By Cary Gronner
A relatively new type of therapy is being used to treat some types of tendon, ligament, and muscle injuries. Platelet-rich plasma (PRP) therapy may help some injuries heal faster, but doctors still have many questions about the type of injuries — and patients — for which it’s most appropriate.
In order to understand platelet-rich plasma therapy, you need to get a handle on two concepts: blood plasma and platelets. Blood plasma is the liquid component of blood, and is made up of about 90 percent water, and 10 percent proteins, hormones, and electrolytes. Platelets are cell fragments that are suspended within blood plasma. Platelets are produced by bone marrow, and contain several growth factors that stimulate bone and tissue healing.
In PRP therapy, a small amount (about 30 milliliters) of the patient’s blood is drawn and then spun in a centrifuge so the PRP can be separated, collected, and prepared (more on that later); it’s then injected into the injured tissue. The idea is that the super-concentration of platelets — about three to nine times the normal amount — will then supercharge the healing process.
PRP therapy is reasonably safe because what’s injected comes from the patient’s own body. But does it work?
Some researchers have reported that PRP isn’t any better than placebo saline injections (a mixture of water and salt). Others have found that it significantly shortens healing times. For example, in a study of athletes who had surgery for torn Achilles tendons, those who received PRP treatment healed about 36 percent faster than those who didn’t.
Like many studies in this relatively new field, however, this one was conducted in a small number of subjects, so clinicians hesitate to put too much weight on the results.
Part of the debate about PRP therapy stems from the fact that there are many different ways that PRP is prepared before it is injected into the tissue. Platelets work by releasing special growth factors into the tissue when they are injected, and must be “activated” in order to perform this release. Some PRP preparations are designed to be activated with chemical compounds (such as calcium, calcium chloride, or thrombin); others are activated after injection, by the patient’s own collagen. The method of activation determines how quickly the platelets release growth factor. For example, preparations activated by the patient’s collagen release growth factor slower and over a longer period of time than preparations activated by chemical compounds.
Different preparations have different platelet concentrations and may be relatively rich or poor in white blood cells (leukocytes). Because studies have been done using PRP prepared in a variety of ways, it can be problematic to compare results. Moreover, researchers have been unable to correlate platelet concentrations with outcomes.
Some physicians argue that more established therapies — eccentric exercise (the lowering part of a motion, as when the hand moves down and away from the body after performing a biceps curl) or percutaneous needle tenotomy, for example — may be more appropriate than PRP therapy. (In tenotomy, the clinician jabs the affected part of the tendon repeatedly with a small needle; the resulting inflammatory response can reawaken the healing process and get things moving again.)
Another issue is that PRP therapy is rarely covered by insurance. As a result, those who choose it may simply be those who can afford it, or those for whom even a slightly quicker return to athletic activities is crucial. One group of people that fits both of these descriptions is professional athletes, and their use of PRP has generated much of the media hype surrounding it. For everyone else, it may be better to just wait a little longer to heal.
One thing many doctors do agree on, however, is that trying PRP therapy is better than resorting to surgery. Even if it doesn’t work, PRP therapy is low-risk, and patients still have the surgical option to fall back on.
There are some clear cases where PRP therapy is beneficial. For instance, PRP therapy is used successfully in several types of surgery to speed healing. In patients who had fractured their lower-leg bone and were treated with PRP, a study showed that the bone fused about twice as fast, versus a control group of patients who didn’t get PRP treatment.
PRP therapy has also been studied in other conditions including tennis elbow, chronic tendinopathy of the patellar tendon, plantar fasciitis, acute injuries of ligaments or muscles, and reconstruction surgery of the anterior cruciate ligament (ACL) of the knee. Some studies have shown promise, but because they were conducted in small numbers of subjects and failed to include a control group (a similar number of subjects who did not receive PRP), doctors aren’t sure how much to trust the results.
Very promising results have been reported when PRP is used to heal wounds associated with diabetes, however. This is noteworthy because diabetes can increase the risk of wounds, slow the healing process, and make it more difficult for patients to know they have an injury. For instance, diabetic foot ulcers (a type of foot wound that results as a complication of diabetes) can be challenging to treat because patients often lose pain sensation due to nerve damage from their diabetes. That, along with poor circulation — another diabetes complication — can cause the wounds to become deeply infected and can lead to amputation of the toes, feet, and even legs. Some research suggests that treating the tissue around such wounds with PRP may help improve healing rates significantly.
If you’re a professional athlete, or even a dedicated weekend warrior, and your doctor has diagnosed you with either an acute or chronic tendon injury, you may want to discuss PRP therapy (and see if your insurance company will pay for it). If you don’t want to spend the money, however — or if you don’t like needles — you may want to consider other options, including, primarily, patience.
If you have diabetes and have a slow-healing foot wound, it may make sense to ask your physician about PRP therapy.
As more and better-designed research is conducted on this promising therapy, PRP treatments may enter the mainstream as an option for people with a variety of injuries and issues. Until then, rest, physiotherapy, or other more traditional treatments may be what the doctor orders.
Published May 29, 2012.
Cary Groner is a writer based in the San Francisco Bay Area. His recent novel, Exiles, placed fourth on the Chicago Tribune’s list of the best books of 2011.