RecruitingPhase 2Drug trialA Trial to Investigate the Safety and Efficacy of Intra-articular 4P004 Injection in Subjects With Knee Synovitis and OsteoarthritisThis phase 2a trial is an international, multicenter, randomized, double-blind, placebo-controlled trial to investigate the efficacy and safety of one single intra-articular (IA) injection of 4P004 or placebo in: * patients between 40 and 80 years of age, * with synovitis and grade 2 to 4 osteoarthritis (OA) of the knee according to Kellgren and Lawrence (KL) classification.