12 women with bilateral knee osteoarthritis (24 affected knees) were each randomized to have one knee receive intra-articular injections of hyaluronic acid, and to have their other knee receive saline placebo injections. The purpose of the study was to examine the mechanisms of action for hyaluronic acid treatment in treating knee osteoarthritis, as measured over 9 weeks. Outcomes of interest included results of MRI and 99mTc scans, changes in levels of KS, 3B3, and CPII biochemical markers in the synovial fluid or blood, and clinical outcomes for pain, stiffness, and patient treatment preference. Results found no significant difference between groups for any measurement taken.