Radial Shock Wave Devices Generate Cavitation

Abstract

BackgroundConflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues.Methods and FindingsWe used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast; Electro Medical Systems, Nyon, Switzerland; D-Actor 200; Storz Medical, Tägerwillen, Switzerland) and a vibrating massage device (Vibracare; G5/General Physiotherapy, Inc., Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms.ResultsFOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device.ConclusionsThe results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices.Clinical RelevancePrior ESWT studies have shown that tissues treated with sufficient quantities of acoustic sound waves undergo cavitation build-up, mechanotransduction, and ultimately, a biological alteration that “kick-starts” the healing response. Due to their different treatment indications and contra-indications rESWT devices cannot be equated to vibrating massage devices and should be used with due caution in clinical practice.

Extracorporeal shock wave treatment can selectively destroy end plates in neuromuscular junctions

“…The energy level of shock waves is a major factor influencing the effectiveness of ESWT . Shock waves are transmitted radially and decrease in energy with distance from the applicator . Thus, our results suggest that application of rESWs to whole muscle is effective for reducing CMAP amplitude.…”

Cadaveric experiments to evaluate pressure wave generated by radial shockwave treatment of plantar fasciitis

“…Given that fSWT and rSWT both appear to be (equally) effective in the treatment of plantar fasciitis [20] it is possible that negative pressure is the main factor contributing to the enhancement of the healing process. If that is the case, cavitation is a potential physical mechanism through which this is achieved; creation of cavitation bubbles by rSWT in water have been documented in published studies [16].…”

“…In-vivo experiments in animal models have already been performed to measure pressure generated by the fSWT treatment of kidney stones [15]. However, the measurement of the pressure field from rSWT sources has been mainly restricted to water baths [13,14,16], and simple silicon experimental models [17,18]. In this study we conducted the first invitro measurement of the pressure generated by rSWT plantar fasciitis treatment in human cadaveric feet.…”

Is Radial Extracorporeal Shock Wave Therapy Combined with a Specific Rehabilitation Program (rESWT + RP) More Effective than Sham-rESWT + RP for Acute Hamstring Muscle Complex Injury Type 3b in Athletes? Study Protocol for a Prospective, Randomized, Double-Blind, Sham-Controlled Single Centre Trial

“…In this regard it should be kept in mind that the majority of clinical trials on rESWT that are listed in the PEDro database [37,38] were performed with the Swiss DolorClast [34]. Furthermore, except of the Power+ handpiece of the Swiss DolorClast, the Evo Blue handpiece was the most powerful handpiece in a comparative study measuring cavitation generated with rESWs [53] (the relevance of cavitation in mediating molecular and cellular mechanisms of ESWT on the musculoskeletal system was discussed in [43,[53][54][55]).…”