Dr. Monto, for example, used PRP for chronic Achilles tendonosis in patients where other treatments had failed. Nearly all showed improvement. Thirty patients with an average age of 47 had follow-up at intervals up to six months, and in the end, 28 were satisfied with the clinical results.

“At the time, it was a little shocking, how well they did,” Dr. Monto says.

Platelet-rich plasma therapy also proved better than injections of gel-like substances called hyaluronates to treat knee pain caused by osteoarthritis (OA), according to an Italian study. The trial tracked 150 participants, with 50 receiving a series of three PRP injections, 50 getting injections of high molecular weight hyaluronic acid, which was comparable to Synvisc, and the remaining 50 received a low-molecular weight hyaluronic acid, such as Hyalgan. All were evaluated at the end of six months. PRP appeared to work better than either kind of hyaluronic acid, says Elizaveta Kon, MD, an orthopaedic surgeon in Bologna, Italy, and lead author of the study. But “It’s not holy water,” Dr. Kon cautions. “You can’t use it for everything.”

In the third trial, PRP was found superior to corticosteroid treatment for patients with chronic tennis elbow, in a double-blind randomized controlled trial. The 100 patients – 51 getting PRP, and the rest receiving corticosteroids – had a follow-up after a year.

The lead author of that study, Taco Gosens, MD, of the Netherlands, says that while it’s “very healthy to be skeptical,” PRP appears to be a valid treatment for that condition.

Not all the studies were positive, however.

Dr. Weber, of Sacramento, Calif., tested the therapy in 60 people who were having minimally invasive surgery to repair torn muscles in the shoulder’s rotator cuff, a procedure known for high failure rates. Half of study participants were treated with platelets after their surgeries and the other half were not. All were treated under anesthesia, so they didn’t know if they had received platelets or not. After three months, he found no apparent differences in pain or overall results between the groups.

“It’s very enticing theoretically,” says Dr. Weber. But he cautions that “patients should be skeptical” until thorough research is done on PRP.

Eddie McDevitt, MD, an orthopaedic surgeon in Annapolis, Md., agrees. He says that PRP has potential, and says demand is high among athletes and other patients. But he also says more research is needed before he will be comfortable using PRP. “We’re always trying to help people with arthritis, but you want to do it the right way,” he says. “I want to see some more good studies.”

Another consideration is cost. The general lack of health insurance coverage for platelet-rich plasma therapy can have patients picking up the entire tab, as much as $2,000 per injection.

Charlotte Marsden says her PRP injections cost more than $10,000. She says she hopes to get some money reimbursed by her health insurer, but adds, “If I don’t get a dime back, it was worth every dollar.”