51 patients with knee osteoarthritis were randomized to receive an intra-articular injection of either sodium hyaluronate (HA) or corticosteroid (CS). The purpose of this study was to determine the comparative efficacy of these two treatments on the basis of clinical outcome and impact on joint biomarkers. Results after 6 months indicated that both treatments significantly reduced pain and inflammation. Hyaluronan levels increased and matrix metalloproteinase-9 (MMP-9) concentrations decreased with injections of sodium hyaluronate, although there did not correlate with clinical outcome.