Metabolic response during early stages of surgically-induced osteoarthritis in mature beagles.

Severance of the anterior cruciate ligament in the knees of mature beagles caused instability and resulted in the slow onset of changes comparable to those present in human osteoarthritis (OA). Heightened cellular activities were reflected in increased levels of arylsulfatase, acid phosphatase, and beta-glucuronidase in the articular cartilage. Similar increases in these lysosomal enzyme activities were found in the synovial fluid of the operated joints. Dietary supplementation with vitamin C resulted in increased serum protein content and increased cartilage formation, although ascorbate had no effect on enzyme activities. The early stages of OA in mature beagles, therefore, were characterized by interference with normal chondrocyte metabolism which resulted in staggered elevation of different lysosomal enzymes.