Metabolic changes of osteoarthritis cartilage reflected by special cartilage markers

Objective To investigate the relationship between the levels of proteoglycan and collagen type Ⅱ in serum and severity of knee osteoarthritis, and to determine whether the two markers could reflect the metabolic changes of cartilage after different knee operations. Methods Serum samples and roentgenographic data of 65 patients with knee osteoarthritis and 22 normal persons in controls were collected. Three different operations were performed for 45 patients respectively. These patients were followed up for half a year. The serum levels of proteoglycan and collagen type Ⅱ epitope were analysed using an enzyme-linked immunosorbent assay(ELISA). Results Epitope levels of proteoglycan and collagen type Ⅱ in serum of osteoarthritis patients were higher than those in control group. The serum levels of both markers in the group that the roentgenograph show minor narrowing of joint space were highest. Half a year after total knee replacement, the level of proteoglycan decreased significantly(P 0.05). In high tibial osteotomy group, collagen type Ⅱ level in serum decreased significantly(P 0.05). Conclusion The serum levels of proteoglycan and collagen type Ⅱ fragment are related with the grade of destruction of osteoarthritis cartilage, the synthetic response of chondrocytes and the total amount of cartilage. Proteoglycan and collagen type Ⅱ are sensitive markers reflecting the metabolic changes of articular cartilage.