A recent report in the Journal of the AMA (De Vos, et al JAMA 2009) reported that platelet rich plasma therapy was no more effective for chronic Achilles tendinopathy than standard, conservative therapy. This study was inherently flawed in its design resulting in incorrect conclusions. Platelet rich plasma is the healing component of blood. It is derived and concentrated from a patient’s own blood and then injected into the affected area. Not all PRP is the same. Blood processing is the key, levels of growth factors are of utmost importance and successful outcomes will vary with the technique, protocol and level of expertise the clinician possesses. Different PRP extraction equipment and how the blood product is handled during this process is also critical.

De Vos et al commented “A limitation of the study was that the amount of platelets and quantity of activated growth factors that were present in the PRP injections were unknown.” This introduces several variables that would invalidate the data and the study’s conclusion:

1. What PRP processing system was used?

2. Were the levels of Growth Factors therapeutic? Therapeutic level ranges  are usually 4-5  times the baseline.

3. No levels or PRP concentrations were taken or reported.

All of these are significant study design flaws that will result in invalid study conclusions. Additionally the study stated “Platelets are slow to activate by exposure to tendon collagen, but it might be that therapeutic pressure within the tendon, a large amount of PRP diffused rapidly out of the tendon thereby reducing its effect.” Additionally thrombin – a critical component in PRP therapy – was not used to activate the platelets. PRP and growth factors will not activate or be as effective if thrombin is not used in this procedure.

Perhaps most significant study design error was that only one PRP injection was given. The study patients, by design criteria, were required to have chronic Achilles tendinopathy that had responded poorly to prior therapies. Chronic tendon injuries, particularly those in the Achilles tendon, heal poorly due to inherently poor blood circulation. The standard PRP technique in this type of injury would be a series of three injections over a period of 3-4 months. A study that specifies treating a patient with a chronic tendinopathy with a single PRP injection is setting up the patient unnecessarily for failure. Lastly, the study had a low number of subjects in it to make any clinically significant conclusions. Only 27 subjects were treated, each with a single PRP injection and there were 27 control subjects.

Regenerative medicine – Platelet rich plasma – has been FDA approved for medical use for 20 years. It has been used widely in dental, cardiac, orthopedic medicine to assist in and improve medical outcomes. The professional horse racing associations widely use PRP therapy to heal leg injuries in their million dollar race horses. Major league sports such as the NFL and MLB consider platelet rich plasma therapy an important treatment option to get their elite athletes “back into the game” in as short of time as possible. PRP healing typically takes six weeks, particularly when combined with rehabilitation. In conclusion, PRP is a highly effective medical treatment for ligament, tendon, muscle and other knee/shoulder injuries as well as lower back pain. Even patients with post-operative knee pain or shoulder pain can benefit from PRP therapy.  Outcomes are entirely dependent on the preparation and handling of the blood, equipment used and experience as well as skill of the treating physician. Additional information on PRP can be found at PRP Stops Pain. Excellent clinical study references can be found by clicking here.


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