IS Case 367: Temporomandibular joint (TMJ) dislocation

Daniel Ginat, MD, MS

2009 URMC Imaging Sciences
Publication Date: 2010-03-02


Patient is a 41-year-old female who is unable to move her jaw.


Panorex and lateral TMJ views reveal anterior dislocation of the right condylar head of the mandible from the glenoid fossa. There are also arthritic changes affecting the left condylar process. However, no fracture is apparent.


Temporomandibular joint (TMJ) dislocation is suspected when patients are unable to close the mandible from a maximally open position. In contrast to TMJ subluxation, the patient is unable to spontaneously reduce the mandible when it is dislocated. Precipitating factors include ligamentous laxity, craniofacial anomalies, yawning, dental procedures, and trauma. Although typically clinically evident, imaging can help establish the diagnosis among differential diagnoses, such as open lock, and to evaluate for complicating factors, such as fractures and TMJ degeneration if dislocation occurs on a chronic basis. A Panorex series can delineate the position of the mandibular condyle head with respect to the glenoid. If the dislocation is unilateral, the mandible will be deviated towards one side. The condyle typically lies anterior to the glenoid and is held in this position due to muscle spasm. MRI can be used to assess for derangement of the TMJ meniscus.


  1. Landry GL, Bernhardt DT. Essentials of primary care sports medicine. Human Kinetics. 2003: 70.

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