Because they get very little blood, injured tendons heal notoriously slowly. Blood platelets attract healing growth factors, so the idea of PRP is to inject a patient's own platelets at the site of a tendon injury.
To date, small studies suggest that PRP works for tennis elbow. However, a recent study in patients with Achilles tendon injuries yielded disappointing results.
At the same time, corticosteroid shots have been losing favor. They are great at relieving acute pain in the short term, but they don't promote healing and may lead to further tendon breakdown.
So what are tennis elbow sufferers supposed to do for their aching arms? A strong hint comes from Taco Gosens, MD, PhD, and colleagues at St. Elisabeth Hospital in Tilburg, Netherlands.
The researchers randomly assigned patients with chronic lateral epicondylitis -- tennis elbow lasting longer than six months and pain ranking at least 5 on a 10-point scale -- to get either a PRP or corticosteroid injection.
Both injections were given directly into the area of maximum tenderness and also into the tendon using a "peppering" technique in which the needle, after being passed through the skin, is inserted several times into the tendon.
What happened? Patients who got the corticosteroid had much faster pain relief. But 26 weeks after treatment, patients in the PRP arm were much more likely to have less pain and more function than those who received the corticosteroid.
And they kept getting better over the next year. By this time, PRP-treated patients reported a 64% improvement in pain and an 84% improvement in disability. Corticosteroid-treated patients reported a 24% improvement in pain and a 17% improvement in disability.
Moreover, only three of the 51 patients in the PRP group went on to get tennis-elbow surgery, and only two went back for a corticosteroid shot. Among the 49 patients in the corticosteroid group, six went on to surgery, six went back for PRP treatment, and one returned for another corticosteroid shot.
"We know that in the natural history of lateral epicondylitis 80% of patients are healed in one year, but all patients had complaints for at least six months," Gosens and colleagues report. "In our [study], significant results were achieved only after 26 weeks [with PRP]."
Kenneth Mautner, MD, of Emory University's sports medicine center says he gets even better results than the Dutch researchers reported. He was not involved in the Gosens study.
"Their results would have been better if they had consistently used ultrasound before treatment to show whether there really was damage to the tendon," Mautner tells WebMD. "And they did not do PRP injections with ultrasound guidance, which I always do. If they did, they could have been in the 90% success range reported in a previous study."
A downside to PRP is that it isn't cheap. Not all insurance plans cover the treatment, which costs from $750 to $1,500. So when might the less-expensive corticosteroid shot be a better option?
"I use steroids for tennis elbow if someone has had two weeks of pain and it is just killing them," Mautner says. "But if it’s been several months of pain and the ultrasound or MRI shows degeneration in the tendon and no swelling around it, I won’t advise it."
Is the elbow the only tendon amenable to PRP? A recent study suggested that the treatment does not work for Achilles tendon injuries. But Mautner says his experience is different.
"PRP success is most predictable with elbows, but I have had amazing success with using it to treat Achilles tendon injuries. We have to do more research on this," he says.
Gosens presented the study findings in a report to the annual meeting of the American Academy of Orthopaedic Surgeons.