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The jury's still out on injection therapy for tendinopathy

Canadian champion Megan Wright faces a daunting challenge from her Kenyan rivals in tomorrow's Commonwealth Games 5,000-metre final. But the Edmonton distance runner has one thing going for her: the full use of both her legs.

At the Beijing Olympics two years ago, Ms. Wright (competing as Megan Metcalfe) was hobbled by an affliction familiar to exercisers ranging from first-timers to hardened vets: Achilles tendinopathy. The tendon becomes swollen and inflexible, and if you keep exercising you progress to "tendinopathy," a catch-all term for problems that include degeneration of the tendon tissue.

For the past few years, platelet-rich plasma (PRP) injection therapy has been the hot clinical hope. But initial results from PRP clinical trials suggest that there's no simple cure yet.

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Problems in the Achilles tendon, which connects the calf muscles to the heel bone, usually begin with some form of overuse - starting a new exercise program, inappropriate footwear, poor form and so on.

"New exercisers often make rookie mistakes like forgetting to stretch or starting to run wearing two-year-old shoes," says Richard Gregory, an Ottawa-based osteopath and manual therapist who is treating the Canadian track team in Delhi.

In more experienced exercisers, the problems may be more subtle. Mr. Gregory looks for leg-length discrepancies, pelvic rotation and other biomechanical imbalances that stress the Achilles, then prescribes strengthening exercises to correct them.

In some cases, though, tendinopathy doesn't respond to conservative treatment. In the months before and after the Olympics, Ms. Wright tried icing, acupuncture, sleeping in a "night splint" and "kinesio taping" - applying special tape along the length of the calf to relieve strain on the tendon. She even tried intramuscular stimulation, sometimes called "deep needling," in her calves - a procedure that, as the name suggests, involves sticking needles deep into the calf muscle.

Finally, she turned to platelet-rich plasma. Since tendons have a very poor blood supply (unlike muscles), minor tears and inflammation tend to heal slowly. PRP therapy involves drawing a small amount of the patient's own blood, spinning it in a centrifuge to concentrate the most useful components (the platelets) and reinjecting this concentrated plasma at the injury site. The platelets then release various "growth factors" that stimulate the body's natural healing response.

The first experiments using PRP for tendon injuries date back about five years, but the technique only gained widespread attention last year when it emerged that Toronto sports doctor Anthony Galea had injected Tiger Woods with PRP at least four times. A long list of other prominent athletes also acknowledged receiving PRP (which is neither illegal nor banned) and Dr. Galea reported that about 40 per cent of the PRP patients in his clinic were recreational rather than professional athletes.

Still, the evidence for PRP remains sketchy, with the first two clinical trials published only this year. In one, Achilles tendinopathy patients who received PRP were indistinguishable from a control group that received saline injections after 24 weeks. The other looked at tennis-elbow patients, and saw 73 per cent of PRP patients achieve a 25-per-cent reduction in pain after a year (not exactly a "cure") compared to 49 per cent of the control group.

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Whether or not these injections manage to relieve pain and swelling, they still don't address the underlying training errors or biomechanical problems that caused the initial tendon trouble, Mr. Gregory points out. That means the injury will likely come back when you start training again.

That's why Ms. Wright, who was able to resume training last spring after six weeks of PRP injections, relies on a rigorous regimen of calf stretching and strengthening using eccentric muscle contractions to ward off future problems.

Ms. Wright says she's not even sure whether PRP worked, or whether it was the six weeks of complete rest dictated by the therapy that finally allowed her tendon to heal.

Special to The Globe and Mail

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