808-572-1388 nat@maui.net

Am J Phys Med Rehabil. 2017 Nov 29. doi: 10.1097/PHM.0000000000000874. [Epub ahead of print]

Effects of platelet-rich plasma on pain and muscle strength in patients with knee osteoarthritis.

Wu YT1,2, Hsu KC1, Li TY1,2, Chang CK3, Chen LC1.

Author information



No studies comparing the effects of platelet-rich plasma (PRP) injection and placebo injection in bilateral knee osteoarthritis (OA) in the same patient, or discussing muscle strength after PRP injection, have been published.


Twenty patients with bilateral knee OA were eligible, and 40 knees were randomized into two groups: PRP (knees [right or left by a coin toss] receiving a single intra-articular PRP injection) and saline group (the contralateral knee of the same patient, into which single 4-mL intra-articular injection of normal saline was administered). The primary outcome measure was Western Ontario and McMaster’s Universities Osteoarthritis Index (WOMAC) and the secondary included isokinetic test results. The evaluation was at baseline and at 2 weeks, 1, 3, and 6 months post-injection.


The PRP group showed a significant reduction in the WOMAC-pain and -total scores compared to normal saline group (p < 0.05). Although a significantly greater percentage of knee strength (extensor > flexor) was found in the PRP group during a longer follow-up period, PRP treatment resulted in insignificant differences in muscle strength compared to normal saline.


PRP treatment significantly improves pain, stiffness, and disability in patients with knee OA compared to normal saline treatment. Additional strength training is recommended to enhance muscle strength recovery.

PMID: 29210705 DOI: 10.1097/PHM.0000000000000874