Body's own cells may treat tennis elbow

By Amy Norton

NEW YORK (Reuters Health) - A simple therapy that uses the natural healing powers of blood cells called platelets could offer a new cure for chronic cases of "tennis elbow," researchers reported Monday.

The one-time treatment involves drawing blood from a patient's arm and spinning it through a centrifuge in order to create a sample with a high concentration of platelets.

This blood derivative, called platelet-rich plasma (PRP), is then injected directly into the injured elbow tendon.

In the new study, the 15 patients who received the injection showed a 60 percent improvement in pain symptoms after 8 weeks. Two years later, nearly all of the patients were "essentially pain free," the study authors report in the American Journal of Sports Medicine.

Tennis elbow is an overuse injury to tendons around the outer side of the elbow. As the name implies, it often arises in racquet-sport enthusiasts, but can also result from other repetitive arm motions, such as using a screwdriver, hammering or painting.

There are many treatment options, including rest, anti-inflammatory pain medications, braces and injections of corticosteroids. However, the effectiveness of some of these tactics is questionable, and some people continue to suffer chronic pain that may eventually require surgery.

PRP injections could offer a simple alternative to surgery, said Dr. Allan Mishra, an orthopedic surgeon at Stanford University Medical Center in California and the lead author of the new study.

"Your body has an excellent ability to heal itself," he told Reuters Health, and PRP injections merely aid that process.

Platelets are best known as cells that cause blood to clot, Mishra explained, but they also contain powerful growth factors. He theorizes that the platelet growth factors initiate a repair process in damaged tendons, which may include recruiting other cells, such as bone marrow stem cells, to the injured area.

Tendons connect muscle to bone and generally have a relatively poor blood supply. Injecting an army of platelets directly into the tendon overcomes this barrier.

PRP therapy is not yet widely available, however, since larger, more rigorous clinical trials have not yet been completed.

This pilot study included 20 patients with chronic tennis elbow that had proven resistant to standard therapy; 15 received an injection of their own platelets, and 5 received an injection of pain medication.

Eight weeks after treatment, the PRP group reported an average 60 percent improvement in their pain, versus only 16 percent in the comparison group. Three of the five patients in this latter group subsequently dropped out of the study or sought other treatment.

At the final follow-up two years later, 93 percent of PRP patients said they were "completely satisfied" with the therapy, and had resumed most of their work and sports activities.

Mishra said the platelet therapy could potentially have "wide application," helping to heal not only other types of tendon injuries, but also damage to other tissue, like cartilage and ligaments.

The study received partial funding from Cell Factor Technologies, a company for which Mishra serves as a consultant.

SOURCE: American Journal of Sports Medicine, November 2006.