Kenneth Craig S. Vincenta, b · Maria Cristina d’Agostinoc
aKompass-FlashWave Regenerative Centre, Auckland, New Zealand; bKompass-FlashWave Regenerative Centre, Victoria, Australia; cShock Wave Therapy and Research Unit, Humanitas Clinical and Research Hospital, Milan, Italy
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Abstract
Shockwaves, which have had several geophysical applications, were successfully introduced into the field of medicine over 3 decades ago for the purpose of eradicating urolithiasis, heralding the era of noninvasive medical intervention. Technological advancements in the area of medical shockwaves made in recent years have broadened the spectrum of its clinical application from being just purely a destructive force into a treatment modality that engenders a myriad of progenesis effects associated with tissue regeneration and functional restoration. Although the exact mechanisms of action (stimulodynamics) of medical shockwaves are yet to be completely elucidated, observation of its effect on tissue revealed; bio-chemical and biocellular modulation, resulting in progenesis effects such as; angiogenesis, osteogenesis, and tendogenesis. These progenesis responses are considered to be precipitated via a sensory derived signal transduction effect (stimulokinetics), commonly known as mechanotransduction. Three decades later medical shockwaves remains a phenomenon that is intransigent against becoming demoded, and continues to see its clinical utilty expand across medical disciplines. This expansion highlights the need for adequate training and education. The safety, systemic neutrality, noninvasive nature, and regenerative properties associated with medical shockwave treatment warrants further research and deserves greater recognition in the global healthcare system. The expansion of the clinical utility of medical shockwaves could elevate the management of multiple pathologies from being merely palliative, toward a more sanative approach, improving the quality of life of patients across their lifespan, while reducing the burden of healthcare costs globally.
© 2018 S. Karger AG, Basel
Introduction
The theory for extracorporeal calculi disintegration utilizing pressure waves has been explored since the 1950s, initially utilizing ultrasound waves [1–3], but its clinical viability was hampered due to the excessive tissue damage associated with this procedure. The geophysical observation of shockwave (SW) propagation by rapid-velocity raindrops, and micrometeorites by aerospace engineers, stimulated much interest and research of this phenomenon. The impact of SWs on human tissue was originally noted during World War II where underwater explosions due to depth charges caused internal tissue damage to the lungs of castaways devoid of any appreciable external evidence of trauma or violence. Professor Eberhard Häusler’s collaboration with physicians from the University of Munich and technicians from Dornier pioneered the concept and investigation of kidney stone disintegration by extracorporeal SWs [4, 5]. In 1974, a research grant titled “Application of Shockwave Lithotripsy” was awarded, and in 1980, the first patient was treated with extracorporeal shockwave lithotripsy (ESWL) [5–7]. This pioneered and revolutionized minimally invasive intervention in urology [5–7], and to date, ESWL remains the gold standard for the treatment of urolithiasis. The use of SWs was first introduced into orthopedics for the emancipation of bone cement removal in the late 1980s [7–11], but ancillary observations in 1991 of the osteoblastic responses to SW on bone [5, 8–10] would change the utility of SWs from being merely a destructive force for the disintegration and emancipation into a regenerative treatment modality. Advancements in technology have witnessed the expansion and utility of SWs in orthopedics [7, 8, 12–22], musculoskeletal medicine [23–48], vulnology [49–52], andrology [53–59], and more recently interventions in cardiology [60–66], spinal cord injury [67–70], interventions in ageing (sarcopenia), and musculoskeletal tissue resilience [71, 72]. Dose dependent stimulus from SWs are seen to engender tissue regeneration and restoration in various pathologies and more investigations are being undertaken to obtain greater elucidation about the transmission (stimulokinetics) and mechanisms of action (stimulodynamics) of medical shockwave treatment (SWT) on tissue.
SW: Basic Characteristics and Methods of Propagation
It is pertinent to note that an SW differs from an ultrasound wave, in that SWs are biphasic supersonic waves that transmit in a non-sinusoidal motion pattern devoid of thermal and micro lesion effects, and achieve peak pressure amplitudes over a thousand times greater than that of an ultrasound wave [26, 28, 34, 76, 78, 79]. In 1997, an International Consensus Conference (1997) established the physical characteristics of an SW (Fig. 1).
Shockwaves utilized in medicine bear these characteristics (Fig. 1) and are propagated utilizing electrohydraulic (Fig. 2a), electromagnetic (Fig. 2b), or piezoelectric (Fig. 2c) technology [35, 76, 78, 79]. SWs created by each of these 3 sources are primarily propagated by a contained high-voltage