Ultrasound Therapy

Excerpt

The first documented and published use of ultrasound began in 1958 when a team led by Ian Donald in Glasgow first utilized sonography as a diagnostic tool in the practice of obstetrics and gynecology. Today, patients benefit from a wide range of sonographic uses. Due to the lack of radiation, low cost, and portability, fetal monitoring, joint injections, arterial line placements, and diagnoses of joint pathology are some of the many uses of ultrasound as an imaging and diagnostic modality. However, technological advancements and engineering have also allowed ultrasound to become a therapeutic modality. Most classically, continuous therapeutic ultrasound has been used to treat various musculoskeletal pathologies like osteoarthritis, soft tissue shoulder pathology, and myofascial pain. Ultrasound use has also expanded into atrial ablation, extracorporeal shockwave lithotripsy, accelerate fracture healing, limited rhytidectomy, and, when paired with MRI, can be used to treat benign and malignant soft tissues tumors. Within this activity, we will focus on the physical principles and theories that form the basis for ultrasound therapies, the interactions between the ultrasound and human anatomy, indications of use, safety concerns, and its utility amongst the healthcare team.

Therapeutic ultrasound relies on a variety of power settings and comes from numerous manufacturers, but the principles remain the same; the ultrasound machine conducts an electrical signal through crystals found in the head of the ultrasound probe. The crystals vibrate and create mechanical waves at frequencies outside the range of human hearing (20 hertz to 20000 hertz). This phenomenon is known as the ‘piezoelectric effect.’ The waves produced transfer energy to the surface of the human body or may be focused to target soft tissue deep to the epidermis. Tissues containing a higher content of proteins (muscle and bone) absorb the energy from the mechanical waves at a higher rate than tissues with higher water content (fat). Additionally, the energy from the ultrasound may be focused to affect tissues deep to the surface without causing harm to more superficial tissues. Extracorporeal shockwave lithotripsy is a common procedure that demonstrates this mechanism.