Ultrasound is a cross-sectional imaging method based on sound waves reflected off tissue interfaces. Ultrasound predates CT and MRI for soft tissue imaging. In the last 30 years it has been increasingly employed in imaging of the musculoskeletal system.
Diagnostic ultrasound has its origins in sonar (sound navigation and ranging), a technique developed as a navigation tool for submarines and for the detection of objects under water. Ultrasound was employed in an unsuccessful attempt to locate the wreck of the Titanic in 1912 and was widely used in the submarine warfare of World War I (1914–1918).1
Medical use of diagnostic ultrasound started in the 1940s, and in the early 1950s the ability to detect lumps in breast tissue was demonstrated. Although ultrasound was the first technique available for accurate diagnosis of soft tissue lesions, it was not until the 1980s that ultrasound gained widespread acceptance for the evaluation of the musculoskeletal system.
Ultrasound in Rehabilitation
Physical therapists increasingly employ ultrasound imaging for diagnosing musculoskeletal disorders. There is a surge in the number of seminars and conference workshops, but there are still only a few publications by physical therapists on diagnostic ultrasound. Physical therapists, however, have a long history with ultrasound as a form of biofeedback. Ultrasound has played a key role in the development of treatment regimens for lumbar pain and is routinely used in physical therapy clinics in order to examine the activity of the stabilizing musculature of the lumbar spine, as well as other muscles. Such application of ultrasound is sometimes referred to as real-time ultrasound imaging or rehabilitative ultrasound imaging (RUSI).
Rehabilitative Ultrasound Imaging
According to a consensus statement by an international symposium on rehabilitative ultrasound, “RUSI is a procedure used by physical therapists to evaluate muscle and related soft tissue morphology and function during exercise and physical tasks. RUSI is used to assist in the application of therapeutic interventions aimed at improving neuromuscular function.”2
Physical therapists have been at the forefront of RUSI for two decades. Numerous studies have employed ultrasound in order to obtain real-time information about the role of the multifidus and transversus abdominis (TrA) muscles in stabilization of the lumbar spine.3 The importance of the TrA for spinal stability was established partly through studies by physical therapists demonstrating that contraction of the TrA precedes movement of the limbs in healthy individuals,4 while this activity is decreased in individuals with low back pain. This difference in activation patterns, and other dysfunctions of the stabilizing musculature in individuals with low back pain, was thought to explain the high recurrence rate of low back pain.5 Findings related to normal and abnormal function of the TrA have been used in order to devise exercise regimes for stabilization employing low-level co-contractions of transversus abdominis and multifidus. ...