Painful knee osteoarthritis? What is the effect of platelet-rich plasma injections?


We come across lots of people who have painful knees due to osetoarthritis. They are always looking for ways to reduce their pain. A relatively new treatment has emerged, platelet-rich plasma (PRP) injections.  PRP is an autologous (where the donor and recipient are the same person) blood product with an elevated platelet concentration. Platelet-derived growth factors regulate some biological processes in tissue repair. But just how effective are they on decreasing pain and improving function in people with OA knee? We found a recently published systematic review on just this topic.

Here’s what they did

The authors searched electronic databases (MEDLINE, EMBASE, CINAHL, CENTRAL, Web of Science and PEDro) until June 2014 for randomised or non-randomised controlled trials in adults with OA knee comparing intra articular injections with PRP or similar products compared with control treatments. Trials were graded for risk of bias by two authors independently.

Here’s what they found

Ten trials were included, almost all revealed a high risk of bias.

The average age was 59.5 years (range 52.8–66.4) RCTs and 53.4 years (range 52.1–55.7) Non-RCTs.

Pain reduction: PRP was more effective at 6 months post injection than

  • placebo (6 trials) (mean difference (MD) −2.45; 95% CI −2.92 to −1.98; p value <0.00001 and MD −2.07; 95% CI −2.59 to −1.55; p value <0.00001, single and double PRP injections, respectively).
  • hyaluronic acid (5 trials) based on the visual analogue scale and numeric rating scale (standardised mean difference −0.92; 95% CI −1.20 to −0.63; p value <0.00001)

Function: insufficient data presented by included studies.

The authors concluded

PRP inta-articular injections reduced pain more effectively than placebo injections and hyaluronic acid injections.


Platelet-rich plasma injections improve pain in people with OA knee


The Musculoskeletal Elf’s view

The Musculoskeletal Elf

We come across one of our familiar issues with research in that the orginal studies were typically of low methodological quality, had relatively small sample sizes and used a variety of outcome measures. This make it very difficult for the authors of this review to come to definitive conclusions. However it does appear that there may have been a positive effect on pain in those people receiving the platelet-rich plasma (PRP) injections. It is less clear how this translates into effects on function.

What do you think?

  • Do you use platelet-rich plasma (PRP) injections for OA knee?
  • Have you seen a reduction in pain?
  • What about effects on function?

Send us your views on this blog and become part of the ever expanding Musculoskeletal Elf community. Post your comment below, or get in touch via social media (FacebookTwitterLinkedInGoogle+).

Do you know that there is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses? This is called the Preferred Reporting Items for Systematic Reviews and Meta-Analyses or PRISMA statement and can be accessed through the website of the EQUATOR Network. The Elves use the PRISMA statement for critical appraisal of systematic reviews, although it is not a quality assessment instrument to gauge the quality of a systematic review.


  • Laudy ABM, Bakker EWP, Rekers M, Moen MH. Efficacy of platelet-rich plasma injections in osteoarthritis of the knee: a systematic review and meta-analysis. Br J Sports Med 2015;49:657-672 doi:10.1136/bjsports-2014-094036 [abstract]
  • PRISMA statement
  • EQUATOR Network
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Tracey Howe

Hi I am Tracey Howe. I am a Professor of Rehabilitation Sciences at Glasgow Caledonian University, UK and Deputy Chair of Glasgow City of Science. I am also an editor for the Cochrane Musculoskeletal Review Group and a convenor for the Cochrane Health Care of Older People Field. I am a Trustee of the Picker Institute Europe. I started my career as a physiotherapist in the National Health Service in England. I have extensive experience of assessing the quality of research in Universities in the UK and internationally. I enjoy strategic visioning, creative problem-solving, and creating vibrant, multi-disciplinary environments, through collaboration, partnerships, and relationships, that empower others to succeed.

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