Spinal News International Issue 55 - May 2020 EU Edition by BIBA Publishing

May 2020 | Issue 55 Joshua Pahys: Vertebral body tethering

Daniel Riew: Page 5

Profile

Yingda Li & Michael Wang:

Endoscopic spinal surgery Page 8

Page 12

Surgeons face pent-up demand for spinal procedures following COVID-19 elective slowdown

Artificial intelligence in spine care is “here to stay”

Spinal surgeons worldwide have seen a drop in case volumes as many nations have halted elective cases, seeking to stem the tide of the COVID-19 pandemic. The curtailment of non-essential cases has been seen as a necessary step to slow the spread of the SARSCOV-2 virus and “flatten the curve” of infections, as well as preserving vital hospital resources. However, this has lead to questions over how quickly healthcare services will be able to clear a backlog in cases that has built up. Some spine care specialists have also questioned the impact that the slowdown in handling non-emergency procedures will have on the health outcomes in patients for whom surgery has been delayed.

he far-reaching impact of COVID-19 on spinal surgery is highlighted in an AO Spine study, which underlines several consistent trends across the globe. The research canvassed views and insights from over 900 spine care specialists on the financial impact; the effect on research; and future challenges created by the pandemic. Key messages from the survey, led by principal investigator Dino Samartzis (Rush Medical College, Chicago, USA), chair of the AO Spine Research Commission, include a disparity in the availability of personal protective equipment (PPE) and concerns over the long-term economic impact of the pandemic on the spinal surgery specialism. “Most of us have never faced a pandemic like COVID-19,” said Philip Louie (Hospital for Special Surgery, New York, USA), commenting on the findings of the study. “The outbreak has resulted in widespread work stoppages, hospital-wide reorganisations, drastic changes in societal norms, and raised amounts of anxiety and uncertainty for everyone.” The survey highlights that while there are variations in societal restrictions imposed by governments, there are similarities with the suspension of elective cases for an undefined time. “Surgeons are not able to operate on patients they feel need surgery without considering the massive constraints on scarce resources and added risk of infection for their patients,” added Dan Sciubba from Johns Hopkins University (Baltimore, USA), who represents North America in the AO Spine Research

Commission. “COVID-19 is not the only thing hurting patients. Those with cancer, heart disease, and other chronic illnesses still need our steadfast support. We cannot abandon these important and vulnerable patients.” A particular area of challenge has been in determining which patients should be considered as “urgent”, and those whose procedures can be delayed. Discussing COVID-19’s impact on the optimisation and treatment of spine pathology in the Global Spine Journal in April, Nickul S Jain (Southern California Orthopedic Institute, Van Nuys, USA) and colleagues describe

The outbreak has resulted in widespread work stoppages, hospital-wide reorganisations, drastic changes in societal norms, and raised amounts of anxiety and uncertainty for everyone.” Continued on page 2

Artificial intelligence (AI) has “tremendous potential” to revolutionise comprehensive spine care across areas including patient selection, outcome prediction, research, preoperative workup and perioperative assistance, the authors of a large systematic review have found. PUBLISHED IN THE Global Spine Journal, the review, led by Jonathan J Rasouli (Cleveland Clinic, Cleveland, USA) looks at the current trends and applications of AI and machine learning in conventional and robotic-assisted spinal surgery. According to Rasouli and colleagues, there has been increasing attention and interest in the systembased benefits of AI and its applications to spinal surgery. This includes helping clinicians and hospital centres define the quality and cost of care, improve outcomes and mitigate financial exposure to both institutions and payers. “While there has also been controversy surrounding AI, if implemented appropriately, it has the potential to revolutionise the standard of care in spine surgery, reduce cost and waste, and improve the efficiency and patient care. In addition, AI could enhance individualised care to patients to reduce heterogeneity in both clinical practice and research,” the study team writes. The first potential area for the employment of AI singled out by Rasouli and colleagues is in preoperative patient care and outcome prediction. The investigators write that while there is evidence to support certain surgical treatments over others, a surgeon’s choice in treatment is often dictated by training, experience and personal performance. They add that there are many patient specific variables that influence cost and outcomes such as body mass index, the presence and severity of comorbidities, tobacco use, and psychosocial factors, to name a few. “It is difficult, if not impossible, for the Continued on page 6

May 2020 | Issue 55

Top stories

Surgeons face pent-up demand for spinal procedures following COVID-19 elective slowdown Continued from page 1

triaging of patients that need emergent or urgent surgery as “a grey zone without clear consensus.“ According to Jain et al medical bodies including the American College of Surgeons (ACS), US Centers for Disease Control and Prevention (CDC), the Orthopaedic Trauma Association (OTA), and the Royal College of Surgeons (RCS) in the UK have all published guidelines to offer a framework of triage in order to address this issue, whilst the North American Spine Society (NASS) has also developed a guidance document specifically for triaging surgical spine cases. Generally, the guidance described by Jain et al recommends that cases with progressive or severe neurologic deficit, and spinal conditions resulting in intractable pain or functional limitations are prioritised, whilst conditions where pain and dysfunction can be reasonably managed non-operatively, should be postponed. “These triaging decisions remain the responsibility of the spine surgeon who must act responsibly within local health care delivery systems while complying with federal, state, and local health policy guidelines,” Jain and colleagues note. Preparedness for the reopening of elective cases is now a key area for focus, with the ACS and the American Society of Anesthesiologists (ASA) warning in a joint statement in April that the “pent-up patient demand for surgical and procedural care may be immense”. The healthcare bodies have issued a list of principles, in the form of a roadmap, outlining steps that should be taken in order to resume elective surgery after the pandemic. The roadmap suggests that in order for procedures to resume, centres will need to witness a sustained reduction in the rate of new COVID-19 cases for at least 14 days, and the facility should have an appropriate number of intensive care unit (ICU) and non-ICU beds, PPE, ventilators and trained staff to treat all non-elective patients without resorting to a crisis standard of care. According to Christopher M Bono (Harvard Medical School, Boston, USA), returning to a full elective schedule “is not going to be like turning the faucet back on full force. “The system has been strained and under duress,” he told Spinal News International. “Nurses have taken the biggest brunt of the workforce depletion. They have been in shortest supply and highest demand. If they can be considered the solder that joins the pieces of pipe of our system together, we have to slowly turn the faucet back on. Too fast, and we’ll bust a seam.” In an article published online by the International Society for the Advancement of Spine Surgery (ISASS) in late April, Nitin Khanna (Munster, USA) considered

News in brief

the steps needed to ensure that a suitable pathway is in place to return to elective spine procedures, which he argues should include detailed protocols on preoperative, intraoperative and post-operative care, use of PPE and testing of staff. Speaking to Spinal News International, he commented that even with strong measures in place to seek to stem the spread of the virus, a full return to elective procedures could still be some months away. “I think when you start talking about complex adult deformity spine surgery specifically, those cases would be better off being pushed down by a couple of months until the pathways can be sorted and people have a handle on what COVID does.” Another potential hurdle, Khanna said, could be patient desire to undergo surgery, with the threat of COVID-19 still present. “If the patient does not feel that is safe to proceed, perhaps they take on the potential for neurologic damage, or maybe they start to take increasing doses of opiate medication and build up some type of a tolerance to this. I think that there is a lot of foreseeable and unforeseen complications based on the fact that a lot of patients do not want to leave their house and they do not want to see a doctor or have any kind of surgical procedure for the time being.” Considering the impact of a slowdown in elective cases on patients, North American Spine Society (NASS) president William J Sullivan (Vanderbilt University, Nashville, USA) told Spinal News International that there may be “two parallel paths” determining outcomes in delayed cases. “The first is that we are kicking the can down the road, and that these problems that we have will still be there when we get back,” he said. “A certain percentage of people, if they wait long enough, will decide that they do not need surgery or injections for their condition. They will potentially get better doing other things, for example by resting or exercising more. “The other patients who would normally be treated ‘now’ may become a long-standing chronic pain patient who may now be dependent on opioid medications for a longer period of time. That will be difficult for us to deal with, but the reality is there is no way around it. We are going to have a backlog, and that backlog is going to necessitate the need to stratify people and triage people appropriately when we go back to doing elective procedures. “You cannot see everybody on that first day that we go back. I think that kicking the can down the road problem will exist, and there will be people who do not have as good outcomes as we would have hoped they would have had.”

The latest stories from the spinal world

SPINAL TETHERING IN FOCUS: Surgeons who have pioneered the use of a technique for the treatment of adolescent idiopathic scoliosis, known as spinal tethering, discuss the potential benefits of the approach compared to fusion surgery. Despite promising early results from the technique, they caution that long-term studies are needed to justify the wider adoption of the technique.

For more on this story go to page 4. DANIEL RIEW IN PROFILE: The cervical spine specialist talks to Spinal News International about his career to date, how the COVID-19 pandemic is likely to impact the field, and how he sees spine care evolving over the coming decade. He also considers some of the main challenges facing spinal surgeons, and discusses which areas of the spine specialism are the most exciting to watch.

For more on this story go to page 8. NASS ISSUES GUIDANCE ON LOW BACK PAIN: The North American Spine Society (NASS) has published evidence-based guidance to assist in the diagnosis and treatment of non-specific low back pain above the knee. The project involved over 45,000 literature searches, producing more than 100 recommendation statements for practitioners. Paul Matz, chair of the NASS development committee that led the drafting of the guidance document discusses its contents, scope and aims, as well as the potential for future developments in the guidance.

For more on this story go to page 10.

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May 2020 | Issue 55

Growth modulation

Long-term evidence needed to support use of spinal tether

This view is backed by Lawrence Haber (Ochsner Hospital for Children, Jefferson, USA) another US exponent of spinal tethering. “Fusions for scoliosis, especially selective thoracic fusions, have been very safe, dependable, and well tolerated. Fusion will continue to be an important tool for patients with insufficient growth remaining or larger curves,” he told Spinal News International when asked about the longterm future of the procedure in the treatment of scoliosis. “However, if long-term results hold up, it seems like an obvious transition for a motion sparing and minimally invasive VBT procedure to replace fusion in appropriate patients. When discussing fusions with patients, I make it clear that we are fusing, not fixing, the spine. With a more physiologic solution like tethering, we are trying to maintain normal function, and ‘fix’, not fuse the spine. One of the challenges will be training enough surgeons to improve access,” he commented. On the issue of surgeon training, Lonner cautioned that the technique involves a “learning curve” that surgeons will need to overcome to perform tethering procedures safely. “First it is a matter of identifying the right patient, with the correct indications, then making sure that the surgeon has the prerequisite skillset to perform it efficiently. They will also need to see enough of these patients to warrant them going through this process.” Lonner expressed optimism at results from early tethering procedures, but said that further evidence of the outcomes from the procedure will be an important development. “I think it is an exciting time,” he remarked. “Our patients and families are excited about this new approach and I think surgeons, as a group, have to collect the data, study these patients and work with the families to understand outcomes. So far we have been very pleased with what we have been seeing.”

US Food and Drug Administration (FDA) approval of a spinal tethering device for the treatment of idiopathic scoliosis in children and adolescents is an “exciting” development in the non-fusion treatment of spinal deformity, but greater evidence is required to determine intermediate and long-term outcomes of the approach in substantial numbers of patients. This is according to Baron S Lonner, professor of orthopaedic surgery and paediatrics, Icahn School of Medicine at Mount Sinai, and chief of minimally invasive scoliosis surgery, Mount Sinai Health System (New York, USA).

Image courtesy of Sinai Health System

Baron S Lonner implants a spinal tether device

LONNER SPOKE TO Spinal News International, after having performed the first spinal tethering procedure in New York, USA, in January 2020 using The Tether (Zimmer Biomet) anterior vertebral body tethering (VBT) device. The Tether received FDA approval in August 2019 and is the first device of its kind to gain approval for the US market. Tethering sees an anchor and bone screw placed into the spine from a lateral approach on the convex side of a spinal deformity. A flexible cord is secured to the bone screws with set screws to connect the levels of the construct, providing a lateral tension band to the spine that can arrest or correct a deformity. The technique is indicated in skeletally immature patients requiring treatment to correct progressive idiopathic scoliosis with a curvature between 30–65 degrees. After surgery, the cord continues to gradually straighten the spine while the patient grows. Advocates of this emerging technique believe that it offers patients a greater growth potential and freedom of movement than the current favoured treatment option, spinal fusion, as well as requiring a less invasive surgery and offering advantages over bracing. “With the tether, we are not fusing the spine, [so] we maintain flexibility. We cannot say it is 100% of what you would have had you not had a tether and no instrumentation, but there is at least some mobility that is preserved,” Lonner added when asked about the advantages of a tether as an option for scoliosis compared to fusion. However, he acknowledged

that there is an element of “unpredictability” in the procedure, given its deployment in skeletally immature patients with growing spines. “Patients can have overcorrection of their curve. If they have a smaller curve and are younger at the time of the tether, they can overcorrect, and if that happens they may need to have the tether removed, loosened, or cut, but correction may still be maintained.” Lonner offered the view that the emergence of tethering will not entirely replace fusion in the treatment

Our patients and families are excited about this new approach.” of scoliosis, but said that he anticipates a reduction in the number of fusion procedures being performed, as tethering becomes more widely adopted. “Fusion will still have its place,” he said, adding: “In my experience, more and more families are leaning towards a tether because they recognise the permanency of a fusion and the downsides. There are still families that opt for fusion because there is longer-term follow-up, and they know there is a predictable outcome, perhaps more predictable than with a tether. But, in my practice, I do far fewer fusions than I used to do, probably from 100% down to 20% or even less than that. So I do see patients more and more leaning towards the tether.”

Baron S Lonner

Lawrence Haber

The need for longer-term evidence was echoed by Haber, who said: “For any procedure we do, longer study is essential to make sure we are offering patients the safest and most effective option. This is especially true for VBT as it is such a dramatic change in care.” Outside of the USA, interest in vertebral body tethering remains high, and results from surgeries using the FDA-approved Tether will be watched closely. Per Trobisch, chief of spine surgery at the Eifelklinik St Brigida (Simmerath, Germany), is among Europe’s foremost exponents of the technique, and says that interest in VBT—which is also known as anterior scoliosis correction (ASC)—has accelerated significantly in light of the FDA’s decision to approve the Tether in 2019. “We have hosted more than 50 international surgeons who were interested in VBT and ASC and there seems to be an increase of interest in this technique, specifically in Europe,” he told Spinal News International. One country watching closely is the UK, where it is not currently an NHS-funded scoliosis treatment technique. VBT remains under evaluation in the UK, and a 2019 NHS England review concluded that, while initial studies showed the technique to be “promising”, further research, including experimental studies, are needed to confirm safety, patient acceptability and effectiveness. This was backed by the British Scoliosis Society (BSS), which in January 2020 issued an updated position statement on VBT, after the technique was

Issue 55 | May 2020

Growth modulation

Correction achieved in a 13-year-old patient

discussed at length at its annual meeting in Cardiff, UK (BSS 2019; 21–22 November) supporting a “robust review” of the procedure before it is found to be suitable

for use in the UK. “We are aware that NHS England is still concerned about the lack of evidence for VBT despite the frequent use of VBT outside of the UK,” BSS said in its January statement. “We are aware that the FDA has approved one type of VBT implant and hope that this will encourage good data and evidence to be published and so help patients, carers, BSS, and NHS England come to a balanced conclusion as to the suitability of this procedure for growing children with scoliosis.” When questioned on the long-term outcomes of the procedure, Trobisch commented: “It really depends on the curve type that is being operated on. We have very good long term results for patients who have had a thoracic fusion. However, long-term results for patients who have had a fusion down to the lower lumbar spine are not as good. Some studies found a more than 50% degeneration rate in the lumbar spine as a result of increased stress on the non-fused segments.” He added that Eifelklinik St Brigida physicians have created a new patient classification for scoliosis that is based on the best to worst potential benefit of non-fusion scoliosis surgery. “We believe that patients with a lumbar curve represent the best candidates because fusion of the

VBT: Understanding the advantages and challenges Joshua Pahys Comment & Analysis Joshua Pahys (Shriners Hospitals for Children, Philadelphia, USA) writes for Spinal News International, sharing insights from over 500 vertebral body tethering (VBT) procedures at his centre since 2011.

rowth modulation is a principle that has been applied to lower extremity deformities in paediatric patients for over 50 years. Utilising the Hueter-Volkmann Law, growth is retarded by increased mechanical compression on the epiphysis of a skeletally-immature patient. Sustained compression of a physiologic magnitude can inhibit growth by up to 40% in long bones, while the rate of increased growth with distraction across the epiphysis is more variable. For the last 20 years, this work has extended to the field of spinal deformity. Scientists and surgeons have successfully created and treated spinal deformity in multiple immature animal models utilising growth modulation. This initial work gave rise to anterior VBT. Compression is applied to the convex side of the vertebral growth plates in an effort to reduce the deformity with continued growth. Newton and colleagues have shown that VBT in an immature porcine scoliosis model can successfully correct the spinal deformity in all three planes (coronal, sagittal, and axial). Crawford and Lenke published the first human case report of anterior VBT in 2010. The authors reported on an eight-year-old male with a 40-degree thoracic curve that

progressively corrected to six degrees at four years postoperatively. Several larger case series were subsequently published outlining the outcomes and complications of VBT as a potential alternative treatment to posterior spinal fusion (PSF) for idiopathic scoliosis in the skeletally immature patient. My partners and I began performing VBT in 2011 at the Shriners Hospitals for Children. Collectively, we have performed nearly 500 VBT procedures over the last nine years. This experience has helped us gain a better understanding of the potential benefits and limitations. The following indications and recommendations stem not only from our experience, but also from discussion and collaboration with our peers in the field. The current indications for VBT as approved by the US Food and Drug Administration (FDA) is idiopathic scoliosis with a curve magnitude of 40–65 degrees in a skeletally immature patient (Risser 0–1 and Sanders 3–4). We recommend female patients be premenarchal, or within six months of menarche to be considered to have enough skeletal growth remaining to make a growth modulation procedure a viable option. The deformity must have some flexibility, bending down to <35 degrees on supine bending films, as

Zimmer Biomet’s Tether received FDA approval in 2019

lumbar spine needs to be prevented whenever possible,” Trobisch said. “However, patients with a thoracic curve are borderline candidates for whom we often recommend fusion instead of VBT/ASC.” Trobisch agreed that further long-term study would validate the technique. He said: “We know that VBT/ ASC works in the short term. We will definitely need long-term studies but we will also need more data on the best indication, the best surgical technique, and we will also need to redefine success. Additionally, we, as surgeons, have to closely collaborate with the industry to work on better implants and surgical instruments.”

rigid deformities have a higher failure rate. Finally, relative contra-indications are patients with thoracic kyphosis >40 degrees, as anterior spine surgery has the potential to be kyphogenic; and apical rotation >25 degrees, as VBT has been less efficacious at vertebral body derotation compared to PSF. VBT offers the potential advantage of sparing trunk motion, which is often diminished after PSF into the lumbar spine. Our preliminary results have shown a <10 degree loss of trunk motion with lumbar VBT compared to an up to 40 degree loss with PSF to L4. We have found that the difference in postoperative trunk motion for a thoracic VBT versus thoracic PSF is negligible. Some patients and families feel the small thoracoscopic incisions in the midaxillary line compared to the posterior midline scar from a PSF is advantageous. Postoperative recovery is typically four to six weeks faster with VBT versus PSF, which is likely related to the thoracoscopic versus open posterior approach. From a surgical perspective, at our institution, VBT surgery typically has lower estimated blood loss (average 50–75mL per procedure) and a shorter operative time (average two to three hours) compared to PSF. During the procedure, we aim to correct the spine to 20–35 degrees to allow for continued deformity correction with growth. However, this must be tailored to each individual patient. More skeletally immature patients should receive less initial correction to minimise the potential for overcorrection. Thoracoscopic apical thoracoplasties using an ultrasonic bone scalpel have been successfully performed on a limited basis if there is a significant rib prominence. We strongly advocate against apical discectomies for more severe and/or rigid deformities as we feel this may potentiate a degenerative process at these levels that could lead to destabilisation or pain in the future. Further, there is no data on the short- or long-term implications of this practice in the absence of a formal fusion.

The overall revision rate for VBT is approximately 10–15%. We extensively counsel our patients that the current reoperation rate for VBT is higher than that for a PSF (historically 5–10%). The majority of reoperations in our experience have been for overcorrection beyond -15 degrees to the contralateral side of the initial deformity. This is typically due to overcorrection at the time of the initial surgery, or performing the procedure on a patient that is too immature. One should be cautious about VBT surgery in males with open triradiate cartilage (TRC), as this group can have extensive remaining growth that is more challenging to predict. We do not advocate for VBT surgery in skeletally mature patients, which we have defined as those with a Risser >2 and/or Sanders digital score >5. We feel these patients do not have sufficient growth remaining for adequate vertebral modulation. This results in a higher rate of tether rupture and regression of the deformity. Revision VBT surgery can be challenging in the chest as the visceral pleura can scar down to the instrumentation. Extensive study of this procedure has been underway and there is still much work to be done. Multicentre, prospective studies are being formed to better evaluate the risks and benefits of this treatment. This will facilitate a more accurate calculation of remaining growth, which may ultimately identify the proper patient, timing, and degree of correction for VBT. Further follow-up studies are also underway to evaluate the long-term implications of this procedure. With this added effort, we feel VBT will become a more widely available treatment option for carefully selected, skeletally immature patients with scoliosis. Joshua Pahys is an orthopaedic spine surgeon for Shriners Hospitals for Children, Philadelphia, USA. He is a member of the Scoliosis Research Society, Harms Study Group, Pediatric Spine Study Group, and a fellow of the American Academy of Orthopaedic Surgeons.

May 2020 | Issue 55

Artificial intelligence

Artificial intelligence in spine care is “here to stay” Continued from page 1

clinician to reconcile and weight all of the discrete data points and his/her personal performance when indicating such a patient for surgery. AI can assist with such decision making. While most published literature are level III evidence or expert-based guidelines, most cannot guide decision making for complex spine surgery, or when there is clinical equipoise.” The team add, “AI could assist surgeons in identifying optimal surgical candidates, advise the surgeon on operative approaches, and predict the likelihood of success cost, and/ or payments of various treatment pathways.” Rasouli and colleagues cite a study carried out by Zoher Ghogawala (Lahey Health, Burlington, USA) examining this AI-driven approach in the setting of degenerative lumbar spondylolisthesis, utilising expert-reviewed imaging data to create a supervised machine learning model. “These innovative approaches could allow for a stronger guarantee of optimised patient outcomes in certified surgical candidates through ensuring proper surgical selection,” Rasouli and colleagues note. The reviewers further cite a study by Christopher Ames (UCSF, San Francisco, USA) and colleagues, which examined preoperative decision making

in the largest spinal deformity patient cohort to date. Ames et al established a model predicting two-year outcomes by constructing a visual risk-benefit grid, which also provides the surgeon insight into which surgical intervention would yield the highest probability of success. Rasouli and colleagues note, “In essence, these models successfully converted surgeons’ gestalt about a patient’s probability of surgical success into an accurate, reproducible, and homogenous clinical decision-making tool in a population of patients at high risk of poor outcome. Ideally, these tools will be Jonathan J Rasouli developed for a variety of patient populations in the future.” However, Rasouli and colleagues acknowledge that AI at its core, “is fundamentally a research tool that could be powerful and disruptive to the current body of a spine surgery literature.” As machine learning applications improve, this may ultimately lead to a paradigm shift in the way evidence-based guidelines are used and interpreted, they add. “AI-based research enables

clinical data to speak for itself. Rather than utilising a data mining approach, which drives much spine research, AI has the ability to revolutionise the field,” the reviewers reiterate. They highlight a recent review by Fabio Galbusera (Istituto Ortopedico Galeazzi, Milan, Italy) identifying several key areas that have benefited from AI and machine learning in spine care, including diagnostic imaging, outcome prediction and clinical decision support. Rasouli and colleagues also propose that advances in technology are facilitating the transformation of image

In the everevolving landscape of spine surgery, one thing is certain: artificial intelligence technologies have arrived—and they are here to stay.” analysis; from qualitative, subjective assessment to the acquisition of quantitative, reproducible data. They cite findings from the Galbusera, noting that AI has already made “critical contributions” to the field of spine surgery. The study described an AI-

based algorithm used in the classification of degenerative discs. Utilising a convolutional neural network, the algorithm extracted salient features of discs, including their shape and intensity. The AI-based algorithm was able to achieve a 70.1% concordance with human observations, “which is extremely comparable to the documented rate of agreement between individual expert radiologists” the study team concluded. “Integration of AI into biomechanical investigations represents yet another frontier of spine surgery research,” Rasouli and colleagues write, adding that while the usage of AI in this field is still in its infancy, AI has promising applications.. Analysis of gait and motion patterns, along with identification of abnormal gait in spinal disorders, represents one area that can benefit from AI usage, they find. Analysing their findings, Rasouli and colleagues speculate: “AI’s evidencebased, predictive analytics can help surgeons improve preoperative patient selection, surgical indications, and improve individualised postoperative care. In the realm of research, AI computing capacity can be used to collect, process, and analyse volumes of patient information to extract valuable clinical information for studies,” the team writes. Ultimately, the study concludes: “In the ever-evolving landscape of spine surgery, one thing is certain: artificial intelligence technologies have arrived— and they are here to stay.”

May 2020 | Issue 55

Interview

Profile

Daniel Riew

One of the worldâ&#x20AC;&#x2122;s foremost specialists in the treatment of the cervical spine, Daniel Riew talks to Spinal News International about his illustrious career. Riew, who has served as the President of the Cervical Spine Research Society (CSRS), and as chairman of the International Board of AO Spine, reflects on the increasing drive towards subspecialisation in spine care, his current research interests, and the emerging trends he sees impacting the field over the next decade.

Why did you decide to become a doctor, and what was it that led you to specialise in spine care?

When I started college, I thought I wanted to be a lawyer. But I soon found that law was a bit too subjective for my personality. I was drawn to the scientific part of medicine. As far as spine, I liked the complexity of the field. To properly diagnose a spine patient, one has to take a very careful history, perform a thorough physical exam and review all of the imaging studies. The diagnosis is often not obvious or simple. I guess that being a former internal medicine doctor, I was particularly drawn to a field that requires more diagnostic skills.

Have you had important mentors throughout your career? What have they taught you?

I have been very fortunate to have outstanding mentors throughout my career. I did my fellowship with Henry Bohlman, who was a great mentor. He taught us how to do thorough decompressions, detailed exams and the importance of spending time with a patient. He would spend an entire day seeing just eight to 10 patients. Every patient felt that he was giving his all for them and they all felt special. Sandy Emery, now chair of orthopaedics at the University of West Virginia, is the unsung hero of my fellowship year. He was an amazing surgeon and teacher and always calm under pressure and never said or did an unkind thing. Richard Gelberman was a tremendous academic mentor during my first 20 years in practice. Without his mentorship and even gentle but firm pressure, I would not have been academically productive and would not be where I am today. John McCulloch taught me microsurgery and the importance of osteology. He was a master anatomist and great mentor. He once said to me that if I, as his mentee, did not surpass him academically and as a surgeon, he would have failed me. I try to follow in his footsteps by passing on what I have learned to the fresidents that I teach. Sadly, he passed away and I will always miss him.

How has the field changed since you started your career, and what do you feel has been the most important development?

When I started, spine care did not have sub-specialties. Now there are surgeons who have sub-specialised in fields such as deformity, minimally invasive surgery, tumour and the cervical spine. Specialisation in spine is going to continue and even accelerate, as it has done in all medical specialties for the last 100 years.

What do you think are the main challenges facing spine care at the moment? What are the potential solutions?

There is too much unnecessary time devoted to learning skills that are not necessary to become a spine surgeon. Neurosurgeons spend seven years in residency. But perhaps only 50% of their training is in spine. Orthopaedic surgeons spend even less time during their

five years of residency training in spine. The difference shows when they do their fellowship, as the average neurosurgery fellow is two years older and has had two more years of training in spine than the average orthopaedic surgeon. But even the three or more years of training in spine that the typical neurosurgery resident gets is not adequate. It would be much better if all spine surgeons spent five years training just in spine, with a fellowship year devoted to subspecialty training.

The COVID-19 pandemic is one of the biggest challenges facing modern healthcare. What impact do you see this having on the field of spine care? In the short-term, until a vaccine or highly effective treatment has been identified, we are going to see significant changes in the indications for surgery, favouring young, healthy patients without comorbidities, such as obesity, diabetes, cardiac, immunologic and respiratory diseases, or those who have already had the infection and are now immune. In the long-run, I think the only change will be related to telehealth. We will be able to see patients remotely, saving patients the time and expense of travelling to see us in person.

You have been a leading advocate for cervical artificial disc replacement. Does this technique have the potential to become more commonplace over the next decade? I believe that it does. More and more patients are asking for it and we are getting a better handle on which patients are good candidates for the procedure.

What are your current research interests, and what are your future priorities for research?

We have a large number of projects that are going on at any given time. I am currently particularly interested in all aspects of research related to artificial disc replacements and anterior cervical fusions.

What is the most interesting piece of research you have read recently?

What really excites me is when I see so many energetic and bright researchers in the next generation doing amazing and ground-breaking research. It tells me that the future of spine research is in outstanding hands.â&#x20AC;?

There is so much research going on out there that it would be hard to point to any one paper. What really excites me is when I see so many energetic and bright researchers in the next generation doing amazing and ground-breaking research. It tells me that the future of spine research is in outstanding hands and we will constantly be learning new things thanks to their efforts.

In your opinion, what are the most exciting new developments in cervical spine care that we can expect in the next five to 10 years?

My guess is that biologics and robotic surgery will be the next wave. I believe that we will learn how to harness the power of growth factors while avoiding the dangers and downsides. As far as robotics, I would guess that many cervical operations could be done more efficiently and safely with advanced robotics and navigation.

You have previously served as president of the CSRS, what do you feel you accomplished in the role?

Issue 55 | May 2020

Interview

Fact File

Qualifications

1980–1984 MD, Case Western Reserve University School of Medicine, Cleveland, USA 1976–1980 AB, Harvard College, Boston, USA

Professional positions (selected)

Co-chief, Spine Division, Department of Orthopedic Surgery, Columbia University Medical Center, New York, USA Co-director, Adult and Pediatric Comprehensive Spine Fellowship, Columbia University Medical Center, New York, USA Deputy editor, Global Spine Journal Associate editor, Spine Past-president, AO Spine International Board of Directors, Cervical Spine Research Society (CSRS)

Memberships (selected)

AO Spine Cervical Spine Research Society (CSRS) Bohlman Society Association of Bone and Joint Surgeons American Orthopaedic Association North American Spine Society Scoliosis Research Society Orthopaedic Research Society

My top goal as president was to get as many young key opinion leaders, especially in neurosurgery, involved in committees and as committee chairs. With the support of the entire board, we increased the size of the board by about 30% and increased the numbers involved in committees by about 50%. This allowed us to get many more neurosurgeons involved in the leadership. But, this is not something I did on my own. The CSRS is a democratic organisation and no leader can accomplish any goal without the support of the entire board.

What is your proudest career achievement to date and why?

I am most proud of seeing how accomplished our former fellows at Washington University, as well as the more recent ones at Columbia have become. I was privileged to be a part of the fellowship that Keith Bridwell started at Washington University in St. Louis. He and Larry Lenke were able to recruit some of the best and brightest fellows in the country. I was the junior member of the group and learned as much from the fellows as I taught them. Now I see that those fellows have grown up to become leaders in the field, as well as in just about every

spine society. John Rhee will be the first of the Bridwell/ Wash U fellows to become a president of a major spine society when he ascends to the presidency CSRS next year. But, I am confident that there are many others who will become presidents of the Scoliosis Research Society (SRS), CSRS and other societies.The proudest moment for any teacher is to see a student’s achievements surpass their own.

What advice would you give to someone hoping to start a career in spinal surgery?

These are exciting times with so many advancements in spinal surgery. I do not think there is a better time to be a spinal surgeon than now.

What would you have been if you had not been a medical doctor? A trial lawyer.

Outside of medicine, what are your hobbies and interests?

My favourite activity is hiking with my family. I have a great pair of hiking sticks by Gossamer Gear that I use when trekking. With the COVID-19 induced shutdown, there is not much else to do in our free time, so every weekend as a family we hike in the nearby mountains.

Awards & prizes (selected)

2014 Washington University School of Medicine Distinguished Educator – Clinical Fellow Mentoring Award 2017 North American Spine Society Leon Wiltse Award for excellence in leadership and/or clinical research in spine care 2018 CSRS-Europe, Mario Boni Award 2018 for Best Oral Presentation: “Preliminary Return to Work data from the Multi-Center Prospective, Randomized CSM-S Study – Approach Matters

Publications

Riew KD. Variations in cervical myotomes and dermatomes. Spine July 2019:19(7):1143–1145. Riew KD, Kang DG. Central Cord Syndrome: Is Operative Treatment the Standard of Care? Spine J 2015;15(3):443–5. Riew KD, Raich AL, Dettori JR, et al. Neck pain following cervical laminoplasty: does preservation of the C2 muscle attachments and/or C7 matter? Evid Based Spine Care J 2013;4(1):42-53. Riew KD, Buchowski JM, Sasso R, et al. Cervical disc arthroplasty compared with arthrodesis for the treatment of myelopathy. J Bone Joint Surg Am 2008;90(11):2354–64.

May 2020 | Issue 55

Low back pain

NASS publishes evidence-based guideline to assist in the treatment of low back pain The North American Spine Society (NASS) has published a guidance document, “Evidence-based clinical guidelines for multidisciplinary spine care: diagnosis and treatment of low back pain, to assist practitioners treating adult patients with nonspecific low back pain above the knee”. The guideline, which is the result of over four years of work, involved 45,000 literature search results, contains 82 clinical questions and offers more than 100 recommendations. It is hoped that the document will provide evidence-based guidance to address key clinical questions surrounding the diagnosis and treatment of adult patients with nonspecific low back pain with leg pain above the knee.

s co-chair of NASS’s evidencebased guideline development committee, neurosurgeon Paul Matz (Wyoming Neurosurgery and Spine, Casper, USA) was a part of the working group that oversaw the drafting of the guideline—the largest clinical guideline ever developed in the organisation’s history. He spoke to Spinal News International about why the document is an important development in the diagnosis and treatment of low back pain, how the project came to fruition, and how NASS hopes it will influence spine care. “As a multidisciplinary organisation for spine care providers, NASS is uniquely positioned to provide specialty expertise and a real-world perspective on multidisciplinary spine care,” Matz explained. NASS opted to write a clinical guideline on low back pain to share the expertise of spine specialists as providers who predominantly treat the spine and its conditions. “Other guidelines do exist, but tend to reflect the perspectives of

first line providers, single specialties or special populations,” said Matz. The intended outcome of the NASS guideline is to provide a framework for better understanding of the evaluation and treatment of lower back pain that is non-radicular in nature. The document is separated into seven different sections, covering: diagnosis; imaging; medical and psychological treatment; physical medicine and rehabilitation; interventional treatment; surgical treatment and cost utility. The patient population for the guideline is adults (≥18 years of age), with low back pain defined as pain of musculoskeletal origin extending from the lowest rib to the gluteal fold that may at times extend as somatic referred pain into the thigh (above the knee).

Education

It is hoped that the guideline will act as an educational document, although NASS is explicit in stating that the recommendations do not form standards of care and should not be used as the sole reason for denial of treatment and services. “The guidelines are intended to establish a reference baseline for consultation that may be utilised by all spine-care practitioners,” Matz commented. “It will also establish a reference from which clinical research projects may be formulated, as the guidelines will have highlighted some of the limitations in current clinical studies. The impact on practice will depend on which type of practitioner is consulting the guidelines and which question that practitioner needs answered.” In terms of the difference

between the new NASS document and previous literature on low back pain, Matz comments that prior guidelines have included patients with lower back pain who may also have had simultaneous radicular pain. NASS’s goal, he explained, was to examine isolated lower back pain. “Each low back pain guideline in existence has different definitions and criteria, and evaluates different literature based on the definition and criteria selected by the developers, resulting in different questions and recommendations,” Matz said. By excluding leg pain below the knee, the NASS guideline recommendations are intended to address only a subset of low back pain and its care, and the selected criteria resulted in the removal of articles that may have influenced overall recommendations for a particular treatment or procedure. “For many sections, the inclusion of leg pain in the literature search would

Paul Matz

Other guidelines do exist but tend to reflect the perspectives of first line providers, single specialties or special populations.” have included many specific causes of back pain, including disc herniation and spondylolisthesis, that would have made the focus on nonspecific low back pain more difficult and less clear,” Matz noted. The development of the inclusion and exclusion criteria, while challenging, was a key part of the process. “If a clinical question about a specific treatment or diagnostic tool was not posed, it was not addressed in the guideline. The questions were widely scoped in the development process,” Matz said. “Without the inclusion of leg pain, these guideline recommendations address a subset of low back pain care, as opposed to low back pain in its entirety. This definition of lower back pain, and exclusion of patients with radicular lower back pain,

ended up being a point of contention in terms of studies reviewed and recommendations formulated. However, this type of focus resulted in some conclusions that were different from previous guidelines formulated by other professional societies which was the main area of contention.”

Collaboration

The resulting effort included input from stakeholder representatives of 11 societies. Contributions were made by more than 60 volunteers who summarised 300 supporting references, resulting in more than 100 recommendations. Participating bodies included the American Academy of Family Physicians; the American Academy of Orthopaedic Surgeons; the American Academy of Pain Medicine; the American Association of Neurological Surgeons/Congress of Neurological Surgeons; the American Society of Anesthesiologists; the American Society of Regional Anesthesia and Pain Medicine; the American Society of Spine Radiology; and, the Spine Intervention Society, alongside contributing societies, the American Academy of Physical Medicine and Rehabilitation; and the American Physical Therapy Association. The final guideline dwarfs a typical NASS guideline document, which is usually likely to be composed of around 30 clinical questions, involving 20–30 volunteers undertaking 400–600 literature searches. “That’s a lot of moving parts and schedules to coordinate,” Matz said. “We also wanted to take the time to make certain it was accurate, and that all of our participants had input, rather than rush it through production.” Development of the scope of the project and recommendations was not without its challenges, Matz concedes. “The complexity and size of this guideline, along with the variety of participants, provided ample opportunity for disagreement. We fully understood in undertaking this project that there might be some who may disagree with the final product, given the number of perspectives. Unfortunately, despite attempts through discussion to reconcile concerns, it wasn’t possible to bring everyone to the table. Many of the areas of disagreement were around methodology, which had been set at the beginning of the project and could not be changed after its conclusion.” In all, 10 of the 11 stakeholder societies agreed to be listed as participating or contributing to the document, which although it does not necessarily imply endorsement, Matz said, it is a sign of the success of the finished product. On the possibility of future developments to the guideline, Matz is open-minded. “There definitely exists the potential,” he said. “However, given the breadth of this guideline, it would definitely be a challenge.” An electronic copy of the guideline is available free to download via the NASS website. A technical report, including the literature search parameters, is also available.

May 2020 | Issue 55

Endoscopic surgery

Is there a bright future for endoscopic spinal surgery?

Figure 2. Extra- (A) and intra-discal (B) endoscopic views demonstrating neural anatomy and endplate preparation, respectively. Reproduced with permission from Yoon et al4.

Yingda Li Michael Wang

Comment & Analysis Yingda Li and Michael Wang consider the increasing interest in endoscopic techniques in spinal surgery. The authors describe how endoscopic techniques have been incorporated into practice at the University of Miami, and discuss how they can be used successfully alongside other emerging surgical techniques.

hilst the history of endoscopic spinal surgery dates back to the 1970s, it was not until recently that it started to garner attention and gain traction in North America. Over the last few years, coupled with burgeoning patient demand for minimally invasive surgery (MIS)10, evolving resource allocation patterns within US health systems12, and a historically unmet need to care for the elderly and infirm11, several landmark advances have been made in the field of endoscopic spinal surgery, some of which have been pioneered at the University of Miami. Percutaneous approaches to the intervertebral space were first described by Kambin in the 1970s, through the eponymous Kambin’s triangle1. Initial approaches remained percutaneous and visualisation indirect, and it was not until a decade later that the first endoscopic views of the intervertebral disc were achieved2. Since then, numerous iterations and improvements in equipment and technique have occurred, although the practice of endoscopic spinal surgery has remained relatively dormant in North America, particularly in comparison to our colleagues in Asia3. Its widespread acceptance and uptake has perhaps been in part hindered by parallel explosions in other potentially more lucrative fields within spinal

surgery, such as instrumentation, expandable technologies, biologics, navigation, and robotics4. Furthermore, the unfamiliar equipment, approach and view afforded by endoscopic spinal surgery have led to steep learning curves

Figure 3. Pre- (A) and postoperative radiographs (B) demonstrating successful spondylolisthesis reduction, foraminal height restoration, and intervertebral fusion.

hastening postoperative mobility and recovery, improving patient satisfaction, and reducing length of stay and costs5. At the University of Miami, we have eliminated one of the key physiological stressors, the general anaesthetic, replacing it with conscious sedation, and applied it to lumbar fusion, resulting in the first-in-man awake endoscopic

The unfamiliar equipment, approach and view afforded by endoscopic spinal surgery have led to steep learning curves and deterred many surgeons away from this field.” and deterred many surgeons away from this field, particularly if perceived effort is unmatched by proportionate remuneration. Over the past five years or so, increasing recognition of the physiological footprint imparted upon the patient by traditional open surgery, combined with a historically nihilistic approach to operating upon the elderly and infirm, a population that often needs our help the most, and traditionally negative public perceptions of spinal surgery, have led to the rise of enhanced recovery after surgery (ERAS) programmes, with endpoints of reducing pain and narcotic consumption,

MIS transforaminal lumbar interbody fusion (TLIF), leveraging long-acting local anaesthetic, expandable interbody technology, biologics, and percutaneous instrumentation6, a feat not long ago considered improbable, if not impossible (Figures 1-3). Indications for endoscopic spinal surgery have continued to broaden and evolve, with stenotic, spondylolisthetic, other degenerative and even tumoural pathology across the entire length of the spine now treatable endoscopically9. At the University of Miami, we have introduced endoscopic techniques to treat complex spinal deformity, ranging from limited, strategic decompressions

Figure 1. Intraoperative fluoroscopy demonstrating transforaminal entrance into the L4-5 intervertebral space via Kambin’s triangle using a spinal needle (A), followed by sequential dilation (B), introduction of percutaneous reamer and stainless steel brush (C and D), and measurement of extent of discectomy and sizing for interbody graft by inflation of a balloon with radioopaque contrast (E).

at the fractional curve on one end of the spectrum7 to efficient, multi-level endoscopic MIS-TLIFs as a workhorse in long-segment constructs. Whilst the exponential development in navigation and robotics has perhaps in some ways occurred previously at the expense of endoscopy, we view these technologies as complementary and potentially synergistic, flattening some of the learning curve associated with traditional fluoroscopic-guided endoscopic spinal surgery approaches and increasing their safety and reproducibility. The time is now for spinal endoscopy, and its future bright. The growing interest in this field is only perhaps matched by its expanding indications, the recognition of the need for techniques that not only minimise iatrogenic anatomical disruption but also the physiological stress imparted upon the patient, and our responsibility to offer hope to patient populations historically denied surgery. There is already randomised trial evidence supporting endoscopic over traditional microdiscectomy approaches8, and as visualisation, instrumentation, and technology continue to improve, there is no reason why endoscopic spinal surgery cannot gradually supplement or succeed other approaches, in the same way that endoscopic anterior skull base surgery has, in many respects, superseded traditional microscopic pituitary surgery and morbid open skull base approaches. Yingda Li is a spine fellow at the University of Miami Miller School of Medicine (Miami, USA). His research covers all aspects of spinal surgery, in particular minimally invasive surgery, intradural surgery, and spinal deformity. Michael Wang is the chief of Neurosurgery at the University of Miami Hospital (Miami, USA). His clinical interests include minimally invasive spinal surgery, intradural spinal surgery, spinal deformity, clinical outcomes, and trials, and spinal cord injury. References 1. Kambin P (ed): Arthroscopic Microdiscectomy: Minimal Intervention Spinal Surgery. Baltimore, MD: Urban & Schwarzenberg, 1990. 2. Kambin P, Nixon JE, Chait A, Schaffer JL. Annular protrusion: pathophysiology and roentgenographic appearance. Spine 1988;13:671–675. 3. Lewandrowski KU, Soriano-Sanchez JA, Zhang X, et al. Regional variations in acceptance, and utilization of minimally invasive spinal surgery techniques among spine surgeons: results of a global survey. Journal of Spine Surgery 2020;6:S260–74 4. Yoon JW, Wang MY. The evolution of minimally invasive spine surgery. J Neurosurgery Spine 2019;30:149–58. 5. Dietz N, Sharma M, Adams S, et al. Enhanced recovery after surgery (ERAS) for spine surgery: A systematic review. World Neurosurg 2019;130:415–426. 6. Kolcun JPG, Brusko GD, Basil GW, et al. Endoscopic transforaminal lumbar interbody fusion without general anesthesia: operative and clinical outcomes in 100 consecutive patients with a minimum 1-year follow-up. Neurosurg Focus 2019;46(4):E14. 7. Madhavan K, Chieng LO, Mcgrath L, et al. Early experience with endoscopic foraminotomy in patients with moderate degenerative deformity. Neurosurg Focus 2016;40(2):E6. 8. Gibson JNA, Subramanian AS, Scott CEH. Erratum to: A randomised controlled trial of transforaminal endoscopic discectomy vs microdiscectomy. Eur Spine J 2017;26(8):2222. 9. Telfeian AE, Veeravagu A, Oyelese AA, et al. A brief history of endoscopic spine surgery. Neurosurg Focus 2016;40(2):E2. 10. Narain AS, Hijji FY, Duhancioglu G, et al. Patient perceptions of minimally invasive versus open spine surgery. Clin Spine Surg. 2018;31(3):E184–E192. 11. Shamji MF, Goldstein CL, Wang M, et al. Minimally invasive spinal surgery in the elderly: Does it make sense?. Neurosurgery 2015;77 Suppl 4:S108–15. 12. Basil GW, Wang MY. Trends in outpatient minimally invasive spine surgery. J Spine Surg 2019;5:S108– S114.

May 2020 | Issue 55

Market watch

Product News Centinel Spine receives FDA approval for two-level indications of prodisc L

Centinel Spine has announced US Food and Drug (FDA) approval of two-level indications for the prodisc L lumbar total disc replacement (TDR) system. The prodisc L device was first implanted in the USA during concurrent IDE studies to obtain FDA approval for one and two-level use. The first twolevel implantation in the USA took place in January 2002, carried out by Jack Zigler at the Texas Health Center for Diagnostics and Surgery (Plano, USA) as a part of the two-level study. Results from the study have been published in numerous papers and are part of the over 540 published studies on the prodisc technology platform. “Patients with two-level prodisc L disc replacements have done remarkably well in long-term follow-up,” Zigler noted. He continued, “We began twolevel prodisc L implantations in January 2002 at the Texas Back Institute as an enrolling site in the FDA study. I have now seen multiple two-level disc replacement patients with over 15year follow-up who are still delighted with their clinical results—and have not needed additional surgery that is commonly required after initial fusion

surgery. Patients with two-level disc replacement are among my most grateful patients.” “The prodisc technology’s remarkable safety and efficacy profile is a tribute to the design of the device,” stated Centinel Spine CEO Steve Murray. “The longevity of the prodisc technology is due to the design principles of a stable bone interface, a consistent mechanism of action enabling guided motion, and instrumentation that facilitates efficient and reliable implantation,” Murray concluded.

Signus receives CE mark for ALIF and cervical cages

Signus has announced that it has received CE mark approval for two implants in its product portfolio, the BIG ST anterior lumbar interbody fusion (ALIF) cage and the JASPIS ST cervical cage. BIG ST is a 3D printed lumbar cage, which can be inserted from an anterior approach, using a minimally invasive retro/transperitoneal approach or using a 45 degree oblique or 90 degree lateral technique. Implanted from an anterior approach it is possible to insert four divergent fixation screws and use it as a standalone fusion device which comes along with both economic benefits and

less invasive surgery for the patient, Signus said in a press release. The implant features a flattened front edge and smooth lateral surfaces combined with a self-distracting design to ensure a reduced preparation and protection of the nerval structures during insertion. An open macroporous structure resembles natural cancellous architecture and enables both growing on and growing in of bone that can be supported by filling the implant with KAINOS Inject. An increased roughness in conjunction with the Signus toothed cage design secures the anchoring in the bone owing to a high primary stability and reduces the risk of implant migration. The large contact area with the vertebral body reduces the risk of subsidence. Also to gain recent CE mark approval, the JASPIS ST originates from the RABEA design, which received the world’s first CE mark approval for a plane-parallel fusion cage in 1996. The implant’s titanium grid structure imitates the architecture of natural cancellous bone to optimise inter-

Signus BIG ST cages

corporeal fusion, Signus said in its release. The open design of the implant permits the cage to be packed with natural or synthetic bone graft substitute such as KAINOS Inject, creating the optimal foundation for osseointegration. The roughness of the implant in addition with Signus’ toothed endplate design secures anchorage in the bone owing to high primary stability.

Spinal ultrasound imaging platform receives US FDA clearance

Tissue Differentiation Intelligence (TDi) has announced that it has received US Food and Drug Administration (FDA) 510(k) clearance for the SonoVision ultrasound platform, which has been designed for intraoperative access to the spine. SonoVision applies layers of imageprocessing algorithms to ultrasound images collected intraoperatively, which allows it to visually differentiate nerve, muscle, bone and vessels in real time. The FDA clearance of SonoVision paves the way for ultrasound to be used as a new imaging modality for spine surgery by overcoming the impracticalities of conventional ultrasound, TDi said in a press release. Expanded applications are also in development. The company currently has multiple systems deployed for clinical study data collection under IRB and for Alpha evaluations, which are focused primarily on the clinical refinement of lateral surgery access.