Extracorporeal Shock Wave Therapy (ESWT) devices generate pulses of high-pressure sound that travel through the skin. Extracorporeal Shock Wave Therapy ESWTis used for Heel Spurs and Plantar Fasciitis.
Soft tissue and bone that are subjected to these pulses of high-pressure energy heal back stronger. The FDA has approved the use of some ESWT machines for heel pain and tennis elbow. ESWT devices evolved from lithotripters (a.k.a. kidney stone shock wave machines).
Physical therapists use ultrasound machines that warm internal tissue by high frequency sound waves, but the ESWT machines send higher-energy pulses 2 or 3 times per second rather than continuous lower-energy waves. Electricity is not sent into the body. It may take as long as 12 weeks to see the full benefit of an ESWT treatment. The beneficial effect of the high-pressure waves may be from the growth of new blood vessels ("neovascularization") in small cavities that are created by the pulses. New blood vessels to an area of tissue would promote healing.
There is a 2006 article by Dr Wang and group evaluating the long term six year follow up with patients receiving single session high energy ESWT . The control group ( patients that didn't have ESWT treatment) had good success rates but very poor re-occurrence rate over the six years. The re-occurrene rate was 55% . Yes 55% of the patient had return of pain . In the group that had ESWT treatment the re-occurrence rate was 11%.