616 - No Clinically Meaningful Benefit of Platelet-Rich Plasma for Achilles Tendon Rupture at Two Years: A Bayesian Re-Analysis of the PATH-2 Trial

Objectives: To determine whether platelet-rich plasma (PRP) meaningfully improves two-year functional recovery after acute Achilles tendon rupture, using a Bayesian re-analysis of the PATH-2 trial follow-up.

Design: Secondary Bayesian analysis of a prior multi-center RCT (n=177; 85 PRP, 92 control). Primary outcome: Achilles Tendon Total Rupture Score (ATRS, 0–100); secondary outcome: Patient-Specific Functional Scale (PSFS, 0–10) at 24 months. Minimally clinically important differences (MCIDs) were set at 8 ATRS points and 2.3 PSFS points based on prior literature. Four prior distributions (flat, neutral, optimistic, pessimistic) were applied. Posterior probabilities were calculated for any benefit and for benefit ≥ MCID. All statistics were completed using R studio 4.5.1.

Results: For ATRS with the neutral prior, the posterior mean difference (PRP minus control) was -0.55 (95% CrI -4.62 to 3.53), corresponding to a 39.6% probability of any functional benefit and less than 0.001% probability of meeting the MCID. Across all priors, the probability of MCID benefit ranged from 0.00006% to 0.00020%. For PSFS, the neutral prior yielded a posterior mean difference of -0.02 (95% CrI -0.61 to 0.57), with a 47.0% probability of any benefit and approximately 5×10^-13 probability of MCID benefit. Probabilities remained negligible across all prior assumptions, indicating that findings were robust regardless of prior belief.

Conclusions: PRP is highly unlikely to provide a clinically meaningful improvement in function at two years following Achilles tendon rupture, supporting current evidence against its routine use in this setting.