Osteoarthritis (OA) is characterized by a progressive degeneration of articular cartilage and loss of joint function. We hypothesized that degradation of articular cartilage results in increased fragmentation of collagen type II. Thus, the concentrations of degradation products of this major cartilage matrix protein may increase in body fluids of patients with OA.
Monoclonal antibodies specific for a human collagen type II C-telopeptide (CTx-II) fragment were used in an ELISA for quantification of collagen type II fragments in urine. Clinical assessment of 88 patients with advanced OA of either hip or knee and 48 age-matched controls was performed with the Harris hip score, the Merle d'Aubigné score and a knee score. Joint space narrowing and the Kellgren and Lawrence score were assessed as radiological signs of OA.
The concentration of CTx-II was significantly higher in OA patients compared with controls (527 vs. 190 ng/mmol, p < 0.001) whether the patients were diagnosed with hip OA (n = 51) or knee OA (n = 37). Mean CTx-II levels were higher in hip OA than in knee OA and a slight increase in levels with age was observed in the controls, but not in OA subjects.
Elevation of CTx-II in urine of patients with severe OA compared with a control group suggests that collagen type II derived fragments may serve as markers for OA.