Cartilage turnover and intra-articular corticosteroid injections in knee osteoarthritis

Intra-articular corticosteroid injections (IACI) are commonly used interventions for pain relief in patients with knee osteoarthritis (OA). Biomarkers may be helpful in further elucidating how IACI exert their effect. The aim of this study is to look at the response of biomarkers of cartilage and bone metabolism after IACI in knee OA. Eighty subjects with symptomatic knee OA [45% male, mean age (SD) 64 (11) years] underwent routine knee joint injection with 40 mg triamcinolone acetonide and 4 ml 1% lignocaine. Knee pain (as pain subscale of WOMAC VAS) and biomarkers [C-telopeptides of type-II collagen (uCTX-II), and N-telopeptides of type-I collagen in urine; cartilage oligomeric matrix protein (COMP), hyaluronic acid, N-terminal propeptide of type-IIA collagen, and human cartilage glycoprotein-39 (YKL-40) in serum] were measured at baseline and 3 weeks after IACI. Radiographic severity of disease was evaluated using knee radiographs. Median uCTX-II, a cartilage degradation marker, was lower at 3 weeks post IACI compared with baseline: 306.3 and 349.9 ng/mmol, respectively (p < 0.01), which remained significant after Bonferroni correction. Apart from a weak trend of lower sCOMP post IACI (p = 0.089), other biomarkers showed no change after IACI. Both baseline uCTX-II values and the change in uCTX-II from baseline to 3 weeks post injection correlated with radiographic severity of joint space narrowing, but not osteophyte grade. No association between uCTX-II and pain was observed. This observational study suggests that IACI in knee OA may reduce cartilage degradation in the short term.