What is Therapeutic Ultrasound?
Therapeutic ultrasound is a treatment modality that has been used by therapists over the last 50 years to treat soft tissue injuries. Ultrasonic waves (sound waves of a high frequency) are produced by means of mechanical vibration of the metal treatment head of the ultrasound machine. This treatment head is then moved over the surface of the skin in the region of the injury. When sound waves come into contact with air it causes a dissipation of the waves, and so a special ultrasound gel is placed on the skin to ensure maximal contact between the treatment head and the surface of the skin.
What are the effects of therapeutic ultrasound?
Thermal Effect:
As the ultrasound waves pass from the treatment head into the skin they cause the vibration of the surrounding tissues, particularly those that containcollagen. 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 may 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.
Effects on the Inflammatory and Repair Processes:
- One of the greatest proposed benefits of ultrasound therapy is that it is thought to reduce the healing time of certain soft tissue injuries.
- Ultrasound is thought to accelerate the normal resolution time of the inflammatory process by attracting more mast cells to the site of injury. This may cause an increase in blood flow which can be beneficial in the sub-acute phase of tissue injury. As blood flow may be increased it is not advised to use ultrasound immediately after injury.
- Ultrasound may also stimulate the production of more collagen- the main protein component in soft tissue such as tendons and ligaments. Hence ultrasound may accelerate the the proliferative phase of tissue healing.
- Ultrasound is thought to improve the extensibility of mature collagen and so can have a positive effect to on fibrous scar tissue which may form after an injury.
Application of Ultrasound:
- Ultrasound is normally applied by use of a small metal treatment head which emits the ultrasonic beam. This is moved continuously over the skin for approximately 3-5 mins. Treatments may be repeated daily in more acute injuries and less frequently in chronic cases.
- Ultrasound dosage can be varied either in intensity or frequency of the ultrasound beam. Simply speaking lower frequency application provides a greater depth of penetration and so is used in cases where the injured tissue is suspected to be deeply situated. Conversely, higher frequency doses are used for structures that are closer to the surface of skin.
