46 patients with symptomatic osteoarthritis (OA) of the knee were randomized to receive either 3 injections of hyaluronan (Orthovisc) or hylan (Hylan G-F 20) in addition to a 3 week physical therapy program, or the physical therapy program alone. The purpose of the study was to assess the efficacy of these two different hyaluronic acid preparations in addition to physical therapy in knee OA patients in terms of pain, disability, and muscle strengthening. Results demonstrated a reduction of symptom severity (Lequesne Index score) in all groups after 3 weeks and 3 months, however no significant between-group differences in mean scores at 3 weeks and 3 months were observed.