An experimental model of osteoarthrosis of the temporomandibular joint in monkeys.

The purpose of this study was to develop a model of osteoarthrosis of the temporomandibular joint in monkeys, which is remarkably similar in structure and function to that of humans. Nine juvenile monkeys, two as controls and seven as an experimental group, were used in this study. In the experimental group, the articular eminence on both sides was surgically made steeper. Two animals were killed at 1 week, four at 6 months, and one at 1 year postoperatively and the temporomandibular joints were examined macroscopically and microscopically. Typical changes of osteoarthrosis were observed in the 6-month and 1-year specimens. These comprised clustering of chondrocytes which resulted in vertical and horizontal splitting in the articular cartilage, and fibrillation of the articular surface resulting in fibrous union in the joint cavity. These degenerative changes advanced progressively over time. Slight anterior displacement and degenerative changes in the articular disc were also seen.