After a period of washout-out for NSAIDs, the patients received a single intra-articular injection of OSTENIL PLUS or of SYNVISC-ONE in the most painful knee. The study involved a preselection visit at D-7 and five further visits: at D0 (baseline, evaluation before intra-articular injection), at D2 ± 2 days (injection), at D30 ± 15 days, at D90 ± 15 days and C5 at D180 ± 15 days.