Patients with symptomatic knee OA, with radiological OARSI grades 1 to 3, were enrolled in a controlled, double-blind, parallel-group, non-inferiority trial. They were randomized to receive three intra-articular injections, at weekly intervals, of either HAnOX-M made of a combination of HA (MW one to 1.5 MDa, 31 mg/2 ml) and mannitol (70 mg/2 ml) or Bio-HA (MW 2.3 to 3.6 MDa, 20 mg/2 ml). The primary outcome was six-month change in the WOMAC pain subscale (0 to 20). Sample size was calculated according to a non-inferiority margin of 1.35. Secondary endpoints included six-month change in function and walking pain, analgesic consumption and safety.