Hard-training, mileage-pounding professional triathlete Tara Norton is no stranger to overuse injuries, and she knows all the tricks and technologies that top athletes use to get over them. “I’ve had every treatment under the sun,” says Norton, who is also a massage therapist and endurance coach in Toronto. Her newest tool, which she turned to for a recent hamstring injury is extracorporeal shockwave therapy, or ESWT.
The shockwaves are powerful bursts of sound waves, which a therapist directs at the affected area. “It’s like a repeated stab,” Norton says. “Once you adapt to it, it’s easy to handle.” The technique breaks down knots and gets muscles to loosen and lengthen. It has been used since the 1980s to break up kidney stones, and its use in sports medicine dates back to the early 1990s in Europe. Shockwave therapy for recreational athletes has been relatively slow to catch on, in part because of continued controversy about how it works and what types of injuries it’s effective for. In the past few years, though, several clinical trials have demonstrated encouraging results for three conditions of great interest to runners: plantar fasciitis, Achilles and hamstring tendinopathy, and shin splints.
For these conditions, doctors recommend shockwave therapy for stubborn cases that have failed to respond to standard conservative treatment options like rest, stretching and strengthening. One theory is that the therapy helps remind the body of the presence of an injury that it has become accustomed to, triggering natural healing processes like the formation of new blood vessels. “The shockwave forces the tissue to essentially undergo a focussed re-injury, which will result in a new vessel formation,” says Lawrence Micheli, a Toronto chiropractor who offers the technique to his patients.
In some respects, shockwave therapy resembles ultrasound, a more commonly used therapeutic approach (non-invasive) that also relies on sound waves. The difference is in the strength of the wave, explains Dr. Robert Gordon, a Toronto-based orthopedic surgeon and long-time promoter of the technology. “The signal with shockwave therapy is a much more intense and higher energy that affects the cellular composition of the tissue very differently,” he says.
The strongest evidence that supports shockwave therapy has been found in treatments for plantar fasciitis. For example, a placebo-controlled trial by researchers at the Rocky Mountain University of Health Professionals, published last year, found that just two sessions significantly reduced pain scores in a group of 25 patients within four weeks. A similar randomized, controlled study published in the American Journal of of Sports Medicine found more participants experienced pain relief with shockwave therapy, compared with the placebo group. On the other hand, another study published last year in the Journal of the American Podiatric Medical Association found no difference between shockwave therapy and cortisone injections.
For shin splints, the proposed mechanism is completely different: the shockwaves stimulate the shin bone itself, triggering an increase in the formation of new bone cells. A study that will be published later this year in the British Journal of Sports Medicine found that patients with shin splints who receive shockwave therapy in addition to a standard rehab program recovered in an average of 59.7 days, compared to 91.6 days for those who didn’t receive the treatment.
The challenges facing shockwave therapy are similar to those faced by other promising but controversial treatments like platelet-rich plasma injections. Although Dr. Gordon points out that shockwave therapy has been highly successful in a few double-blinded studies, some of the most encouraging studies were unblinded: the patients and doctors were aware of who was receiving the treatment and who wasn’t, which can skew results in studies where the outcome is a subjective assessment of pain. In fact, the patients in some of the studies were paying for the treatment, which has been shown to create an even stronger placebo effect.
But even if shockwaves aren’t a miracle cure, they still compare favourably to many of the alternatives. Patients with stubborn cases of plantar fasciitis and Achilles tendinopathy often end up undergoing surgery – an approach backed by evidence that’s just as shaky, with far more risks. These days, shockwave therapy is much affordable than it used to be: while Dr. Gordon’s original machine cost $450,000, he says new ones are available for as little as $17,500. Typical clinic costs for the patient range from $150 to $300 per visit. With that in mind, it certainly seems worth trying shockwave therapy before going under the knife.