60 patients (120 knees) with primary knee osteoarthritis were randomized to receive either intra-articular hyaluronic acid (HA) injections combined with physical therapy or only physical therapy. The purpose of this study was to investigate the effect of 3 intra-articular Hylan G-F 20 injections combined with physical therapy on pain and disability in patients with knee osteoarthritis. It was found that intra-articular HA injections combined with physical therapy were more successful in improving pain and function when compared to treatment with only physical therapy; however, both of these treatments significantly improved both pain and function from baseline. These findings suggest that intra-articular injections are an effective method of treatment for the management of knee osteoarthritis.