Ultrasound therapy is one of the physical therapy procedures. It is a mechanical therapy because ultrasound consists of sound waves (longitudinal, wave-like propagations of the smallest pressure fluctuations of a medium such as air or liquids) with a high frequency. Furthermore, ultrasound therapy can be used as thermotherapy due to its heat-generating effect. In addition, ultrasound therapy is also a form of electrotherapy in the broadest sense. This is based on the fact that ultrasound is obtained from electrical energy. This form of therapy is mainly used for chronic degenerative diseases of the musculoskeletal system.
Indications (areas of application)
- Acute disease states after trauma – e.g., fractures.
- Acute disease states after surgery
- Chronic degenerative diseases of the musculoskeletal system – e.g. muscle or tendon pain.
- Circulatory disorders
- Myalgia (muscle pain)
- Myogeloses – nodular or bulging, clearly circumscribed hardening in the muscles (colloquially also called hard tension).
- Scar and tissue adhesions
- Pseudoarthrosis (failure of a bone fracture to heal).
- Improving the trophic (supply of nutrients and vital substances) poorly healing wounds.
The procedure
As mentioned above, ultrasound has a mechanical and a thermal, as well as numerous other effects on tissues. The mechanical ultrasound effect produces microvibration, which causes a variety of changes:
- Permeability changes (changes in permeability) of cell membranes.
- Improvement of cellular metabolism
- Increasing the transport of substances by diffusion into the cells.
- Shift of the pH value in the alkaline range
- Change in protein structures
- Muscle detonation (reduction of muscle tension).
The thermal effect is mainly due to the promotion of blood circulation. The heat is generated by friction of the sliding tissue layers against each other and is generated by the high-frequency mechanical vibrations of ultrasound. The extensibility of the tissue is improved by the heat, this has a positive effect on tendons, ligaments and joint capsules. In addition, muscle contractures can be treated. The secondary effects of heat are as follows:
- Muscle detonation
- Relief from pain
- Hyperemia (increase blood flow)
- Antiphlogistic (anti-inflammatory) effect
- Improving the viscosity (viscosity) of the synovial fluid
- Resorption increase
The place of sonication is given by the indication. In cases of trauma (injury) or myogelosis (circumscribed hardening in the muscles), the ultrasound probe is placed locally. However, reflex ultrasound can also be applied, which influences the organ system via connections of visceral nerves with skin nerves (Head‘s zone). Several options are available for optimal application of ultrasound therapy. Ultrasound is transmitted to the patient’s tissues via an ultrasound probe and can be guided in different ways:
- Dynamic sonication – The ultrasound probe is moved rhythmically over the skin at a steady pace with light pressure. Circular, stroking as well as overlapping movements are common.
- Semistatic sonication – The ultrasound probe is moved in a circular motion on the spot. This serves the targeted sonication of small areas.
- Static sonication – The ultrasound probe is not moved. This form of treatment can easily cause thermal damage. For this reason, the intensity is reduced and the application is performed at intervals.
Since the ultrasound is easily reflected by the skin and then does not penetrate into the tissue, it must be applied via a coupling medium. Suitable for this purpose, for example, the usual ultrasound gel, kerosene oil or even gel containing drugs (so-called phonophoresis – improving the drug effect by promoting blood circulation and improved absorption). This direct coupling differs from indirect coupling, where ultrasound is transmitted to the patient’s tissues under water. Further notes
- Treatment outcomes of pseudarthroses with low-intensity pulsed ultrasound (LIPUS) can rival those of surgery, according to a meta-analysis. Pseudarthroses that were at least three months old healed in 82% of cases under LIPUS, and those that were at least eight months old healed in 84% of cases.
Benefit
Ultrasound therapy can be used as a complement to conventional medical treatment of many diseases of the musculoskeletal system, thus exerting its curative effects. In addition, it can be used as a combination treatment with low-frequency electrotherapy.
