PRP (Platelet-Rich Plasma) Therapy: What the Evidence Shows
Platelet-rich plasma (PRP) is prepared from the patient’s own blood: the blood is centrifuged to concentrate platelets, which contain growth factors, and then injected into a joint, tendon or muscle.
Where is PRP used?
- Knee osteoarthritis
- Tendon problems such as tennis elbow
- Some muscle and ligament injuries
Further reading: the guide “Knee Osteoarthritis” and the articles Hyaluronic Acid Injections for Knee Osteoarthritis and Knee Osteoarthritis Treatment Without Surgery.
What does the evidence show?
- In knee osteoarthritis, some meta-analyses report better pain and function scores than hyaluronic acid [1], but trials vary widely in preparation methods and quality
- For soft-tissue injuries, a Cochrane review found insufficient evidence to support PRP [2]
- An American orthopaedic technology overview noted that the evidence is limited and heterogeneous [3]
- The American College of Rheumatology guideline recommends against PRP for knee and hip osteoarthritis
PRP preparations are not standardised, which makes comparing studies difficult.
Who may consider it?
PRP is not a first-line treatment. It may be discussed for selected patients after first-line treatment, with clear information about uncertain benefit and costs.
How PRP is thought to work
Platelets release growth factors and other signalling molecules involved in healing and inflammation. The idea behind PRP is that delivering a concentrated dose of these substances to a damaged tissue may modify pain and inflammation or support repair. How strongly this happens in practice, and in which conditions, is still being researched.
Why studies differ
- Preparation: the number of platelets, the presence of white blood cells and the processing method vary between systems
- Protocol: the number of injections, interval and volume differ between studies
- Patients: severity of osteoarthritis or tendon disease differs
- Comparison: some trials compare PRP with saline (placebo), others with hyaluronic acid or corticosteroid, which affects conclusions
Because of this variability, results from one study cannot simply be applied to every PRP preparation or patient.
The procedure
A blood sample is taken from the arm and processed in a centrifuge (a machine that spins the sample to separate its components). The platelet-rich part is injected into the target area under sterile conditions, sometimes with ultrasound guidance. Some anti-inflammatory medicines may be paused around the procedure on medical advice. After injection, temporary pain and stiffness for a few days are common, and a gradual return to activity is advised.
Who should not have PRP
PRP is generally avoided in active infection at or near the injection site, some blood and platelet disorders, active cancer and certain other medical conditions. Blood-thinning medicines and pregnancy need to be discussed beforehand.
Placing PRP in the bigger picture
For osteoarthritis and tendon problems, the foundation of care is exercise, load management, weight management where relevant, and education. PRP, if considered at all, is an addition to an active rehabilitation programme planned by your physical medicine and rehabilitation specialist and the physiotherapist, not a replacement. No outcome can be guaranteed, and the evidence is mixed.
Red flags after injection
Seek prompt assessment if the treated area becomes increasingly hot, red, swollen and painful, or if you develop fever, as infection, although rare, needs urgent treatment.
When to see your physical medicine and rehabilitation specialist
Seek assessment if pain is severe, keeps getting worse, wakes you at night or does not start to improve within a few weeks; if numbness, weakness or any warning sign appears; or if you are unsure what your test results mean. Your physical medicine and rehabilitation (PM&R) specialist, a doctor trained to diagnose and treat musculoskeletal and nerve problems without surgery, examines you, explains the findings and plans treatment together with the physiotherapist. Whether injections or other advanced treatments are suitable for you is decided by a PM&R specialist after examination. Prof. Dr. Engin Çakar works in this field and can be consulted online or in person; otherwise, please consult a PM&R specialist near you.
To make the most of the consultation, it helps to bring:
- A short timeline of your symptoms and what makes them better or worse
- A list of your medicines and other health conditions
- Previous imaging (the images themselves, not only the reports), test results and treatment summaries
- Your questions and goals, such as returning to work, sport or a particular activity
Frequently asked questions
Is PRP safe? Because it is made from the patient’s own blood, serious reactions are rare; temporary pain is common.
Does PRP regenerate cartilage? There is no reliable evidence that it does. See Cell-based knee treatments.
How many injections are needed? There is no agreed standard; protocols vary between one and several injections, which is part of why results are hard to compare.
Who decides if PRP is suitable for me? Suitability is decided by a physical medicine and rehabilitation specialist after examination, considering your diagnosis, previous treatments and the uncertain evidence.
Assessment and contact
You can request an appointment or a second-opinion review of existing reports and imaging: Contact & second opinion (WhatsApp). This page is general health information. Diagnosis and treatment decisions are made individually after examination.
Sources
- Belk JW, et al. Platelet-Rich Plasma Versus Hyaluronic Acid for Knee Osteoarthritis: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Am J Sports Med. 2021. PMID: 32302218
- Moraes VY, et al. Platelet-rich therapies for musculoskeletal soft tissue injuries. Cochrane Database Syst Rev. 2014. PMID: 24782334
- Dubin J, et al. American Academy of Orthopaedic Surgeons Technology Overview Summary: Platelet-Rich Plasma (PRP) for Knee Osteoarthritis. J Am Acad Orthop Surg. 2024. PMID: 38295392