EXTRACORPOREAL SHOCK WAVE THERAPY (ESWT)
WHAT IS SHOCK WAVE
Shock wave is a type of propagating wave that moves faster than the normal speed of sound and it shows a high-energy sound waves that determines in a bursting of energy similar to that of a mini-explosion.
Extracorporeal refers to any medical procedure which is performed outside the body.
Extracorporeal shock wave therapy is application of shock waves which are generated through a fluid medium and coupling gel to activate the transmission of the shock wave energy into the body tissues to produce therapeutic effects.
But in order for the ESWT to be therapeutic, shock wave energy should be focused directly at the point of the treatment site or part that is the existing pathology.
Chung and Wiley et al, explained extracorporeal shock wave therapy according to energy categories:
- Low energy category (<0.08mJ/mm2)
- Medium energy category (0.08 to 0.28mJ/mm2)
- High energy category (>0.6mJ/mm2)
MAIN IMPORTANCE OF SHOCK WAVE
Shock wave has two main effects which include the following:
(1) Primary effect: is the effect of shock which is direct generation of mechanical forces in the tissue, which results in maximum beneficial pulse energy concentrated at the point where treatment is to be directed.
(2) Secondary effect: is the effect which generate indirect mechanical forces by cavitation, which may cause damage to the tissue.
because when shock wave hits the target tissue, it generates cavitation and this cavitation lead to the generation and movement of bubbles in a extracellular fluid or tissue in the body which is mainly caused by changing of gases dissolved in the fluids and then change back into their gaseous state. this process leads to the formation of free-radicals, which in turn affect cellular oxidation defence process in the body.
Also these cavitation bubbles, they expand to maximum and burst, which result in creating resultant force (which is a strong enough force to break calcific deposits). more the shock waves change their physical properties through attenuation and steeping when travelling through a medium, and through reflection and refraction at the boundaries when entering new medium.
METHODS OF SHOCK WAVE GENERATION
There are three main ways or techniques of generation of shock wave:
(1) Electro-hydraulic: this is a device works like a spark plug of car. a high voltage is applied to the electric plates, which produces heat and vaporizes the surrounding water, through which generating of gas bubbles propagates as shock wave. it is characterized by large axial diameters of focal volume.
(2) Electromagnetic: in this type of device the current is passed through a coil to produce a strong magnetic wave. the magnetic field causes generation of shock wave, which cause compression of surrounding structures.
(3) Piezoelectric principles: In this device, the generation of shock wave is based on piezoelectric principle, which make the shock wave to be called Piezowave, in which piezoelectric crystals are mounted over each other in a sphere and receive a rapid electric discharge that induces a pressure pulse in surrounding water.
MECHANISM OF SHOCK WAVE THERAPY
In contrast to lithotripsy in which shock waves break down kidney stones, here they microscopically cause interstitial and extracellular responses.
when shock waves hit the cortical bone, 65% are transmitted and 35% reflected.
INDICATION OF EXRACORPOREAL SHOCK WAVE THERAPY
(1) Calcific tendinopathy of shoulder
(2) Patellar tendinitis (Jumper's knee)
(3) Acute and chronic wounds
(4) Planter fascitis
(5) Trochanteric bursitis
(6) Avascular of femoral head e.t.c.
CONTRAINDICATION OF EXTRECORPOREAL SHOCK WAVE THERAPY
(1) Patient with hemophilia
(2) Over the heart
(3) Over the rib or clavicle with fracture
(4) Over kidney because it can cause damage to the kidney
SIDE EFFECTS OF SHOCK WAVE THERAPY
(1) Reddening of the skin (21.1%
(2) Pain (4.8%)
(3) Small hematomas (3%)
Wldn👍
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