PRP Improves Muscle Function

Platelet Rich Plasma in a study just published in the American Journal of Sports Medicine was found to significantly improve muscle function. This was in a high repetition injury model. This is excellent evidence to enable a human trial of PRP for muscle injuries.

AM
Total Tendon

Use of autologous platelet-rich plasma to treat muscle strain injuries.

Hammond JW, Hinton RY, Curl LA, Muriel JM, Lovering RM.

Am J Sports Med. 2009 Jun;37(6):1135-42.

BACKGROUND: Standard nonoperative therapy for acute muscle strains usually involves short-term rest, ice, and nonsteroidal anti-inflammatory medications, but there is no clear consensus on how to accelerate recovery. HYPOTHESIS: Local delivery of platelet-rich plasma to injured muscles hastens recovery of function. STUDY DESIGN: Controlled laboratory study. METHODS: In vivo, the tibialis anterior muscles of anesthetized Sprague-Dawley rats were injured by a single (large strain) lengthening contraction or multiple (small strain) lengthening contractions, both of which resulted in a significant injury. The tibialis anterior either was injected with platelet-rich plasma, was injected with platelet-poor plasma as a sham treatment, or received no treatment. RESULTS: Both injury protocols yielded a similar loss of force. The platelet-rich plasma only had a beneficial effect at 1 time point after the single contraction injury protocol. However, platelet-rich plasma had a beneficial effect at 2 time points after the multiple contraction injury protocol and resulted in a faster recovery time to full contractile function. The sham injections had no effect compared with no treatment. CONCLUSION: Local delivery of platelet-rich plasma can shorten recovery time after a muscle strain injury in a small-animal model. Recovery of muscle from the high-repetition protocol has already been shown to require myogenesis, whereas recovery from a single strain does not. This difference in mechanism of recovery may explain why platelet-rich plasma was more effective in the high-repetition protocol, because platelet-rich plasma is rich in growth factors that can stimulate myogenesis. CLINICAL RELEVANCE: Because autologous blood products are safe, platelet-rich plasma may be a useful product in clinical treatment of muscle injuries.