MUSCULOSKELETAL REVIEWED BY Michelle Fenech ASA SIG Musculoskeletal REFERENCE
Advanced ultrasound screening for temporomandibular joint (TMJ) internal derangement
Friedman SN, Grushka M, Beituni HK, Rehman M, Bressler HB, Friedman L. Advanced Ultrasound Screening for Temporomandibular Joint (TMJ) Internal Derangement. Radiol Res Pract. 2020; 2020:1809690. READ THE FULL ARTICLE HERE
WHY WAS THE STUDY PERFORMED? The temporomandibular joint (TMJ) exists between the mandibular condyle and the concave mandibular fossa (or glenoid fossa) of the temporal bone, and the convex articular eminence of the temporal bone (Figure 1). This joint is unique in that all the articular surfaces are covered by fibrocartilage instead of articular cartilage1. The TMJ contains a flexible fibrocartilage disc which is reported to be 2mm thick anteriorly and 3 mm thick posteriorly2. This hinge joint allows both forward and backward translation of the mandibular condyle and articular disc2. Internal derangement of the TMJ is defined as a mechanical fault of the joint that interferes with smooth joint function which is attributed to abnormal interaction between the articular disc, condyle and articular eminence1. Articular disc displacement is the most common cause of internal derangement of the TMJ3. Disc displacement is categorised based on the relationship of the disc to the mandibular condyle and can be described as anterior, anterolateral, anteromedial, lateral, medial and posterior1. The most common pattern of disc displacement is either anterior or anterolateral, which accounts for more than 80% of disc displacement4.
Figure 1. Anatomy of the Temporomandibular joint (TMJ) with the mouth in the closed position. MC = mandibular condyle, AE = articular eminence of temporal bone, MF = mandibular fossa of temporal bone, EAM = external auditory meatus. Fibrocartilage lining MF, AE and MC shown in blue.
Articular disc displacement is the most common cause of internal derangement of the TMJ
Sonographic assessment of the TMJ may be undertaken to investigate the structural integrity of the TMJ using static and dynamic imaging and identify structural changes such as displacement or snapping of the articular disc if present and guide injections if required3,5. Such a request can induce panic in a sonographer, particularly if they are not familiar with the relational anatomy, sonographic technique, and normal and abnormal sonographic appearances of this joint. This study was undertaken to investigate a sonographic technique that may be used for dynamic and static imaging of the TMJ and as a screening diagnostic tool for TMJ internal derangement6.
HOW WAS THE STUDY PERFORMED? Sonographic imaging of the TMJ using a defined technique was compared with coronal and sagittal magnetic resonance (MR) imaging in bilateral TMJs in 10 asymptomatic control participants (between 20 and 30 years of age). The main structures identified include the mandibular condyle, mandibular fossa, articular eminence, and articular disc.
Making waves
JANUARY 2022 | 16
