Does PRP (platelet-rich plasma) actually work for knee arthritis, tendons and hair loss?

Knee osteoarthritis is the most-studied indication for PRP injections. A meta-analysis of randomized controlled trials found that PRP injections provided better pain relief and functional improvement compared to hyaluronic acid (HA) injections at 6 and 12 months². A five-year follow-up of a double-blind randomized trial confirmed that PRP outperformed HA for mild-to-moderate knee osteoarthritis, though benefits diminished over time and repeat injections were needed¹.

Key takeaways for knee OA:

• PRP appears most effective in early-to-moderate osteoarthritis (Kellgren-Lawrence grades I-III)²
• Multiple injection series (typically 3 injections spaced 1-2 weeks apart) tend to outperform single injections²
• Results typically last 6-12 months before re-treatment is needed¹
• Leukocyte-poor PRP may be preferable for intra-articular use²

Tennis Elbow (Lateral Epicondylitis)

PRP has shown promise for chronic lateral epicondylitis (tennis elbow) that has not responded to conservative treatment. A systematic review and meta-analysis found that PRP injections provided significant pain reduction compared to corticosteroid injections at follow-up beyond 3 months⁴. Unlike corticosteroids, which provide short-term relief but may worsen long-term outcomes, PRP appears to support actual tendon healing⁴.

Hair Loss (Androgenetic Alopecia)

PRP injections into the scalp have become a popular treatment for androgenetic alopecia (pattern hair loss). A review of clinical trials found that the majority of studies reported improvements in hair density and thickness after PRP treatment³. Typical protocols involve 3-4 sessions spaced 4-6 weeks apart, with maintenance treatments every 3-6 months³.

Results vary considerably between individuals, and PRP works best as an adjunct to other hair loss treatments such as minoxidil or finasteride rather than as a standalone therapy³.

Skin Rejuvenation and Microneedling

Combining microneedling with topical PRP application has shown benefit for acne scarring and general skin rejuvenation. Studies have demonstrated that microneedling plus PRP produces greater improvements in scar appearance compared to microneedling alone⁵. The growth factors in PRP enhance the wound-healing response triggered by microneedling, leading to more robust collagen remodeling.

Despite promising results, PRP has important limitations that patients and clinicians should understand:

Lack of standardization. There is no universally accepted PRP preparation protocol. Different centrifuge systems, spin speeds, and activation methods produce different concentrates. This makes it difficult to compare studies directly and explains some of the conflicting results in the literature².

Cost and insurance. PRP is rarely covered by insurance for most indications. Treatment costs typically range from $500-$2,000 per session, with multiple sessions often recommended. For knee osteoarthritis, a full course of treatment may cost $1,500-$5,000 out of pocket.

Regulatory status. PRP is not FDA-approved as a drug. It is classified as a medical procedure using autologous tissue, which means it falls into a regulatory gray area. While FDA-cleared devices exist for preparing PRP, the specific clinical applications are not individually approved.

Evidence quality. While the body of evidence is growing, many PRP studies suffer from small sample sizes, short follow-up periods, and heterogeneous protocols. Large, well-designed RCTs with standardized preparations and long-term follow-up are still needed for most indications^1,4.

Contraindications. PRP should not be used in patients with platelet disorders, active infections at the injection site, blood cancers, or those on anticoagulant therapy. Patients should avoid NSAIDs for several days before and after treatment, as these drugs can inhibit platelet function.