Disc mobility and arthroscopic condition of the temporomandibular joint lint associated with long-term mandibular discontinuity

Purpose: The present study aimed to explore disc mobility and arthroscopica lly diagnosed morphologic changes in the temporomandibular joint (TMJ) asso ciated with long-term mandibular discontinuity. Patients and Methods: Twelve patients (24 TMJs) who had undergone mandibule ctomy including the unilateral condyle or segmental mandibulectomy without mandibular reconstruction, more than 8 months before this study were examin ed. The 24 TMJs were classified into 3 groups as follows: group 1, TMJs wit h a major mandibular fragment including the mandibular body (n = 11); group 2, TMJs with a mandibular ramus including the coronoid process (n = 5); an d group 3, TMJs with only a condylar process, a mandibular ramus not includ ing the coronoid process, or without a condyle (n = 8). Disc mobility was e valuated by magnetic resonance imaging, and arthroscopic observation of the superior joint compartment (SJC) was performed in all TMJs. The relationsh ip between disc mobility and the arthroscopic findings was also studied. Results: The frequency of immobile discs differed significantly among group s 1 (0%), 2 (40.0%), and 3 (100%). Arthroscopic findings were normal in all SJCs of group 1. Various types of fibrous adhesions were observed in 40.0% of group 2 and in 75.0% of group 3. The development of fibrous adhesions i n the SJC was significantly related to the presence of an immobile disc. Conclusions: Long-term immobilization of the TMJ in a nonfunctional state s eems to promote the development of fibrous adhesions in the SJC. Preservati on of the mandibular fragment including the coronoid process, during mandib ulectomy appears to contribute to postoperative TMJ mobility. To ensure rec overy of a physiologic TMJ after mandibulectomy, it seems important to re-e stablish TMJ mobility by establishing mandibular continuity as soon as poss ible. (C) 2001 American Association of Oral and Maxillofacial Surgeons.