Human ear can hear frequencies of the sounds between 20 Hz and 20 kHz. Oscillations below 20 Hz are called infrasounds, and those above 20 kHz ultrasounds.
When do we use ultrasound therapy
In physical medicine, ultrasound is used primarily for therapy. It is a mechanic device; more specifically, a micromassage, mechanical compressing and elongating of the tissue, and moving the tissue components. The most important effect of the ultrasound is creating heat.
Mechanical energy transforms the ultrasound into warmth, especially in places where the ultrasound is reflected, such as boundaries between soft tissue and bone. The usage of the ultrasound is also commonly called ultrasound diathermy, and it is possible to affect the deeper parts of the tissue.
The ultrasound machine consists of the alternating current generator of 800 kHz frequency , which is led to the crystal in the applicator’s head.alternating crystal polarization leads to its oscillations of the same frequency, and that is the ultrasound. To avoid the presence of air in the skin crevices, we use contact solutions (paraffin oil, gels, even Voltaren).
High ultrasound exposure can mechanically damage the tissue, so nothing greater than 2 W/cm2 of the applicator head is used. On the bent parts (hands, feet) ultrasound can be applied in the water, but the frequency should be 800 kHz-1MHz.
Application should take 5-10 minutes depending on the condition (if acute, the period is shorter). Ultrasound is not used in the structures of the central neural system, the heart, or the gravid uterus.
WHEN TO USE THE ULTRASOUND:
- chronic degenerative diseases
- ligamenat injury
- painful and blocked shoulder
- radial and ulnar epicondylitis
WHEN NOT TO USE THE ULTRASOUND:
- acute and fresh inflammation
- any condition where hyperaemia would be dangerous
- if the patient is prone to hemorrhaging