Extracorporeal shockwave therapy (herein referred to as ‘ESWT’) is non-surgical, non-invasive treatment of medical conditions using acoustic shockwaves. First use of shockwave therapy in the early 1980's was utilized to fragment kidney stones termed shockwave lithotripsy. Continued development of shockwave treatment showed the possibility of stimulating bone formation, angiogenesis, chronic orthopedic inflammation healing, bone healing (osteogenesis), wound healing, revascularization, angiogenesis are well known and described in medical literature.
A shockwave is a form of acoustic energy resulting from phenomena that create a sudden intense change in pressure for example an explosion or lightning. The intense changes in pressure produce strong waves of energy that can travel through any elastic medium such as air, water, human soft tissue, or certain solid substances such as bone.
Acoustic shockwaves may be generated by various methods, electrohydraulic (also referred to as spark gap), electromagnetic (also referred to as ‘EMSE’), piezoelectric and ballistic shockwave.
Each method needs an apparatus to focus the generated shockwave so as to provide a focal point and/or focal zone for the treatment area. In the focal zone shockwaves produce much higher pressure impulses as compared with the zones outside of the focal zone.
Mechanical means for focusing each of these methods is generally realized with an appropriate arrangement of surfaces reflecting the wave toward the desired focal point and/or an appropriate arrangement of the generating devices.
Spark gap systems incorporate an electrode (spark plug), to initiate a shockwave, and ellipsoid to focus the shockwave. EMSE systems utilize an electromagnetic coil and an opposing metal membrane. Piezoelectric systems form acoustical waves by mounting piezoelectric crystals to a spherical surface to provide focus. Of the three systems, the spark gap system is generally preferred in the art for generating therapeutic shockwaves ESWT as it introduces more of the generated shockwave energy to the treatment target site.
In spark gap systems, high energy shockwaves are generated when electricity is applied to an electrode positioned in an ellipsoid immersed in treated water. When the electrical charge is fired, a small amount of water is vaporized at the tip of the electrode and a shockwave is produced. The shockwave ricochets from the side of an ellipsoid and converges at a focal point, which may then be transferred to the area to be treated.
In electromagnetic systems an electrical impulse is circulated in a coil. The coil produces an electromagnetic field that expels a metallic membrane to produce the mechanical impulse.
In piezoelectric systems ceramic material with piezoelectric characteristics is subjected to an electrical impulse. The electric impulse modifies the dimension of the ceramic material to generate the desired mechanical impulse. A focal point is attained by covering a concave spherical surface with piezoelectric ceramics converging at the center of the sphere.
The electrohydraulic, electromagnetic, and piezoelectric are all forms of shockwave generators that utilize high voltage power sources from 10 kV to about 25 kV in order to generate the required shockwave of about 100 bar to about 1000 bar). The drawbacks for such high voltage shockwave technology includes limitations both relating to the actual treatment and to the actual device and system. Treatment related limitations for example include production of a limited focal zone treatment area and low treatment efficacy. System limitations for example include cost, size, and durability where systems are generally expensive, large, heavy and require frequent maintenance. However, the biggest limitation of such system relates to the operating costs where such systems require many disposable accessories and integral electronic parts.
While high voltage device produce a shockwave pressure wave of about 100 bar to about 1000 bar, state of the art ballistic shockwave system offer generation of low level shockwaves, having pressure wave from about 50 bar to about 150 bar. As its name suggests ballistic shockwave system generate shockwaves as a result of a ballistic collision between a projectile and a generating surface. The projectile is accelerated and allowed to collide with the shockwave generating surface.
State of the art, ballistic shockwave systems are utilized for medical applications such as in physiotherapy applications for example for the treatment of inflammations and/or in dermatology and cosmetic applications, for example in the treatment of cellulite.
Current ballistic shockwave systems are limited in that a low pressure gas source (1-6 bar) leads to shockwaves that have low tissue penetration, small treatment and/or focal zone, high rates of re-treatment, discomfort due to the applicator's movement during the ballistic collision, are not readily mobile as they require an air compressor to produce the appropriate pressure. Other prior art ballistic shockwave system utilize an operational pressure of 15-30 bar, for example as described in U.S. Pat. No. 7,470,274 to Lebet. Moreover ballistic shockwave system generally do not provide for non-invasive extracorporeal shockwave treatment.
Similarly other prior art US2005/0209586, U.S. Pat. No. 6,413,230, WO2003084608, WO2008/007502 A1, WO2008/145273, U.S. Pat. No. 6,736,784, WO2010049519 describe ballistic shockwave systems using low level shock wave production by low gas pressure ballistic technology.
Other forms of ballistic shockwave generators include electromagnetic ballistic systems are further limited in that they tend to heat up and therefore require a cooling system due to the inclusion of an electromagnetic components.