Degenerated human articular cartilage at autopsy represents preclinical osteoarthritic cartilage: Comparison with clinically defined osteoarthritic cartilage

Objective. To investigate whether macroscopically fibrillated human articular knee cartilage observed at autopsy can be considered an early, preclinical phase of osteoarthritis (OA). Methods. Histological and biochemical characteristics of 3 types of articular knee cartilage were compared: macroscopically degenerated knee cartilage obtained at autopsy (6 donors) from donors without clinical history of OA, normal healthy knee cartilage obtained at autopsy (6 donors), and OA cartilage obtained during joint replacement surgery from patients (n = 6) with clinically defined OA of the knee. From the same donors synovial tissue and synovial fluid were obtained and analyzed for features of inflammation. Results. Histological changes of OA were comparable for degenerated and OA cartilage and significantly different from normal cartilage. Content and synthesis of proteoglycans showed intermediate levels for degenerated tissue compared to normal and OA cartilage. Analysis of synovial tissue revealed a low, mild, and moderate degree of inflammation for joints with normal, degenerated, and OA cartilage, respectively. The same sequence was found for metalloproteinase activity in synovial fluid. Conclusion. In general, all changes observed in OA joints were, to a lesser extent, observed in the joints with degenerated cartilage and were significantly different from joints with normal cartilage. We conclude that cartilage degeneration observed at autopsy can be considered a preclinical phase of OA, suitable for studying the process of cartilage degeneration in OA.