Primary lesion in osteoarthrosis.

The primary disturbance in osteoarthrosis is generally regarded as occurring in the articular cartilage and as resulting from a combination of ageing and mechanical factors. An alternative hypothesis is that the primary disturbance is located in the synovial lining cells. It is suggested that proteolytic enzymes which normally leak from the phagocytic (A type) lining cells are in the healthy joint neutralised by inhibitors synthesised by the B-type lining cells. Osteoarthrosis is the result of an imbalance between leakage of enzymes and provision of inhibitors.