Morphologic changes in the unloaded temporomandibular joint after mandibulectomy.
OBJECTIVE
The aim of this study was to examine intra-articular conditions in unloaded temporomandibular joints (TMJs) after mandibulectomy including the condyle or segmental mandibulectomy.


METHODS
Seventeen joints were defined as unloaded TMJs. Eleven of the 17 joints were classified into the "without condyle" (WOC) group in which TMJs had the condyle removed but the disc and superior joint compartment were preserved, and remaining 6 joints were classified into the "with condyle" (WC) group in which TMJs were connected to the condylar process. Disc configuration, bony changes, and joint effusion were examined by magnetic resonance imaging. In 8 of the 17 joints, arthroscopic examination of the superior joint compartment was performed. Correlation between data of the WOC and WC groups was evaluated. The relationship between arthroscopic findings and joint effusion was also analyzed.


RESULTS
Deformed discs were observed in 7 of the 11 joints (63.6%) of the WOC group but were not observed in the WC group, in which there was a normal relationship between the disc and condyle. Bony changes were not detected in any joints. Joint effusion and arthroscopically diagnosed fibrous adhesion were observed in nearly all joints of both groups.


CONCLUSIONS
We conclude that alteration of the relationship between the disc and condyle is more important for the initiation of disc deformation than loading conditions on the disc. The present findings suggest that, in the unloaded TMJs, articular degeneration is induced by disturbance of synovial fluid metabolism but that bony conditions are not affected.
Hamada
Yoshiki
Y
First Department of Oral and Maxillofacial Surgery, School of Dental Medicine, Tsurumi University, Yokohama, Japan. hamada-y@tsurumi-u.ac.jp
Kondoh
Toshirou
T
Sekiya
Hideki
H
Seto
Kanichi
K
D001182:Arthroscopy; D003799:Dental Stress Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008334:Mandible / Q000601:surgery*; D008335:Mandibular Condyle / Q000601:surgery; D008410:Masticatory Muscles / Q000502:physiology; D019647:Oral Surgical Procedures / Q000009:adverse effects*; D013582:Synovial Fluid / Q000378:metabolism; D013704:Temporomandibular Joint / Q000473:pathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology; D013705:Temporomandibular Joint Disorders / Q000209:etiology*; D000267:Tissue Adhesions / Q000209:etiology / Q000473:pathology