1. What are Shock Waves?
Shock waves are acoustic disturbances or sonic pulses that propagates through a medium carrying the energy.
Shock waves consist of two phases:
1. High peak positive pressure (50-100 MPa, < 10 ns)
2. Tensile wave (ms)
The pressure changes mentioned above lead to:
1. Cavitation bubble formation
2. Impact on tissues
3. Effects such as healing and pain relief
Below are images and videos showing cavitation bubbles generated by different shock wave devices:
Radial ESWT, SWISS DOLORCLAST
Focused ESWT, SWISS PIEZOCLAST
2. The Historical Development of ESWT
The history of ESWT in medicine can be traced back to the late 1970s.
It was developed by a clinical research team led by Professor Christian G. Chaussy at the University of Munich's Urology Department, in collaboration with the German company Dornier.
They developed a shock wave machine to break kidney stones from outside the body, marking a breakthrough in urological treatments for kidney and ureteral stones.
This innovation launched a new era of using shock waves for stone fragmentation globally.
Subsequently, academia developed low-energy shock waves (in contrast to the high-energy shock waves used for lithotripsy) and introduced them into orthopedics.
These shock waves successfully treated musculoskeletal disorders and tendinopathies (Note).
They were later applied in cardiology (angiogenesis) and urology (erectile dysfunction) treatments.
3. How are Shock Waves Generated?
First, a "generator" converts electrical energy into an acoustical impulse.
Then, a focusing system concentrates the sound waves into shock waves, which act on tissues to produce biological effects.
4. Mechanisms of Shock Wave-Induced Healing and Pain Relief
a. Angiogenesis
⁃ Release of vascular endothelial growth factor (VEGF) and nitric oxide (NO)
⁃ Vasodilation, neo-angiogenesis, and improved microcirculation
b. Cell Proliferation
• Recruitment of progenitor and resident stem cells
• PCNA, TGF-ß1, IGF-I, cyclins, and induction of ATP release
c. Collagen Synthesis
• TGF-ß1, NO, IL-6 → Enhanced collagen synthesis
d. Regulation of Inflammatory Response
• Anti-inflammatory effects: induction of moderate NO production, stimulation of TLR3, reduction of CGRP and Substance P, regulation of macrophage activity
Lecture Announcement
Note: Successful treatments include plantar fasciitis, lateral epicondylitis, and calcific or non-calcific tendinitis of the shoulder and patella, with success rates ranging from 65% to 91%
References:
https://www.sciencedirect.com/science/article/pii/S2050052120300317
https://www.frontiersin.org/articles/10.3389/fvets.2022.851894/full
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8944950/
