PRP Therapy for Joint Pain: Evidence and Reality

Platelet-rich plasma (PRP) is the most widely used regenerative treatment in modern orthopedic clinics. The concept is elegant: concentrate a patient’s own platelets — which contain growth factors that drive tissue repair — and inject the concentrate into an injured joint or tendon to stimulate healing. The reality is more nuanced. PRP is genuinely helpful for some conditions, marginal for others, and oversold across the internet. This article gives an evidence-based, doctor’s-eye view of where PRP works, where it doesn’t, and how it fits into the wider treatment landscape.

How PRP is prepared

A small amount of the patient’s blood (15–30 ml) is drawn from a vein and spun in a centrifuge to separate the plasma layer rich in platelets. The platelet concentrate is then injected, often under ultrasound guidance, into the joint or tendon being treated. The whole process takes 30–45 minutes in clinic.

Not all PRP preparations are equal. Different commercial systems produce concentrations from 2x to 8x baseline; different protocols include or exclude leukocytes; activation methods vary. The literature is messy partly because the treatment itself is not standardised.

Where the evidence is strongest

• Mild to moderate knee osteoarthritis — Meta-analyses consistently show PRP outperforms placebo and hyaluronic acid for pain and function over 6–12 months in early to moderate disease. End-stage bone-on-bone arthritis responds poorly.
• Lateral epicondylitis (tennis elbow) — Strong evidence in chronic cases that have not responded to rehabilitation, particularly when combined with continued eccentric loading.
• Chronic Achilles tendinopathy — Reasonable evidence in mid-portion tendinopathy refractory to loading.
• Patellar tendinopathy (jumper’s knee) — Modest evidence; useful adjunct to loading.
• Plantar fasciitis — Evidence is favourable in chronic cases.

Where the evidence is weak or absent

• Complete tendon or ligament tears requiring surgery
• End-stage osteoarthritis
• Spinal pain
• Hair restoration (a different topic entirely)

How PRP fits into a treatment plan

PRP is most useful as part of a structured plan, not as a standalone fix. In knee osteoarthritis, we combine PRP with weight management and a strengthening programme. In tendinopathy, PRP combined with progressive loading rehabilitation works better than either alone. PRP is rarely the right first treatment for any condition — it is generally a step taken after first-line care has fallen short.

What to expect

The injection itself is briefly uncomfortable. Pain at the injection site may worsen for 24–72 hours as the inflammatory healing cascade activates — this is expected and not a sign that anything has gone wrong. Improvement typically starts at 2–4 weeks and peaks at 8–12 weeks. Effect duration varies: in knee arthritis, 6–12 months of meaningful benefit is typical.

How many injections?

Most protocols use a series of 1–3 injections spaced 2–4 weeks apart. Some patients respond to a single injection; others need a series.

Safety

PRP uses the patient’s own blood, so allergic reactions are not a concern. Infection risk is similar to any joint injection — very low. There are no significant systemic side effects. The main downside is cost; PRP is not covered by most insurance.

Stem cells, exosomes, and the marketing landscape

Stem cell injections, exosome therapy, and amniotic membrane injections are heavily marketed for orthopedic conditions, often at high cost. The current evidence base for most of these is weaker than for PRP. We discuss them honestly with patients and recommend them selectively. The presence of marketing does not equal the presence of evidence.