Ultrasound (UD) is a treatment classified as physical therapy. The name derives from the sound waves above 20,000 Hz used in the treatment, just called ultrasound.
They are inaudible to humans (human hearing range is 16 – 20,000 Hz). The procedure takes advantage of the ability of sound waves to propagate in different media. The slowest ultrasound propagates in air, slightly faster in liquids, while the fastest in solids. This is due to the transfer of energy to the particles they encounter, setting them into an oscillating motion. As more obstacles are overcome, less and less energy reaches the layers deeper down.
The main indications for ultrasound are:
- Pain syndromes in osteoarthritis and neuralgia;
- Inflammatory and degenerative changes of tendons (e.g., heel spurs);
- Muscle and tendon overload syndromes;
- Post-amputation pains;
- Tendon contractures;
- Painful scars.