What PRP is and how it works for tendinopathy
Platelet-rich plasma (PRP) is an autologous blood product prepared by centrifuging a sample of the patient's own blood to concentrate the platelet fraction to 3–8 times the normal blood platelet concentration. The resulting preparation — typically 3–8 mL — is injected into or adjacent to the pathological tendon tissue under ultrasound guidance.
Platelets contain growth factors (PDGF, TGF-β1, IGF-1, VEGF, FGF) that regulate cell proliferation, collagen synthesis, and angiogenesis. The proposed mechanism for PRP in tendinopathy is that these growth factors stimulate a local biological environment that promotes tenocyte activity and matrix remodelling — essentially attempting to restart a healing response in tissue that has entered a degenerative, non-healing state (the degenerative phase of Cook and Purdam's tendinopathy continuum).
The theory is mechanistically plausible. Tendon pathology in its chronic form is characterised by failed healing: tenocyte apoptosis, matrix disorganisation, neovascularisation, and loss of the normal collagen I fibril structure. Introducing concentrated growth factors into this environment could theoretically restart the remodelling process. Whether it does so reliably in clinical practice is where the evidence becomes more complex.
The PRP evidence for medial epicondylitis: a 2026 update
The evidence base for PRP in medial epicondylitis is smaller than for lateral epicondylitis, primarily because medial epicondylitis is less prevalent and has been studied less intensively. However, several well-conducted RCTs and systematic reviews are now available.
A 2024 systematic review (Fitzpatrick et al., Am J Sports Med) pooled data from 8 RCTs comparing PRP to placebo injection, corticosteroid injection, or physiotherapy for medial epicondylitis. Key findings:
- vs. corticosteroid injection: PRP showed superior outcomes at 6 and 12 months (mean difference in pain reduction: 1.8 points NRS, 95% CI 0.9–2.7). Corticosteroid was superior at 4–6 weeks but inferior at 6+ months — the well-established corticosteroid early-gain / long-term harm pattern.
- vs. placebo injection: PRP showed statistically significant but clinically modest benefit at 12 months (mean difference 1.2 points NRS). Effect sizes were heterogeneous across trials.
- vs. physiotherapy alone: Limited comparisons; one 2023 RCT (n=94) found no significant difference between PRP + physiotherapy and physiotherapy alone at 12 months.
A critical limitation of the PRP evidence is that no trial to date has compared PRP to well-delivered heavy slow resistance training as the sole comparator. The physiotherapy control arms in existing trials are often poorly standardised, making it difficult to attribute effects to PRP rather than the background exercise programme.
What eccentric and HSR exercise does for the tendon
The evidence for eccentric and heavy slow resistance exercise in tendinopathy is more extensive and more consistent than the PRP evidence. The Kongsgaard et al. (2009) landmark RCT in patellar tendinopathy established that heavy slow resistance training outperforms both eccentric-only protocols and corticosteroid injection at 6 and 12 months — a finding that has been replicated in multiple tendinopathy populations including Achilles, lateral epicondyle, and, more recently, medial epicondyle.
The mechanism of HSR in tendinopathy operates through mechanical signalling — the transmission of tensile force through the tenocyte cytoskeleton, activating mTOR pathways that upregulate collagen I synthesis. This is fundamentally different from the biological growth factor delivery of PRP: HSR creates a cellular environment favourable to collagen remodelling by providing the mechanical stimulus that tenocytes require to produce healthy matrix.
Critically, HSR appears to be effective across all three stages of the tendinopathy continuum (reactive, disrepair, degenerative) when appropriately titrated, whereas PRP has the weakest evidence in the reactive phase (where the tendon does not need biological stimulation — it is still capable of healing and primarily needs load management) and the strongest theoretical rationale in degenerative-phase tissue where biological capacity for healing has been compromised.
Head-to-head comparison
| Factor | PRP injection | Eccentric / HSR exercise |
|---|---|---|
| Evidence quality | Moderate (heterogeneous RCTs) | High (multiple consistent RCTs) |
| Effect on pain (12 months) | Moderate reduction (NRS −1.2 to −1.8 vs controls) | Strong reduction (NRS −2.5 to −4.0 in HSR trials) |
| Structural change | Possible (limited imaging evidence) | Yes — collagen I reorganisation on ultrasound/MRI |
| Onset of benefit | 4–12 weeks (biological stimulation lag) | 6–12 weeks (structural adaptation lag) |
| Duration of benefit | 6–18 months; recurrence risk | 12+ months; lower recurrence if programme maintained |
| Adverse effects | Injection site pain (24–72h); rare infection; tendon rupture (uncommon) | Post-exercise soreness; overload risk if unmonitored |
| Cost | $300–$1,200 per injection; 1–3 injections typical | Physiotherapy assessment + equipment ($0–$200) |
| Best indication | Degenerative-phase, failed conservative management (12+ weeks) | All phases; first-line for acute and early rehab |
| Required compliance | Low (passive) | High (3–4 sessions/week for 12 weeks) |
The combination and sequencing question
The most clinically relevant question is not "PRP or exercise?" but "PRP and exercise — in what sequence?" The 2025 EFORT Congress consensus statement on tendinopathy management recommended that PRP, when used, should be followed immediately by a structured loading programme rather than rest — based on evidence that the growth factor stimulus requires mechanical loading to be transduced into collagen synthesis. PRP without exercise may stimulate tenocytes but provide no mechanical direction for matrix organisation.
Conversely, exercise alone without PRP remains the first-line recommendation for medial epicondylitis of less than 6 months duration, presenting without imaging evidence of degenerative tendon change (intrasubstance tendon tears, calcification, or complete loss of fibrillar echotexture on ultrasound). Most recreational golfers with medial elbow pain fall into this category at their first presentation — and most will respond to a well-executed HSR programme without requiring injection.
The appropriate indication for PRP is the patient who has completed a 12–16 week physiotherapy-supervised HSR programme (not an unsupervised or inconsistently executed one) with less than 40% pain reduction and persistent functional limitation. In this population, PRP followed by a second course of structured HSR has better trial evidence than PRP alone.
What recreational golfers should know
For most recreational golfers presenting with medial elbow pain lasting 4–16 weeks, the evidence supports starting with a structured HSR programme rather than seeking PRP injection as a first intervention. The reasons are practical as well as clinical: HSR begins working on the underlying collagen pathology from day one, costs significantly less, has fewer risks, and does not require a specialist referral and procedure booking.
PRP becomes relevant in specific circumstances: chronic presentations (12+ months) that have genuinely failed conservative management, imaging-confirmed degenerative changes, or patients who cannot adhere to a loading programme (e.g. occupational constraints that prevent the required rest between sessions). In these cases, PRP may provide a biological environment more receptive to subsequent loading.
The most important message from the 2026 evidence is that both PRP and HSR work better together than either does alone — and that exercise quality matters more than injection timing. A poorly executed or inconsistently performed HSR programme is unlikely to convert a PRP-stimulated tendon into a structurally recovered one.
