Histological changes in the rabbit condyle following posterolateral disk perforation.

PURPOSE: To examine changes in condylar cartilage following perforation in the posterolateral region of the articular disk of the craniomandibular joint of a rabbit.

MATERIAL AND METHODS: The circular perforation in the left joint of 25 female Japanese white rabbits measured precisely one-sixteenth of a disk. Histological examination, including the immunohistochemical proliferating cell nuclear antigen (PCNA) procedure, was performed on separate sets of five rabbits each 2, 4, 8, 12, and 24 weeks postoperatively.

RESULTS: Microscopic examination revealed hypertrophy of the condylar cartilage with osteophyte formation up to 8 weeks after perforation. Proliferative activity then decreased near the condylar surface as the perforation flattened. Twenty-four weeks postoperatively, the condylar surface was found to be fibrous and flattened. Positive PCNA results in cartilage cells indicated proliferation following disk perforation which peaked in the 4th week and then decreased.

CONCLUSION: Disk perforation was followed initially by hypertrophy of condylar cartilage, and later by degeneration of the condylar surface. Although osteoarthritic cartilage was found 24 weeks after perforation, degeneration decreased over time. This suggests that remodelling took place after the perforation.