35, 76]. c SW generated by an piezoelectric device. Several hundred ceramic piezocrystal transducers (9) are arranged in a mosaic pattern on a bowl-shaped carrier at the reflection site (10). Upon a rapid electrical discharge, the piezocrystals react with an expensory deformation (inverse piezoelectric effect), that propagates a pressure pulse in the surrounding fluid and is directly self-focused at the secondary focal region (11). The secondary wave region or the wave refraction point is where the SW is aimed at and transmitted into the desired treatment region. Note: For latest updates on the various technologies, readers should contact each manufacturer directly for propriety infromation. Image adapted from [8, 28, 35, 76].
Fig. 3. Characteristic divergence between a shockwave (SW; left), and a radial pressure pulse (right). Radial waves do implode to a negative pressure value (Figure 4), and is not depicted in this illustration. The negative pressure of radial waves occurs slower when compared to SWs. Image adapted from [84, 85].
Fig. 4. Comparative characteristic divergence between an SW (Solid Red), ultrasound wave (Solid Blue), and a radial pulse wave (Dotted Black). Wave pattern, peak pressure, speed of wave rise time, and implosion. Image adapted from [85].
SWT is developing exponentially along with advances in technology (Fig. 5a–d), and the need for appropriate professional education and training becomes essential in order to obtain optimal clinical outcomes while ensuring patient safety. When incorrect treatment protocols (i.e. energy density flux level, treatment applicator placement, etc.) and technology are utilized, treatment outcomes are often severely compromised and often lead to poor clinical results [41, 86, 87]. When medical SWT is performed by an experienced and licensed clinician with the appropriate selection of technology, it has proven to yield excellent and sustainable clinical outcomes across a broad spectrum of pathologies [7, 8, 12–70, 77–83] . Therefore, the importance is underscored to obtain adequate professional training and education, as it is a key factor for clinical success, and patient safety.
Fig. 5. a The 1st-generation orthopedic extracorporeal shockwave (SW) device: Ossatron (electrohydraulic). Manufacturer: High Medical Technologies. This device was a strictly focused SW device. b Newer generation SW device: Duolith SD-1 Ultra® (electro-magnetic). Manufacturer: Storz Medical AG. c Newer generation multiple application extracorporeal SW device: RWPiezowave2® (Piezoelectric). Manufacturer: Richard Wolf GmbH/Elvation Medical GmbH. d Latest evolution FlashWaveTM technology (electrohydraulic) Manufacturer: NonVasiv GmbH.
The European Society for Musculoskeletal Shockwave therapy (ESMST) was founded in 1997. The ESMST and its founding members actively conducted research and established treatment guidelines and protocols for SWT. In 1999, the ESMST was renamed as the International Society for Medical Shockwave Treatment (ISMST) due to the growing number of international participation and interest in ESWT. The ISMST is the society presently responsible for research, training, and education for medical shockwave treatment, and RPT. The ISMST and its affiliated regional societies hold regular scientific congresses and certification courses (www.ismst.com)
SWT Stimulodynamics: Mechanisms of Action and Biological Responses
Pathophysiologies especially in chronic states are multifactorial and are often indocile to most treatments and remain an enigma for clinicians to ameliorate. Dissimilar from its use for the eradication of urolithiasis at its inception, the utility of medical shockwave treatment (SWT) today is considered for its regenerative properties to address impervious conditions encountered by various medical disciplines as mentioned earlier in the chapter. Stimulodynamics may be considered as the action or influence exacted by a particular force on tissue, and the ensuing biochemical and biocellular responses derived from it. Although the exact mechanisms of action (stimulokinetics) of SWs on tissue is yet to be completely elucidated (as is the case for most if not all medical interventions), researchers (i.e., Schaden et al. [13], Ogden et al. [26], Wang [28], Notanicola and Moretti [35], Mittermayr et al. [51], among others) have provided insights into the biological responses associated with SWT and the regenerative outcomes observed in non-union fractures, tendinopathies, and chronic wounds [13, 21, 26, 35, 51]. More recently, ground-breaking investigations by Lobenwein et al. [69], Sukubo et al. [89], and Holfeld et al. [90] have provided greater elucidation into the possible mechanics of action of SWT on tissue. These investigations revealed that a dose-dependent signal transduction from SWT influenced toll-like receptors, macrophages, and interleukins leading to a cascade of biochemical and biocellular responses commencing with angiogenesis [65, 69, 87–90], which then translates into a combination of regenerative processes leading toward homeostatic return and function. The culminating biochemical and biocellular responses influenced by SWT are seen to effectively address multiple aberrances associated with complexities, which include modulation of neurotransmitters (i.e., Substance P Calcitonin Gene-Related
