Ultrasound Therapy As Used By Physiotherapists?
Ultrasound therapy in physiotherapy is the utilization of sound waves to help stimulate a healing response. As a result, this from of ultrasound is referred to as therapeutic ultrasound, the sound waves in therapeutic ultrasound are sound waves that sit above the range capable of being detected by human hearing. Such sound waves have been used for decades by physiotherapists to help treat musculoskeletal problems.
The normal human audible range is considered to be ranging from 16Hz to around 15-20,000Hz. Beyond this upper limit of 20,000Hz the mechanical vibration generated by a therapeutic ultrasound machine is referred to as ultrasound. The frequencies used in physiotherapy practices are are typically 1.0 MHz and 3.0 MHz indicating the sound waves are operating at 1-3 million cycles per second.
The basic principle of ultrasound therapy as a healing aid is about “stimulating” tissue using these high frequency sound waves. These ultrasonic waves are produced by means of mechanical vibration in the metal application head of the machine. During the treatment, your physiotherapist moves the application head slow rhythmical circular motions over the treatment area transmitting the energy into the target tissues. An ultrasound coupling agent is used between the application head and the skin because when ultrasound waves meet air it causes a dissipation of these waves. The most common coupling agent is an aqueous gel, this coupling gel helps ensure maximal contact between the treatment head and the surface of the skin, providing a medium through which the sound waves can travel passing into the body. Ultrasound can also be applied under water, seeing as water is another medium ultrasound waves can travel through. Therapeutic ultrasound may be used in this way when dealing with difficult areas that are difficult to treat when using a coupling gel such as the hand.
What Injuries Can Ultrasound Therapy Be Used To Treat?
Therapeutic ultrasound is used in physiotherapy to treat a variety of musculoskeletal conditions. Research has shown the modality to cause an increase in tissue healing rates and scar tissue breakdown. Some common applications are to apply ultrasound to ligament sprains, muscle strains and soft tissue bruising. Seeing as ultrasound can cause an increase in tissue activity certain uses ultrasound therapy are contraindicated including:
- Application over local malignancy
- Application of metal implants
- Application over an area of acute infection
- Use on individuals with vascular abnormalities
- Application directly on the abdomen of pregnant women
- It is also contraindicated to apply ultrasound directly overactive growth plates in children, over the eyes, skull, or testes.
However, when used by highly trained professionals, therapeutic ultrasound is very unlikely to cause any adverse effects.
How Does Ultrasound Therapy Work?
The therapeutic effects of ultrasound therapy are generally divided into two categories, thermal and non thermal effects.
Thermal Effects Of Ultrasound Therapy:
Sound waves are longitudinal waves consisting of areas of compression and rarefaction, tissues exposed to a sound wave will oscillate as the energy within the sound wave is passed into the tissue. An increase in the molecular vibration in tissue due to ultrasound therapy can result in the production of heat in the tissue, thus ultrasound can be used to produce thermal changes in tissues. It is relevant to note here that as an ultrasound wave passes through tissues, energy levels within the wave diminish as energy is transferred to then tissues, meaning tissues sitting farther from the surface will be exposed to less ultrasonic energy than the superficial tissues. This necessitates the appropriate selection of treatment frequency relative to the target tissue. This is vital for the effectiveness of the therapy because the different frequencies (1.0 MHz and 3.0 MHz) of therapeutic ultrasound have different depths of penetration.
Human tissues most effectively heated via ultrasound include:
- Collagenous tissues (ligament, tendon & fascia)
- Fibrotic muscle tissue
Non-Thermal Effects Of Ultrasound
As well as ultrasound therapy having the above-mentioned thermal effects, this electrotherapeutic device is reported to have non-thermal effects too. Ultrasound treatment is thought to accelerate the normal resolution time of the inflammatory process by attracting more mast cells to the site of injury and may cause an increase in blood flow which can be beneficial in the sub-acute phase of tissue injury.
Ultrasound may also stimulate the production of collagen (being the main component in tendons and ligaments) hence this may accelerate the proliferative phase of tissue healing. Ultrasound is also thought to improve the extensibility of mature collagen thus can have a positive effect on fibrous scar tissue which forms following injury.
It is generally considered that any positive effects regarding healing with the use of ultrasound therapy are attributed to these stated non‑thermal effects more so than the thermal ones.
Ultrasound Therapy And Sydney Physio Clinic
At Sydney Physio Clinic we realize that physiotherapists will develop their own style of practice as they mature as a practitioner. This will be based on influences during their training, practice and through their continuing education. These educational influences coupled with subjective and objective experiences as a treating practitioner will dictate how they treat patients and what modalities of treatment they prefer to use. Physiotherapists have a number of treatment approaches at their disposal when helping their clients and electrotherapeutic devices such as ultrasound therapy, laser and shocwkave therapy make up only a small part of their arsenal.
Disclaimer: This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific medical advice or assistance on Physio And Ultrasound Therapy should consult his or her general practitioner, physiotherapist, orthopaedic surgeon or otherwise appropriately skilled practitioner.