The effects of therapeutic ultrasound are still being disputed. To date, there is still very little evidence to explain how ultrasound causes a therapeutic effect within an injury.
Therapeutic ultrasound in physical therapy (used since the 1950’s) is a relatively low intensity technique that uses high-frequency sound waves (ultrasonic). It is thought to reduce pain, inflammation and speed the healing process within an injury site. It also has a therapeutic effect on the overall soft tissue tensegral structure encapsulating joint injuries.
As the ultrasound waves pass from the treatment head into the skin they cause a vibration within the surrounding tissues, particularly those that contain collagen. This increased vibration leads to the production of heat within the tissue. In most cases this cannot be felt by the patient themselves. This increase in temperature is thought to cause an increase in the extensibility of structures such as ligaments, tendons, scar tissue and fibrous joint capsules. In addition, heating may also help to reduce pain and muscle spasm and promote the healing process.
Inflammatory and Repair Effects
One of the greatest proposed benefits of ultrasound therapy is that it is thought to reduce the healing time of certain soft tissue injuries hence accelerating normal resolution time in the inflammatory process attracting more repair cells to the injury site. This may cause an increase in blood flow which can be beneficial in sub-acute phases.
Studies have shown that it also aids in the reduction of trigger point pain; trigger points can be predisposing factors to headache, back ache and several types of soft tissue injuries.