Extracorporeal Shock Wave Therapy Explained Simply

1. What It Is About

Extracorporeal shock wave therapy delivers sound waves from outside the body. “Extracorporeal” means: originating from outside the body. The waves are directed at a specific area of tissue without cutting the skin. A gel is applied to the skin to ensure good contact with the device. Each session lasts only a few minutes, and several sessions are usually spread over a few weeks. There are two types of devices: focused systems concentrate the energy at a single point, while radial systems distribute it more broadly. Energy levels are also classified as low or high. The treatment site is located depending on the condition, using palpation, ultrasound or other imaging techniques. The procedure is used, among other areas, on tendon insertions, joints and bones. Important to know: the term encompasses several procedures. When comparing results, one is not comparing a single procedure but an entire family of treatment methods.

2. What Studies Show

The best-studied application of shock wave therapy is in musculoskeletal conditions. For knee osteoarthritis, a large review pooled 14 studies involving 782 participants and 877 knees. Pain and mobility improved significantly compared to a sham treatment. A sham treatment feels similar but is intended to have no effect. The quality of the evidence was rated as moderate 1. In another review of six studies with 589 patients, pain scores decreased after four, eight and twelve weeks 6. For lateral epicondylopathy (pain on the outer elbow), a review of 27 studies with 1,871 patients found that pain was reduced in the medium term compared to a sham treatment, and grip strength improved shortly after treatment 5. In post-stroke spasticity—a pathological muscle stiffness—25 patients received physiotherapy alone, 27 received additional shock waves to the affected muscles, and 30 to the opposing muscles. After treatment, 70.4 % and 63.3 % of the treated groups responded, compared to 16.0 % in the physiotherapy-only group 7. For myofascial pain in the neck and shoulder region (trapezius), a review of ten studies with 477 patients showed significant pain relief compared to sham treatment or ultrasound 4. In men with erectile dysfunction unresponsive to PDE-5 inhibitors, erectile function improved more markedly in a sham-controlled study after three months than in the sham group 3.

3. What Remains Unclear

Shock wave therapy does not always show an advantage. For patellar tendinopathy (knee tendon pain), a review of two studies found no superiority over sham treatment 9. For insertional Achilles tendinopathy, no clear long-term difference was found between shock wave therapy and sham treatment 2. In children with cerebral palsy, only four studies met the criteria, and the authors state that further research is needed 8. It is also often unclear which energy level and number of sessions are optimal. Many studies compare different treatment protocols, and not all include a sham treatment. As a result, results cannot be directly compared. Moreover, most studies assess pain using questionnaires rather than the progression of the underlying condition. It remains a Hypothesis: that part of the observed effect may be due to participants’ expectations. This hypothesis still needs to be tested.

4. What This Means in Practice

Extracorporeal shock wave therapy is a non-surgical procedure that is generally well tolerated. Research shows that for some conditions, such as knee osteoarthritis or elbow pain, the treatment can reduce pain and improve function. For other conditions, such as patellar tendinopathy, no advantage over sham treatment has been demonstrated. Anyone considering this treatment should be aware that different devices and protocols exist and that the evidence base varies by application. This page does not recommend any treatment or provide dosage information. It summarises what has been studied and what remains open. What needs to be clarified next: direct comparisons between different energy levels and analyses that report pain and function separately by energy and session count.

All details with study numbers and sources: detailed page on Extracorporeal Shock Wave Therapy (ESWT). For children: Extracorporeal Shock Wave Therapy (ESWT) for children.