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Ultrasound Vs. Diathermy



Ultrasound


Ultrasound is a modality that uses high and low frequency sound waves.  Theses sound waves penentrate tissues and vibrate the molecules to cause friction.  The effects of friction cause the resulting tissue to warm up causing theraputic effects.
Pros

Ultrasound can be used for joint contractures, scar tissues, reduction of pain, reduction of muscle spasm, and even bone healing.  Ultrasound can reach tissues up to 5cm deep and can leave a heating window up to 3 minutes long.  Ultrasound has thermal and non thermal effects.  Some thermal effects include elevation of tissue temperature, increasion of collagen tissue extensibility, increase blood flow to the area, alter nerve conduction velocities, increase pain threshold, increase enzymatic activity, and even decrease spasm.  Non thermal effects of ultrasound include stable cavitation which hleps increase fibroblasts to the area, increases protein synthesis, and even increases phagocytosis.  Acoustical microstreaming is another benifit of ultrasound because this is the unidirectional movement of fluids along cell membrane resulting in an ion flux of calcium, changes in cellular activity, and increases in cell membrane permeablity.  Ultrasound can heat deeper tissues without heating superficial tissues.  Phonophoresis is the use of ultrasound to inhance the absorbtion of anti-inflamatory creams into the tissue so that the medicine can be absorbed quicker.

Cons

The down side of ultrasound is that fact that it can only treat a small area.  Typically ultrasound treats 2-3 times the size of the sound head and the sound head is usually only 1-3cm in diameter.  Another downfall of ultrasound is that you only get about a 3 minute window after treatment to stretch the tissue in order to increase tissue extensibility.  Ultrasound can also cause hot spots or spots that cause burns on the patient.  Burns usually happen from broken cyrstalls inside the sound head or improper method of use.  When using ultrasound alot of energy can be lost if the operator does not use the correct amound of coupleing gel.


Diathermy


Pros

There are three different forms of diathermy used today  . In shortwave diathermy  the part to be treated is placed between two condenser plates, and the highest temperature is concentrated in the subcutaneous tissues. Shortwave usually is prescribed as treatment for deep muscles and joints and is sometimes used to localize deep inflammatory disease. Ultrasound diathermy uses high-frequency acoustic vibrations; their heating effect increases circulation and metabolism and speeds up the rate of ion diffusion across cellular membranes. During treatment the apparatus is moved slowly across the surface of the area to be affected. Ultrasound is used to heat selected muscles that are too deep to be significantly affected by surface heating. Microwave diathermy uses radiation of very high frequency and short wavelength similar to that used in microwave oven, all the physiologic responses are due to its heating effect. Diathermy also treats a much larger area then that of ultrasound.  Diathermy gives you a greater window of stretching, about 9 minutes, rather then 3 minutes from ultrasound. Pulsed shortwave diathermy produces the same magnitude and depth of muscle heating as 1 MHz of ultrasound.

Cons

 Cons of diathermy include the fact that the treatment time is about 20-30 minutes.  In order to treat a patient using diathermy one will also need a few layers of toweling in to prevent burning.  The diathermy machine is has many precautions some of which include direct contact, staying away from metal and electical equipment, removing jewlery, and avoiding fluid filled organs.  Some older diathermy machines do not have automatic tuning and so one must learn the correct way to tune the instrument in order for proper use.