205 patients with radiological grade 1-3 knee osteoarthritis were randomized to three weekly intra-articular injections of either a combination of intermediate molecular weight hyaluronic acid and high concentration mannitol, or high molecular weight hyaluronic acid alone. The purpose of this study was to determine whether the combination of intermediate molecular weight hyaluronic acid and mannitol offered non-inferior pain relief over 6-month follow-up compared to high molecular weight hyaluronic acid alone. Results indicated non-inferiority between the two groups in pain reduction.