100 participants with knee osteoarthritis and joint effusion were randomized into one of 5 groups. The purpose of the study was to evaluate and compare clinical results of three different dosing schedules - 1, 3, or 5 weekly injections - of intra-articualr hyaluronic acid, to that of placebo treatment and control arthrocentesis. Outcomes of interest included pain at rest, pain during motion, functional improvement, range of motion, and subjective global assessment of both patient and observer. Results demonstrated significantly positive effects on efficacy outcome parameters of either the 3- or 5-injection hyaluronic acid groups when compared to the placebo and arthrocentesis groups. The 1-injection hyaluronic acid group demonstrated not significant differences in any of the outcome parameters when compared to the placebo group.