Intraarticular injection of high molecular weight hyaluronan for osteoarthritis of the knee - Prediction of effectiveness with biological markers

Objective. The possibility of predicting the effectiveness of intraarticular injection of high molecular weight hyaluronan (HA) was investigated using biological markers. Methods. In 32 patients with osteoarthritis (OA) of the knee, 38 knees were treated with HA injection, and the clinical symptoms were evaluated using the Japanese Orthopaedic Association (JOA) score and pain visual analog scale (VAS). The concentrations of chondroitin 6-sulfate, 4-sulfate (C6S, C4S), and aggrecan were measured in synovial fluid collected at the time of initiation of injection. The relationship between the biological markers and the improvement of clinical symptoms after injection for 1 month was investigated. Results. C6S/C4S and concentration of aggrecan decreased after injection, although these decreases were not significant. Positive correlations were noted between the concentrations of C6S and aggrecan before HA injection and the improvement of the JOA score after injection; however, radiological OA stage had no significant relation with improvement both of the JOA score and VAS. Conclusion. It has been reported that the concentration of aggrecan-derived fragments in synovial fluid decreases with advancement of the OA stage, reflecting decreases in the amount of residual cartilage and suppression of chondrocyte metabolism. Our findings suggested that HA injection exhibits a greater clinical effect in cases with a high intraarticular aggrecan fragment concentration, i.e., cases in which a high amount of residual cartilage and chondrocyte metabolic activity remain. The biological markers were useful in predicting the effectiveness of HA injection for OA of the knee.