Wave effectiveness
Depending on their emission intensity, acoustic waves can act as destructive forces or healing tools in the human body. This contradictory transition is due to the fact that mechanical stimulations bring about versatile biological functions through mechanotransduction (the transfer of force by acoustic wave).
Extracorporeal shock waves have been used for over 30 years in urology for the disintegration of kidney stones, and more recently in orthopedic disorders such as tendinopathies, fasciopathies and fracture healing. Acoustic wave therapy is also a noninvasive method for tightening skin and subcutaneous tissue, strengthening connective tissues, reducing undesirable fat and stimulating blood and lymph flow.
The acoustic wave energy is transmitted in the form of longitudinal, transversal and radial pressure disturbances in three-dimensional space, and reaches its peak value at the point where it hits the body. The physical foundation of this phenomenon was recognized as early as 1687 by Isaac Newton, who stated that any change in momentum is accompanied by the action of a force.
Shock waves create a localised mechanical impact in the treated area, which is called the “cavitation zone”. The shock wave pressure behind this zone increases cell membrane permeability and stimulates cellular metabolism by increasing microscopic circulation in the treatment area. In turn, this leads to the dissolution of calcific deposits embedded in damaged tissue and to an increase in new bone formation. Shock wave therapy can also stimulate fibroblasts, cells responsible for the healing of connective tissues such as tendons.
The mechanical effect of shock wave therapy is accompanied by the formation of micro-ruptures in tissue and vascular ingrowth, which result in a favourable inflammation response. This enables the acoustic wave to reduce pain, stiffness and swelling, as well as increasing joint mobility.
It has also been found that acoustic wave treatment can help reduce sagging facial skin and improve the appearance of cellulite, as well as strengthen collagen fibres and elastin to promote skin tightening and face lift. In addition, acoustic wave therapy can accelerate the metabolism of lipids, thereby reducing unwanted adipose tissue.
A meta-analysis of 17 studies in the field of spasticity showed that acoustic wave therapy is effective and safe, with few side effects observed in patients. In the study, participants were treated with acoustic wave therapy for one to 20 sessions per week over 3 months. In some cases, patients were treated with focused shock wave therapy to target the spasticity.
For the analysis, all published studies were examined to determine the demographic data of the participants and their treatment protocol, including the type of shock wave used in the study, frequency, duration and power, as well as whether the results were measured in terms of clinical improvements or radiologic changes. The meta-analysis was performed using the statistical software Stata v12.1. The quality of the studies was assessed by using the Cochrane Collaboration’s Quality Assessment Tool. The authors identified no obvious flaws in the methodology or interpretation of the results.