246 patients age 60 or older with knee osteoarthritis were randomized to 1 of 3 groups: one group received three intra-articular injections of Artzal hyaluronan, one group received three intra-articular injections of Synvisc hyaluronan, and one group received three intra-articular injections of placebo. The primary outcomes of interest were weight-bearing pain 26 weeks after treatment, and the percentage of patients reporting positive outcomes 1 year after treatment. Other outcomes of interest included change to resting pain, maximum pain, algofunctional score, quality of life, and number of adverse events. While results indicated a significant reduction in weight-bearing pain from baseline for all groups starting at 4 weeks and continuing to 26 weeks, no significant between-group differences were reported at any time point. No significant difference in duration of treatment was found for either hyaluronan treatment when independently compared to placebo, but pooled analysis of the hyaluronan groups revealed a significant effect on Kaplan-Meier curve analysis regarding treatment failure (ie. need to additional or concurrent intervention) compared to the placebo group.