This article, from The Journal of Arthroscopic and Related Surgery in March 2017, is a meta-analysis that shows PRP injection to be superior to hyaluronic acid injection for patients with mild to moderate knee osteoarthritis, at both six and 12 months post injection, in terms of pain and function.
Efficacy of Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: A Meta-analysis of Randomized Controlled Trials
Wen-Li Dai, M.Sc.Ai-Guo Zhou, M.D.Hua Zhang, M.D.Jian Zhang, M.D.
Department of Orthopaedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China