Temporomandibular Joint Eminectomy for Recurrent Dislocation

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Since the days of Hippocrates, repositioning of the dislocated mandible has been an important topic in medicine and dentistry, and the first surgical techniques for the prevention of recurrent mandibular dislocation and for the treatment of long standing luxation were described in the late 1800s. Dislocation of the mandible is usually bilateral. The symptoms are open mouth, protruding chin, tense masticatory muscles, salivation, speech difficulties, and pain. In unilateral cases, the mandible deviates toward the opposite side from the dislocated condyle. On manual palpation, the glenoid fossa is empty, and the condylar head can be palpated anterior to the eminence. Some investigators have defined normal maximum translation of the condyle as the point at which the greatest convexity of the condyle meets the greatest convexity of the articular eminence. About 60% of normal subjects translate more anterior to that point without any symptoms. Subluxation occurs when the condyle translates anterior to its normal range, and the patient exhibits a temporary locking or sticking sensation that either abates spontaneously or can be reduced with selfmanipulation (Fig. 1). Dislocation is a more advanced hypertranslation in which the condyle locks anterior to the eminence in a position that cannot be self-reduced because the condyle is fixed in that position by muscular spasm (Fig. 2). This state requires medical assistance to relocate the condyle in its normal position. In some cases, periarticular application of local anesthetics or tranquillizer premedication is necessary before manual reduction of the mandible is possible. Recurrent mandibular dislocation is uncommon. Boering found an incidence of 1.8% in a population of 400 patients with symptomatic temporomandibular joint (TMJ) disorders. Recurrent mandibular dislocation is found more frequently in people with general joint laxity and in patients with internal derangement of the TMJ or with occlusal disturbances, such as loss of teeth and vertical height. It may be associated with neurologic diseases encountering increased muscular activity or tension as well as in patients suffering from extrapyramidal symptoms who are receiving neuroleptic therapy. Recurrent dislocation of the condyle may cause injury to the disc, the capsule, and the ligaments, leading to progressive TMJ internal derangement. Conservative treatment modalities and indications for surgery The rationale foroperativeinterventionisofteninfluencedbythedurationofthepatient’ssymptoms and theexhaustionofotherforms oftreatment.Conservativetreatmentincludesphysiotherapy,training the muscles to avoid excessive translation of the condyles, and prosthetic restoration of vertical height. Following an acute dislocation, immobilization of the jaw in the closed position for some days to some weeks has been advocated. For edentulous patients with repeated luxations, wearing their prostheses during the night has been successfully recommended. In patients with extrapyramidal motor disorders,