PRP has been more hype than substance as gathering evidence has put it more into the realm of cherry picking based marketing. The following an excerpt from an updated article in Pain Science in 2015 by Paul Ingraham from Vancouver.
“Taken as a whole, the evidence is somewhere between inconclusive and discouraging. Although more research is needed (of course!) enough decent studies have now been done that the evidence reviews have started to come out. They all warn that most of the evidence is poor quality, and they are all basing their conclusions on just barely enough good data. They all emphasize that PRP methods are not standardized — there are many versions of PRP, all based on speculation, not data.
The bad news got rolling in 2010. The New York Times reported (very) bad science news:
Now, though, the first rigorous study asking whether the platelet injections actually work finds they are no more effective than saltwater.
Nothing has improved since. Three noteworthy reviews were published in 2014. Sandrey found “strong evidence” that PRP does not improve plantar fasciitis when combined with several other therapies, and limited evidence that it might be beneficial on its own.7 Moraes et al found “insufficient evidence to support the use of PRT for treating musculoskeletal soft tissue injuries.” And de Vos et al was extremely negative.
Three high-quality studies (75%) and two low-quality studies showed no significant benefit at the final follow-up measurement or predefined primary outcome score when compared with a control group. One high-quality study (25%) showed a beneficial effect of a PRP injection when compared with a corticosteroid injection (corticosteroid injections are harmful in tendinopathy). Based on the best evidence synthesis, there is strong evidence that PRP injections are not efficacious in chronic lateral epicondylar tendinopathy.
Another biologic that is also currently being reviewed is Amnion injections derived from placental tissue and purified to remove immunogenic factors. Although my anecdotal evidence has been very good along with many colleagues we are all anxiously awaiting the number crunching and publication of the first widespread single blind trial that just finished up this year. Once science has put the evidence on the balance assuming a well constructed study it is time to halt marketing an unsound treatment if that is the way the egg breaks.