349 patients with knee osteoarthritis were randomized to either one intraarticular injection of Durolane hyaluronic acid followed by four weekly subcutaneous sham injections, or five weekly intraarticular injections of Artz hyaluronic acid. Patients were assessed for primarily for response on the Western Ontario and McMaster Universities Osteoarthritis Index to determine if Durolane was noninferior to Artz, as well as to compare the incidence of complications between groups. Analyses suggested that Durolane was noninferior to Artz for pain and functional improvement after 18 and 26 weeks. Incidence of treatment-related adverse events was similar between groups.