A method for the quantification of cartilage proteoglycan structures liberated to the synovial fluid during developing degenerative joint disease.

An enzyme linked immunosorbent assay for the quantification of proteoglycans or proteoglycan fragments in biological fluids is presented. The assay has been used to determine concentrations of articular cartilage proteoglycans and/or fragments thereof in synovial fluid in early stages of osteoarthrosis. Osteoarthrosis was induced in one knee joint of nine German wire haired pointers by transection of the anterior cruciate ligament. All dogs developed osteoarthrosis in terms of macroscopic as well as microscopic criteria. Attempts were made to aspirate synovial fluid, prior to surgery and at various times in the postoperative period, from the joint operated on as well as from the contralateral joint. Concentrations of proteoglycans (fragments) of one type of aggregating proteoglycan were significantly higher in the synovial fluid samples from the joint operated on compared to the contralateral joint (p less than 0.001), while the difference observed when the other type of aggregating proteoglycan was used as the test antigen was less significant (p less than 0.05). The concentration of proteoglycans (fragments) in synovial fluid samples from joints operated on was significantly higher after the operation when compared with the preoperative concentration (p less than 0.001). No correction has been made for the increased dilution due to hydrops of the joints operated on.