Therapeutic ultrasound, used by physical therapists and chiropractors for more than 70 years, can help heal injured tendons and treat other soft tissue as well. The idea is to heat the joint tissue with ultrasound to allow for better tendon movement. The collagen inside tendons, composed of both viscous and elastic materials, responds to the heat waves, which creates a "stretching window" -- an opportunity for more effective manual therapy.
Combination Treatment
A combination of ultrasound, heat and stretching provides very effective therapy for injured tendons, according to a 1996 article in the "Journal of Athletic Training." The combined approach helps to permanently elongate tendons while ensuring that the heated tissue is able to take the overload during the stretches. Ultrasound is considered to be the best way to heat the tissue is because it achieves a higher temperature at the deeper levels without really heating up or burning the upper layer.
Ultrasound Heating
Ultrasound is able to achieve this kind of heating because different tissues have different capabilities of absorbing ultrasound. Tissues that contain a higher protein content absorb more ultrasound as compared to tissues with a larger amount of water content. Therefore, blood and fat does not absorb as much ultrasound as compared to tendons and ligaments. This unique property of ultrasound enables therapists to use it for heating up deeper tissues like tendons that need to be stretched later.
Benefits
The clinical effects of thermal ultrasound include a reduction in viscosity, muscle spasm, pain perception, joint stiffness and nerve conduction velocity. Ultrasound therapy also provides an increase in metabolism and blood flow. Some inflammation is expected during treatment; however, treatment also relieves chronic inflammation due to the injury. Ultrasound helps to increase tissue length, helping to protect tendons against future injuries. Tissue length occurs because the ultrasound therapy thins the normally thick collagen in tendons.
Stretching Window
Therapists perform manual stretches while the tissue is still heated up from the ultrasound. This is the period of opportunity referred to as the "stretching window." If the heated tissue cools down before beginning the stretches, the tendon can be damaged if the therapist applies too much pressure. Therefore, stretching, traction and mobilization exercises should be performed in the window of five to 10 minutes after the ultrasound has been administered.
References
- "Journal of Athletic Training"; The Stretching Window Part Two: Rate of Thermal Decay in Deep Muscle Following 1-MHz Ultrasound; Sharon Rose, et al.; June 1996
- Eletroterapia; A Winning Combination; David O. Draper
- University of Hertfordshire Research Archive: Ultrasound in Contemporary Physiotherapy Practice
