5-yr longitudinal study of type IIA collagen synthesis and total type II collagen degradation in patients with knee osteoarthritis: association with disease progression

Objectives. The 5-yr longitudinal study tested the hypothesis that serum and urinary markers of type II collagen metabolism would be associated with radiological progression of disease in patients with mild-to-moderate knee osteoarthritis (OA). Methods. Synthesis of type IIA collagen and degradation of total type II collagen were assessed in 135 patients with mild-to-moderate knee OA over 5 yrs using serum concentration of the N-propeptide of collagen type IIA (PIIANP) and urinary excretion of crosslinked C-telopeptide (CTX-II), respectively. The markers were measured at baseline, 2, 3 and 5 yrs’ follow-up corresponding to X-ray time points. Analysis of variance (ANOVA) was performed to determine longitudinal changes over 5 yrs in the biomarkers in all patients and between progressors and non-progressors. Results. Complete X-ray progression data over 5 yrs, serum PIIANP and urinary CTX-II were available for 84/135 patients. There were 24 progressors and 60 non-progressors. Overall, over the 5-yr study period average PIIANP and CTX-II levels were higher in progressors compared with non-progressors (P