PRP has been used in surgeries to promote cell regeneration since 1987,10,11 and a growing body of evidence shows it is a viable treatment for tendinosis.12,13,14,15 Not until recently, though, have experts researched and debated whether or not platelet-rich plasma (PRP) injections are an effective treatment for osteoarthritis.

See Osteoarthritis Treatment

Nearly all of the research investigating the use of PRP to treat osteoarthritis and other cartilage defects has been done since 2000, and the vast majority of research articles on the topic have been published since 2010.

See What Is Cartilage?

Not all studies support the use of PRP to treat osteoarthritis; however, experts who have reviewed the existing body of research believe the evidence is largely encouraging and merits further investigation.16,17,18

See Stem Cell Therapy for Arthritis

Article continues below

Knee Osteoarthritis Treated with PRP

Researchers studying PRP and osteoarthritis often work with patients who have knee osteoarthritis, a condition that experts estimate will affect nearly half of all Americans at some point during their lives.19 Two clinical studies that examine PRP to treat knee arthritis are described below.

  1. One study, published in 2013, involved 78 patients with osteoarthritis in both knees (156 knees).20 Each knee received one of three treatments: 1 PRP injection, 2 PRP injections, or 1 placebo saline injection. Researchers evaluated the subjects' knees 6 weeks, 3 months, and 6 months after injection. Researchers found:
    • Knees treated with 1 or 2 PRP injections saw a reduction in pain and stiffness as well as improvement in knee function at 6 weeks and 3 months.
    • At the 6-month mark positive results declined, though pain and function were still better than before PRP treatment.
    • The group that received placebo injections saw a small increase in pain and stiffness and a decrease in knee function.

    The platelet-rich plasma used in this clinical study had 3 times the platelet concentration of normal blood and had been filtered to remove white blood cells.

  1. A second, smaller study examined patients who had experienced mild knee pain for an average of 14 months.21 Each arthritic knee underwent an MRI to evaluate joint damage and then received a single PRP injection. Patients' knees were assessed at the 1 week, 3 month, 6 month and 1 year marks. In addition, each knee underwent a second MRI after one year. Researchers found:
    • One year after receiving a PRP injection, most patients had less pain than they did the year before (though pain had not necessarily disappeared).
    • MRIs showed that that the degenerative process had not progressed in the majority of knees.

    While knee cartilage did not seem to regenerate for patients, the fact that the arthritis did not worsen may be significant. Evidence suggests that an average of 4 to 6% of cartilage disappears each year in arthritic joints.22,23

PRP Does Not Work for Everyone

Not all clinical studies provide evidence that PRP alleviates osteoarthritis symptoms. In several clinical studies PRP injections were no better than a placebo treatment. Even in studies that do provide evidence that PRP works, not all patients benefit.

See Is Stem Cell Therapy for Arthritis Safe and Effective?

PRP proponents assert that PRP fails to successfully treat symptoms in some cases because of differences in PRP formulation or injection administration - in other words, certain changes in variables, such as PRP preparation methods, the amount of PRP injected, and the frequency of injections, can make the PRP less effective. Others suggest that PRP therapy may be a passing fad that has limited value.24,25

It may be that PRP therapy, like other osteoarthritis treatments, works for some people but not for others, or works best in conjunction with other treatments, such as physical therapy.

Read more: Knee Exercises for Arthritis


  1. Ferrari M, Zia S, Valbonesi M. A new technique for hemodilution, preparation of autologous platelet-rich plasma and intraoperative blood salvage in cardiac surgery.
  2. Marx R, Garg A. Dental and craniofacial applications of platelet- rich plasma.
  3. Kajikawa Y, Morihara T, Sakamoto H, Matsuda K, Oshima Y, Yoshida A, Nagae M, Arai Y, Kawata M, Kubo T. Platelet-rich plasma enhances the initial mobilization of circulation-derived cells for tendon healing.

Complete Listing of References