Osteoarthrosis of the ankle joints in old rats.

The paper describes results of histological investigations on 26-month-old rats with osteoarthrosis of the ankle joints. From the morphological appearance a sequence of alterations from focal chondrocytic necroses, fibrillation to partial or total cartilage loss occurred. The reported changes were often present in opposing cartilage contact zones. A synovitis seems not to be involved in this cartilage destructive process. It is assumed that this spontaneously occurring osteoarthrosis can be used as a model to study the mechanisms leading to cartilage destruction. The model may further be useful to elucidate protective or detrimental effects of therapeutic substances.