Platelet-rich-plasma (PRP) injections have emerged in recent years as a treatment for a variety of sports injuries, ranging from severe tendonitis to muscle tears. As with any new treatment, there are few studies reporting on the effectiveness of PRP, and even those that have been published are debated by experts, leading the American Academy of Orthopaedic Surgeons to the "hottest topic in orthopedics."
As a companion piece to Keith Cronin's excellent article on the use of PRP in which the both sides of the debate about PRP are presented, and based on a point-counterpoint debate conducted via email between the two experts whose views are expressed in Keith's piece, Dr. Nathan Mall, associate physician for the St. Louis Cardinals and Director for the St. Louis Center for Cartilage Restoration and RepairRegeneration Orthopedics, and Andrew M. Blecher MD, a Primary Care Sports Medicine physician and Medical Director of the Center for Rehabilitation Medicine at the Southern California Orthopedic Institute in Van Nuys, California, here are what Drs. Mall and Blecher have to say about the current state of the research on PRP.
Dr. Mall leads off
Dr. Mall recently completed researching the topic of PRP injections. Based on that review of the literature, he notes the following:
- Those studies that show some improvement in pain or symptoms typically have low numbers of patients, do not report platelet concentration of the injected fluid, or lack control groups, and there are other studies that show no effect.
- Most of the studies that have produced the craze over PRP have been done using animal models. These studies have demonstrated higher levels of the growth factors that improve healing and lower levels of the growth factors that are thought to reduce healing rates. Therefore, PRP has the potential to aid in the healing of multiple acute and chronic injuries; however, the benefit of PRP in human clinical studies has not been proven;
- A search of Pubmed [a data base containing all medical journal articles] for platelet rich plasma yields 6,811 articles, but less than 20 are clinical studies evaluating patient outcomes for orthopedic sports medicine conditions. The number of randomized, blinded, controlled studies (the highest quality clinical research) is less than 5. "Therefore, there is much that needs to be learned about PRP and its use, which is why insurance companies do not cover the use of PRP";
- In a study of 20 patients with elbow tendonitis, 15 received PRP with 5 receiving a placebo (local anesthetic). At four and eight weeks, the patients receiving PRP had better outcomes scores.
- In a 100-patient randomized study of elbow tendonitis, pain and outcomes scores improved more in the PRP group as compared to the control group that received steroid injections. A second randomized trial evaluating PRP, saline, and steroid injections, however, found no difference amongst the three groups at 3 months.
- A 2013 study  found steroid injection more effective in reducing tendon size to a more normal level than PRP; and
- A small 2010 study evaluating use of PRP for chronic Achilles tendonitis also showed some benefit, but a larger, better studydemonstrated no difference between PRP and a physical therapy program compared to a therapy program alone.
Dr. Blecher bats second
While he agrees with many of Dr. Mall's general statements about PRP in the companion article, including that it is expensive, not covered by insurance, may not be the most cost-effective first line treatment and is often used when all other conservative treatments fail," and "that much more research needs to be done in order to establish the optimal concentrations, protocols and procedure techniques for the various musculoskeletal indications for which PRP is being used," Dr. Blecher differs in his interpretation of the research studies conducted so far.
"In regards to the current research, Dr Mall states that we have no evidence that PRP works for any musculoskeletal conditions. He cites to studies that have low numbers of patients, don't report platelet concentrations and lack control groups. While I agree that much of the research out there for PRP is less than desirable, I think it important to cite to some studies as a counterpoint which do have large numbers, platelet concentrations and control groups.
He points to research by a Stanford University researcher, Allan K. Mishra, who has studied PRP for years, whose in his most recent published research includes a large multicenter study  involving a host of well-respected orthopedic surgeons around the country who followed 230 patients in a double-blind randomized control study [the gold standard for medical research]. "The study showed with level 1 evidence that PRP was more effective than control for tennis elbow," says Blecher.Another popularly used indication for PRP is knee osteoarthritis (admittedly, not a condition ordinarily found in youth athletes, but to which those who have undergone ACL reconstruction surgery are more prone later in life). Blecher notes that two large prospective studies of PRP vs. control [9,10] have yielded level I and II evidence that PRP is more effective than control for treating the condition.
Dr. Mall bats third
In response to Dr. Blecher, Dr. Mall emphasized, as previously stated, that of all the PRP data, the best is for lateral epicondylitis. "However, when critically looking at the Mishra article,"  Dr. Mall points to the fact that it found that 37% of PRP patients still had pain compared with 48% of the control group." Dr. Mall also argues that the Mishra study contains "multiple flaws," among them inadequate controls over inclusion of patients whose pain was not controlled by one of three more conservative treatments: NSAIDS, PT, or cortisone. "If someone went to two therapy visits," Mall notes, "then they would have been considered a failure and then would be eligible for the study. Therefore they may have gotten better regardless."
Dr. Mall also observed that only 119 patients were available for follow-up at 24 weeks, which is where the biggest difference was noted. There are many reasons for errors, one of which is not having appropriate follow-up. "Only having 119 of 231 patients follow up basically negates the findings of the study. Most good quality studies require 80% follow-up; the MIshra study only had 51%. Therefore, we have no idea how the other 49% are doing and they may not have followed up because they weren't any better after spending a lot of money on PRP injections."
With respect to the study on baseball pitchers, Dr. Mall observes that it says absolutely nothing about the speed at which these players got back to playing sports, and that, because there was no control group, "we don't know if these kids would have gotten better by simply resting an additional six weeks and then starting a return to throwing program."
"The study by Kon et al, when looked at critically, is simply saying that 3 PRP injections costing $2,400-$5,000 or more is equivalent to hyaluronic acid injection, which is covered by insurance plans. Therefore patients are paying out of pocket to get an equivalent result, I find it difficult to recommend this."
"The study by Patel has multiple errors in the methodology, which are outlined by Fillardo, Giuseppe et al in a letter to the editor of the American Journal of Sports Medicine in September 2013. Plus, the study compares PRP to saline or salt water, so it is basically saying that PRP is better than doing nothing, but not comparing it to standard treatments covered by insurance."
"The key," argues Dr. Mall, "is to look critically at the data, as the study may not really be able to say what the authors are suggesting it does. None of the studies cited prove without a reasonable doubt that PRP works or doesn't work. I am not saying PRP does not have a role, because I do use it in certain situations. However, parents and patients really need to understand that there is no proof that PRP will prevent surgery, relieve their symptoms, or be better than standard treatment options. This is a lot of money to spend for a treatment that has not been proven and I think it is irresponsible to recommend this treatment to patients without a full and upfront discussion that must include that there is still little to no data that show that this will do anything. If Dr. Blecher and other physicians have had such great results with this treatment I would encourage them to publish these results so that we can better educate our patients."