Ultrasound Therapy
ultrasound therapy is a common form of electrotherapy that involves the use of sound waves of high frequency (greater than the audible frequency of humans, or higher than 20 kHz) to treat soft-tissue injuries. Therapeutic ultrasound usually runs on a frequency of 1 MHz or 3 MHz and the medium of coupling is usually gel.
Ultrasound is primarily applied to enhance the healing process of tissues, decrease pain, decreases inflammation, and enhances the extensibility of tissues. It is either capable of delivering in continuous mode (thermal effects), or in pulsed mode (non-thermal effects) depending on stage of injury.
Pathophysiology
The mechanism of the ultrasound therapy is to send high-frequency sound waves to body tissues, which results in mechanical vibration of the cellular level. As the ultrasonic waves go through tissues, they cause compression and rarefaction alternating phases. This mechanical effect generates microscopic movement in the cells and in interstitial fluids and is the foundation of the thermal and non-thermal physiological effects that promote tissue healing.
In the process of continuous ultrasound, the sound energy absorbed is changed into heat, which leads to an increase in the temperature of tissues, particularly collagenous (tendons, ligaments, joint capsules, and scar tissue). This profound heating results in vasodilation, augmentation of local blood circulation, boostabloity of oxygen delivery as well as a stimulated rate of metabolic activities. Increase in temperature also decreases muscle spasm, pain and increases the extensibility of connective tissue and it can be applied in chronic conditions and joint stiffness.
The major effects are non-thermal in pulsed ultrasound. Among them is one phenomenon, known as stable cavitation, in which microscopic size gas bubbles in tissue fluids are stretched and shrunk rhythmically without collapsing. In this process, the cell membrane becomes more permeable facilitating the better exchange of the nutrients and waste products. The other important effect is the acoustic streaming which is defined as the one-way flow of fluid around the cells. Sound stimulation of cells activates protein synthesis, stimulates inflammatory cell repair in the inflammatory and proliferation phases of healing and repair.
All in all, the pathophysiological actions of ultrasound therapy increase the metabolism of the cells, circulation, fibroblast activity, and collagen formation and alignment. The overall effects of this are faster healing of the tissue, lessened pain and inflammation, and restoration of normal tissue functioning, thus making ultrasound a modality that is effective in the management of musculoskeletal injuries at various stages of recovery.
Commonly Used Injuries & Conditions
Soft Tissue Injuries
Muscle strain
Ligament sprain
Tendinitis / Tendinopathy
Tenosynovitis
Bursitis
Joint & Periarticular Conditions
Osteoarthritis
Rheumatoid arthritis (subacute/chronic phase)
Adhesive capsulitis (frozen shoulder)
Joint stiffness
Sports Injuries
Hamstring strain
Achilles tendinitis
Tennis elbow (lateral epicondylitis)
Golfer’s elbow (medial epicondylitis)
Plantar fasciitis
Post-Traumatic & Post-Surgical Conditions
Scar tissue
Soft tissue adhesions
Delayed wound healing
Neuromuscular Conditions
Myofascial pain syndrome
Trigger points
Contraindications
Malignant tumors – Ultrasound may stimulate cancerous tissue growth.
Pregnancy (over the abdomen or lower back) – May affect the fetus.
Over the eyes – Risk of damage to sensitive ocular tissues.
Over the heart or carotid sinus – Can affect cardiac function or blood pressure.
Over active bleeding or hemorrhagic regions – May exacerbate bleeding.
Over areas of thrombophlebitis – Risk of dislodging a blood clot.
Pacemakers or implanted electrical devices – Avoid direct contact.
Acute infections – Heat may worsen inflammation.
Epiphyseal plates in children – Risk of affecting bone growth if misused.
Sensory deficits – Patient may not perceive excessive heat.