Does Platelet-Rich Plasma (PRP) Injection Work?
From PainScience.Com - Sep 2014
Blood therapy, anyone? Platelet-rich plasma (PRP) injections bathe troubled cells in a concentrated mixture made from your own blood. Hopefully this stimulates healing where it is otherwise failing — especially stubborn, slow-motion injuries like tendinitis — but no one really knows for sure yet.
Despite all the not-knowing, it’s easy to pay someone to do this for you these days: extract some of your blood, spin it in a centrifuge to get the platelets, and then pump them back into you. It’s not cheap, but PRP injections have become super popular, particularly with elite athletes (ever the guinea pigs for unproven, expensive new treatments for musculoskeletal injuries). In the fall of 2009, ScienceBasedMedicine.org scathingly criticized the marketing of PRP:
Without any clear evidence of benefit beyond placebo, PRP is now being marketed aggressively as a cure-all for sports injuries. And at about $300 per injection (the NYT reports $2000/treatment), there’s plenty of money to be made. … a nation-wide marketing initiative has begun, using sports celebrities as guinea pigs.At that time, the problem was that the marketing was irresponsible in light of the lack of evidence. It was a short wait for more. Today, the marketing is irresponsible in light of the evidence we now have …
A Case Study In Aggressive Quackery Marketing, Jones (ScienceBasedMedicine.org)
Cynics can stop reading here. You know this doesn’t end well.
Why platelets?
Meet the Clotters! Platelets are the major clotting tool in your blood, and they are curious critters, neither cells nor molecules, but a strange hybrid often called “cell fragments”: platelets are to blood cells what wood chips are to a log … if the chips were extremely clever. Platelets have a bunch of interesting biological features, but they are best known for their work in clotting — and that’s mainly what gives them that healing mystique.
There are countless biochemical factors that regulate healing — it’s complex, to say the least. Platelets are part of that equation, playing “a critical role in tissue repair and regeneration”; specifically they “regulate fundamental mechanisms involved in the healing process including cellular migration, proliferation, and angiogenesis.”2 Since they are involved in healing, so more of them must be good, right? This is the basic rationale for PRP.
In fact, PRP is often called “regenerative medicine,” because the idea of genuinely accelerated heating is so tantalizing, like science fiction (or salamanders). But it’s more marketing than biology, surprise surprise.3 You could probably talk people into drinking a platelet smoothie if you told them it would “regenerate” them. It is not safe to assume a soup of platelets is regenerative. It’s not even safe to assume it’s safe …
Myotoxic? Myo-maybe!
Injecting medications into muscles might not be harmless. (No one’s surprised by that, right? Good!) Anaesthetics and NSAIDs probably are a little myotoxic — poisonous to muscles — and there’s “conflicting evidence” about PRP. It might be fine, but it’s important to bear in mind that faddish new injection treatments are never risk free.
Who says more platelets stimulates healing? Is that in the Platelet User Guide? “For extra healing, generously apply platelets to wound.” Dosage is critical with many medicines. More is not only not always better, it’s routinely worse. Do other cells like being bathed in ten times the normal number of platelets? Or is it a suffocating mess that throws everything off kilter?
Or is it just kind of ho hum?
In PRP marketing and hype, it’s common to see claims that it’s a “natural” treatment — because it’s your own blood being returned to you, see? — and what could be safer and healthier than you-stuff? But this is bio-illogical: there’s lots of stuff inside of me that I do not want to be extracted, concentrated, and returned! Pick any hormone, for instance: many of those are just as involved in healing as platelets, but too much of most of them is just a disaster. In general, what you want in biology is just-right amounts of everything, not lots of extra anything. For an example close to platelets conceptually, there is a disease of excessive iron, hemochromatosis — a major component of red blood cells, essential to life, something you could easily think you want a lot of for vitality and healing. And indeed you do, if you’re anemic. But chronically absorb too much, and it’s a disease.
It’s really quite odd to assume that a platelet-rich sauce o’ blood is natural and safe and helpful just because the stuff came from you. Which is why this treatment needs to be tested, not assumed — like every treatment.
Science says “probably not”
PRP fans and purveyors will tell you there is good evidence that PRP works, but they are cherry picking from a few studies that worked out in their favour one way or another. A few positive studies never not mean much; indeed, most “positive” study results are actually just bogus.
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. 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.
Bummer.
Any good news?
The only good news is coming from isolated or fatally flawed studies. Isolated positive evidence about over-hyped treatments is a huge red flag, which usually means “researchers made errors in their favour.” It’s the pattern of evidence that counts, and so far the pattern is distinctly bad.
Any hope? Maybe a little. There are different ways of doing PRP, and there different conditions in different stages may respond better or worse. It’s biologically plausible that PRP could fail with chronic tendinitis but still succeed with an acute muscle strain, for instance, or even fail with one kind of muscle strain and succeed with another. Hammond et al, an experiment on rats — rats were harmed and treated for our edification — reported a difference between two kinds of muscle strain.
It worked better on a more serious injury, where regeneration of muscle tissue was part of the healing process. PRP might assist with that regenerative process, but have no effect on a less serious strain where no regeneration is occurring.9
But these are faint hopes. In general, one would hope that the methods and conditions tested so far are at least in shouting distance of being the right formula — close enough to be at least a little more encouraging.
Initially promising in principle, I predict that PRP will now be mired in trumped-up controversy for years. It will die a slow death, only beaten into submission over many years by a growing pile of underwhelming evidence, while its proponents continue to overconfidently sell the service and defend it from detractors, mainly by betting — with dwindling odds — that just the right formula can still be proven effective for just the right kind of patient. If so, great: I will be pleased to admit that my prediction was wrong! But I’m betting against them for now.
Platelets give good placebo
My final word on this topic has to be “placebo” — PRP is a perfect storm for it. It’s got everything! Bearing in mind that it’s been thoroughly demonstrated that people get stronger placebo effects from treatment features trivial as a more potent pill colour…
- People expect injected medicines to be more powerful.
- People are also strongly influenced by what elite athletes are doing.
- And of course it’s both high-tech and “natural” — a rare combination. Usually these qualities are contradictory, but PRP is blessed by both.
I can hardly imagine a better formula for a powerful expectation effect or “relief from belief.” Unfortunately, despite placebo’s weirdly good reputation, its powers are quite limited.10 The next time you hear a positive anecdote about PRP, remember: it’s probably the placebo talking.
Related article from ScienceBasedMedicine -A Case Study In Aggressive Quackery Marketing
Oct 2009 - With some degree of sadness I recently “outed” a former co-resident of mine who has turned to the dark side and begun putting money-making before truth and science. Without any clear evidence of benefit beyond placebo, platelet-rich plasma (PRP) is now being marketed aggressively as a cure-all for sports injuries. And at about $300 per injection (the NYT reports $2000/treatment), there’s plenty of money to be made.
Like the fake “stem cell” clinics in Russia (where, according to Sanjay Gupta’s recent book, Chasing Life, a person’s fat cells are harvested, washed, and re-injected into their blood stream), PRP also involves injection of autologous body fluids. Essentially, a small amount of blood is drawn from the patient, centrifuged, and the plasma supernatant is then injected directly into tendons and/or joints. After a series of 3 injections (one/month), most sports injuries are “cured.” Of course, most injuries would heal themselves in three months anyway.
It was bothersome enough that Steve Sampson, D.O., began a practice in Los Angeles, catering to those who could afford to do more than the usual RICE (rest, ice, compression, elevation) therapy for sports injuries. But now a nation-wide marketing initiative has begun, using sports celebrities as guinea pigs. Consider the email I received yesterday:
Val,Superstar athletes have been fighting back from injuries with the help of a new, innovative treatment technique that has enabled them to return to action more quickly. Two players for the Pittsburgh Steelers, Hines Ward and Troy Polamalu, used this technique to lead their team to victory in Super Bowl XLIII.
Now, that same treatment method offers promising results for weekend warriors and seniors in our region suffering from osteoarthritis in their joints and spine as well as those who’ve suffered ligament and tendon injuries.
It’s called Platelet Rich Plasma (PRP) therapy and one of its leading practitioners in the country is Capitol Spine & Pain Centers, the interventional pain practice in the Washington D.C. area for more than 30 years.
PRP therapy relieves pain by rejuvenating injured tissues. The process jump-starts and strengthens the body’s natural curative signals.
Capitol Spine and Pain Centers provides PRP therapy at all eight of its locations in Virginia and the District of Columbia. We would be glad to provide you with both a representative of its medical staff and a patient to discuss the benefits of PRP therapy.
To find out more about Capitol Spine and Pain Centers, go to www.treatingpain.com. Thanks for your time and I look forward to hearing from you.
George Evanko President George Evanko Communications 9156 Riesley Lane Vienna, VA 22182
Notice how this wonderful treatment is not only useful for superstar athletes, but also for seniors and weekend warriors. Yes, the market for PRP is almost unlimited! And aren’t I lucky, there’s a “leading practitioner” of PRP right here in Washington, DC. Now I too can jump start and strengthen my body’s natural curative signals.
Ugh.
As with the most successful forms of pseudoscience, there may be a grain of plausibility here. Knowing that human plasma does in fact contain growth factors that are implicated in wound healing – it’s not complete fantasy that injection of said factors may improve injuries in some way. So I decided to take a fresh look at Medline to see what sort of evidence there may be for the therapy. In my search I found:
1. One abstract discussing PRP’s use in degenerative knee arthritis. The study is not available for review in its entirety – but the abstract suggests that an improvement was noted at 6 months (in pain scores) with a significant worsening at month 12. No control group.
2. One small study that did not find a benefit to ACL healing in the presence of PRP.
3. Quite a number of studies related to the treatment of bone defects (mostly periodontal) with PRP. Most of those showed no improvement or a fleeting, temporary improvement with PRP.
Overall it seems that the dental and oral and maxillofacial surgery literature has found no use for PRP, and the orthopods simply haven’t paid too much attention to it. There is almost no published research related to tendon injuries – the major indication for PRP suggested by Dr. Sampson. So that leaves us with testimonials, celebrities, and true believers who are researching PRP “…to help further refine the treatment and demonstrate its efficacy.”
I suspect that, given Dr. Sampson’s recent appearance on The Doctors, he is well and truly committed to marketing his way to an early retirement with profits from PRP. The only thing standing in his way is this nasty little problem of evidence of efficacy. No matter, if it’s good enough for the Pittsburgh Steelers, it’s good enough for grandma.
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