue du Faubourg Saint Jacques, 75014 Paris, France c Institut de Radioprotection et de Sureté Nucléaire, BP 17, 31 Avenue de la Division Leclerc, 92262 Fontenay-aux-Roses Cedex, France b

a r t i c l e

i n f o

Article history: Received 8 April 2013 Received in revised form 29 October 2013 Accepted 29 October 2013 Keywords: Dosimetry CT scan Stereoradiography Lower extremity Genital organs

a b s t r a c t Objectives: To calculate and compare the doses of ionizing radiation delivered to the organs by computed tomography (CT) and stereoradiography (SR) during measurements of lower limb torsion and anteversion. Materials and methods: A Rando anthropomorphic phantom (Alderson RANDO phantom, Alderson Research Laboratories Inc., Stanford, Conn) was used for the dose measurements. The doses were delivered by a Somatom 16-slice CT-scanner (Siemens, Erlangen) and an EOS stereoradiography unit (EOS-Imaging, Paris) according to the manufacturers’ acquisition protocols. Doses to the surface and deeper layers were calculated with thermoluminiscent GR207P dosimeters. Dose uncertainties were evaluated and assessed at 6% at k = 2 (that is, two standard deviations). Results: The absorbed doses for the principal organs assessed were as follows: for the ovaries, 0.1 mGy to the right ovary and 0.5 mGy to the left ovary with SR versus1.3 mGy and 1.1 mGy with CT, respectively; testes, 0.3 mGy on the right and 0.4 mGy on the left with SR versus 8.5 mGy and 8.4 mGy with CT; knees, 0.4 mGy to the right knee and 0.8 mGy to the left knee with SR versus 11 mGy and 10.4 mGy with CT; ankles, 0.5 mGy to the right ankle and 0.8 mGy to the left with SR versus 15 mGy with CT. Conclusion: The SR system delivered substantially lower doses of ionizing radiation doses than CT to all the organs studied: CT doses were 4.1 times higher to the ovaries, 24 times higher for the testicles, and 13–30 times higher for the knees and ankles. The use of the SR system to study the torsion of lower limbs makes it possible to reduce the amount of medical irradiation that patients accumulate. © 2013 Elsevier Ireland Ltd. All rights reserved.

1. Introduction Lower limb torsion values (anteversion of femoral necks or torsion of the knees or legs) play a role in the functioning of these limbs and in the development of osteoarthritis of the hip [1]. These values

Authors or their institution did not at any time receive payment or support in kind for any aspect of this work (including but not limited to grants, data monitoring board, study design, manuscript preparation, statistical analysis, etc.. . .). ∗ Corresponding author. Tel.: +33 142264900; fax: +33 142284490. E-mail addresses: cdelin@maunol.fr (C. Delin), stephane.silvera@gmail.com (S. Silvera), celine.bassinet@irsn.fr (C. Bassinet), pthelen@maunol.fr (P. Thelen), jean-luc.rehel@irsn.fr (J.-L. Rehel), paul.legmann@cch.aphp.fr (P. Legmann), dfolinais@gmail.com (D. Folinais). 1 Tel.: +33 142264900; fax: +33 142284490. 2 Tel.: +33 158412469; fax: +33 158412475. 3 Tel.: +33 158358306; fax: +33 147469777.

must be measured before placement of hip or knee prostheses [2] but also before osteotomies for femoral or tibial correction of bone calluses or dysmorphisms. They are also useful before surgical revision of hip and knee prostheses in cases of poor positioning, given the frequent imprecision of surgeons’ intraoperative evaluation of prosthetic femoral anteversion [3]. Orthopedists and radiologists have long used computed tomography (CT) to take these measurements [4]. Its advantages include ease and speed of performance, combined with the wide availability of equipment. CT examination also provides a look at bone morphology and at the quantity and qualite of the bone matrix. Its greatest disadvantage is its irradiation, especially of the pelvis and genital organs. Lower limb torsion is measured most often among the elderly (65 years or older) during work-ups before or after prosthesis placement. Nonetheless, work-ups before correction of acquired or congenital dysmorphisms involve a younger population (younger

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Table 1 Scanner parameters. Scanner

Region explored

High-tension (kV)b

Current (mAs)c

Collimation (mm)

Acquisition length (cm)

Pitch

CTDI volume (mGy)a

DLP§ (mGy cm)

Siemens sensation 16

Hips Knees Ankles

120 120 120

98 90 113

12 12 12

18.5 12.1 5.6

1 1 1

7.57 7.02 8.79

150 93 64

Three acquisitions were performed for each area of interest to have adequate statistics for the thermoluminescent signal. Manufacturer’s acquisition protocol (use of the Care Dose) were used. a CTDI: computed tomography dose index. b kV: tube voltage. c mAs: tube current. §

DLP: dose length product.

than 18 years). Some abnormalities even require regular followup (surgery to lengthen an unequal leg) with repeated lower limb measurements. These examinations are a source of irradiation and its risks are greatest for the youngest subjects [5,6]. Population irradiation from medical sources has been rising quite substantially; in the US, the annual such dose received per person has climbed from 0.53 mSv in 1980 to 3.1 mSv, on average, with the mean overall dose rising from 3 mSv to 5.6 mSv [7,8]. Some studies [8] suggests that the effective cumulative dose from radiologic procedures exceeds 20 mSv per year for approximately 4 million nonelderly American adults (from 18 through 64 years of age) and 30 to 40% of this subpopulation receiving high doses is younger than 50 years. CT scans are very largely responsible for this increase: the number of CT scans increased by more than 10% per year from 1993 to 2008 (although the US population has increased at less than 1% annually) [7]. Accordingly, in 2006, CT was responsible for 49% of the collective effective doses from radiology and nuclear medicine procedures in the US, even though these CT examinations accounted for only 17% of all procedures [7]. No data are currently available about the number of CT examinations performed annually to measure lower limb torsion. We can nonetheless suppose that it is rising, in view of the aging of the population in western countries and the consequent increase in the number of cases of osteoarthritis and joint replacement surgery [9,10] even if presurgical assessment of lower limb torsion is not routine in all countries. A 3D stereoradiography (SR) unit named EOS (EOS-Imaging, Paris, France), a full-body imaging system, has been used to model spinal scoliosis in 3D and thereby obtain precise measurements of the spine [11]. This system uses very sensitive ionization chamber detectors, based on Charpak’s multiwire chamber technique, and an X-ray source collimated in a narrow beam that scans the area to be explored. It thus makes it possible to use very low doses of Xrays. The doses used in work-ups of scoliosis are 6 to 9 times lower than those from full spine radiography [12], the standard technique for studying the spine in standing position. This SR system can also be used for the lower limbs to determine both morphologic (bone dimensions and torsion) and static (ﬂexion, varus or valgus) parameters [13,14] with the patient standing in his or her natural position. CT is the technique currently used to measure lower limb torsion. Two recent studies have shown that the SR system and CT perform similarly in measuring femoral and tibial torsion and essentially provide interchangeable measurements [14,15]. Neither the X-ray dose delivered during this SR examination of the lower limbs nor the dose delivered during a helical CT examination for torsional measurements has ever been measured by direct dosimetry. Only several very old studies explored the doses from torsional measurements taken by the (now obsolete) sequential CT [16–19]. The aim of this study is to compare the doses delivered to the lower limbs and pelvis by helical CT and SR during measurements of torsion of the lower limbs.

2. Materials and methods 2.1. CT and EOS protocols Dosimeters acquired the doses delivered by a CT scanner (Sensation 16 model, Siemens, Erlangen, Germany) and the EOS system (EOS-Imaging, Paris, France). For the CT scanner, the protocol called for the helical acquisition of the anteroposterior (AP) scout (digital) view, focused on 3 areas of interest: (1) the coxofemoral joints and entire femoral necks; (2) the knees (femoral condyles and tibial plateaus); and (3) the ankles (malleoli). Table 1 reports the scanner’s acquisition characteristics. We used the manufacturer’s acquisition protocol, adapted to the height and weight of the individual represented by the phantom, without modification, as well as the scanner’s dose reduction system (Care Dose). The SR system acquired the images by continuous simultaneous scanning of both whole limbs, in standing position (cf. Fig. 1), by two orthogonal narrow (collimated) X-ray beams. Table 2 summarizes the technical characteristics of the acquisition, for which we again used the manufacturer’s acquisition protocol adapted to the height and weight of the individual represented by the phantom. A SR examination does not require a preliminary scout view, and the starting point of the acquisition is chosen by using the graduated landmarks available on the system (see Fig. 2). The two X-ray beams make it possible to obtain 2 planar images, from which a model of the patient’s lower limbs (see Fig. 3) can be calculated, given the fixed mounting positions of the X-ray sources and detectors. Lower limb anatomical measurements (anteversion of the femoral neck, leg and knee torsion), normally determined by CT (see Fig. 4), were also calculated by SR, which can also calculate numerous other measurements (lower limb varus or valgus, total limb or segment lengths, HKS angle, cervical length, femoral offset, and cervicodiaphyseal angle), some of which (lower limb standing positions, for example) cannot be calculated by CT (because the patient is in a lying position in the CT scanner and standing in the SR system) [20,21]. 2.2. Dosimetry The doses received by a Rando phantom (Alderson RANDO phantom, Alderson Research Laboratories Inc., Stanford, Conn) were measured. This phantom (composed of abdominal and pelvic segments as well as lower limbs) corresponds to a medium-sized subject (1.75 m and 73.5 kg). All measurements were made with dosimeters made of LiF, Mg, Cu, P (GR207P) thermoluminescent powder placed in plastic tubes (diameter: 5 mm, length: 25 mm), placed in 25-mm slices inside the phantom, at the level of the ovaries (4 dosimeters in each ovary) (see Fig. 5). The ovarian dosimeters were in the EOS irradiation field, but were just above the scanner irradiation field (so that the dosimeter measured only the radiation scatter received by the ovaries in CT). Other

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C. Delin et al. / European Journal of Radiology 83 (2014) 371–377 Table 2 EOS stereoradiography parameters.a Type system

Incidence

High-tension (kV)c

Current (mAs§ )/line)

Collimation (mm)

Acquisition length (cm)

SDP (mGy cm2 )b

EOS

AP Lateral

90 120

0.67 1.07

0.5 0.5

109 109

559 1461

Three acquisitions were performed for each area of interest to have adequate statistics for the thermoluminescent signal. a Manufacturer’s acquisition protocol. b SDP: surface dose product. c kV: tube voltage. § mAs: tube current.

Fig. 1. EOS stereoradiographic (SR) system. (A) An EOS stereoradiographic (SR) system with a subject in position for image acquisition. (B) Technical drawing of the SR system with its two X-ray sources (black stars) of the two orthogonal X-ray beams, with the ﬁeld of exploration situated inside the trapezoid outlined in orange (black arrowheads).

Fig. 2. Rando phantom and the SR device. (A) Rando phantom for the lower limbs, in standing position, in the SR device. The choice of the superior level for the image acquisition zone is based on graduated landmarks placed on the instrument ﬂank (white arrows) without an initial scout view. (B) SR images of the phantom, composed of two images: anteroposterior and lateral.

dosimeters were placed on the surface of the phantom, at the knees and ankles, on the anterior side of these joints as well as on the inside of the right knees and ankles and outside of the left knees and ankles, given that the EOS X-ray sources were in front and on

the left side of the patient. Moreover, 2 dosimeters were placed on the surface at the location of the testes. Dosimeter placement on the phantom surface was identical for the acquisitions by CT and SR and within the irradiation ﬁeld of both machines. The dosimeters were

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Fig. 3. Example of gonometry with the 3D SR system. (A) Anteroposterior and lateral images with modeling of the surface. (B) Resulting in a 3D model of the lower limbs.

Fig. 4. Example of torsional measurements by CT. (A) Thick axial section at the hip with a measurement of the angle of the femoral neck relative to the horizontal (18◦ ). (B) Thin axial section at the femoral condyles with a measurement of the condyle anteversion relative to the horizontal (1◦ ). Subtracting this angle from the preceding one (A) yields an angle of 17◦ for the anteversion of the femoral neck relative to the femoral condyles. (C) Thin axial section at the tibial plateaus with a measurement of the angle of their posterior edges relative to the horizontal (7◦ ). (D) Thin axial section at the malleoli with a measurement of the bimalleolar angle compared with the horizontal (31◦ ). Subtracting the preceding angle from this one yields a measurement of 24◦ for the tibial torsion.

calibrated at the reference irradiation facilities of the IRSN Ionizing Radiation Dosimetry Laboratory (LDRI, metrology laboratory, clearance number n◦ 2-1612). Dose calibration was performed with cobalt-60 in terms of experimental and applied air kerma with electron equilibrium conditions. To take into account the difference in

energy response of dosimeters in spectra similar to those encountered on the radiologic devices, correction factors determined at the LDRI for this type of thermoluminescent powder were applied. Air kerma was converted to tissue kerma by applying the coefﬁcients in the literature [22].

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Fig. 5. Position dosimeters ovaries. (A) Slice of the Rando phantom at the level of the pelvis with placement of the dosimeters (white arrows) recording the X-ray dose delivered to the ovaries. (B) Same slice of the Rando phantom (arrowheads) on the SR device. (C) Same slice of the Rando phantom (arrowheads) on the scout view of the CT-scan.

Due to the lower sensitivity of the powder and to have sufficient statistical data for the thermoluminescent signal, 3 identical exposures of each phantom measurement were acquired with each technique (cumulative mode). The doses reported in the results have been normalized to 1 acquisition and are expressed as tissue kerma. Dose uncertainties were evaluated according to the rules recognized in the literature [23] and assessed at 6% at k = 2 (that is, two standard deviations). 2.3. Assessment of image quality A subjective assessment of image quality was performed only on the EOS images of the Alderson RANDO phantom, while the images obtained by the CT scanner used the manufacturer’s parameters, validated by the company. Because the EOS device is such new technology, we felt it would also be useful to confirm that the quality of the images obtained with the constants we studied (furnished by the manufacturer) was good enough for a good analysis. Thirty-one consecutive patients (mean age, 63.7 years; range, 39–76 years) who had undergone EOS knee examinations were retrospectively included in the present study. These EOS examinations had been performed for pretreatment work-ups of osteoarthritis of the hips or knees and were used to make 3D models of the patients’ lower limbs. Exclusion criteria were EOS parameters different from those used in the study. Approval of the local institutional ethics board for research was not necessary because of the retrospective study design. Image data were anonymized and reread on the sterEOS workstation that is integrated with the EOS-system. Two radiologists with more than 4 years (C.D. and D.F.) of experience in EOS imaging assessed the image quality, rating their visual perception of noise in all data sets in AP and lateral views as minimal (score 1, excellent image quality), moderate (score 2, satisfactory image quality that did not impede diagnostic accuracy), or severe (score 3, poor image quality impeding diagnostic accuracy). Interobserver agreement between the two readers was evaluated with the Kappa statistic. Agreement was considered moderate for values of 0.4–0.6, substantial for values of 0.6–0.8, and high for values of 0.8–1. We did not study the quality of the CT images, because the acquisition protocols used to study lower limb torsion and anteversion are well defined and have been validated by the manufacturers. We also did not use experimental low-dose CT protocols, which, contrary to these standard images, might require consideration of whether the reduction in the quantity of X-rays used resulted in a reduction in the quality of the images. 3. Results All images were acquired with the techniques recommended by the manufacturers of these machines to obtain images of adequate

diagnostic quality. The helical acquisitions and the scout views were summed to determine the CT doses to each organ. The maximum surface entrance dose measured on the anterior side of the phantom pelvis was 0.57 mGy with SR, with a posterior exit dose of 0.15 mGy. The maximum surface dose measured with the CT scanner (combining entrance and exit doses because of the circular movement of the X-ray tube) was 1.2 mGy for the posterior side of the pelvis and 0.71 mGy for the anterior side. Table 3 summarizes the doses received by the different anatomic regions. Normalized to 1 acquisition and expressed as tissue kerma (see Table 3), the SR doses at the level of the ovaries were 0.1 mGy on the right and 0.5 mGy on the left, and the CT scanner doses, 1.3 mGy and 1.1 mGy, respectively. For the testes, the absorbed doses were 0.3 mGy on the right and 0.4 mGy on the left with SR, and 8.5 mGy and 8.4 mGy with the CT scanner. For the ovaries, the absorbed dose during the CT examination was 4.1 times higher than that absorbed during the SR examination. For the testes, the absorbed dose during CT was 24 times the absorbed dose with SR. For the image quality assessment of the SR system, the mean of the subjective score was 1.11 ± 0.08. The interobserver agreement was high, with a k value of 0.84. 4. Discussion The effects of low doses (approximately 10 mGy) and very low doses (1 mGy or less) on the risk of radiation-induced cancer have been hotly debated for many years. During very low X-ray doses, the cell damage is the same as at low doses, but the number of cells affected diminishes linearly as the dose decreases. This is the argument for a linear no-threshold (LNT) model to estimate the effects of ionizing radiation on living tissue [24]. Nonetheless, a range of recently observed untargeted effects of biological responses to radiation shows other mechanisms of activity that might be important in determining biological responses at very low doses of radiation [25]. Currently, however, no experimental or epidemiologic study has clearly conﬁrmed or disproved the LNT model [26,27], which has been used in several studies to estimate the risks of radiationinduced cancer and which serves as the principal reference for the recommendations of the International Commission on Radiological Protection (ICRP 103, 2007). Richards et al. [28] calculated a risk ratio for inducing cancer of about 1 in 3200 for a CT scan of the whole lumbar spine and about 1 in 1800 for the whole dorsal spine, while the risk ratio calculated by Smith-Bindman et al. [5] for inducing cancer is about 1 in 4100 for a 20-year-old woman having a routine CT brain scan; the risk ratio for CT coronary angiography is considerably higher. Other studies of the consequences of irradiation during CT in children [29] and adults undergoing full-body CT screening [30] also found slight but nonzero increases in the risk of death from radiation-induced cancer. The SR unit studied is an X-ray system utilizing ionization chamber detectors that allow the use of low doses of X-rays. This SR

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Table 3 Dose as tissue kerma (mGy). Type system

SR CT CT/SR

Ovaries

Testicles

Knees

Ankles

Right

Left

Right

Left

Right

Left

Right

Left

0.1 1.3 13

0.5 1.1 2.2

0.3 8.5 28.3

0.4 8.4 21

0.4 11 27.5

0.8 10.4 13

0.5 15.2 30.4

0.8 15.6 19.5

Dose normalized to 1 acquisition and expressed as tissue kerma. Conversion from air kerma to tissue kerma with coefﬁcients determined by Ref. [22].

device is used to study postural imbalance and, more recently, the lower limbs. It allows the calculation of all the data usually obtained with CT during measurements of lower limb torsion. Our results show that the dose received by the testes with EOS was around 24 times less than with CT, and the ovarian dose four times lower. This SR system thus makes it possible to reduce the doses delivered to patients and accordingly their risk of irradiation. This reduction is naturally lower for elderly patients [5], who make up the majority of the patients receiving this type of radiologic exploration; young subjects (pretreatment work-up of articular dysmorphisms or of the sequelae, of epiphysiolysis or osteochondritis, etc.) are only a minority. Nonetheless the young are at the greatest risk from ionizing radiation [5]. Moreover, these examinations are often repeated, sometimes several times (presurgical work-up, post-surgical assessment, later postoperative check-ups, or before surgical revision when there are problems). The scanner doses to the ovaries observed in our study are close to some previous assessments at the pelvis [7,31], although these relatively recent assessments do not correspond to a CT examination to measure femoral neck anteversion. Our CT results, on the other hand, disagree with findings from older studies [16,17,19], which used a sequential scanner, in which irradiation differed according to the number and site of each slice. Some groups used a slice passing by the femoral neck [16], or two slices through the cervix and the femoral head [17], or 3 slices [19] or more. Depending on the position of the slices, the ovaries could be directly in the scanning area, which would explain the greater irradiation in the studies by Waidelich et al. [18] (who found 2.5 mGy to the ovaries), Kushner et al. [17] (who found 480 mrad to the ovaries, that is, 4.8 mGy) and Hernandez et al. [16] (1.7 R, or 14.8 mGy at the center of the phantom). The age of the sequential scanner used in the latter study might also explain the high dose measured. In contrast, the position of ovaries out of the scanning plane could explain the low dose found by Buddenbrock et al. [19] (0.1 mGy at the ovaries). This irradiation field factor also explains the relatively low ovarian doses from CT in this study: the helical acquisition used now does not quite reach the theoretical position of the ovaries of the Alderson RANDO phantom. Thus the irradiation received by the ovaries in our study comes from scattered but not from direct irradiation. The doses to the testicles obtained with our scanner are higher than those reported by Waidelich et al. [18] (0.7 mGy) and Buddenbrock et al. [19] (0.5 mGy). The frequently low position of the testicles, at a distance from several of the slices, might explain the low dose observed in these older studies. Depending on the patient’s morphology, the testicles may or may not be in the field of irradiation. In our study, we considered the case of the testicles placed in the CT field, to measure the maximum dose that these organs might receive in this type of examination, as some surgeons request that the upper part of the femur be visualized to assess femoral bone capital. During CT, the doses we measured at the level of the testicles were 7 times higher than those at the ovaries, both because of the very small amount of tissue between the testicles and the X-ray source during a good portion of its movement and, especially, because the testicles are in the CT irradiation field, while the

ovaries received only radiation scatter. Nonetheless, this difference in the scanner doses received by the testicles and the ovaries is relatively close to the differences observed by both Waidelich et al. and Buddenbrock et al. [18,19]. Because the SR system uses continuous scanning of the lower limbs for image acquisition, the testicles are necessarily in the irradiation field. Similarly, because its starting point is imprecise (no scout view, with positioning according to external markers), acquisition starts higher up and includes the position of the phantom’s ovaries. Moreover, the absorbed dose for each paired organ studied (ovaries, testes, knees and ankles) was higher to the left side than to the right side in the SR system. The X-ray sources are in orthogonal to each other. One X-ray source faces the phantom, while the other is beside it, on its left side, so that all the left organs are closer to one of the X-ray sources (cf. Fig. 1) than are the right organs. This explains the left/right dose asymmetry: for ovaries the left/right ratio is 5; it is much less for testicles because they are closer to each other. The ratio is 2 for knees and a little less than 2 for ankles, partly because ankles are less thick and attenuate the X-rays less, and partly because ankles are closer to each other than knees are (cf. Fig. 1). The second SR X-ray source faces the subject, at an equal distance from the various organs in the same frontal plane. The surface dose with the SR system is therefore clearly greater to the anterior side of the pelvis than to its posterior side. With CT, the circular movement of the X-ray around the patient’s body does not produce any significant difference between the doses absorbed by the right and left organs (the small dose difference between the two ovaries on the CT scan in this study may be explained by a difference in density between the bony structures on the left and right side of the phantom’s pelvis). On the other hand, we cannot explain the presence of a posterior surface dose with CT clearly higher (69%) than that to the anterior surface at the level of the pelvis, for X-ray backscatter phenomena are clearly an insufficient explanation [32]. With the scanner, the doses we recorded at the knees (mean of 10.7 mGy) and ankles (mean of 15.4 mGy) are relatively close to those in the literature for CT explorations focused on knees (effective dose: 0.16 mSv [31]) and ankles (effective dose: 0.07 mSv [31]) after application of the tissue weighting factors [33]. This dose delivered to the ankles and knees results from the acquisition protocol recommended by the manufacturer, which used the dose reduction procedure (care dose) but kept the same constants on all three image acquisition zones (hips, knees and ankles). Few published studies have sought to optimize the dose received by patients during exploration of the lower limbs and more particularly the hips. Arai et al. [34] used a cadaver to optimize the irradiation used to measure acetabular cup orientation in total hip arthroplasty. The CT scan constants reported by this group (30 mA) are higher than those in our study, although the dose delivered by the scanner (1.1 mSv) that they calculated is very close to the dose we measured at the ovaries. Nonetheless, it seems difficult to us to compare irradiation doses from an examination exploring a bony skeleton and those calculated from an examination intended to assess the orientation of metal prosthetic components (therefore very dense) that remain visible by scanner despite the low acquisition constants used.

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Moreover, efforts to optimize irradiation doses, although implemented by some imaging centers that are highly aware of and competent in radioprotection, are far from widespread. Daily practice most often involves application of the manufacturer’s protocols with occasional modifications that lead to additional irradiation. Smith-Bindman [5] showed that in daily practice the effective dose varies significantly within and between institutions, with a mean 13-fold variation between the highest and lowest dose for each type of CT study. Our study has several limitations. First, we could have reduced the irradiation by the SR system still further, by using shields for radioprotection of the ovaries and testes or by placing the phantom with its back to one of the sources, thus increasing absorption of one of the two X-ray beams, required to cross a thicker layer of tissue to reach the genital organs. Nonetheless, the morphology of some patients can make shield positioning difficult. Similarly, positioning the patient’s back to one of the two sources is not always possible, for the morphology of some patients makes it difficult to control their exact placement in the machine. We chose to place the phantom in the SR apparatus in a position applicable to all patients, regardless of morphology. The constants used for CT were those recommended by the manufacturer, but they can of course be optimized by using iterative reconstruction protocols, especially to reduce the dose received at the knees and ankles. Nonetheless, to our knowledge, CT iterative reconstruction protocols for studying torsion of lower limbs are not well defined and depend on each radiologist’s choices. The choice of iterative reconstruction protocols can always be criticized and will require validation, as much for the legibility of the images as for their diagnostic quality. It is for this reason that we wanted to conduct this study using the manufacturer’s standard acquisition protocols, most often applied in current practice [5]. The acquisition constants for the SR system could also have been optimized, but for the same reasons as for the CT scanner, we chose to use the manufacturer’s standard protocol. Using the EOS SR system on the lower limbs in standing position to calculate their morphologic and static parameters resulted in an X-ray dose to the ovaries and testes clearly lower than with CT and reduced the patient’s lifetime total irradiation and the proportion attributable to medical use. In a single acquisition period, this 3D SR system also determined the valgus and varus measurements of the weight-bearing lower limbs [13]. This too should reduce the patients’ medical irradiation a little more, by avoiding the need for other medical imaging with X-rays. Acknowledgments We thank Michel Bourguignon for his advice in the preparation of this manuscript. References [1] Tonnis D, Heinecke A. Acetabular and femoral anteversion: relationship with osteoarthritis of the hip. J Bone Joint Surg Am 1999;81(12):1747–70. [2] Karachalios T, Hartofilakidis G. Congenital hip disease in adults: terminology, classification, pre-operative planning and management. J Bone Joint Surg Br 2010;92(7):914–21. [3] Dorr LD, Wan Z, Malik A, Zhu J, Dastane M, Deshmane P. A comparison of surgeon estimation and computed tomographic measurement of femoral component anteversion in cementless total hip arthroplasty. J Bone Joint Surg Am 2009;91(11):2598–604. [4] Widjaja PM, Ermers JW, Sijbrandij S, Damsma H, Klinkhamer AC. Technique of torsion measurement of the lower extremity using computed tomography. J Comput Assist Tomogr 1985;9(3):466–70. [5] Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 2009;169(22):2078–86.

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A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system. Bull Acad Natl Med 2005;189(2):287–97, discussion 297–300. [12] Deschenes S, Charron G, Beaudoin G, et al. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine (Phila Pa 1976) 2010;35(9):989–94. [13] Chaibi Y, Cresson T, Aubert B, et al. Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays. Comput Methods Biomech Biomed Eng 2011;15(5):457–66. [14] Buck FM, Guggenberger R, Koch PP, Pfirrmann CW. Femoral and tibial torsion measurements with 3D models based on low-dose biplanar radiographs in comparison with standard CT measurements. AJR Am J Roentgenol 2012;199(5). W607-12. [15] Folinais D, Thelen P, Delin C, Radier C, Catonne Y, Lazennec JY. Measuring femoral and rotational alignment: EOS system versus computed tomography. Orthop Traumatol Surg Res 2013;99(5):509–16. [16] Hernandez RJ, Tachdjian MO, Poznanski AK, Dias LS. CT determination of femoral torsion. AJR Am J Roentgenol 1981;137(1):97–101. [17] Kushner DC, Cleveland RH, Ehrlich MG, et al. Low-dose transaxial tomography. An alternative to computed tomography for the evaluation of anteversion of the femur during childhood. Invest Radiol 1985;20(9):978–82. [18] Waidelich HA, Strecker W, Schneider E. Computed tomographic torsion-angle and length measurement of the lower extremity. The methods, normal values and radiation load. Rofo 1992;157(3):245–51. [19] Buddenbrock B, Wissing H, Muller RD, John V. Radiological determination of femoral rotation deformity – computerized tomography, optimized measurement accuracy and exposure dosage. Z Orthop Ihre Grenzgeb 1997;135(1):9–16. [20] Guenoun B, Zadegan F, Aim F, Hannouche D, Nizard R. Reliability of a new method for lower-extremity measurements based on stereoradiographic three-dimensional reconstruction. Orthop Traumatol Surg Res 2012;98(5):506–13. [21] Than P, Szuper K, Somoskeoy S, Warta V, Illes T. Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop 2012;36(6):1291–7. [22] Hubbell JH, Seltzer SM, 2004. Gaithersburg, MD: National Institute of Standards and Technology. Available at: http://physics.nist.gov/xaamdi. Assessed May 20, 2010.2004. [23] Joint Committee for Guides in Metrology (JCGM 100). Evaluation of measurement data – guide to the expression of uncertainty in measurement. International Organization for Standardization (ISO); 2008, corrected version 2010. [24] Chadwick KH, Leenhouts HP. Radiation risk is linear with dose at low doses. Br J Radiol 2005;78(925):8–10. [25] Buzatu S. Cellular low-dose effects of ionizing radiation. Riv Biol 2008;101(2):279–98. [26] Brenner DJ, Sachs RK. Estimating radiation-induced cancer risks at very low doses: rationale for using a linear no-threshold approach. Radiat Environ Biophys 2006;44(4):253–6. [27] Brenner DJ. Extrapolating radiation-induced cancer risks from low doses to very low doses. Health Phys 2009;97(5):505–9. [28] Richards PJ, George J, Metelko M, Brown M. Spine computed tomography doses and cancer induction. Spine (Phila Pa 1976) 2010;35(4):430–3. [29] Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001;176(2):289–96. [30] Brenner DJ, Elliston CD. Estimated radiation risks potentially associated with full-body CT screening. Radiology 2004;232(3):735–8. [31] Biswas D, Bible JE, Bohan M, Simpson AK, Whang PG, Grauer JN. Radiation exposure from musculoskeletal computerized tomographic scans. J Bone Joint Surg Am 2009;91(8):1882–9. [32] Butson MJ, Cheung T, Yu PK. Measurement of dose reductions for superficial x-rays backscattered from bone interfaces. Phys Med Biol 2008;53(17): N329–36. [33] ICRP. Recommendation of the International Commission on Radiological Protection. ICRP Publication 103. Ann ICRP 2007;37(2–4). [34] Arai N, Nakamura S, Matsushita T, Suzuki S. Minimal radiation dose computed tomography for measurement of cup orientation in total hip arthroplasty. J Arthroplasty 2010;25(2):263–7.

ANEXO

EOS & sterEOS Full List of Publications January 2019

Publications on EOS •

Newton PO, Osborn EJ, Bastrom TP, Doan JD, Reighard FG. The 3D Sagittal Profile of Thoracic Versus Lumbar Major Curves in Adolescent Idiopathic Scoliosis. Spine Deformity 2019

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Trac S, Zheng R, Hill DL, Lou E. Intra- and Interrater Reliability of Cobb Angle Measurements on the Plane of Maximum Curvature Using Ultrasound Imaging Method. Spine Deformity 2019

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Fitzgerald R, Upasani VV, Bastrom TP, Bartley CE, Reighard FG, Yaszay B, Newton PO. ThreeDimensional Radiographic Analysis of Two Distinct Lenke 1A Curve Patterns. Spine Deformity 2019

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Pasha S, Sankar WN, Castelein RM. The Link Between the 3D Spino-pelvic Alignment and Vertebral Body morphology in Adolescent Idiopathic Scoliosis. Spine Deformity 2019

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Dagneaux L, Marouby S, Maillot C, Canovas F, Riviere C. Dual mobility device reduces the risk of prosthetic hip instability for patients with degenerated spine: A case-control study. Orthopaedics and Traumatology: Surgery and Research 2018

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Chung CL, Kelly DM, Steele JR, DiAngelo DJ. A mechanical analog thoracolumbar spine model for the evaluation of scoliosis bracing technology. Journal of Rehabilitation and Assistive Technologies Engineering

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Ilharreborde B, Pesenti S, Ferrero E, Accadbled F, Jouve JL, De Gauzy JS, Mazda K. Correction of hypokyphosis in thoracic adolescent idiopathic scoliosis using sublaminar bands: a 3D multicenter study. Eur Spine J 2018

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Sebaaly A, Grobost P, Mallam L, Roussouly P. Description of the sagittal alignment of the degenerative human spine. Eur Spine J 2018

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Bao HD, Shu SB, Shi J, Liu SN, Sun MH, Hu AN, Liu Z, Zhu ZZ, Qian BP, Qiu Y. [Similar coronal curvature may not represent the same 3-dimensional deformity in adolescent idiopathic scoliosis: a matched-pair study using EOS imaging system].. Zhonghua yi xue za zhi 2018

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Chung N, Cheng YH, Po HL, Ng WK, Cheung KC, Yung HY, Lai YM. Spinal phantom comparability study of Cobb angle measurement of scoliosis using digital radiographic imaging. Journal of Orthopaedic Translation 2018

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Le Goic M, Wang D, Chiarovano E, Lecompte J, Laporte S, Duysens J, Vidal P. An Initial Passive Phase That Limits the Time to Recover and Emphasizes the Role of Proprioceptive Information. Frontiers in Neurology 2018

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Bahadir T, Werner J, Clair AJ, Walker PS. Guidelines for Instrumentation for Total Knee Replacement Based on Frontal Plane Radiographs. Bulletin of the NYU Hospital for Joint Diseases 2018

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Hasegawa K, Okamoto M, Hatsushikano S, Caseiro G and Watanabe K. Difference in whole spinal alignment between supine and standing positions in patients with adult spinal deformity using a new comparison method with slot- scanning three-dimensional X-ray imager and computed tomography through digital reconstructed radiography. BMC musculoskeletal disorders 2018

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Post M, Verdun S, Roussouly P, Abelin-Genevois K. New sagittal classification of AIS: validation by 3D characterization. Eur Spine J 2018

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Theologis A, Iyer S, Lenke LG, Sides BA, Kim HJ, Kelly MP. Cervical and Cervicothoracic Sagittal Alignment According to Roussouly's Thoracolumbar Subtypes. Spine 2018

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Kim SB, Heo YM, Hwang CM, Kim TG, Hong JY, Won YG, Ham CU, Min YK, Yi JW. Reliability of the EOS Imaging System for Assessment of the Spinal and Pelvic Alignment in the Sagittal Plane. Clin Orthop Surg 2018

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Iorio J, Lafage V, Lafage R, Henry JK, Stein D, Lenke LG Gupta M, Kelly MP, Sides B, Kim HJ. The Effect of Aging on Cervical Parameters in a Normative North American Population. Global Spine J 2018

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Vergari C, Aubert B, Lallemant-Dudek P, Haen TX, Skalli W. A novel method of anatomical landmark selection for rib cage 3D reconstruction from biplanar radiography. CMBBE: Imaging & Visualization 2018

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Pasha S, Flynn J. Data-driven Classification of the 3D Spinal Curve in Adolescent Idiopathic Scoliosis with an Applications in Surgical Outcome Prediction. Scientific Reports 2018

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Gajny L, Ebrahimi S, Vergari C, Angelini E, Skalli W. Quasi-automatic 3D reconstruction of the full spine from low-dose biplanar X-rays based on statistical inferences and image analysis. Eur Spine J 2018

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Pedersen D, Vanheule V, Wirix-Speetjens R, Taylan O, Delport HP, Scheys L, Andersen MS. A novel non-invasive method for measuring knee joint laxity in four dof: In vitro proof-ofconcept and validation. J Biomech 2018

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Passmore E, Graham HK, Pandy, MG, Sangeux M. Hip- and patellofemoral-joint loading during gait are increased in children with idiopathic torsional deformities. Gait & Posture 2018

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Rosskopf A, Sutter R, Pfirmann C, Buck F. 3D hindfoot alignment measurements based on low-dose biplanar radiographs: a clinical feasibility study. Skeletal Radiol. 2018

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Pedersen PH, Vergari C, Alzakri A, Vialle R, Skalli W. A reduced micro-dose protocol for 3D reconstruction of the spine in children with scoliosis: results of a phantom-based and clinically validated study using stereo-radiography. Eur Radiol 2018

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Garcia-Cano E, Arambula Cosio F, Duong L, Bellefleur C, Roy-Beaudry M, Joncas J, Parent S, Labelle H. Prediction of spinal curve progression in Adolescent Idiopathic Scoliosis using Random Forest regression. Comput Biol Med 2018

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Tokunaga K, Okamoto M, Watanabe K. Implant Orientation Measurement After THA Using the EOS X-Ray Image Acquisition System. Adv Exp Med Biol 2018

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Lecoanet P, Vargas M, Pallaro J, Thelen T, Ribes C, Fabre T. Leg length discrepancy after total hip arthroplasty: Can leg length be satisfactorily controlled via anterior approach without a traction table? Evaluation in 56 patients with EOS 3D. Orthop Traumatol Surg Res 2018

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Berliner JL, Esposito CI, Miller TT, Padgett DE, Mayman DJ, Jerabek SA. What preoperative factors predict postoperative sitting pelvic position one year following total hip arthroplasty?. The Bone & Joint Journal 2018

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Fader RR, Tao MA, Gaudiani MA, Turk R, Nwachukwu BU, Esposito CI, Ranawat AS. The role of lumbar lordosis and pelvic sagittal balance in femoroacetabular impingement. The Bone & Joint Journal 2018

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Staub BN, Lafage R, Kim HJ, Shaffrey CI, Mundis GM, Hostin R, Burton D, Lenke L, Gupta MC, Ames C, Klineberg E, Bess S, Schwab S, Lafage V. Cervical mismatch: the normative value of T1 slope minus cervical lordosis and its ability to predict ideal cervical lordosis. JNS Spine 2018

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Rampal V, Rohan PY, Saksik R, Wicart P, Skalli W. Assessing 3D paediatric foot morphology using low-dose biplanar radiography: Parameter reproducibility and preliminary values. Orthop Traumatol Surg Res 2018

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Macron A, Pillet H, Doridam J, Verney A, Rohan PY. Development and evaluation of a new methodology for the fast generation of patient-specific Finite Element models of the buttock for sitting-acquired deep tissue injury prevention. J Biomech, 2018

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Mustafy T, Arnoux PJ, Benoit A, Bianco RJ, Aubin CE, Villemure I. Load-sharing biomechanics at the thoracolumbar junction under dynamic loadings are modified by anatomical features in adolescent and pediatric vs adult functional spinal units. J Mech Behav Biomed Mater, 2018

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Khalil N, Bizdikian AJ, Bakoury Z, Salameh M, Bou Zeid N, Yared F, Otayek J, Kharrat K, Kreichati G, Ghanem J, Lafage R, Lafage V, Obeid I, Assi A. Cervical and postural strategies for maintaining horizontal gaze in asymptomatic adults. Eur Spine J, 2018

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Hu Z, Man GCW, Kwok AKL, Law SW, Chu WWC, Cheung WH, Qiu Y, Cheng JCY. Global sagittal alignment in elderly patients with osteoporosis and its relationship with severity of vertebral fracture and quality of life. Arch Osteoporos, 2018

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Horn SR, Segreto FA, Ramchandran S, Poorman GR, Sure A, Marascalachi B, Bortz CA, Varlotta CG, Tishelman J, Vasquez-Montes D, Ihejirika Y, Zhou P, Moon J, Lafage R, Diebo BG, Vira S, Jalai CM, Wang C, Shenoy K, Errico T, Lafage V, Buckland A, Passias PG . The Influence of BMI on Achieving Age Adjusted Alignment Goals in Adult Spinal Deformity Corrective Surgery with Full Body Analysis at 1 Year. World Neurosurgery, 2018

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Akbar M, Almansour H, Lafage R, Diebo BG, Wiedenhofer B, Schwab F, Lafage V, Pepke W. Sagittal alignment of the cervical spine in the setting of adolescent idiopathic scoliosis. J Neurosurg Spine, 2018

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Cobetto N, Aubin CE, Parent S. Contribution of Lateral Decubitus Positioning and Cable Tensioning on Immediate Correction in Anterior Vertebral Body Growth Modulation. Spine Deformity, 2018

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Sullivan T, Marino N, Reighard F, Newton P. Relationship Between Lumbar Lordosis and Pelvic Incidence in the Adolescent Patient: Normal Cohort Analysis and Literature Comparison. Spine Deformity, 2018

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Yoshihara H, Hasegawa K, Okamoto M, Hatsushikano S, Watanabe K. Relationship between sagittal radiographic parameters and disability in patients with spinal disease using 3D standing analysis. Orthop Traumatol Surg Res, 2018

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Donaldson TK, Smith EJ, Koutalos A, John A, Lazennec J, Clarke I. Adverse Wear in MOM HipArthroplasty Related to the Production of Metal Fragments at Impingement Sites. Open Journal of Orthopedics 2018

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Turner A, Edwards J, Kinene E. Digital radiography vs low dose 3D imaging technology: A comparison of radiation doses and image quality. RAD Magazine, 2018

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Bakouny Z, Khalil N, Otayek J, Bizdikian AJ, Yared F, Salameh M, Bou Zeid N, Ghanem I, Kharrat Km Kreichati G, Lafage R, Lafage V, Assi A. Are the sagittal cervical radiographic modifiers of the Ames-ISSG classification specific to adult cervical deformity?. J Neurosurg Spine, 2018

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Bakouny Z, Assi A, Yared F, Khalil N, Mansour E, Yaacoub JJ, Skalli W, Ghanem I. Combining acetabular and femoral morphology improves our understanding of the down syndrome hip. Clinical Biomechanics, 2018

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van Drongelen S, Fey B, Stief F, Kaldowski H, Ipek D, Meurer A. Changes in leg alignment after total hip replacement detected with the EOS system. Gait & Posture, 2018

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Choisne J, Valiadis JM, Travert C, Kolta S, Roux C, Skalli W. Vertebral strength prediction from Bi-Planar dual energy x-ray absorptiometry under anterior compressive force using a finite element model: An in vitro study. Journal of the Mechanical Behavior of Biomedical Materials, 2018

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Yu P, Qiu JR, Xie L, Wu WJ, Zhang XK, Cao P, Liang Y. [Two-year clinical and radiological outcomes of minimally invasive surgery for severe adult degenerative scoliosis]. Zhonghua yi xue za zhi, 2018

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Bailly R, Lempereur M, Thepaut M, Rémy Neris O, Pons C, Houx L, Brochard S. 3D lower limb bone morphology in ambulant children with cerebral palsy and its relation to gait. Annals of Physical and Rehabilitation Medicine, 2018

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Blandin C, Boisson M, Segretin F, Feydy A, Rannou F, Nguyen C. Pelvic parameters in patients with chronic low back pain and an active disc disease: A case-control study. Annals of Physical and Rehabilitation Medicine, 2018

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Massaad A, Assi A, Bizdikian AJ, Yared F, Bakouny Z, Khalil N, Ghanem I, Pillet H, Bonnet X, Skalli W. How do postural parameters vary during gait in children with cerebral palsy? A 3D subject-specific skeletal segment registration technique.. Gait Posture, 2018

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Bizdikian AJ, Assi A, Bakouny Z, Yared F, Saghbini E, Bakhos GE, Esber S, Khalil N, Otayek J, Ghanimeh J, Sauret C, Skalli W, Ghanem I. Validity and reliability of different techniques of neck–shaft angle measurement. Clinical Radiology, 2018

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Rohan PY, Perrier A, Ramanoudjame M, Hausselle J, Lelièvre H, Seringe R, Skalli W, Wicart P. Three-Dimensional Reconstruction of Foot in the Weightbearing Position From Biplanar Radiographs: Evaluation of Accuracy and Reliability. J Foot and Ankle Surgery, 2018

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Tono O, Hasegawa K, Okamoto M, Hatsushikano S, Shimoda H, Watanabe K, Harimaya K. Lumbar lordosis does not correlate with pelvic incidence in the cases with the lordosis apex located at L3 or above. European Spine Journal, 2018

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Kolta S, Etcheto A, Fechtenbaum J, Feydy A, Roux C, Briot K. Measurement of Trabecular Bone Score of the spine by low-dose imaging system (EOS®); a feasibility study. J Clinical Densitometry, 2018

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De Francesco CJ, Pasha S, Miller DJ, Betz, RR, Clements DH, Fletcher ND, Glotzbecker MG, Hwang SW, Kelly MP, Lehman RA, Lonner BS, Newton PO, Roye BD, Sponseller PD, Upasani VV, Cahill PJ. Agreement Between Manual and Computerized Designation of Neutral Vertebra in Idiopathic Scoliosis. Spine Deform 2018

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Fougeron N, Rohan PY, Macron A, Travert C, Pillet H & Skalli W . Subject specific finite element mesh generation of the pelvis from biplanar x-ray images: application to 120 clinical cases. Computer Methods in Biomechanics and Biomedical Engineering, 2018

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Assi A, Bakouny Z, Bizdikian AJ, Otayek J, Yared F, Lafage V, Khalil N, Massaad A, Ghanem I, Skalli W.. Variation of the sagittal vertical axis during walking and its determinants.. Gait Posture. 2018

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García-Cano E, Arámbula Cosío F, Duong L, Bellefleur C, Roy-Beaudry M, Joncas J, Parent S, Labelle H. Dynamic ensemble selection of learner-descriptor classifiers to assess curve types in adolescent idiopathic scoliosis.. Med Biol Eng Comput. 2018

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Sterba M, Arnoux PJ, Labelle H, Warner WC, Aubin CE. Biomechanical analysis of spinopelvic postural configurations in spondylolysis subjected to various sport-related dynamic loading conditions. European Spine Journal, 2018

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Passmore E, Sangeux M. Is it the right moment to change how we report kinetics?. Gait & Posture, 2018

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Bao HD, Shu SB, Shi J, Liu SN, Sun MH, Hu AN, Liu Z, Zhu ZZ, Qian BP, Qiu Y. Similar coronal curvature may not represent the same 3-dimensional deformity in adolescent idiopathic scoliosis: a matched-pair study using EOS imaging system. Zhonghua Yi Xue Za Zhi, 2018

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"Celestre PC, Dimar JR, Glassman SD. Spinopelvic Parameters: Lumbar Lordosis, Pelvic Incidence, Pelvic Tilt, and Sacral Slope

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What Does a Spine Surgeon Need to Know to Plan a Lumbar Deformity Correction?. Neurosurgery Clinics, 2018"

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Markus I, Schlegl AT, Burkus M, Jozsef K, Niklai B, Than P, Tunyogi-Csapo M. The effect of coronal decompensation on the biomechanical parameters in lower limbs in adolescent idiopathic scoliosis. Orthopaedics and Traumatology: Surgery and Research, 2018

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Jackson TJ, Miller D, Nelson S, Cahill PJ, Flynn JM. Two for One: A Change in Hand Positioning During Low-Dose Spinal Stereoradiography Allows for Concurrent, Reliable Sanders Skeletal Maturity Staging. Spine Deformity, 2018

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Hernandez T, Thenard T, Vergari C, Robichon L, Skalli W, Vialle R. Coronal Trunk Imbalance in Idiopathic Scoliosis: Does Gravity Line Localisation Confirm the Physical Findings?. Orthopaedics and Traumatology: Surgery and Research, 2018

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Burkus M, Schlégl AT, O'Sullivan I, Markus I, Vermes C, Tunyogi-Csapo M. Sagittal plane assessment of spino-pelvic complex in a Central European population with adolescent idiopathic scoliosis: a case control study. Scoliosis and Spinal Disorders, 2018

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Cobetto N, Aubin CE, Parent S. Surgical Planning and Follow-up of Anterior Vertebral Body Growth Modulation in Pediatric Idiopathic Scoliosis Using a Patient-Specific Finite Element Model Integrating Growth Modulation. Spine Deformity, 2018

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Assi A, Bakouny Z, Mansour E, Yaacoub JJ, Yared F, Ghanem I. Spinopelvic Alignment in Subjects With Down Syndrome. Clinical Spine Surgery, 2018

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Hurry JK, Rehan S, Spurway AJ, Laende EK, Astephen Wilson JL, Logan KJ, Dunbar MJ, ElHawary R. The reliability of radiostereometric analysis in determining physeal motion in slipped capital femoral epiphysis in standard uniplanar and low-dose EOS biplanar radiography: a phantom model study. Journal of Pediatric Orthopaedics B, 2018

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Abelin-Genevois K, Sassi D, Verdun S, Roussouly P. Sagittal classification in adolescent idiopathic scoliosis: original description and therapeutic implications. Eur Spine J, 2018

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Passmore E, Kerr Graham H, Pandy MG, Sangeux M. Hip- and patellofemoral-joint loading during gait are increased in children with idiopathic torsional deformities. Gait & Posture, 2018

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Thompson W, Cogniet A, Challali M, Saddiki R, Rigal J, Le Huec JC. Analysis of cervical sagittal alignment variations after lumbar pedicle subtraction osteotomy for severe imbalance: study of 59 cases. European Spine Journal, 2018

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Bagheri A, Liu X-C, Tassone C, Thometz J, Tarima S. Reliability of Three-Dimensional Spinal Modeling of Patients With Idiopathic Scoliosis Using EOS System. Spine Deformity, 2018

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Ben-Sira L, Shiran SI, Pratt L-T, Precel R, Ovadia D, Constantini S, Roth J. Use of EOS® lowdose biplanar X-ray for shunt series in children with hydrocephalus: a preliminary study. World Neurosurgery, 2018

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Jankowski PP, Yaszay B, Cidambi KR, Bartley CE, Bastrom TP, Newton PO. The Relationship Between Apical Vertebral Rotation and Truncal Rotation in Adolescent Idiopathic Scoliosis Using 3D Reconstructions . Spine Deformity, 2018

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Sekiya T, Aota Y, Yamada K, Kaneko K, Ide M, Saito T. Evaluation of functional and structural leg length discrepancy in patients with adolescent idiopathic scoliosis using the EOS imaging system: a prospective comparative study. Scoliosis and Spinal Disorders, 2018

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Illés TS, Burkus M, Somoskeőy S, Lauer F, Lavaste F, Dubousset JF. Axial plane dissimilarities of two identical Lenke-type 6C scoliosis cases visualized and analyzed by vertebral vectors. Eur Spine J, 2018

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Lahkar BK, Rohan P-Y, Pillet H, Thoreux P, Skalli W. Fast subject specific finite element mesh generation of knee joint from biplanar X-ray images. CMBBE, 2018

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Girinon F, Gajny L, Ebrahimi S, Dagneaux L, Rouch P, Skalli W. Quasi automated reconstruction of the femur from bi-planar X-rays. CMBBE, 2018

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Gajny L, Robichon L, Hernandez T, Vialle R, Skalli W. 3D reconstruction of adolescent scoliotic trunk shape from biplanar X-rays: a feasibility study. CMBBE, 2018

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Obid P, Yiu KKL, Cheung KM, Kwan K, Ruf M, Cheung JPY. Reliability of Rod lengthening, Thoracic and Spino-Pelvic Measurements on Biplanar Stereoradiography in Patients Treated with Magnetically Controlled Growing Rods. Spine, 2018

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Aubry S, Padoin P, Petegnief Y, Vidal C, Riethmuller D, Delabrousse E. Can threedimensional pelvimetry using low-dose stereoradiography replace low-dose CT pelvimetry?. Diag & Interventional Imaging, 2018

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Westberry DE, Wack LI, Davis RB, Hardin JW. Femoral anteversion assessment: Comparison of physical examination, gait analysis, and EOS biplanar radiography. Gait & Posture, 2018

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Rivière C, Lazic S, Villet L, Wiart Y, Muirhead Allwood S, Cobb J. Kinematic alignment technique for total hip and knee arthroplasty: the personalized implant positioning surgery. EFORT open reviews, 2018

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Pea R, Dansereau J, Caouette C, Cobetto N, Aubin CE. Computer-assisted design and finite element simulation of braces for the treatment of adolescent idiopathic scoliosis using a coronal plane radiograph and surface topography. Clin Biomech, 2018

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Pasha S, Flynn JM, Sankar WN. Outcomes of selective thoracic fusion for Lenke 1 adolescent idiopathic scoliosis: predictors of success from the sagittal plane. Eur Spine J, 2018

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Pasha S, Ecker M, Deeney V. Considerations in sagittal evaluation of the scoliotic spine. Eur J Ortho Surg & Trauma, 2018

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Nielsen E, Goldstein RY. Adolescent spine patients have an increased incidence of acetabular overcoverage. J Hip Preserv Surg. 2018

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Madkouri R, Brauge D, Vidon-Buthion A, Fahed E, Mourier KL, Beaurain J, Grelat M. Improvement in Sagittal Balance After Decompression Surgery without Fusion in Patients with Degenerative Lumbar Stenosis: Clinical and Radiographic Results at 1 Year. World Neurosurgery, 2018

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and circumferential fusion: a retrospective series of twenty consecutive cases with a minimum of 2 years follow‑up. European Spine Journal, 2018 •

Elkin JM, Simoens KJ, Callaghan JJ. Lower Extremity Geometry in Morbid Obesity – Considerations for TKA. J Arthroplasty, 2018

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Dzialo Cm, Pedersen PH, Simonsen CW, Jensen KK, de Zee M, Andersen MS. Development and validation of a subject-specific moving-axis tibiofemoral joint model using MRI and EOS imaging during a quasi-static lunge. J Biomech, 2018

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Barbier O, Skalli W, Mainard D. Changes in pelvic orientation after total hip arthroplasty: a prospective study with EOS™. Acta Orthop Belg, 2018

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Law M, Ma WK, Lau D, Cheung K, Ip J, Yip L, Lam W. Cumulative effective dose and cancer risk for pediatric population in repetitive full spine follow-up imaging: how micro dose is the EOS microdose protocol?. Eur J Radiol, 2018

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Lazennec JY, Folinais D, Florequin C, Pour AE. Does patients’ perception of leg length after total hip arthroplasty correlate with anatomical leg length?. J Arthroplasty. 2018

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Kaya O, Ulusoy OL, Karadereler S, Hamzaoglu A. Cervicothoracic spine duplication: a 10‑year follow up of a neurological intact boy. European Spine Journal, 2018

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Diebo BG, Shah NV, Stroud SG, Paulino CB, Schwab FJ, Lafage V. Realignment surgery in adult spinal deformity. Der Orthopäde, 2018

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Zeighami A, Aissaoui R, Dumas R. Knee medial and lateral contact forces in a musculoskeletal model with subject-specific contact point trajectories. Journal of Biomechanics, 2018

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Day LM, DelSole EM, Beaubrun BM, Zhou PL, Moon JY, Tishelman JC, Vigdorchik JM, Schwarzkopf R, Lafage R, Lafage V, Protopsaltis T, Buckland AJ. Radiological severity of hip osteoarthritis in patients with adult spinal deformity: the effect on spinopelvic and lower extremity compensatory mechanisms. European Spine Journal, 2018

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Yeganeh A, Moghtadaei M, Motalebi M. A challenge on orthopedic sciences: The Influence of Spinal Disease and Deformities on Total Hip Arthroplasty: A review on literature. European Spine Journal, 2018

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Langlais T, Vergari C, Pietton R, Dubousset J, Skalli W, Vialle R. Shear-wave elastography can evaluate annulus fibrosus alteration in adolescent scoliosis. European Radiology, 2018

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Operative Treatment of Adolescent Scheuermann Kyphosis - Prospective Evaluation of 96 Patients. Spine Deformity, 2018

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Passmore EHP, Graham HK, Sangeux M. Defining the medial-lateral axis of the femur: Medical imaging, conventional and functional calibration methods lead to differences in hip rotation kinematics for children with torsional deformities. Journal of Biomechanics, 2018

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Bernard JC, Berthonnaud E, Deceuninck J, Journoud-Rozand L, Notin G, Chaleat-Valayer E. Three-dimensional reconstructions of Lenke 1A curves. Scoliosis and Spinal Disorders, 2018

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Morel B, Moueddeb S, Blondiaux E, Richard S, Bacy M, Vialle R, Ducou Le Pointe H. Dose, image quality and spine modeling assessment of biplanar EOS micro-dose radiographs for the follow-up of in-brace adolescent idiopathic scoliosis patients. European Spine Journal, 2018

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Bourghli A, Cawley D, Novoa F, Rey M, Alzakri A, Larrieu D, Vital JM, Gille O, Boissiere L, Obeid I. 102 lumbar pedicle subtraction osteotomies: one surgeon’s learning curve. European Spine Journal, 2018

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Clément J, de Guise JA, Fuentes A, Hagemeister N. Comparison of soft tissue artifact and its effects on knee kinematics between non-obese and obese subjects performing a squatting activity recorded using an exoskeleton. Gait & Posture, 2018

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Pedersen PH, Petersen AG, Ostgaard SE, Tvedebrink T, Eiskjaer SP. EOS® Micro-Dose Protocol: First Full-Spine Radiation Dose Measurements in Anthropomorphic Phantoms and Comparisons with EOS Standard-Dose and Conventional Digital Radiology (CR). Spine, 2018

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Ling FP, Chevillotte T, Ieglise A, Thompson W, Bouthors C, Le Huec JC. Which parameters are relevant in sagittal balance analysis of the cervical spine? A literature review. European Spine Journal, 2018

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Hey HWD, Tan KLM, Moorthy V, Lau ETC, Lau LL, Liu G, Wong HK. Normal variation in sagittal spinal alignment parameters in adult patients: an EOS study using serial imaging. European Spine Journal, 2018

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Bakouny Z, Assi A, Yared F, Bizdikian AJ, Otayek J, Nacouzi R, Lafage V, Lafage R, Ghanem I, Kreichati G. Normative Spino-Pelvic Sagittal Alignment of Lebanese Asymptomatic Adults: Comparisons with Different Ethnicities. Orthopaedics and Traumatology: Surgery and Research. 2018

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Henao J, Labelle H, Arnoux P-J, Aubin C-E. Biomechanical Simulation of Stresses and Strains Exerted on the Spinal Cord and Nerves During Scoliosis Correction Maneuvers. Spine Deformity. 2018

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Passias PG, Horn SR, Frangella NJ, Poorman GW, Vasquez-Montes D, Diebo BG, Bortz CA, Segreto FA, Moon JY, Zou PL, Vira S, Sure A, Beaubrun B, Tishelman JC, Ramchandran S, Jalai CM, Bronson W, Wang C, Lafage V, Buckland AJ, Errico TJ. Full-Body Analysis of Adult Spinal Deformity Patients’ Age-Adjusted Alignment at 1 Year. World Neurosurgery, 2018

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Van den Abbeele M, Li F, Pomero V, Bonneau D, Sandoz B, Laporte S, Skalli W. A subjectspecific biomechanical control model for the prediction of cervical spine muscle forces. Clin Biomech. 2018

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Simon AL, Apostolou N, Vidal C, Ferrero E, Mazda K, Ilharreborde B. Paediatric tibial shaft fractures treated by open reduction and stabilization with monolateral external fixation. J Child Orthop. 2018

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Lazennec JY, Kim Y, Pour AE. Total Hip Replacement in patients with Parkinson's disease: improved outcomes with dual mobility implants and cementless fixation. J Arthroplasty. 2018

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Ferrero E, Mazda K, Simon A-L, Ilharreborde B. Preliminary experience with SpineEOS, a new software for 3D planning in AIS surgery. Eur Spine J, 2018

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Pasha S, Cahill PJ, Flynn JM, Sponseller P, Newton P. Relationships Between the Axial Derotation of the Lower Instrumented Vertebra and Uninstrumented Lumbar Curve Correction: Radiographic Outcome in Lenke 1 Adolescent Idiopathic Scoliosis With a Minimum 2-Year Follow-up. Journal of Pediatric Orthopaedics, 2018

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Ilharreborde B. Sagittal balance and idiopathic scoliosis: does final sagittal alignment influence outcomes, degeneration rate or failure rate?. European Spine Journal, 2018

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Le Huec JC, Gille O, Fabre T. Sagittal balance and spine-pelvis relation: a French speciality?. Orthopaedics and Traumatology: Surgery and Research, 2018

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Okamoto M, Jabour F, Sakai K, Hatsushikano S, Le Huec JC, Hasegawa K. Sagittal balance measures are more reproducible when measured in 3D vs in 2D using full-body EOS® images. European Radiology, 2018

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Alqroom R. The Quest of Sagittal Balance Parameters and Clinical Outcome after Short Segment Spinal Fusion. Acta Informatica Medica, 2018

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Janjua MB, Tishelman JC, Vasquez-Montes D, Vaynrub M, Errico TJ, Buckland AJ, Protopsaltis T. The value of sitting radiographs: analysis of spine flexibility and its utility in preoperative planning for adult spinal deformity surgery. J Neurosurgery Spine 2018

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Esposito C, Carroll KM, Sculco PK, Padgett DE, Jerabek SA, Mayman DJ. Total hip Arthroplasty patients With Fixed Spinopelvic Alignment are at Higher Risk of hip Dislocation. J Arthroplasty. 2018

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Yamato Y, Matsuyama Y. Will a low-dose biplanar radiograph become "gold standard" for three-dimensional assessment of spinal deformity in patients with adolescent idiopathic scoliosis?. J Spine Surg, 2018

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Rehm J, Germann T, Akbar M, Pepke W, Kauczor HU, Weber MA, Spira D. 3D-modeling of the spine using EOS imaging system: Inter-reader reproducibility and reliability. PLoS One. 2017 Feb 2;12(2):e0171258

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Gille O, Bouloussa H, Mazas S, Vergari C, Challier V, Vital JM, Coudert P, Ghailane S. A new classification system for degenerative spondylolisthesis of the lumbar spine. Eur Spine J. 2017 Aug 23

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Mainard D, Barbier O, Knafo Y, Belleville R, Mainard-Simard L, Gross JB. Accuracy and reproducibility of preoperative three-dimensional planning for total hip arthroplasty using biplanar low-dose radiographs: A pilot study. Orthop Traumatol Surg Res. 2017 Jun;103(4):531-536

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Berven SH, Kamper SJ, Germscheid NM, Dahl B, Shaffrey CI, Lenke LG, Lewis SJ, Cheung KM, Alanay A, Ito M, Polly DW, Qiu Y, de Kleuver M, A OSpine Knowledge Forum Deformity. An international consensus on the appropriate evaluation and treatment for adults with spinal deformity. Eur Spine J, 2017

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Lerisson H, Amzallag-Bellenger É, Cebulski-Delebarre A, Nectoux E, Desmulliez G, Duhamel A, Drumez E, Herbaux B, Boutry N. Assessment of micro-dose biplanar radiography in lower limb measurements in children. Eur Radiol. 2017 Nov 21

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Issa SP, Angelliaume A, Vidal C, Mazda K, Ilharreborde B. Do Sublaminar Polyester Bands Affect the Outcomes of Postoperative Infections After Adolescent Idiopathic Scoliosis Surgery?. J Pediatr Orthop, 2017

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Cobetto N. Planification chirurgicale pour la correction 3D de la scoliose pédiatrique proressive à l'aide d'un dispositif sans fusion flexible. PhD thesis, 2017

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Law M, Ma WK, Chan E, Lau D, Mui C, Cheung K, Yip L, Lam W. Evaluation of cumulative effective dose and cancer risk from repetitive full spine imaging using EOS system: Impact to adolescent patients of different populations. Eur J Radiol. 2017 Nov;96:1-5

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Burkus M, Márkus I, Niklai B, Tunyogi-Csapó M. Assessment of sacroiliacal joint mobility in patients with low back pain. Orv Hetil. 2017

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Le Huec JC, Richards J, Tsoupras A, Price R, Léglise A, Faundez AA. The mechanism in junctional failure of thoraco‑lumbar fusions. Part I: Biomechanical analysis of mechanisms responsible of vertebral overstress and description of the cervical inclination angle (CIA). Eur Spine J. 2017 Dec 14

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Faundez AA, Richards J, Maxy P, Price R, Léglise A, Le Huec JC. The mechanism in junctional failure of thoraco-lumbar fusions. Part II: Analysis of a series of PJK after thoraco-lumbar fusion to determine parameters allowing to predict the risk of junctional breakdown. Eur Spine J. 2017 Dec 15

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Alzakri A, Boissière L, Cawley DT, Bourghli A, Pointillart V, Gille O, Vital JM, Obeid I. L5 pedicle subtraction osteotomy: indication, surgical technique and specificities. Eur Spine J. 2017 Nov 29

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Pasha S, Baldwin K. Are we simplifying balance evaluation in adolescent idiopathic scoliosis?. Clin Biomech. 2017

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Nerot A, Skalli W, Wang X. Estimation of spinal joint centers from external back profile and anatomical landmarks. Journal of Biomechanics. 2017

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Buckland A, DelSole E, George S, Vira S, Lafage V, Errico T, Vigdorchik J. Sagittal Pelvic Orientation: A Comparison of Two Methods of Measurement. Bull Hosp Jt Dis. 2017 Dec;75(4):234-240

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Branchini M, Del Vecchio A, Gigliotti CR, Loria A, Zerbi A, Calandrino R. Organ doses and lifetime attributable risk evaluations for scoliosis examinations of adolescent patients with the EOS imaging system. Radiol Med. 2017 Nov 21

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Cobetto N, Parent S, Aubin CE. 3D correction over 2 years with anterior vertebral body growth modulation tethering: A finite element analysis of screw positioning, cable tensioning and postoperative. Clin Biomech. 2017

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Pietton R, Bouloussa H, Vergari C, Skalli W, Vialle R. Rib Cage Measurement Reproducibility Using Biplanar Stereoradiographic 3D Reconstructions in Adolescent Idiopathic Scoliosis. J Pediatr Orthop. 2017

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Choisne J, Travert C, Valiadis JM, Follet H, Skalli W. A new method to determine volumetric bone mineral density from bi-planar dual energy radiographs using a finite element model: an ex-vivo study. J. Musculoskelet. Res. 2017

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Rampal V, Rohan PY, Assi A, Ghanem I, Rosello O, Simon AL, Gaumetou E, Merzoug V, Skalli W, Wicart P. Lower-Limb Lengths and Angles in Children Older than Six Years: Reliability and Reference Values by EOS® Stereoradiography. Orthop Traumatol Surg Res. 2017 Nov 6

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Bistazzoni S, De Angelis M, D'ercole M, Chiaramonte C, Carotenuto A, Cardarelli G, Ricciardi F, Innocenzi G, Guizzardi G. Evaluation of Effect of Posterior Dynamic Stabilization IntraSPINE System on Sagittal Spinal Balance using EOS® X-Ray Imaging System. J Neurol Neurophysiol 2017, 8:4

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Fuller CB, Farnsworth CL, Bomar JD, Jeffords ME, Murphy JS, Edmonds EW, Pennock AT, Wenger DR, Upasani VV. Femoral Version: Comparison Among Advanced Imaging Methods. J Orthop Res. 2017 Oct 27

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Fougeron N, Macron A, Pillet H, Skalli W, Rohan PY. Subject specific hexahedral Finite Element mesh generation of the pelvis from bi-Planar X-ray images. Comput Methods Biomech Biomed Engin. 2017 Oct;20(sup1):75-76

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Ramchandran S, Foster N, Sure A, Errico TJ, Buckland AJ. Normal Age-Adjusted Sagittal Spinal Alignment Is Achieved with Surgical Correction in Adolescent Idiopathic Scoliosis. Asian Spine J. 2017 Oct; 11(5): 770–779

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Hey D, Tan K, Ho VC, Azhar SB, Lim JL, Liu GK, Wong HK. Radiologically defining horizontal gaze using EOS® imaging – a prospective study of healthy subjects and a retrospective audit. Spine J. 2017 Oct 18

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Pasha S, Flynn J, Sponseller P, Orlando G, Newton PO, Cahill PJ. Timing of Changes in ThreeDimensional Spinal Parameters After Selective Thoracic Fusion in Lenke 1 Adolescent Idiopathic Scoliosis: Two-Year Follow-up. Spine Deformity. 2017; 5(6) 409-415

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Goodbody C, Kedem P, Thompson M, Do HT, Mintz DN, Widmann RF, Dodwell ER. Reliability and Reproducibility of Subject Positioning with EOS Low-Dose Biplanar X-ray. HSS J. 2017 Oct;13(3):263-266

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Bao H, Liabaud B, Varghese J, Lafage R, Diebo BG, Jalai C, Ramchandran S, Poorman G, Errico T, Zhu F, Protopsaltis T, Passias P, Buckland A, Schwab F, Lafage V. Lumbosacral stress and age may contribute to increased pelvic incidence: an analysis of 1625 adults. Eur Spine J. 2017 Oct 12

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Mainard-Simard L, Lan L, Fort D. The advantages of 3D imagery in diagnosing and supervising children's and teenagers' scoliosis. Arch Pediatr. 2017 Sep 8

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Alnachoukati O, Emerson R, Ennin K, Vidal A. How well do lower femoral neck shaft angled stems match patients with coxa vara hip deformities?. Clin Trials Orthop Disord, 2017 Sep 20;2:91-6

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Chiron P, Demoulin L, Wytrykowski K, Cavaignac E, Reina N, Murgier J. Radiation dose and magnification in pelvic X-ray: EOS™ imaging system versus plain radiographs. Orthop Traumatol Surg Res. 2017 Sep 20

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Hey HWD, Tan KA, Kantharajanna SB, Teo AQA, Chan CX, Liu KG, Wong HK. Using spinopelvic parameters to estimate residual lumbar lordosis assuming previous lumbosacral fusion—a study of normative values. Spine J. 2017 Aug 16

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Westberry DE, Carpenter AM. 3D Modeling of Lower Extremities With Biplanar Radiographs: Reliability of Measures on Subsequent Examinations. J Pediatr Orthop. 2017 Aug 2

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Lazennec JY, Thauron F, Robbins CB, Pour AE. Acetabular and Femoral Anteversions in Standing Position are Outside the Proposed Safe Zone After Total Hip Arthroplasty. J Arthroplasty. 2017 Jun 20

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Pasha S, Schlösser T, Zhu X, Mellor X, Castelein R, Flynn J. Application of Low-dose Stereoradiography in In Vivo Vertebral Morphologic Measurements: Comparison With Computed Tomography. J Pediatr Orthop. 2017 Jun 30

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Hey HWD, Wong GC, Chan CX, Lau LL, Kumar N, Thambiah JS, Ruiz JN, Liu KG, Wong HK. Reproducibility of sagittal radiographic parameters in adolescent idiopathic scoliosis-a guide to reference values using serial imaging. Spine J. 2017 Jun;17(6):830-836

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Hey HWD, Tan KA, Neo CS, Lau ET, Choong DA, Lau LL, Liu GK, Wong HK. T9 versus T10 as the upper instrumented vertebra for correction of adult deformity-rationale and recommendations. Spine J. 2017 May;17(5):615-621

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Hey HW, Lau ET, Wong CG, Tan KA, Liu GK, Wong HK. Cervical Alignment Variations in Different Postures and Predictors of Normal Cervical Kyphosis - A New Understanding. Spine (Phila Pa 1976). 2017 Mar 16

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Loppini M, Longo UG, Caldarella E, Rocca AD, Denaro V, Grappiolo G. Femur first surgical technique: a smart non-computer-based procedure to achieve the combined anteversion in primary total hip arthroplasty. BMC Musculoskelet Disord. 2017 Aug 1;18(1):331

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Loppini M, Longo UG, Ragucci P, Trenti N, Balzarini L, Grappiolo G. Analysis of the Pelvic Functional Orientation in the Sagittal Plane: A Radiographic Study With EOS 2D/3D Technology. J Arthroplasty. 2017 Mar;32(3):1027-1032

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Lafage R, Liabaud B, Diebo BG, Oren JH, Vira S, Pesenti S, Protopsaltis TS, Errico TJ, Schwab FJ, Lafage V. Defining the Role of the Lower Limbs in Compensating for Sagittal Malalignment. Spine (Phila Pa 1976). 2017 Mar 16

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Cobetto N, Aubin CE, Parent S, Barchi S, Turgeon I, Labelle H. 3D correction of AIS in braces designed using CAD/CAM and FEM: a randomized controlled trial. Scoliosis and Spinal Disorders. 2017, 12:24

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Bao H, Varghese J, Lafage R, Liabaud B, Diebo B, Ramchandran S, Day L, Jalai C, Cruz D, Errico T, Protopsaltis T, Passias P, Buckland A, Qiu Y, Schwab F, Lafage V. Principal radiographic characteristics for cervical spinal deformity: A health-related quality of life analysis. Spine (Phila Pa 1976). 2017 Mar 8

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Obeid I, Diebo BG, Boissiere L, Bourghli A, Cawley DT, Larrieu D, Pointillart V, Challier V, Vital JM, Lafage V. Single Level Proximal Thoracic Pedicle Subtraction Osteotomy for Fixed Hyperkyphotic Deformity: Surgical Technique and Patient Series. Operative Neurosurgery, 2017

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Aubin CE, Clin J, Rawlinson J. Biomechanical simulations of costo-vertebral and anterior vertebral body tethers for the fusionless treatment of pediatric scoliosis. J Orthop Res. 2017 Jul 7

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Smith JS, Shaffrey CI, Bess S, Shamji MF, Brodke D, Lenke LG, Fehlings MG, Lafage V, Schwab F, Vaccaro AR, Ames CP. Recent and Emerging Advances in Spinal Deformity. Neurosurgery. 2017 Mar 1;80(3S):S70-S85

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Sullivan TB, Bastrom T, Reighard F, Jeffords M, Newton PO. A Novel Method for Estimating Three-Dimensional Apical Vertebral Rotation Using Two-Dimensional Coronal Cobb Angle and Thoracic Kyphosis. Spine Deform. 2017 Jul;5(4):244-249

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Bao H, Lafage R, Liabaud B, Elysée J, Diebo BG, Poorman G, Jalai C, Passias P, Buckland A, Bess S, Errico T, Lenke LG, Gupta M, Kim HJ, Schwab F, Lafage V. Three types of sagittal alignment regarding compensation in asymptomatic adults: the contribution of the spine and lower limbs. Eur Spine J. 2017 Jun 6

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Ilharreborde B, Ferrero E, Angelliaume A, Lefèvre Y, Accadbled F, Simon AL, de Gauzy JS, Mazda K. Selective versus hyperselective posterior fusions in Lenke 5 adolescent idiopathic scoliosis: comparison of radiological and clinical outcomes. Eur Spine J. 2017 Jun;26(6):1739-1747

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Angelliaume A, Ferrero E, Mazda K, Le Hanneur M, Accabled F, de Gauzy JS, Ilharreborde B. Titanium vs cobalt chromium: what is the best rod material to enhance adolescent idiopathic scoliosis correction with sublaminar bands?. Eur Spine J. 2017 Jun;26(6):17321738

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Abrisham SM, Bouzarjomehri F, Nafisi-Moghadam R, Sobhan MR, Gadimi M, Omidvar F. A Comparison of Patients Absorption Doses with Bone Deformity Due to the EOS Imaging and Digital Radiology. Arch Bone Jt Surg. 2017; 5(3): 145-148

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Pesenti S, Ghailane S, Varghese JJ, Ollivier M, Peltier E, Choufani E, Bollini G, Blondel B, Jouve JL. Bone substitutes in adolescent idiopathic scoliosis surgery using sublaminar bands: is it useful? A case-control study. Int Orthop. 2017 May 24

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Buckland AJ, Ramchandran S, Day L, Bess S, Protopsaltis T, Passias PG, Diebo BG, Lafage R, Lafage V, Sure A, Errico TJ. Radiological lumbar stenosis severity predicts worsening sagittal malalignment on full-body standing stereoradiographs. Spine J. 2017 May 17

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Giudici F, Galbusera F, Zagra A, Wilke HJ, Archetti M, Scaramuzzo L. Determinants of the biomechanical and radiological outcome of surgical correction of adolescent idiopathic scoliosis surgery: the role of rod properties and patient characteristics. Eur Spine J. 2017 May 23

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Zeighami A, Dumas R, Kanhonou M, Hagemeister N, Lavoie F, de Guise JA, Aissaoui R. Tibiofemoral joint contact in healthy and osteoarthritic knees during quasi-static squat: A biplanar X-ray analysis. J Biomech. 2017 Jan 19

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Le Navéaux F, Aubin CE, Parent S, O Newton P, Labelle H. 3D rod shape changes in adolescent idiopathic scoliosis instrumentation: how much does it impact correction? Eur Spine J. 2017 Feb 8

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Sailhan F, Jacob L, Hamadouche M. Differences in limb alignment and femoral mechanicalanatomical angles using two dimension versus three dimension radiographic imaging. Int Orthop. 2017 Feb 24

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Agten CA, Jonczy M, Ullrich O, Pfirrmann CW, Sutter R, Buck FM. Measurement of Acetabular Version based on Biplanar Radiographs with 3D Reconstructions in Comparison to CT as Reference Standard in Cadavers. Clin Anat. 2017 Mar 13

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Ortiz A. The EOS Imaging System: Promising Technology in Skeletal Imaging. Radiol Technol. 2017 Mar;88(4):448-450

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Assi A, Bakouny Z, Sauret C, Saghbini E, Khalil N, Chelala L, Naoum E, Yared F, Skalli W, Ghanem I. Influence of patient rotational malpositioning on pelvic parameters assessed on lateral radiographs. Clin Radiol. 2017 Apr 22

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Parvaresh K, Osborn E, Reighard F, Doan J, Bastrom TP, Newton P. Predicting 3D Thoracic Kyphosis Using Traditional 2D Radiographic Measurements in Adolescent Idiopathic Scoliosis. Spine Deformity, Volume 5, Issue 3, May 2017, Pages 159-165.

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Lazennec JY, Clark IC, Folinais D, Tahar IN, Pour A. What is the impact of a spinal fusion on acetabular implant orientation in functional standing and sitting positions? J Arthroplasty. 2017

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Le Navéaux F, Labelle H, Parent S, Newton PO, Aubin CE. Are there 3D Changes in Spine and Rod Shape in the 2 Years After Adolescent Idiopathic Scoliosis Instrumentation? Spine. 2017

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Sullivan TB, Reighard FG, Osborn EJ, Parvaresh KC, Newton PO. Thoracic Idiopathic Scoliosis Severity Is Highly Correlated with 3D Measures of Thoracic Kyphosis. J Bone Joint Surg Am. 2017 Jun 7;99(11):e54

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DelSole EM, Vigdorchik JM, Schwarzkopf R, Errico TJ, Buckland AJ. Total Hip Arthroplasty in the Spinal Deformity Population: Does Degree of Sagittal Deformity Affect Rates of Safe Zone Placement, Instability, or Revision? J Arthroplasty. 2017 Jun;32(6):1910-1917

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Ferrero E, Lafage R, Diebo BG, Challier V, Illharreborde B, Schwab F, Skalli W, Guigui P, Lafage V. Tridimensional Analysis of Rotatory Subluxation and Sagittal Spinopelvic Alignment in the Setting of Adult Spinal Deformity. Spine Deform. 2017 Jul;5(4):255-264

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Lazennec JY, Chometon Q, Folinais D, Robbins CB, Pour AE. Are advanced threedimensional imaging studies always needed to measure the coronal knee alignment of the lower extremity? Int Orthop. 2016 Nov 14

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Ben Abdennebi A, Aubry S, Ounalli L, Fayache MS, Delabrousse E, Petegnief Y. Comparative dose levels between CT-scanner and slot-scanning device (EOS system) in pregnant women pelvimetry. Phys Med. 2016 Dec 16

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Le Navéaux F, Larson AN, Labelle H, Wang X Aubin CE. How does implant distribution affect 3D correction and bone-screw forces in thoracic adolescent idiopathic scoliosis spinal instrumentation?. Clin Biomech. 2016

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Hui SCN, Chu WCW. Supplementary Addendum to “Radiation dose of digital radiography (DR) versus micro-dose x-ray (EOS) on patients with adolescent idiopathic scoliosis: 2016 SOSORT- IRSSD “John Sevastic Award” Winner in Imaging Research”. Scoliosis Spinal Disord, 2018

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Skalli W, Vergari C, Ebermeyer E, Courtois I, Drevelle X, Kohler R, Abelin-Genevois K, Dubousset J. Early Detection of Progressive Adolescent Idiopathic Scoliosis: A Severity Index. Spine (Phila Pa 1976). 2016 Oct 24

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Rouissi J, Arvieu R, Dubory A, Vergari C, Bachy M, Vialle R. Intra and inter-observer reliability of determining degree of pelvic obliquity in neuromuscular scoliosis using the EOS-CHAIR® protocol. Childs Nerv Syst. 2016 Dec 27

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Thelen T, Thelen P, Demezon H, Aunoble S, Le Huec JC. Normative 3D acetabular orientation measurements by the low-dose EOS imaging system in 102 asymptomatic subjects in standing position: analyses by side, gender, pelvic incidence and reproducibility. Orthop Traumatol Surg Res. 2016 Dec 23

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Hui SC, Pialasse JP, Wong JY, Lam TP, Ng BK, Cheng JC, Chu WC. Radiation dose of digital radiography (DR) versus micro-dose x-ray (EOS) on patients with adolescent idiopathic scoliosis: 2016 SOSORT- IRSSD "John Sevastic Award" Winner in Imaging Research. Scoliosis Spinal Disord. 2016 Dec 29;11:46

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Tabard-Fougère A, Bonnefoy-Mazure A, Hanquinet S, Lascombes P, Armand S, Dayer R. Validity and Reliability of Spine Rasterstereography in Patients with Adolescent Idiopathic Scoliosis. Spine (Phila Pa 1976). 2016 May 11

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Assi A, Sauret C, Massaad A, Bakouny Z, Pillet H, Skalli W, Ghanem I. Validation of hip joint center localization methods during gait analysis using 3D EOS imaging in typically developing and cerebral palsy children. Gait Posture. 2016 Jul;48:30-5

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Yaszay B, Bastrom TP, Bartley CE, Parent S, Newton PO. The effects of the threedimensional deformity of adolescent idiopathic scoliosis on pulmonary function. Eur Spine J. 2016 Aug 11.

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Singhatanadgige W, Kang DG, Luksanapruksa P, Peters C, Riew KD. Correlation and Reliability of Cervical Sagittal Alignment Parameters between Lateral Cervical Radiograph and Lateral Whole-Body EOS Stereoradiograph. Global Spine J. 2016 Sep;6(6):548-54.

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Pytiak A, Bomar JD, Peterson JB, Schmitz MR, Pennock AT, Wenger DR, Upasani VV. Analysis of spinal alignment and pelvic parameters on upright radiographs: implications for acetabular development. J Hip Preserv Surg. 2016 Apr 4;3(3):208-14

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Lazennec JY, Folinais D, Bendaya S, Rousseau MA, Pour AE. The global alignment in patients with lumbar spinal stenosis: our experience using the EOS full-body images. Eur J Orthop Surg Traumatol. 2016 Oct;26(7):713-24

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Schlégl ÁT, O'Sullivan I, Varga P, Than P, Vermes C. Determination and correlation of lower limb anatomical parameters and bone age during skeletal growth (based on 1005 cases). J Orthop Res. 2016 Aug 11.

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Sauret C, Pillet H, Skalli W, Sangeux M. On the use of knee functional calibration to determine the medio-lateral axis of the femur in gait analysis: comparison with EOS biplanar radiographs as reference. Gait Posture. 2016 Sep 12;50:180-184

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Price R, Okamoto M, Le Huec JC, Hasegawa K. Normative spino-pelvic parameters in patients with the lumbarization of S1 compared to a normal asymptomatic population. Eur Spine J. 2016 Sep 26

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Knafo J, Thelen T, Verdier D, Creppy L, Tournier C, Fabre T. Reproducibility of low-dose stereography measurements of femoral torsion after IM nailing of femoral shaft fractures and in normal femurs. Orthop Traumatol Surg Res. 2016

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Hey HW, Wong CG, Lau ET, Tan KA, Lau LL, Liu KG, Wong HK. Differences in erect sitting and natural sitting spinal alignment-insights into a new paradigm and implications in deformity correction. Spine J. 2016 Aug 22

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Nerot A, Skalli W, Wang X. A principal component analysis of the relationship between the external body shape and internal skeleton for the upper body. J Biomech. 2016 Sep 14

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Vidal C, Mazda K, Ilharreborde B. Sagittal spino-pelvic adjustment in severe Lenke 1 hypokyphotic adolescent idiopathic scoliosis patients. Eur Spine J. 2016 Oct;25(10):31623169

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Kim YC, Lenke LG, Lee SJ, Gum JL, Wilartratsami S, Blanke KM. The cranial sagittal vertical axis (CrSVA) is a better radiographic measure to predict clinical outcomes in adult spinal deformity surgery than the C7 SVA: a monocentric study. Eur Spine J. 2016 Oct 14

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Day LM, Ramchandran S, Jalai CM, Diebo BG, Liabaud B, Lafage R, Protopsaltis T, Passias PG, Schwab FJ, Bess S, Errico TJ, Lafage V, Buckland AJ. Thoracolumbar Realignment Surgery Results in Simultaneous Reciprocal Changes in Lower Extremities and Cervical Spine. Spine (Phila Pa 1976). 2016 Oct 17

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Donzelli S, Zaina F, Lusini M, Minnella S, Respizzi S, Balzarini L, Poma S, Negrini S. The three dimensional analysis of the Sforzesco brace correction. Scoliosis Spinal Disord. 2016 Oct 14;11(Suppl 2):34

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Ferrero E, Lafage R, Vira S, Rohan PY, Oren J, Delsole E, Guigui P, Schwab F, Lafage V, Skalli W. Three-dimensional reconstruction using stereoradiography for evaluating adult spinal deformity: a reproducibility study. Eur Spine J. 2016 Nov 5

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Ruzbarsky JJ, Goodbody C, Dodwell E. Closing the growth plate: a review of indications and surgical options. Curr Opin Pediatr. 2016 Nov 14

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Jalai CM, Cruz DL, Diebo BG, Poorman G, Lafage R, Bess S, Ramachandran S, Day LM, Vira S, Liabaud B, Henry JK, Schwab FJ, Lafage V, Passias PG. Full-Body Analysis of Age-Adjusted Alignment in Adult Spinal Deformity Patients and Lower-Limb Compensation. Spine (Phila Pa 1976). 2016 Aug 23

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Morvan A, Moreau S, Combourieu B, Pansard E, Marmorat JL, Carlier R, Judet T, Lonjon G. Standing radiological analysis with a low-dose biplanar imaging system (EOS system) of the position of the components in total hip arthroplasty using an anterior approach: a cohort study of 102 patients. Bone Joint J. 2016 Mar;98-B(3):326-33

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Newton P, Khandwala Y, Bartley C, Reighard F, T. Bastrom T, Yaszay B. New EOS Imaging Protocol Allows a Substantial Reduction in Radiation Exposure for Scoliosis Patients. Spine Deformity, 2016.

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Rosskopf AB, Pfirrmann CW, Buck FM. Assessment of two-dimensional (2D) and threedimensional (3D) lower limb measurements in adults: Comparison of micro-dose and lowdose biplanar radiographs. Eur Radiol. 2016

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Hocquelet A, Cornelis F, Jirot A, Castaings L, de Sèze M, Hauger O. Patient-specific 3D models created by 3D imaging system or bi-planar imaging coupled with Moiré-Fringe projections: a comparative study of accuracy and reliability on spinal curvatures and vertebral rotation data. Eur Spine J. 2016

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Kato S, Debaud C, Zeller RD. Three-dimensional EOS Analysis of Apical Vertebral Rotation in Adolescent Idiopathic Scoliosis. J Pediatr Orthop. 2016

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Massaad A, Assi A, Bakouny Z, Sauret C, Khalil N, Skalli W, Ghanem I. Three-dimensional evaluation of skeletal deformities of the pelvis and lower limbs in ambulant children with cerebral palsy. Gait Posture. 2016 Jun 23;49:102-107.

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Hasegawa K, Okamoto M, Hatsushikano S, Shimoda H, Ono M, Watanabe K. Normative values of spino-pelvic sagittal alignment, balance, age, and health-related quality of life in a cohort of healthy adult subjects. Eur Spine J, 2016

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Mahboub-Ahari A, Hajebrahimi S, Yusefi M, Velayati A. EOS imaging versus current radiography: A health technology assessment study. Med J Islam Repub Iran 2016 (17 February). Vol. 30:331

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Clément J, Dumas R, Hagemeister N, de Guise JA.Can generic knee joint models improve the measurement of osteoarthritic knee kinematics during squatting activity? Comput Methods Biomech Biomed Engin. 2016

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Zhang C, Skalli W, Lagacé PY, Billuart F, Ohl X, Cresson T, Bureau NJ, Rouleau DM, Roy A, Tétreault P, Sauret C, de Guise JA, Hagemeister N. Investigation of 3D glenohumeral displacements from 3D reconstruction using biplane X-ray images: Accuracy and reproducibility of the technique and preliminary analysis in rotator cuff tear patients. J Electromyogr Kinesiol. 2016

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Kaneko K, Aota Y, Sekiya T, Yamada K, Saito T. Validation study of arm positions for evaluation of global spinal balance in EOS imaging. Eur J Orthop Surg Traumatol. 2016 Jul 7.

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Sattout A, Clin J, Cobetto N, Labelle H, Aubin CE. Biomechanical Assessment of Providence Nighttime Brace for the Treatment of Adolescent Idiopathic Scoliosis. Spine Deform. 2016 Jul;4(4):253-260

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Melhem E, Assi A, El Rachkidi E, Ghanem I. EOS® biplanar X-ray imaging: concept, developments, benefits, and limitations. J Child Orthop. 2016.

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Verdier N, Billaud A, Masquefa T, Pallaro J, Fabre T, Tournier C. EOS-based cup navigation: Randomised controlled trial in 78 total hip arthroplasties. Orthop Traumatol Surg Res. 2016 Jun;102(4):417-21

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Obeid I, Boissière L, Yilgor C, Larrieu D, Pellisé F, Alanay A, Acaroglu E, Perez-Grueso FJ, Kleinstück F, Vital JM, Bourghli A; European Spine Study Group, ESSG. Global tilt: a single parameter incorporating spinal and pelvic sagittal parameters and least affected by patient positioning. Eur Spine J. 2016 Nov;25(11):3644-3649

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Hirsch C, Ilharreborde B, Mazda K. Flexibility analysis in adolescent idiopathic scoliosis on side-bending images using the EOS imaging system. Orthop Traumatol Surg Res. 2016 Jun;102(4):495-500

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Ferrero E, Liabaud B, Challier V, Lafage R, Diebo BG, Vira S, Liu S, Vital JM, Ilharreborde B, Protopsaltis TS, Errico TJ, Schwab FJ, Lafage V. Role of pelvic translation and lower-extremity compensation to maintain gravity line position in spinal deformity. J Neurosurg Spine. 2016 Mar;24(3):436-46

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Simon AL, Ferrero E, Noelle Larson A, Kaufman KR. Stereoradiography imaging motion artifact: does it affect radiographic measures after spinal instrumentation? Eur Spine J. 2016 Mar 3

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Morin SN, Wall M, Belzile EL, Godbout B, Moser TP, Michou L, Ste-Marie LG, de Guise JA, Rahme E, Brown JP. Assessment of femur geometrical parameters using EOS™ imaging technology in patients with atypical femur fractures; preliminary results. Bone. 2016 Feb;83:184-9

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Amabile C, Pillet H, Lafage V, Barrey C, Vital JM, Skalli W. A new quasi-invariant parameter characterizing the postural alignment of young asymptomatic adults. Eur Spine J. 2016

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Cogniet A, Aunoble S, Rigal J, Demezon H, Sadikki R, Le Huec JC. Clinical and radiological outcomes of lumbar posterior subtraction osteotomies are correlated to pelvic incidence and FBI index: Prospective series of 63 cases. Eur Spine J. 2016

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Vira S, Diebo B, Spiegel M, Liabaud B, Henry J, Oren J, Lafage R, Tanzi E, Protopsaltis T, Errico T, Schwab F, Lafage V. Is There a Gender-Specific Full Body Sagittal Profile for Different Spinopelvic Relationships? A Study on Propensity-Matched Cohorts? Spine Deformity. 2016

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Buckland AJ, Vira S, Oren JH, Lafage R, Harris BY, Spiegel MA, Diebo BG, Liabaud B, Protopsaltis TS, Schwab FJ, Lafage V, Errico TJ, Bendo JA. When is compensation for lumbar spinal stenosis a clinical sagittal plane deformity? Spine J. 2016

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Iyer S, Lenke LG, Nemani VM, Fu M, Shifflett GD, Albert TJ, Sides BA, Metz LN, Cunningham ME, Kim HJ. Variations in Occipitocervical and Cervicothoracic Alignment Parameters based on Age: A Prospective Study of Asymptomatic Volunteers using Full-Body Radiographs. Spine. 2016

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Iyer S, Lenke LG, Nemani VM, Albert TJ, Sides BA, Metz LN, Cunningham ME, Kim HJ. Variations in Sagittal Alignment Parameters based on Age: A Prospective Study of Asymptomatic Volunteers using Full-Body Radiograph. Spine. 2016

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Nam D, Vajapey S, Nunley R, Barrack R. The Impact of Imaging Modality on the Measurement of Coronal Plane Alignment Following Total Knee Arthroplasty. J Arthroplasty. 2016 Oct;31(10):2314-9

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Meijer MF, Boerboom AL, Bulstra SK, Reininga IH, Stevens M. Do CAS measurements correlate with EOS 3D alignment measurements in primary TKA? Knee Surg Sports Traumatol Arthrosc. 2016

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Meijer MF, Velleman T, Boerboom AL, Bulstra SK, Otten E, Stevens M, Reininga IH. The Validity of a New Low-Dose Stereoradiography System to Perform 2D and 3D Knee Prosthetic Alignment Measurements. Plos one. 2016

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Caouette C, Ikin N, Villemure I, Arnoux PJ, Rauch F, Aubin CÉ. Geometry reconstruction method for patient‑specific finite element models for the assessment of tibia fracture risk in osteogenesis imperfecta. Med Biol Eng Comput. 2016

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Liow L, Tsai T, Dimitriou D, Li G, Kwon Y. Does 3D In-Vivo Component Rotation Affect Clinical Outcomes In Unicompartmental Knee Arthroplasty? J Arthroplasty. 2016

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Flecher X, Ollivier M, Argenson JN. Lower limb length and offset in total hip arthroplasty. Orthop Traumatol Surg Res. 2016 Feb;102(1 Suppl):S9-20

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Esposito CI, Miller TT, Kim HJ, Barlow BT, Wright TM, Padgett DE, Jerabek SA, Mayman D. Does Degenerative Lumbar Spine Disease Influence Femoroacetabular Flexion in Patients Undergoing Total Hip Arthroplasty? Clin Orthop Relat Res. 2016

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Bendaya S, Anglin C, Lazennec JY, Allena R, Thoumie P, Skalli W. Good vs. Poor Results after Total Hip Arthroplasty: An Analysis Method using Implant and Anatomical Parameters with the EOS® Imaging System. J Arthroplasty. 2016

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Lazennec JY, Brusson A, Rousseau MA, Robbins C, Pour AE. Do Patients’ Perceptions of Leg Length Correlate with Standing 2- and 3-dimensional Radiographic Imaging? J Arthroplasty. 2016

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Tsai TY, Dimitriou D, Hosseini A, Liow MH, Torriani M, Li G, Kwon YM. Assessment of accuracy and precision of 3D reconstruction of unicompartmental knee arthroplasty in upright position using biplanar radiography. Med Eng Phys. 2016 Jul;38(7):633-638

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Irrera P, Bloch I, Delplanque M. A flexible patch based approach for combined denoising and contrast enhancement of digital X-ray images. Med Image Anal. 2016 Feb;28:33-45

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Dubois G, Rouch P, Bonneau D, Gennisson JL, Skalli W. Muscle parameters estimation based on biplanar radiography. Comput Methods Biomech Biomed Engin. 2016

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Rochcongar G, Pillet H, Bergamini E, Moreau S, Thoreux P, Skalli W, Rouch P. A new method for the evaluation of the end-to-end distance of the knee ligaments and popliteal complex during passive knee flexion. Knee. 2016

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Amabile C, Choisne J, Nérot A, Pillet H, Skalli W. Determination of a new uniform thorax density representative of the living population from 3D external body shape modeling. J Biomech. 2016.

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La Barbera L, Costa F, Villa T. ISO 12189 standard for the preclinical evaluation of posterior spinal stabilization devices - II: A parametric comparative study. Proc Inst Mech Eng H. 2016 Feb;230(2):134-44

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Cebulski-Delebarre A, Boutry N, Szymanski C, Maynou C, Lefebvre G, Amzallag-Bellenger E, Cotten A. Correlation between primary flat foot and lower extremity rotational misalignment in adults. Diagn Interv Imaging. 2016 Jun 13

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Clavel A, Thevenard-Berger P, Verdun F, Létang J, Darbon A. Organ radiation exposure with EOS: GATE simulations versus TLD measurements. Physics of Medical Imaging, 2016

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Dominguez D, Faundez A, Demezon H, Cogniet A, Le Huec JC. Normative values for the L5 incidence in a subgroup of transitional anomalies extracted from 147 asymptomatic subjects. Eur Spine J. 2016

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Hey H, Teo AQ, Tan KA, Ng LW, Lau LL, Liu KG, Wong HK. How the spine differs in standing and in sitting-important considerations for correction of spinal deformity. Spine J. 2016

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Henao J, Aubin CÉ, Labelle H, Arnoux PJ. Patient-specific finite element model of the spine and spinal cord to assess the neurological impact of scoliosis correction: preliminary application on two cases with and without intraoperative neurological complications. Comput Methods Biomech Biomed Engin. 2016;19(8):901-10.

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Le Huec JC, Hasegawa K. Normative values for the spine shape parameters using 3D standing analysis from a database of 268 asymptomatic Caucasian and Japanese subjects. Eur Spine J. 2016

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Pasha S, Capraro A, Cahill PJ, Dormans JP, Flynn JM. Bi-planar spinal stereoradiography of adolescent idiopathic scoliosis: considerations in 3D alignment and functional balance. Eur Spine J. 2016

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Pasha S, Ho M, Ho‑Fung V, Davidson RS. Application of weight bearing biplanar stereoradiography in assessment of lower limb deformity. Journal of Limb Lengthening & Reconstruction, 2016

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Pasha S, Cahill PJ, Dormans JP, Flynn JM. Characterizing the differences between the 2D and 3D measurements of spine in adolescent idiopathic scoliosis. Eur Spine J. 2016

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Vergari C, Courtois I, Ebermeyer E, Bouloussa H, Vialle R, Skalli W. Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis. Eur Spine J. 2016

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Schmid SL, Buck FM, Böni T, Farshad M. Radiographic measurement error of the scoliotic curve angle depending on positioning of the patient and the side of scoliotic curve. Eur Spine J. 2015 Sep 30

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Ilharreborde B, Ferrero E, Alison M, Mazda K. EOS microdose protocol for the radiological follow-up of adolescent idiopatic scoliosis. Eur Spine J. April 2015.

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Lazennec JY, Brusson A, Folinais D, Zhang A, Pour AE, Rousseau MA. Measuring extension of the lumbar-pelvic-femoral complex with the EOS system. Eur J Orthop Surg Traumatol. 2015 Feb.

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Demzik A, Alvi H, Delagrammaticas D, Martell J, Beal M, Manning M. Inter and Intra-rater Repeatability & Reliability of EOS Three Dimensional Imaging Analysis Software. Journal of arthroplasty. Nov 2015.

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Thépaut M, Brochard S, Leboucher J, Lempereur M, Stindel E, Tissot V, Borotikar BS. Measuring physiological and pathological femoral anteversion using a biplanar low-dose X-ray system: validity, reliability, and discriminative ability in cerebral palsy. Skeletal Radiol. 2015 Nov.

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Barbier O, Mainard D. Comments on: Acetabular component navigation in lateral decubitus based on EOS imaging: A preliminary study of 13 cases of A. Billaud, N. Verdier, R. de Bartolo, N. Lavoine, D. Chauveaux, T. Fabre. Published in Orthop Traumatol Surg Res 2015;101(3):271-5. Orthop Traumatol Surg Res. 2015 Nov;101(7):883.

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Dervaux B, Szwarcensztein K, Josseran A; participants of round table N°4 of Giens XXX:, Barna A, Carbonneil C, Chevrie K, Debroucker F, Grumblat A, Grumel O, Massol J, Maugendre P, Méchin H, Orlikowski D, Roussel C, Rumeau-Pichon C, Sales JP, Vicaut E. Assessment and non-clinical impact of medical devices. Therapie. 2015 Jan-Feb;70(1):5768

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Galbusera F, Bassani T, La Barbera L, Ottardi C, Schlager B, Brayda-Bruno M, Villa T, Wilke HJ. Planning the Surgical Correction of Spinal Deformities: Toward the Identification of the Biomechanical Principles by Means of Numerical Simulation. Front Bioeng Biotechnol. 2015 Nov 3;3:178

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Nérot A, Choisne J, Amabile C, Travert C, Pillet H, Wang X, Skalli W. A 3D reconstruction method of the body envelope from biplanar X-rays: Evaluation of its accuracy and reliability. J Biomech. 2015 Dec 16;48(16):4322-6

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Dagneaux L, Thoreux P, Eustache B, Canovas F, Skalli W. Sequential 3D analysis of patellofemoral kinematics from biplanar x-rays: In vitro validation protocol. Orthop Traumatol Surg Res. 2015 Nov;101(7):811-8

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Courvoisier A, Garin C, Vialle R, Kohler R. The change on vertebral axial rotation after posterior instrumentation of idiopathic scoliosis. Childs Nerv Syst. 2015

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Newton PO, Fujimori T, Doan J, Reighard FG, Bastrom TP, Misaghi A. Defining the "ThreeDimensional Sagittal Plane" in Thoracic Adolescent Idiopathic Scoliosis. J Bone Joint Surg Am. 2015 Oct 21

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Vergari C, Ribes G, Aubert B, Adam C, Miladi L, Ilharreborde B, Abelin-Genevois K, Rouch P, Skalli W. Evaluation of a Patient-Specific Finite-Element Model to Simulate Conservative Treatment in Adolescent Idiopathic Scoliosis. Spine Deformity, 2015

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Hull NC, Binkovitz LA, Schueler BA, Kolbe AB, Larson AN. Upright Biplanar Slot Scanning in Pediatric Orthopedics: Applications, Advantages, and Artifacts. AJR Am J Roentgenol. 2015.

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Luo D, Stans A, Schueler B, Larson N. Cumulative radiation exposure with EOS imaging compared with standard spine radiographs. Spine Deformity. 2015 Mar.

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Yvert M, Diallo A, Bessou P, Rehel JL, Lhomme E, Chateil JF. Radiography of scoliosis: Comparative dose levels and image quality between a dynamic flat-panel detector and a slot-scanning device (EOS system). Diagn Interv Imaging. 2015 Aug 14.

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Tarhan T, Froemel D, Meurer A. EOS imaging acquisition system: 2D/3D diagnostics of the skeleton. Orthopade. 2015 Nov 13. German.

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Hirsch C, Ilharreborde B, Mazda K. EOS suspension test for the assessment of spinal flexibility in adolescent idiopathic scoliosis. Eur Spine J. 2015 Feb.

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Bouloussa H, Dubory A, Seiler C, Morel B, Bachy M, Vialle R. A radiolucent chair for sittingposture radiographs in non-ambulatory children: use in biplanar digital slot-scanning. Pediatr Radiol. 2015

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Briot K, Fechtenbaum J, Etcheto A, Kolta S, Feydy A, Roux C. Diagnosis of vertebral fractures using a low-dose biplanar imaging system. Osteoporos Int. 2015.

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Fechtenbaum J, Etcheto A, Kolta S, Feydy A, Roux C, Briot K. Sagittal balance of the spine in patients with osteoporotic vertebral fractures. Osteoporos Int. 2015 Aug 14.

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Ferrero E, Lafage R, Challier V, Diebo B, Guigui P, Mazda K, Schwab F, Skalli W, Lafage V. Clinical and stereoradiographic analysis of adult spinal deformity with and without rotatory subluxation. Orthop Traumatol Surg Res. 2015 Jul 17.

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Lazennec JY, Rousseau MA, Brusson A, Folinais D, Amel M, Clarke I, Pour AE. Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology. Open Orthop J. 2015 Feb.

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Tiberi JV 3rd, Antoci V, Malchau H, Rubash HE, Freiberg AA, Kwon YM. What Is the Fate of THA Acetabular Component Orientation When Evaluated in the Standing Position? The Journal of arthroplasty. 2015 Mar.

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Nam D, Williams B, Hirsch J, Johnson S, Nunley R, Barrack R. Planned Bone Resections Using an MRI-Based Custom Cutting Guide System Versus 3-Dimensional, Weight-Bearing Images in Total Knee Arthroplasty. The Journal of arthroplasty. 2015 Apr.

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Billaud A, Verdier N, De Bartolo R, Lavoinne N, Chauveaux T, Fabre T. Acetabular component navigation in lateral decubitus based on EOS imaging: A preliminary study of 13 cases. Orthop Traumatol Surg Res. 2015 May.

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Masquefa T, Verdier N, Gille O, Boissière L, Obeid I, Maillot C, Tournier C, Fabre T. Change in acetabular version after lumbar pedicle subtraction osteotomy to correct post-operative flat back: EOS measurements of 38 acetabula. Orthop Traumatol Surg Res. 2015 Sept.

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Clavé A, Fazilleau F, Cheval D, Williams T, Lefèvre C, Stindel E. Comparison of the reliability of leg length and offset data generated by three hip replacement CAOS systems using EOS™ imaging. Orthop Traumatol Surg Res. 2015 Aug 20.

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Bredow J, Katinakis F, Schlüter-Brust K, Krug B, Pfau D, Eysel P, Dargel J, Wegmann K. Influence of hip replacement on sagittal alignment of the lumbar spine: An EOS study. Technol Health Care. 2015.

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Tsai, T-Y. Dimitrou D, Lincoln Liow M-H, Rubah H, Li G, Kwon Y-M. 3D Imaging Analysis of Unicompartmental Knee Arthroplasty Evaluated in Standing Position: Component Alignment and In-Vivo Articular Contact. Journal of arthroplasty. Nov 2015.

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Garner MR, Dow M, Bixby E, Mintz DN, Widmann RF, Dodwell ER. Evaluating Length: The Use of Low-dose Biplanar Radiography (EOS) and Tantalum Bead Implantation. J Pediatr Orthop. 2015 Apr.

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Duprey S, Billuart F, Sah S, Ohl X, Robert T, Skalli W, Wang X. Three-Dimensional Rotations of the Scapula During Arm Abduction: Evaluation of the AMC Method by Comparison With a Model-Based Approach Using Biplanar X-ray. J Appl Biomech. 2015

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Cidambi K, Glaser D, Doan J, Newton P. Generation of a Patient-Specific Model of Normal Sagittal Alignment of the Spine. Spine Deformity 2015.

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Nérot A, Wang X, Pillet H, Skalli W. Estimation of hip joint center from the external body shape: a preliminary study. CMBBE 2015 Aug 3.

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Langlois K, Pillet H, Lavaste F, Rochcongar G, Rouch P, Thoreux P, Skalli W. Assessing the accuracy and precision of manual registration of both femur and tibia using EOS imaging system with multiple views. CMBBE 2015.

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Zhang C, Skalli W, Lagacé PY, Billuart F, Ohl X, Cresson T, Bureau NJ, Rouleau DM, Roy A,Tétreault P, Sauret C, de Guise JA, Hagemeister N. Investigation of 3D glenohumeral displacements from 3D reconstruction using biplane X-ray images: Accuracy and reproducibility of the technique and preliminary analysis in rotator cuff tear patients. J Electromyogr Kinesiol. 2015

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Clavel AH, Monnin P, Létang JM, Verdun FR, Darbon A. Characterising the EOS Slot-Scanning System with the Effective Detective Quantum Efficiency. Radiat Prot Dosimetry. 2015

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Ohl X, Hagemeister N, Zhang C, Billuart F, Gagey O, Bureau NJ, Skalli W. 3D scapular orientation on healthy and pathologic subjects using stereoradiographs during arm elevation. J Shoulder Elbow Surg. 2015

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Schlégl ÁT, Szuper K, Somoskeöy S, Than P. Three dimensional radiological imaging of normal lower-limb alignment in children. Int Orthop. 2015 Oct;39(10):2073-80

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Clément J, Dumas R, Hagemeister N, de Guise JA. Soft tissue artifact compensation in knee kinematics by multi-body optimization: Performance of subject-specific knee joint models. J Biomech. 2015 Nov 5;48(14):3796-802

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Nérot A, Skalli W, Wang X. An assessment of the realism of digital human manikins used for simulation in ergonomics. Ergonomics. 2015 May 28:1-13

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Gaumétou E, Mallet C, Souchet P, Mazda K, Ilharreborde B. Poor Efficiency of Eight-Plates in the Treatment of Lower Limb Discrepancy. J Pediatr Orthop. 2015 May 15

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Diebo BG, Ferrero E, Lafage R, Challier V, Liabaud B, Liu S, Vital JM, Errico TJ, Schwab FJ, Lafage V. Recruitment of compensatory mechanisms in sagittal spinal malalignment is age and regional deformity dependent: a full-standing axis analysis of key radiographical parameters. Spine (Phila Pa 1976). 2015 May 1;40(9):642-9

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Carreau J, Bastrom T, Petcharaporn M, Schulte C, Marks M, Illés T, Somoskëoy S, Newton P. Computer-Generated Three-Dimensional Spine Model From Biplanar Radiographs: A Validity Study in Idiopathic Scoliosis Curves Greater than 50 degrees. Spine Deformity. March 2014.

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Guggenberger R, Pfirrmann CW, Koch PP, Buck FM. Assessment of Lower Limb Length and Alignment by Biplanar Linear Radiography: Comparison With Supine CT and Upright FullLength Radiography. AJR. 2014

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Sigmann M, Delabrousse E, Riethmuller D, Runge M, Peyron C, Aubry S. An evaluation of the EOS X-ray imaging system in pelvimetry. Diagnostic and interventional imaging. 2014.

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Barbier O, Skalli W, Mainard L, Mainard D. The reliability of the anterior pelvic plane for computer navigated acetabular component placement during total hip arthroplasty: Prospective study with the EOS imaging system. Orthop Traumatol Surg Res. 2014

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Rungprai C, Goetz JE, Arunakul M, Gao Y, Femino JE, Amendola A, Phisitkul P. Foot and Ankle Radiographic Parameters: Validation and Reproducibility With a Biplanar Imaging System Versus Conventional Radiography. Foot Ankle Int. 2014

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Guenoun B, El Hajj F, Biau D, Anract P, Courpied JP. Reliability of a New Method for Evaluating Femoral Stem Positioning After Total Hip Arthroplasty Based on Stereoradiographic 3D Reconstruction. J Arthroplasty. 2014

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Lazennec JY, Brusson A, Folinais D, Rousseau M, Pour AE, Offset and anteversion reconstruction after cemented and uncemented total hip arthroplasty: an evaluation with

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the low-dose EOS system comparing two- and three-dimensional imaging. Int Orthop. 2014. •

Pomerantz ML, Glaser D, Doan J, Kumar S, Edmonds EW. Three-dimensional biplanar radiography as a new means of accessing femoral version: a comparative study of EOS three-dimensional radiography versus computed tomography. Skeletal Radiol, 2014

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Blumer SL, Dinan D, Grissom LE. Benefits and unexpected artifacts of biplanar digital slotscanning imaging in children. Pediatr Radiol. 2014 Feb 22.

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Molto A, Freire V, Feydy A, Paternotte S, Maksymowych P, Benhamou M, Rannou F, Dougados M, Gossec L. Assessing structural changes in axial spondyloarthritis using a low dose biplanar imaging system. Rheumatology. 2014.

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Dubousset J, Ilharreborde B, Le Huec JC, Use of EOS imaging for the assessment of scoliosis deformities: application to postoperative 3D quantitative analysis of the trunk. Eur Spine J. 2014.

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Le Huec JC, Faundez A, Dominguez D, Hoffmeyer P, Aunoble S. Evidence showing the relationship between sagittal balance and clinical outcomes in surgical treatment of degenerative spinal diseases: A literature review. Int Orthop. 2014 Sep 06.

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Amzallag-Bellenger E, Uyttenhove F, Nectoux E, Moraux A, Bigot J, Herbaux B, Boutry N. Idiopathic scoliosis in children and adolescents: assessment with a biplanar X-ray device. Insights Imaging. 2014 Sep 13.

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Le Huec JC, Demezon H, Aunoble S. Sagittal parameters of global cervical balance using EOS imaging: normative values from a prospective cohort of asymptomatic volunteers. Eur Spine J Oct 2014.

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Boissière L, Vital JM, Aunoble S, Fabre T, Gille O, Obeid I. Lumbo-pelvic related indexes: impact on adult spinal deformity surgery. Eur Spine J. 2014

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Ferre R, Gibon E, Hamadouche M, Feydy A, Drapé JL. Evaluation of a method for the assessment of anterior acetabular coverage and hip joint space width. Skeletal Radiol. 2014

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Rosskopf AB, Ramseier LE, Sutter R, Pfirrmann CW, Buck FM. Femoral and Tibial Torsion Measurement in Children and Adolescents: Comparison of 3D Models Based on Low-Dose Biplanar Radiography and Low-Dose CT. AJR. 2014

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Pailhé R, Bedes L, Sales de Gauzy J, Tran R, Cavaignac E, Accadbled F. Derotational femoral osteotomy technique with locking nail fixation for adolescent femoral antetorsion: surgical technique and preliminary study. J Pediatr Orthop B. 2014.

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Szuper K, Schlégl AT, Leidecker E, Vermes C, Somoskeöy S, Than P. Three-dimensional quantitative analysis of the proximal femur and the pelvis in children and adolescents using an upright biplanar slot-scanning X-ray system. Pediatr Radiol. 2014

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Schlegl AT, Szuper K, Somoskeoy S, Than P. Evaluation of the usefulness of the EOS 2D/3D system for the measurement of lower limbs anatomical and biomechanical parameters in children. Orv Hetil Oct, 2014.

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Meijer MF, Boerboom AL, Stevens M, Bulstra SK, Reininga IHF. Assessment of prosthesis alignment after revision total knee arthroplasty using EOS 2D and 3D imaging: a reliability study. Plos one. 2014

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Meyrignac O, Moreno R, Baunin C, Vial J, Accadbled F, Sommet A, de Gauzy JS, Sans N. Lowdose biplanar radiography can be used in children and adolescents to accurately assess femoral and tibial torsion and greatly reduce irradiation. Eur Radiol, 2014

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Bendaya S, Lazennec JY, Anglin C, Allena R, Sellam N, Thoumie P, Skalli W. Healthy vs. osteoarthritic hips: A comparison of hip, pelvis and femoral parameters and relationships using the EOS® system. Clin Biomech, 2014

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Sangeux M, Pillet H, Skalli W. Which method of hip joint centre localisation should be used in gait analysis?. Gait and Posture. 2014.

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Damet J, Fournier P, Monnin P, Sans-Merce M, Ceroni D, Zand T, Verdun FR, Baechler S. Occupational and patient exposure as well as image quality for full spine examinations with the EOS imaging system. Medical physics. 2014.

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Aubert B, Vergari C, Ilharreborde B, Courvoisier A, Skalli W. 3D reconstruction of rib cage geometry from biplanar radiographs using a statistical parametric model approach. CMBBE. 2014.

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Begon M, Scherrer SA, Coillard C, Rivard CH, Allard P. Three-dimensional vertebral wedging and pelvic asymmetries in the early stages of adolescent idiopathic scoliosis. Spine J, 2014.

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Al-Aubaidi Z, Lebel D, Oudjhane K, Zeller R. Three-dimensional imaging of the spine using the EOS system: is it reliable? A comparative study using computed tomography imaging. J Pediatr Orthop B. 2013.

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Folinais D, Thelen P, Delin C, Radier C, Catonne Y, Lazennec JY. Measuring femoral and rotational alignment: EOS system versus computed tomography. Orthop Traumatol Surg Res. 2013.

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Rousseau MA, Brusson A, Lazennec JY. Assessment of the axial rotation of the pelvis with the EOS imaging system: intra- and inter-observer reproducibility and accuracy study. Eur J Orthop Surg Traumatol. 2013.

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Escott BG, Ravi B, Weathermon AC, Acharya J, Gordon CL, Babyn PS, Kelley SP, Narayanan UG. EOS low-dose radiography: a reliable and accurate upright assessment of lower-limb lengths. J Bone Joint Surg Am. Dec 2013.

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Quijano S, Serrurier A, Aubert B, Laporte S, Thoreux P, Skalli W. Three-dimensional reconstruction of the lower limb from biplanar calibrated radiographs. Med Eng Phys. 2013.4

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Schmitz MR, Bittersohl B, Zaps D, Bomar JD, Pennock AT, Hosalkar HS. Spectrum of Radiographic Femoroacetabular Impingement Morphology in Adolescents and Young Adults: An EOS-Based Double-Cohort Study. J Bone Joint Surg. July 2013

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Monazzam S, Agashe M, Hosalkar HS. Reliability of Overcoverage Parameters With Varying Morphologic Pincer Features: Comparison of EOS1 and Radiography. Clin Orthop Relat Res. 2013 May 9

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Ilharreborde B, Sebag G, Skalli W, Mazda K. Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system. Eur Spine J. 2013 Apr 12

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Gaumétou E, Quijano S, Ilharreborde B, Presedo A, Thoreux P, Mazda K, Skalli W. EOS analysis of lower extremity segmental torsion in children and young adults. Orthop Traumatol Surg Res. 2013

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Dietrich TJ, Pfirrmann CW, Schwab A, Pankalla K, Buck FM. Comparison of radiation dose, workflow, patient comfort and financial break-even of standard digital radiography and a novel biplanar low-dose X-ray system for upright full-length lower limb and whole spine radiography. Skeletal Radiol. 2013.

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Boutry N, Dutouquet B, Leleu X, Vieillard MH, Duhamel A, Cotten A. Low-dose biplanar skeletal survey versus digital skeletal survey in multiple myeloma. Eur Radiol. 2013.

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Delin C, Silvera S, Bassinet C, Thelen P, Rehel JL, Legmann P, Folinais D. Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography. Eur J Radiol. 2013.

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Lazennec JY, Brusson A, Rousseau MA. Lumbar-pelvic-femoral balance on sitting and standing lateral radiographs. Orthop Traumatol Surg Res. 2013;99(1 Suppl):S87-103.

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Boissiere L, Bourghli A, Vital JM, Gille O, Obeid I. The lumbar lordosis index: a new ratio to detect spinal malalignment with a therapeutic impact for sagittal balance correction decisions in adult scoliosis surgery. Eur Spine J. 2013.

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Illes T, Somoskeoy S. Comparison of scoliosis measurements based on three-dimensional vertebra vectors and conventional two-dimensional measurements: advantages in evaluation of prognosis and surgical results. Eur Spine J. 2013. Epub 2013/01/24.

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Vidal C, Ilharreborde B, Azoulay R, Sebag G, Mazda K. Reliability of cervical lordosis and global sagittal spinal balance measurements in adolescent idiopathic scoliosis. Eur Spine J. 2013.

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Lebel DE, Al-Aubaidi Z, Shin EJ, Howard A, Zeller R. Three dimensional analysis of brace biomechanical efficacy for patients with AIS. Eur Spine J. 2013.

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Ilharreborde B, Dubousset J, Skalli W, Mazda K. Spinal penetration index assessment in adolescent idiopathic scoliosis using EOS low-dose biplanar stereoradiography. Eur Spine J. 2013.

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Courvoisier A, Drevelle X, Vialle R, Dubousset J, Skalli W. 3D analysis of brace treatment in adolescent idiopathic scoliosis. Eur Spine J. 2013.

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Courvoisier A, Vialle R, Skalli W. EOS 3D imaging: assessing the impact of brace treatment in adolescent idiopathic scoliosis. Expert Rev Med Devices. 2013.

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Scherrer SA, Begon M, Leardini A, Coillard C, Rivard CH, Allard P. Three-dimensional vertebral wedging in mild and moderate adolescent idiopathic scoliosis. Plos One. 2013.

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Nam D, Shab R, Nunley R, Barrack R. Evaluation of the 3-Dimensional, weight-bearing orientation of the normal adult knee. Journal of arthroplasty. 2013.

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Assi A, Chaibi Y, Presedo A, Dubousset J, Ghanem I, Skalli W. Three-dimensional reconstructions for asymptomatic and celebral palsy children’s lower limbs using a biplanar X-ray system. Eur J Radiol. 2013.

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Pillet H, Sangeux M, Hausselle J, El Rachkidi R, Skalli W. A reference method for the evaluation of femoral head joint center location technique based on external markers. Gait & Posture. 2013.

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Wade R, Yang H, McKenna C, Faria R, Gummerson N, Woolacott N. A systematic review of the clinical effectiveness of EOS 2D/3D X-ray imaging system. Eur Spine J. 2013 Feb;22(2):296-304

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Courvoisier A, Ilharreborde B, Constantinou B, Aubert B, Vialle R, Skalli W. Evaluation of a three-dimensional reconstruction method of the rib cage of mild scoliotic patients. Spine deformity. 2013.

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Somoskeoy S, Tunyogi-Csapo M, Bogyo C, Illes T. Accuracy and reliability of coronal and sagittal spinal curvature data based on patient-specific three-dimensional models created by the EOS 2D/3D imaging system. Spine J2012 Oct 23.

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Somoskeoy S, Tunyogi-Csapo M, Bogyo C, Illes T. Clinical validation of coronal and sagittal spinal curve measurements based on three-dimensional vertebra vector. Spine J2012 Sep 24.

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Glaser DA, Doan J, Newton PO. Comparison of 3D Spinal Reconstruction Accuracy: Biplanar Radiographs with EOS Versus Computed Tomography. Spine (Phila Pa 1976)2012 Mar 13.

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Sutter R, Pfirrmann CW, Espinosa N, Buck FM. Three-dimensional hindfoot alignment measurements based on biplanar radiographs: comparison with standard radiographic measurements. Skeletal Radiol2012 Nov 20.

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Buck FM, Guggenberger R, Koch PP, Pfirrmann CW. Femoral and Tibial Torsion Measurements With 3D Models Based on Low-Dose Biplanar Radiographs in Comparison With Standard CT Measurements. AJR Am J Roentgenol2012 Nov;199(5):W607-12.

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Journe A, Sadaka J, Belicourt C, Sautet A. New method for measuring acetabular component positioning with EOS imaging: feasibility study on dry bone. Int Orthop2012 Sep 5.

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Guenoun B, Zadegan F, Aim F, Hannouche D, Nizard R. Reliability of a new method for lowerextremity measurements based on stereoradiographic three-dimensional reconstruction. Orthop Traumatol Surg Res2012 Jul 31.

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Thelen P, Delin C, Folinais D, Radier C. Evaluation of a new low-dose biplanar system to assess lower-limb alignment in 3D: a phantom study. Skeletal Radiol2012 Jun 9.

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Wybier M, Bossard P. Musculoskeletal imaging in progress: The EOS imaging system. Joint Bone Spine2012 Nov 21.

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Illes T, Somoskeoy S. The EOS imaging system and its uses in daily orthopaedic practice. Int Orthop2012 Feb 28.

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Ilharreborde B, Vidal C, Skalli W, Mazda K. Sagittal alignment of the cervical spine in adolescent idiopathic scoliosis treated by posteromedial translation. Eur Spine J2012 Sep 11.

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Illes T, Somoskeoy S. [Principles of the EOS X-ray machine and its use in daily orthopedic practice]. Orv Hetil2012 Feb 19;153(8):289-95.

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Lazennec JY, Brusson A, Rousseau MA. THA Patients in Standing and Sitting Positions: A Prospective Evaluation Using the Low-Dose “Full-Body” EOS® Imaging System. Semin Arthro. 2012;23(4):220-5.

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Polkowski GG, Nunley RM, Ruh EL, Williams BM, Barrack RL, Does Standing Affect Acetabular Component Inclination and Version After THA? Clin Orthop Relat Res. 2012 May 19.

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Lazennec JY. Hip-Spine Relations: An Innovative Paradigm in THR Surgery. In: Fokter SK, editor. Recent Advances in Arthroplasty: InTech; 2012. p. 69-94.

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Humbert L, Steffen JS, Vialle R, Dubousset J, Vital JM, Skalli W. 3D analysis of congenital scoliosis due to hemivertebra using biplanar radiography. Eur Spine J2012 Oct 17.

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Foley G, Aubin CE, Labelle H, Sanders J, d'Astous J, Johnston C, Parent S. The Rib Vertebra Angle Difference and its Measurement in 3D for the evaluation of early onset scoliosis. Stud Health Technol Inform2012;176:238-41.

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Sapin-de Brosses E, Jolivet E, Travert C, Mitton D, Skalli W. Prediction of the vertebral strength using a finite element model derived from low-dose biplanar imaging: benefits of subject-specific material properties. Spine (Phila Pa 1976)2012 Feb 1;37(3):E156-62.

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McKenna C, Wade R, Faria R, Yang H, Stirk L, Gummerson N, Sculpher M, Woolacott N. EOS 2D/3D X-ray imaging system: a systematic review and economic evaluation. Health Technol Assess. 2012;16(14):1-188

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Rampal V, Hausselle J, Thoreux P, Wicart P, Skalli W. Three-dimensional Morphologic Study of the Child's Hip: Which Parameters Are Reproducible? Clin Orthop Relat Res2012 Oct 26.

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Serrurier A, Quijano S, Nizard R, Skalli W. Robust femur condyle disambiguation on biplanar X-rays. Med Eng Phys2012 Feb 18.

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Lagace PY, Billuart F, Ohl X, Skalli W, Tetreault P, de Guise J, Hagemeister N. Analysis of humeral head displacements from sequences of biplanar X-rays: repeatability study and preliminary results in healthy subjects. Comput Methods Biomech Biomed Engin2012 Mar;15(3):221-9.

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Ilharreborde B, Steffen JS, Nectoux E, Vital JM, Mazda K, Skalli W, Obeid I. Angle measurement reproducibility using EOS three-dimensional reconstructions in adolescent idiopathic scoliosis treated by posterior instrumentation. Spine (Phila Pa 1976)2011 Sep 15;36(20):E1306-13.

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Lazennec JY, Rousseau MA, Rangel A, Gorin M, Belicourt C, Brusson A, Catonne Y. Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: measurements reproductibility with EOS imaging system versus conventional radiographies. Orthop Traumatol Surg Res2011 Jun;97(4):373-80.

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Chaibi Y, Cresson T, Aubert B, Hausselle J, Neyret P, Hauger O, de Guise JA, Skalli W. Fast 3D reconstruction of the lower limb using a parametric model and statistical inferences and clinical measurements calculation from biplanar X-rays. Comput Methods Biomech Biomed Engin2011 Jan 1:1.

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Lazennec JY, Brusson A, Rousseau MA. Hip-spine relations and sagittal balance clinical consequences. Eur Spine J2011 Sep;20 Suppl 5:686-98.

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Le Huec JC, Leijssen P, Duarte M, Aunoble S. Thoracolumbar imbalance analysis for osteotomy planification using a new method: FBI technique. Eur Spine J2011 Sep;20 Suppl 5:669-80.

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Obeid I, Hauger O, Aunoble S, Bourghli A, Pellet N, Vital JM. Global analysis of sagittal spinal alignment in major deformities: correlation between lack of lumbar lordosis and flexion of the knee. Eur Spine J2011 Sep;20 Suppl 5:681-5.

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Morvan G, Mathieu P, Vuillemin V, Guerini H, Bossard P, Zeitoun F, Wybier M. Standardized way for imaging of the sagittal spinal balance. Eur Spine J2011 Sep;20 Suppl 5:602-8.

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Illes T, Tunyogi-Csapo M, Somoskeoy S. Breakthrough in three-dimensional scoliosis diagnosis: significance of horizontal plane view and vertebra vectors. Eur Spine J2011 Jan;20(1):135-43.

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Illes T. [Comparison of classical 2D measurement of scoliosis and 3D measurement using vertebral vectors; advantages for prognostication and treatment evaluation]. Bull Acad Natl Med2011 Mar;195(3):629-42; discussion 42-3.

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Than P, Szuper K, Somoskeoy S, Warta V, Illes T. Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop2011 Nov 18.

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Gheno R, Nectoux E, Herbaux B, Baldisserotto M, Glock L, Cotten A, Boutry N. Threedimensional measurements of the lower extremity in children and adolescents using a lowdose biplanar X-ray device. Eur Radiol2011 Oct 20.

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Dubousset J, Lavaste F, Skalli W, Lafage V. [Modeling the spine and spinal cord]. Bull Acad Natl Med2011 Nov;195(8):1831-42.

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Travert C, Jolivet E, Sapin-de Brosses E, Mitton D, Skalli W. Sensitivity of patient-specific vertebral finite element model from low dose imaging to material properties and loading conditions. Med Biol Eng Comput2011 Dec;49(12):1355-61.

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Rousseau MA. Three-dimensional assessment of the intervertebral kinematics after MobiC total disc replacement at the cervical spine in vivo using the EOS stereoradiography system. SAS Journal2011 Sept;5(3):63-8.

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Deschenes S., Charron G., Beaudoin G., Miron M., Labelle H. and Dubois J., "Diagnostic imaging of spinal deformities: Reducing patients radiation dose with a new slot-scanning x-ray imager"” Spine, (avril 2010)

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Dubousset J., Charpak G., Skalli W., De Guise J.A., Kalifa G. EOS : A new imaging system with low dose radiation in standing position for spine and bone & joint disorders. Journal of Musculoskeletal Research 13(1):1 – 12, 2010.

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Steffen JS, Obeid I, Aurouer N, Hauger O, Vital JM, Dubousset J, Skalli W. “ 3D postural balance with regard to gravity line: an evaluation in the transversal plane on 93 patients and 23 asymptomatic volunteers. ». Eur Spine J. 2010 May;19(5)

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Sandoz B, Laporte S, Skalli W, Mitton D. “Subject-specific body segment parameters' estimation using biplanar X-rays: a feasibility study”. Comput Methods Biomech Biomed Engin. 2010 Dec;13(6)

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Sabourin M, Jolivet E, Miladi L, Wicart P, Rampal V, Skalli W. “Three-dimensional stereoradiographic modeling of rib cage before and after spinal growing rod procedures in early-onset scoliosis”. Clin Biomech (Bristol, Avon). 2010 May;25(4):284-91. Epub 2010 Feb 2.

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Azmy C., Guérard S., Bonnet X., Gabrielli F., Skalli W., EOS® orthopaedic imaging system to study patellofemoral kinematics: Assessment of uncertainty, Orthopaedics & Traumatology : Surgery & Research, 96(1) : 28-36, 2010.

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Ohl X., Stanchina C., Billuart F., Skalli W. Shoulder bony landmarks location using the EOS® low-dose stereoradiography system: a reproducibility study. Surgical and radiologic anatomy (Surg Radiol Anat), 32(2):153-8, 2010.

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Jolivet E., Sandoz B., Laporte S., Mitton D., Skalli W. Fast 3D reconstruction of the rib cage from biplanar radiographs. Medical & biological engineering & computing 48(8):821-828, 2010.

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Humbert, L. et al. "3D reconstruction of the spine from biplanar X-rays using parametric models based on transversal and longitudinal inferences." Medical Engineering and Physics (2009)

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Schlatterer, B. and I. Suedhoff. "Skeletal landmarks for TKR implantations: Evaluation of their accuracy using EOS imaging acquisition system." Orthopaedics and Traumatology: Surgery and Research (2009)

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JM Vital, J Dubousset, O Gille, O Hauger, N Aurourer, I Obeid, « Clinical Applications of the EOS System in diseases of the locomotor apparatus ». Argos Spine Journal, Springer, N° 20 dec. 2008, ISSN 1967-7729

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Mezghani N, Chav R, Humbert L, Parent S, Skalli W, de Guise JA. "A Computer Based Classifier of Three-Dimensional Spinal Scoliosis Severity." International Journal of Computer Assisted Radiology and Surgery, avril 2008.

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Feydy, S. Ferey, V. Merzoug, H. Guerini, A. Chevrot, J. Dubousset, G. Kalifa, J.-L. Drapé. Imagerie De La Scoliose. Place Du Système Eos Société D’imagerie Musculo Squelettique, Getroa Gel Opus Xxxv Rachis. Sauramps Medical / Isbn : 9782840235767. 2008 425-441

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G. Morvan, M. Wybier, P. Mathieu, V. Vuillemin et H. Guerini, Clichés simples du rachis : statique et relations entre rachis et bassin. J. Radiol. 2008 ;89 :654-66.

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Dubousset J, Charpak G, Skalli W, de Guise J, Kalifa G, Wicart P. [Skeletal and spinal imaging with EOS system]. Arch Pediatr. 2008 Jun;15(5):665-6.

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Baudouin, A. and W. Skalli. "Parametric subject-specific model for in vivo 3D reconstruction using bi-planar X-rays: application to the upper femoral extremity." Medical and Biological Engineering and Computing 46 (2008): 799-805.

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Humbert L, Carlioz H, Baudoin A, Skalli W, Mitton D. 3D Evaluation of the acetabular coverage assessed by biplanar X-rays or single anteroposterior X-ray compared with CTscan. Computer Methods in Biomechanics and Biomedical Engineering 2008.

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Bertrand, S. and S. Laporte. "Three dimensional reconstruction of the rib cage from biplanar radiography." IRBM 29 (2008): 278-286.

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Sapin, E. and K. Briot. "Bone mineral density assessment using the EOS low-dose X-ray device: a feasibility study." Journal of Engineering in Medicine 222 (2008): 1263-1271.

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Dubousset J, Charpak G, Skalli W, Kalifa G, Lazennec JY. « EOS stereo-radiography system: whole-body simultaneous anteroposterior and lateral radiographs with very low radiation dose”. Rev Chir Orthop Reparatrice Appar Mot. 2007 Oct;93(6 Suppl):141-3. French.

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Rousseau, M.A. and M.S. Laporte. "Reproducibility of measuring the shape and threedimensional position of cervical vertebrae in upright position using the EOS stereoradiography system." Spine 32.23 (2007): 2569-2572.

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J.Y Lazennec, M.A. Rousseau, E. Sari-Ali, E. Rolland, Y. Catonne. Biomécanique du complexe lombo-pelvi-fémoral. Conséquences fonctionnelles des relations hanche rachis. Société d’Imagerie Musculo Squelettique, Getroa Gel Opus XXXIV Bassin et Hanche. Sauramps Medical / ISBN : 9782840235125 . 2007 17-33

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Vallée, C. Marty, R. Carlier. Etude critique des mesures de l’équilibre pelvien. Société d’Imagerie Musculo Squelettique Getroa Gel Opus XXXIV Bassin et Hanche. Sauramps Medical / ISBN : 9782840235125 . 2007 35-50

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Südhoff I, Van Driessche S, Laporte S, de Guise JA, Skalli W. (2007) « Comparing Three Attachment Systems Used to Determine Knee Kinematics During Gait.» Gait & Posture, 25 (4): 533-543

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Skalli W, Mitton D, de Guise JA, Dubousset J. (2006) "The EOS System: New Perspectives for Musculoskeletal Biomechanics." Journal of Biomechanics, 39(S1): S460

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Gangnet N, Dumas R, Pomero V, Mitulescu A, Skalli W, Vital JM. Three-dimensional spinal and pelvic alignment in an asymptomatic population. Spine 2006 ; 31(15):E507 - 512.

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Sari Ali el H, Lemaire JP, Pascal-Mousselard H, Carrier H, Skalli W. In vivo study of the kinematics in axial rotation of the lumbar spine after total intervertebral disc replacement: long-term results: a 10-14 years follow up evaluation. European Spine Journal 2006; 21:1 10.

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G. Biette, D. Zeitoun, E. Dion, J. Dubousset, Y. Catonne. Apports du système EOS dans l’analyse tridimensionnelle des déformations du membre inférieur. 12e journée de la Pitié Salpétrière. Sauramps Médical / ISBN : 2840234688. 2006 25-37

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J.Y Lazennec, M.A. Rousseau, S. Hansen, A. Riwan, F. Gravez, M. Gorin, P. Piriou, N. Mora, M. Karouia, F. Khiami, W. Skalli, Y. Catonné. Influence du bloc lombo-pelvien sur l’orientation fonctionnelle des membres inférieurs. 12e journée de la Pitié Salpétrière. Sauramps Médical / ISBN : 2840234688. 2006 59-82

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Mitton D, Deschenes S, Laporte S, Godbout B, Bertrand S, de Guise JA, Skalli W. 3D Reconstruction of the pelvis from bi-planar radiography. Computer Methods in Biomechanics and Biomedical Engineering 2006; 9(1):1 - 5.

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Skalli W, Zeller R, Miladi L, Bourcereau G, Savidan M, Lavaste F, Dubousset J. Importance of Pelvic Compensation in Posture and Motion after Posterior Spinal Fusion Using CD Instrumentation for Idiopathic Scoliosis. Spine 2006; 31(12):E 359 - 366.

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Le Bras A, Kolta S, Soubrane P, Skalli W, Roux C, Mitton D. Assessment of femoral neck strenght by 3 dimensional X-ray absorptiometry (3D-XA). Journal of Clinical Densitometry 2006; 9(4):425 - 430.

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Bertrand S, Skalli W, Delacherie L, Bonneau D, Kalifa G, Mitton D. External and internal geometry of European adults. Ergonomics 2006; 49(15):1547-1564

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Rousseau M-A, Laporte S, Chavary E, Skalli W. Reproducibility of measuring the shape and 3D position of cervical vertebrae in standing position using the EOS stereoradiography system. Spine 2006

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Després P, Gravel P, Beaudoin G, de Guise JA. (2005) "Physical Characteristics of a Lowdose Gas Microstrip Detector for Orthopedic X-rays Imaging", AAPM - Medical Physics, 32(4):1193-1204.

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Després P, Beaudoin G, Gravel P, de Guise JA. (2005) "Evaluation of a Full-Scale Gas Microstrip Detector for Low-Dose X-Ray Imaging". Nuclear Instruments and Methods in Physics Research

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Dubousset J, Charpak G., Dorion I., Skalli W., Lavaste F., de Guise J., Kalifa G., Ferey S. A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with lowdose radiation and the standing position: the EOS system. Bulletin de l'Académie Nationale de Médecine 2005; 189(2):287-297; discussion 297-300.

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Dubousset J., Charpak G., Dorion I., Skalli W., Lavaste F., Deguise J. et al. – Une nouvelle imagerie ostéoarticulaire basse dose en position debout : le système EOS. Radioprotection 2005; 40: 245 à 255.

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Benchikh E-F, A., Schwab F, Gamez L, Champain N, Skalli W, Farcy JP. Center of Gravity and Radiographic Posture Anaysis: A Preliminary Review of Adult Volunteers and Adult Patients Affected by Scoliosis. Spine 2005; 30(13):1535 - 1540.

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Rillardon L, Campana S, Mitton D, Skalli W, Feydy A. Evaluation of the intervertebral disc spaces with a low dose radiographic system]. J Radiol. 2005 Mar;86(3):311-9. French. PubMed PMID: 15908871.

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Dumas R, Lafage V, Lafon Y, Steib JP, Mitton D, Skalli W. Finite Element Simulation of Spinal Deformities Correction by In Situ Contouring Technique. Computer Methods in Biomechanics and Biomedical Engineering 2005; 8(5):331 – 337

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Kolta S, Le Bras A, Mitton D, Bousson V, de Guise JA, Fechtenbaum J, Laredo JD, Roux C, Skalli W. Three-dimensional X-ray absorptiometry (3D-XA):a method for reconstruction of human bones using a dual X-ray absorptiometry device. Osteoporosis International 2005;16(8):969-76.

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Dumas R, Aissaoui R, Mitton D, Skalli W, de Guise JA. Personalized Body Segment Parameters from Biplanar Low-Dose Radiography. IEEE Transactions on Biomedical Engineering. 2005:1756 - 1763.

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Dumas R, Le Bras A, Champain N, Savidan M, Mitton D, Kalifa G, Steib JP, de Guise JA, Skalli W. Validation of The Relative 3D Orientation of Vertebrae Reconstructed by Bi-Planar Radiography. Medical Engineering & Physics 2004; 26(5):415 - 422.

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Lafage V, Dubousset J, Lavaste F, Skalli W. 3D Finite Element Simulation of CD Correction. Computer Aided Surgery 2004; 9(1/2):17-25.

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Le Bras A, Laporte S, Bousson V, Mitton D, de Guise JA, Laredo JD, Skalli W. 3D Reconstruction of The Proximal Femur with Low-Dose Digital Stereoradiography. Computer Aided Surgery. 2004:51-57.

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Pomero V, Mitton D, Laporte S, de Guise JA, Skalli W. Fast Accurate Stereoradiographic 3DReconstruction of The Spine Using a Combined Geometric and Statistic Model. Clinical biomechanics 2004; 19(3):240 - 247.

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Steib JP, Dumas R, Mitton D, Skalli W. Surgical Correction of Scoliosis by The In Situ Contouring: a Detorsion Analysis. Spine 2004; 29(2):193 - 199.

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Dorion I, Le Bras A, Pomero V, Campana S, Teysseyre S, Meynadier M, Skalli W, Maccia C. Rhumatologie et orthopédie : apport d'une nouvelle modalité d'imagerie radiologique tridimensionnelle multi-énergie, faible dose, et haute résolution à l'imagerie du système ostéo-articulaire. ITBM-RBM (Revue Européenne de Technologie Biomédicale) 2004; 25:274 - 279.

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Dumas R, Mitton D, Laporte S, Dubousset J, Steib JP, Lavaste F, Skalli W. Explicit Calibration Method and Specific Device Designed for Stereoradiography. Journal of Biomechanics 2003; 36(6):827- 834.

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Dumas R, Steib JP, Mitton D, Lavaste F, Skalli W. Three-Dimensional Quantitative Segmental Analysis of Scoliosis Corrected by the In situ Contouring Technique. Spine 2003; 28(11):1158 -1162

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Gangnet N, Pomero V, Dumas R, Skalli W, Vital JM. Variability of The Spine and Pelvis Location with Respect toThe Gravity Line:A 3D Stereoradiographic Study Using a Force Platform. Surgical and Radiologic Anatomy 2003; 25(5/6):424 - 433.

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Laporte S, Skalli W, de Guise JA, Lavaste F, Mitton D. A Biplanar Reconstruction Method Based on 2D and 3D Contours: Application to the Distal Femur. Computer Methods in Biomechanics and Biomedical Engineering 2003; 6(1):1-6.

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Le Bras A, Laporte S, Mitton D, de Guise JA, Skalli W. Three-Dimensional (3D) Detailed Reconstruction of Human Vertebrae from Low-Dose Digital stereoradiography. European Journal of orthopaedic Surgery and Traumatology 2003; 13(2):57-62.

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Mitulescu A, Skalli W, Mitton D, de Guise JA. Three-Dimensional Surface Rendering Reconstruction of Scoliotic Vertebrae Using a Non Stereo-corresponding Points Technique. European Spine Journal 2002; 11(4):(344 - 352).

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Mitulescu A, Semaan I, de Guise JA, Le Borgne P, Adamsbaum C, Skalli W. Validation of The Non Stereo Corresponding Points (N.S.C.P.) Stereoradiographic 3D Reconstruction Technique. Medical & Biological Engineering & Computing 2001; 39(2):152-158.

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Mitton D, Landry C, Véron S, Skalli W, Lavaste F, de Guise JA. 3D Reconstruction Method from Biplanar Radiography Using Non-Stereocorresponding Points and Elastic Deformable Meshes. Medical &Biological Engineering & Computing 2000; 38(2):133 -139.

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Kalifa G, Charpak, Y, Maccia C, Fery-Lemonnier E, Bloch J, Boussard J, Attal M, Dubousset J, Adamsbaym C. Evaluation of a new low-dose digital x-ray device: first dosimetric and clinical results in children. Pediatr Radiol; 28(7):557-61. 1998.

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Lavaste F, Skalli W, Robin S, Roy-Camille R, Mazel C. Three-Dimensional Geometrical and Mechanical Modelling of the Lumbar Spine. Journal of Biomechanics 1992; 25(10):1153 1164.

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