MSK ultrasound of temporomandibular joint disk displacement

The temporomandibular joint (TMJ) is a synovial joint between the condyle of the mandible and the glenoid fossa of the squamous temporal bone. It is divided into two compartments by a fibrocartilaginous disk, which allows movements in the lower and upper compartments.

The most frequent cause of TMJ dysfunction is disk displacement, which is an abnormal relationship between the disk and the condyle. Anterior displacement with reduction is defined as disk displacement with the mouth closed that reduces (with a click) to the normal relationship at some time during opening. The mandible deviates to the affected side on opening until the click occurs and then returns to the midline. This situation may worsen from intermittent locking of the disk to anterior disk displacement without reduction (closed lock), the dislocated disk acting as a mechanical obstruction to opening and translation of the condyle, leading to a marked decrease in mandible opening on the affected side and a variable degree of pain. The indications for imaging include failure of conservative treatment, worsening of symptoms or atypical symptoms, and preoperative assessment. [According to Kiné Care - www.msk-ultrasound.com - also for treatment evaluation].

Because of its greatly improved nearfield tissue differentiation, current state-of-the art highresolution sonography is a potential imaging method for diagnosis of TMJ disk displacement and for depicting further TMJ disorders, although MRI is still needed in select cases. Better standardization of the sonographic technique and normal parameters need to be determined.

> From: Habashi et al., J Ultrasound Med 34 (2015) 75-82. All rights reserved to the American Institute of Ultrasound in Medicine. Click here for the Pubmed summary.