PRP and injection treatments: when do they work, and when don't they?

Short answer

PRP (platelet-rich plasma) is not a solution for every pain and every joint — the evidence varies greatly by indication. Because it is prepared from your own blood, it is generally safe, but it is often expensive and, for many uses, has not been shown to be superior to placebo. Relatively more favorable signals have been reported in chronic tennis elbow (lateral epicondylitis) and in selected mild-to-moderate knee osteoarthritis; however, even in these areas the evidence of superiority over placebo remains uncertain and inconsistent. By contrast, its efficacy has not been proven in Achilles and patellar tendinopathy or in acute muscle injury.

Corticosteroid (cortisone) injection, on the other hand, can reduce pain in the short term, but in tendon problems it may worsen the long-term outcome and carries a risk of tissue weakening with repeated use. In short: injections may help in selected situations; but for most musculoskeletal problems, the core treatment is exercise and load management.

PRP: evidence by indication

Tennis elbow (lateral epicondylitis) — relatively more favorable, but debated: In some network meta-analyses, corticosteroids stand out in the short term, while PRP appears better in the long term. However, this "superiority" may partly stem from the corticosteroid group worsening over time; PRP's superiority over placebo (sham) is inconsistent, and in a 2025 tendinopathy meta-analysis the difference in pain was not statistically significant. So it is an option that may be considered in chronic/refractory cases, but its evidence remains uncertain.
Knee osteoarthritis — mixed/debated: The highest-quality placebo-controlled trial (RESTORE) found no significant difference between PRP and placebo at 12 months, either in pain or in cartilage. Although some analyses find PRP superior to hyaluronic acid, superiority over placebo is inconsistent, and major guidelines do not recommend routine use.
Achilles / patellar tendinopathy — weak/absent: Randomized trials and meta-analyses show that PRP does not provide significant superiority over placebo. In these conditions the core treatment is progressive tendon loading.
Acute muscle (hamstring) injury — no benefit: Double-blind trials and meta-analysis show that PRP does not improve time to return to play or recurrence rate.

Why do the studies conflict?

In PRP, platelet concentration, white-cell content, preparation, and the number of injections vary from clinic to clinic — meaning that "what is actually injected" is not standardized. This makes studies difficult to compare. In addition, the needle itself creates a strong placebo effect; for this reason, double-blind trials with a saline comparator are essential. "PRP vs nothing" designs are misleading.

Corticosteroid (cortisone) injection

In tendinopathy and some joint flare-ups, it reduces pain in the short term (a few weeks).
However, in tendinopathy the medium-to-long-term outcome may be worse than with conservative treatment, and even worse than doing nothing.
Repeated injections can weaken the tendon/tissue; in knee osteoarthritis, frequently repeated corticosteroids have been shown to increase cartilage loss.
So: it may serve as a short-term "bridge" in a selected, refractory case; it is not appropriate for routine and repeated use.

An honest frame for patients

The marketing of "PRP for every pain / stem cells for every joint" does not match the evidence. The right question is not "Does PRP work?" but rather "What does the evidence say for my condition?" For most tendon and muscle problems, the core treatment is progressive loading and load management; injections should at most be considered in selected situations, with realistic expectations, and with the cost discussed.

For clinicians

The PRP debate in knee OA is real: some meta-analyses show superiority over HA, while the highest-quality RCT (RESTORE) and OARSI/ACR recommend against it — a one-sided presentation is misleading. Signals for leukocyte-poor PRP are not conclusive. For corticosteroids, the Coombes 2010 (Lancet) framework should be shared with the patient (short-term gain, long-term loss). Stem-cell/regenerative claims lack strong evidence.

Frequently asked questions

Is PRP safe?

Generally yes — because it is prepared from your own blood, serious side effects are rare; those seen are mostly mild and transient. The main issue is not safety but the fact that, for most indications, efficacy has not been proven, along with cost.

PRP has been recommended to me; should I have it?

It depends. In chronic tennis elbow it may be a reasonable option; however, no benefit has been shown in Achilles/patellar tendinopathy or in muscle injury, and in knee osteoarthritis the evidence is debated. First discuss with your doctor the level of evidence for your condition and the role of the core treatment (exercise).

Is a cortisone shot harmful?

It can provide short-term relief, but in tendon problems it may worsen the long-term outcome and can weaken the tissue with repeated use. It may be used briefly in selected situations; routine/repeated injection is not appropriate.

Does PRP regenerate cartilage, is it like "stem cells"?

PRP is not stem-cell therapy; it is a blood concentrate rich in platelets. There is no strong evidence that it regenerates cartilage. Most "regenerative" and "stem cell" claims are not supported by strong evidence in musculoskeletal problems.

What should I do instead of an injection?

For most tendon and joint problems, the core treatment is progressive strengthening, load management, and (if appropriate) weight control. Injections are considered not as a replacement for these, but at most as an addition in selected situations.

Scientific references

Bennell KL et al. Effect of intra-articular platelet-rich plasma vs placebo injection on knee osteoarthritis (RESTORE). JAMA 2021;326(20):2021-30.
Coombes BK, Bisset L, Vicenzino B. Efficacy and safety of corticosteroid injections and other injections for management of tendinopathy: systematic review. Lancet 2010;376:1751-67.
Keene DJ / Kearney RS et al. PRP vs sham for chronic midportion Achilles tendinopathy (ATM). JAMA 2021;326:137-44.
Reurink G et al. Platelet-rich plasma injections in acute muscle injury. N Engl J Med 2014;370:2546-7 (and related meta-analyses).
OARSI (Bannuru 2019) and ACR/Arthritis Foundation (2019) knee OA guidelines — recommendation against PRP.

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.