A histochemical study of alkaline and acid phosphatase activity in osteoarthritic synovial membrane

In order to determine the localization and activity of alkaline and acid phosphatase in the synovial membrane of osteoarthritic hip joints, enzymo-histochemical analyses were performed using Burstone's and Barka & Anderson's methods. Frozen sections of synovial biopsy material from 12 osteoarthritic and 6 control hip joints were studied. Alkaline phosphatase was found located in fibroblasts below the lining cells and in capillaries and precapillary arterioles. Acid phosphatase was seen in the lysosomes in the lining cells. Semiquantitative evaluation by means of initial time determination showed significantly greater activity in osteoarthritic synovia than in the control group. Whilst the increased activity of lysosomal enzymes is presumably implicated in the joint cartilage damage seen in osteoarthritis, the significance of elevated alkaline phosphatase levels is not yet clear.