Effect of intra-articular injection of hyaluronic acid in rheumatoid arthritis patients with knee osteoarthritis

Background: Intra-articular injection of hyaluronic acid (HA) is a well-documented treatment for knee osteoarthritis (OA). One of the multifactorial mechanisms is that exogenous HA can stimulate endogenous HA production. HA can regulate the growth and function of chondrocytes by binding to CD44 receptors on the chondrocytes. Synovitis is often found in patients with rheumatoid arthritis (RA) and is supposed to result from CD44 activity. The aim of this study was to investigate the effect of intra-articular injection of HA in patients with RA combined with knee OA. Methods: Twenty RA patients with CA knees were enrolled; 11 patients were placed into a stage II group and 9 into a stage III group, in accordance with the Kellgren-Lawrence classification of knee OA. All patients received intra-articular injection of HA (ARTZ) once a week for 5 weeks, and were evaluated with the WOMAC index (including the pain, stiffness and physical function subscales) at baseline, week 5 and week 9. The Friedman test and Wilcoxon signed rank test with Bonferroni correction method were used for statistical analysis. Results: The effect of intra-articular injection of HA was significant at week 5 (p<0.0167) and persisted to week 9 (p<0.0167). This therapy was equally efficacious with stage II and stage III patients, with no difference between the 2 groups. Conclusion: Intra-articular injection of HA was beneficial in patients with RA combined with knee OA.