Extracorporeal shock wave therapy (ESWT) in orthopedics and traumatology is still a young therapy method. In the last few years the development of shock wave therapy was very fast and successful. Meanwhile ESWT has gained acceptance within the orthopedic community. Today physicians have an overview of several ten thousand treated patients worldwide. Nevertheless the healing mechanism of ESWT for treatment of the established indications like epicondylitis or heel spur is not completely understood. Shock waves have changed medical therapy substantially. Advantages of ESWT are avoidance of surgeries, safety and effectiveness. Compared to open surgery the costs of the ESWT are very reasonable. But nevertheless it's necessary to improve the basic understanding of the biological and medical effects of shock waves in cooperation between institutes, hospitals, physicians, societies and manufacturer of ESWT devices.
Shock waves are acoustic waves, which accompany our daily life without being noticed. The sound of thunderstorms, bangs of an explosion or of an applauding crowd are typical examples in which shock waves play an important role. An earthquake and the collapse of gas bumbles in a liquid generate shock waves. By means of shock waves energy can be broadcast over long distances. An airplane, which breaks the sound barrier, generates a very loud bang, which can lead to the jingle of glasses in a cupboard. The shock wave has transmitted energy from the airplane to the glasses.
The opportunity to transmit mechanical energy with shock waves leads to different applications, which can be classified in two groups [1].
Destruction of material structure:
Examples of this group are purification of nozzles, crushing of hard material like concrete, glass in a recycling process and removal of deposits in pipes. The extracorporeal shock wave therapy belongs to this group.
The other group is the application of shock waves as a source of signal.
In deep sea shock waves were used to measure distances because of the low energy loss over large distances.