“I start where the last man left off”, Thomas Edison (1847-1931), American inventor. Science has clearly taught us that innovation is not always about brand new ideas and technology. A lot of new medicine and science is about taking something already established and finding a new use, or a new disease or group of patients that can benefit. The story of shockwave therapy is an excellent example of this.
The concept for shockwave therapy in medicine is not new. The technology has been around for nearly three decades, used in urology to non-invasively disintegrate urinary stones as well as now for orthopaedic indications that has successfully helped millions of patients worldwide (1). But new research by a group in Austria has discovered brand new uses for the technology in patients with chronic untreatable deep-tissue wounds, which could have massive implications for whole new groups of patients.
The technology initially stems from an unlikely place: aerospace science. In the early 1900’s, Claude Dornier, pioneering German aircraft designer and builder, noticed that pitting (localised corrosion) was occurring on the surface of aircraft as they approached the sound barrier. Dornier put this phenomenon down to a unique occurrence resulting from the shock waves, which were abrupt, intense waves that travel faster than the speed of sound (2,3). Dornier collaborated closely with hospitals to develop extracorporeal shock wave lithotripsy (ESWL), initially modifying equipment developed to test supersonic aircraft parts, and it has been used to treat millions of patients successfully.
But when the concept was shown to be effective on chronic wounds in Austria this opened the door to millions more patients including those with diabetic foot ulcers, which are notoriously difficult to manage and can at times lead to amputation (4). “I was very skeptical about the technology, at first, but started looking into the mechanism”, said Dr Rainer Mittermayr (Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria) when his mentor Dr Wolfgang Schaden (Trauma surgeon, AUVA trauma center Meidling, Vienna, Austria) brought forth the concept of shockwave therapy to him back in 1999. This was a clearly a highly effective clinical tool, explained Rainer, but we were not sure how it worked so we decided to move it back from bedside to the bench to understand its mechanism. Shockwave therapy could successfully already break down kidney stones in urology but it was later found that the therapy did not just have a destructive effect and could be used for repairing bone fractures and other orthopedic conditions. The exact mechanisms of shockwave therapy have never really been understood until the Austrian group did some further research.
THESE MECHANISMS GIVE THE NON-INVASIVE TECHNOLOGY OF SHOCKWAVE THERAPY GREAT POTENTIAL IN A BROAD RANGE OF INDICATIONS BECAUSE IT ACTIVATES THE BODY'S OWN MECHANISMS
What Mittermayr found surprised him. “I was convinced that shockwave therapy has great potential in various indications including wound healing, the waves had a fundamental influence on the biological system in terms of activating the endogenous regeneration potential”. What Mittermayr and his team showed was that by a mechanism of mechanotransudction, the high-energy acoustic waves translated into biochemical signals, which could activate various cellular and molecular pathways leading to cell activation. This triggering of the cells triggered a few mechanisms including angiogenesis (that is the development of new blood vessels), the recruitment of stem cells to the site of shockwave therapy application, cell proliferation and differentiation and modulation of the inflammatory response, explained Mittermayr. “These mechanisms give the non-invasive technology of shockwave therapy great potential in a broad range of indications because it activates the bodies own mechanisms”.
The discoveries of the mechanisms of action of shockwave therapy have extended to ischemic heart diseases, and disorders in the peripheral and central nervous system. The problem with chronic wounds, like diabetic foot ulcers where necrotic tissue has formed, is the lack of an adequate supply of oxygen and nutrition to the area, explained Mittermayr. Completely by accident, as many discoveries in science are often made, the research group found that when applying shockwaves to treat a patient with first degree open tibial bone fracture, that surprisingly not only the bone healed but so did the wound. The group experimentally showed that shockwave therapy initiated angiogenesis, vasculogeneseis, lyphangiogenesis and recruitment of endothelial progenitor cells in the area. “Moreover we showed that not only the treatment of already ischemic tissues respond to shockwave therapy in terms of reducing tissue necrosis, but also that it was possible prime the tissue in advance of ischemic impact”, said Mittermayr. This discovery could have massive implications in terms of its potential as a prophylactic tool in patients prone to developing wound healing disturbance after surgical interventions (5), which was also shown in 2008 in coronary artery bypass surgery (6).
Together with his Austrian team, Mittermayr is collaborating closely with researcher, Professor CJ Wang, who is considered the pioneer of shockwave therapy in orthopaedic and trauma indications, in Taiwan. The team is in the midst of open clinical phase II trials to assess the use of shockwave therapy in wound healing.
“Through all the years of experimenting and research, I never once made a discovery. I start where the last man left off…All my work was deductive, and the results I achieved were those of invention pure and simple”, Thomas Edison.