240 patients aged 40-75 with knee osteoarthritis (OA) were randomized to receive 5 weekly injections of hyaluronan, or to receive 5 placebo injections. The purpose of the study was to determine the effects of hyaluronan injection on OA symptoms and knee function, up to 20 weeks after the start of treatment. Primary outcomes of interest were visual analogue scale (VAS) results for pain and disease activity, as well as algofunctional index score. Overall results indicated no difference between treatment and placebo groups, but stratification of participants by age and baseline functional score revealed that older patients (age 60-75) with low knee function (baseline score >10) benefited significantly more from hyaluronan injection than from placebo in terms of pain reduction, disease activity, and functional improvement.