Injection of platelet-rich plasma (PRP) is a novel treatment for painful degenerative tendons that is becoming increasingly popular among sport and musculoskeletal physicians. In vitro, platelet growth factors have been shown to enhance tissue repair processes and early studies of injected PRP appeared promising. PRP is prepared from the patient’s own blood by centrifugation and then injected into the degenerative tendon. The current, rather small, evidence-base for this treatment has recently experienced something of a setback. A small randomised, double-blind, placebo-controlled trial from the Netherlands
failed to demonstrate any benefit of injecting PRP over saline placebo. A timely editorial in the 1 British Journal of Sports Medicine discussed the difficulties involved with the use of PRP. 2
At different times and in different patients the activity of the growth factors in platelets may vary according to influences that as yet we do not fully understand. Notably, growth factors may be inhibited by the use of anti-inflammatory medication. Methods of preparation from whole blood vary. Clinicians using PRP employ commercially available kits which may produce preparations of variable therapeutic activity. Clearly there is a great deal more to discover about this treatment before we can be confident about its effectiveness.