Reduction of temporomandibular dislocation

PATHOGENESIS

The temporomandibular joint (TMJ) is the articulation of the temporal and mandibular bones (figure 1) [1]. TMJ dislocation occurs when the condyle travels anteriorly along the articular eminence and becomes locked in the anterior superior aspect of the eminence, preventing closure of the mouth (figure 2) [1]. This results in stretching of the ligaments, and is associated with severe spasm of the muscles that open and close the mouth (ie, the masseter, internal pterygoid, and temporalis) [2,3]. The resultant trismus prevents the condyle from returning to the mandibular fossa.

CLINICAL FEATURES

TMJ dislocation may occur with trauma, but most often follows extreme opening of the mouth during yawning, laughing, singing, vomiting, or dental treatment [4,5]. Dislocation also can result from dystonic reactions to drugs [6]. Symmetric mandibular dislocation is most common, but unilateral dislocation with the jaw deviating to the opposite side also can occur.

TMJ dislocation is painful and frightening for the patient. On examination, the patient is unable to close the mouth and there is excessive salivation [4,7]. A depression may be noted in the preauricular area. Palpation of the TMJ reveals one or both of the condyles trapped in front of the articular eminence and spasm of the muscles of mastication.

Patients prone to mandibular dislocation include those with an anatomic mismatch between the fossa and articular eminence, weakness of the capsule and the temporomandibular ligaments, and torn ligaments. Patients who have had one episode of dislocation are predisposed to recurrence [8].

EVALUATION

Radiographs of the TMJ are not always necessary, but should be obtained to exclude condylar fracture if the dislocation is related to trauma [9,10]. Jaw fractures are discussed separately. (See "Jaw fractures in children".)