Monday, November 1, 2010

Shockwave Therapy Beneficial for Tendon Pain

In The NewsA small study of athletes suggests that shockwave therapy, which delivers pulses of sound waves to injured body tissue via a hand-held probe placed on the skin, may heal chronically injured hamstring tendons. However, further research on shockwave therapies is needed and it should be recommended cautiously.

Writing in the American Journal of Sports Medicine, Italian researchers report on testing the effectiveness of shockwave therapy in chronic cases of so-called proximal hamstring tendinopathy (PHT) in 40 professional athletes [Cacchio et al. 2010]. (Hamstring muscles, with their associated tendons are on the back side of the thigh, superficially observed from the bottom of the buttocks to the back of the knee.) All of the athletes had experienced recurrent, debilitating pain and tenderness from PHT for at least 6 months.

Subjects were randomly assigned to either 4 sessions of shockwave therapy during a 1-month period or a standard regimen of conservative therapy — consisting of NSAIDs, physical therapy, and strengthening and stretching exercises. At the primary followup point 3 months after starting treatment, patients in the shockwave therapy group reported significantly greater improvement in pain symptoms, on average, than those on conservative therapy; 85% (17/20) of patients administered shockwave-therapy reported at least a 50% reduction in pain, compared with only 10% (2/20) in the comparison group. There were no serious complications in the shockwave group and the subjects reported fewer limits on their activity than their counterparts on conservative therapy.

COMMENTARY: During the past decade in the United States, shockwave therapy devices have been approved for treating plantar fasciitis and tennis elbow; although, the approach is more widely used for other conditions in Europe where it was developed. We have previously reported in Pain Treatment Topics [here], [here], and [here] on research regarding its use for plantar fascitis.

Usually referred to as Extracorporeal Shockwave Therapy or ESWT, it also has been studied, with mixed success, as an alternative noninvasive treatment when more conservative therapies fail for a range of orthopedic and sports-related injuries, including Achilles tendon injuries, patellar tendinitis, stress fractures, and "frozen" shoulder. Despite growing published evidence supporting ESWT for recalcitrant conditions, there remains some skepticism regarding its long-term palliative effects and cost-effectiveness — in many cases it may not be covered by public or private health insurance plans.

In a brief overview in the October 2010 edition of Practical Pain Management, Tiziano Marovino, DPT, notes that ESWT involves the delivery of high energy sound waves (ie, mechanical acoustical energy) to affected ligaments or tendons, which triggers natural healing processes [Marovino 2010]. Exact mechanisms are still unknown but it is believed that induced "microtrauma" from ESWT boosts blood flow to the treated area (neovascularization) to stimulate tissue regeneration and restoration. A secondary and possibly beneficial effect is thermal (heat) energy, which is a byproduct of sound wave interaction with tissues. During treatment, ESWT may incur some localized discomfort, or possible pain, in the affected areas but it is typically administered without anesthesia during a brief office procedure for tendon or ligament disorders (that are sometimes called “enthesopathies”).

The Italian study treating PHT, described above, was very small in scale, involving only professional athletes, and the validity and appropriateness for recreational athletes or other patients is unknown. Furthermore, it is important to consider that inappropriately applied ESWT can actually damage tissues or produce temporary swelling, pain, and skin irritation at the treatment site; so, operator skill may be a critical factor in therapeutic success. Lead author of the study, Angelo Cacchio, MD, pointed out in a news interview that shockwave therapy is generally used as a last resort to avoid surgery, after rest, pain medication, and physical therapy fail. Certain patients — such as those taking medications that may increase the chances of internal bleeding, or having implanted metal in the area (bone screws and pins) — should not have ESWT. And its safety in children, pregnant women, and patients with neuropathies from conditions such as diabetes is not yet established.

> Cacchio A, Rompe JD, Furia JP, et al. Shockwave Therapy for the Treatment of Chronic Proximal Hamstring Tendinopathy in Professional Athletes. Amer J Sports Med. 2010(Sep 20), online ahead of print [
abstract here].
> Marovino T. High Potency Ultrasound for the Treatment of Connective Tissue Disorders. Prac Pain Manag. 2010;10(8):68-70.