Looking for relief from joint injuries or arthritis pain? Your own blood may hold the key.

Tendon injuries account for 30 to 50 percent of all sports injuries. An experimental but promising new therapy has athletes using their own blood to end the pain. Tiger woods claims it helped heal his injured knee, and the surgery-free alternative has athletes and weekend warriors alike lining up to give it a try.

Thirty years of pounding has taken a toll on John Spezzano's arms. The martial arts instructor had a bad case of tennis elbow.

Spezzano couldn't find a treatment to ease the pain caused by the muscle and tendon tears. So John turned to doctor Steven Sampson and an experimental treatment that uses john's own blood to repair his injuries.

During the 45-minute procedure doctors draw blood from John's arm. A filtration machine spins the blood separating red blood cells from platelets -- the part of the blood that stimulates healing. This high concentration of platelets -- up to 23 times that of normal blood -- is injected into the injury, triggering the healing process.

"They branch out like sea sponges, and they expand and release growth factor, and they coordinate repair and regenerate new tissue," said Sampson,a physical medicine and rehabilitation specialist at Orthohealing Center in Los Angeles.

Studies show it reduced pain for 81 percent of patients with tennis elbow after six months. 93 percent reported a reduction in pain up to three years later.

The therapy is considered experimental so it's not covered by insurance. Doctor Sampson is also using the platelet therapy for patients with knee osteoarthritis. He reports 62 percent of patients were satisfied with their pain reduction after one year.

Research Summary

BACKGROUND: Platelet Rich Plasma Therapy (PRP) is a treatment being newly applied to tendon injuries and osteoarthritis. Although PRP was developed 30 years ago to aid in wound healing and blood loss, researchers recently found it can also facilitate the healing of tendons and cartilage.

HOW IT WORKS: In PRP, a patient's blood is taken and spun in a centrifuge to single out platelets. "Platelets, we’ve learned in the last 20 years, release powerful growth factors that stimulate healing and regenerate tissues," said Steven Sampson, D.O., physical medicine and rehabilitation specialist at the Orthohealing Center in Los Angeles, Calif. Then, under ultrasound guidance, doctors inject the platelets into the injured area.

"Basically, we’re mimicking the natural ability of the body to heal itself," Dr. Sampson explained. "We’re taking these platelets and increasing them up to ten-fold and then reintroducing them into the body, almost tricking the body [into thinking] that there’s a new injury to maximize healing."

Dr. Sampson is currently involved in an FDA trial testing PRP in the treatment of tennis elbow. In another study Dr. Sampson is submitting for publication, he treated 13 patients with moderate to severe knee arthritis with a series of three PRP injections four weeks apart. The patients had failed many conservative treatments. He says results show 62 percent of patients expressed "overall satisfaction" one year after treatment, and patients reported no long-term complications. Dr. Sampson reports that patients showed statistically significant improvement in pain scores.

Dr. Sampson says patients who follow a course of physical therapy following PRP treatment are likely to see the most improvement.

RISKS: Although doctors say risks associated with PRP are uncommon, they include pain, infection, worsening of symptoms, blood clots, nerve injury, skin discoloration, calcification, scarring, loss of fat and allergic reaction.