335 patients with knee osteoarthritis were randomized to receive either intra-articular hyaluronan or placebo injections. The purpose of this study was to investigate the long-term efficacy and safety of five intra-articular hyaluronan injections compared with placebo injections. Primary outcome was the "time to recurrence" in each group, assessed via the Lequesne Algofunctional Index (AFI). Results demonstrated no significant difference in the primary outcome to "time to recurrence" between groups, or in secondary outcome measures during clinical examination.