Comparison of joint degeneration models. Surgical instability and repetitive impulsive loading.

We used surgical instability and repetitive impulsive loading in rabbits to initiate degenerative changes in knee joints. Synovial membrane and cartilage samples were examined by light and electron microscopy. Early synovial inflammation at three days postoperatively preceded cartilage destruction in the instability model. Synovial inflammation was only apparent after eight weeks in the loading model and increased subsequently to cartilage destruction. Cartilage breakdown was focal and limited to the weight-bearing area. Comparison of the histological data of the two arthrosis models suggests that different inductive mechanisms may be involved in cartilage degeneration, but in both models the inflammatory changes appeared to be secondary to mechanical factors.