Platelet-Rich Plasma injections have not proven to have increased effectiveness over standard therapies in any well designed study. But as with all things that don’t work there is always people who say it worked for them – anecdotes, and promoted by doctors who are making a living advocating for its use.

The Hypothesis:
There are in platelets a number of growth factors that assist in healing. If you concentrate those factors, and apply them directly to the injury the theory is an increased speed of healing. Tendon injuries are problematic in orthopedics because tendons have a poor blood supply. The hypothesis would be that applying those factors directly is would speed up healing.

Hypothetical Issues:
The products of inflammation that assist healing also have a lot of oxidative components that break down tissue.
Platelet factors are only a part of the inflammatory-healing cascade of products that help the body heal. There are a number of others factors that work with the platelet factors.

Renumeration for PRP is high
The sad fact is that PRP is driven by market-forces more than science. Since PRP is not covered by insurance, and has the promise of “better and shorter healing,” people are willing to spend dollars for something that has no proven efficacy. It is an economic boon to the physicians who use it- so when studies show there is no real difference between PRP and placebo they state that no one does it “the way” that they do it. They have some method that is a better “secret sauce,” to make this work.

“However, the current evidence also shows only a very limited influence of platelet concentrates on graft-bone interface healing and no significant difference in clinical outcomes.” (1)

Tiger Woods has had injections in his knee, but Woods didn’t heal any faster than anyone else who had conventional therapy. Some will tell you that it has improved their outcome – but the evidence that this expensive therapy works isn’t there. It is powerful to have a celebrity endorse a product, it is as close to word-of-mouth as advertising can achieve. Celebrities, however, are not doctors or scientists, they are customers who can often afford therapies that many cannot. Professional athletes are more prone to the pseudoscience of healing than others.

Conclusion: This randomized controlled trial showed no clinical and ultra sonographic superiority of platelet-rich plasma injection over a placebo injection in chronic Achilles tendinopathy at 1 year combined with an eccentric training program. (2)

The key – the clinical outcome, not that someone feels better, not that there are more or less inflammatory products at the site of surgery or injury, but the outcome. The key is what is the outcome when the product is studied by people who have no interest in promoting it, just an interest in science. This means the study is done in a manner where the researchers and the patients don’t know if they are getting a product or a placebo (called a double-blinded randomized study).  When those studies are looked at, real evidence based medicine studies, PRP offers no benefit.

In medicine we have ethics – Medical Ethics. One of the four pillars of medical ethics is autonomy :

Autonomy
As a physician we have ethical obligations, and expectations to our patients of autonomy – people are truly free to choose their treatment, but must have the information that is required to make a choice.  It is the patient who has the choice- even if we think we know what is good for the patient; it is not up to us to make that choice for them.

In this case: I wonder how many of those who offer PRP tell their patients that well done studies do not show a benefit. If they don’t say that, then they would be in violation of modern medical ethics

References:
(1) The effect of platelet concentrates on graft maturation and graft-bone interface healing in anterior cruciate ligament reconstruction in human patients: a systematic review of controlled trials. Arthroscopy. 2011 Nov;27(11):1573-83. doi: 10.1016/j.arthro.2011.06.003. Epub 2011 Aug 20.One-Year Follow-up of Platelet-Rich Plasma Treatment in Chronic Achilles Tendinopathy Pub Med ID 21862277

(2) A Double-Blind Randomized Placebo-Controlled Trial Am J Sports Med. 2011 Aug;39(8):1623-9. Pub Med ID 21602565