New on the Horizon: Musculoskeletal Ultrasound
I learned something new this week. My class in radiology is looking at ultrasound. Before I did the reading I thought it would be the same old, same old. Everyone knows about US. I was wrong. We're not studying the therapeutic US we use in our clinics. We're studying musculoskeletal US which is a diagnostic procedure. I had no idea anything like this even existed much less the implications for PT.
First I need to provide some background information. Musculoskeletal US or rehabilitative ultrasound imaging (RUSI) works on the same principle as the US we're familiar with. It uses sound waves to create images similar to the way ECHO cardiograms and prenatal pictures are created. RUSI is used to measure different aspects of muscle morphology including thickness, cross-sectional area and volume. It shows the relationship of the muscle under study to the tissues surrounding it. RUSI creates a real-time picture of what the muscle is doing when the image is created. RUSI is also used in research. The research can have continuous images of a muscle before, during and after contraction. Compared to X-ray, CT and MRI, RUSI has the advantages of being less expensive, less time consuming and doesn't involve exposure to radiation. The machines are similar to those used for ECHOs so it is also portable.
Most of the research I saw involved images of the shoulder, although it can be used on any superficial structure such as a joint or on deeper structures such as organs. One study looking at rotator cuff repairs found RUSI had an 86% accuracy rate for correct diagnosis as determined by surgery. The same study found MRI to have an 82% accuracy. All of the research concluded that RUSI was excellent for diagnosing rotator cuff repairs.
So, what does this mean for PT? Some of the same individuals who are pushing for direct access and the ability to order X-ray also believe PTs should be able to perform RUSI examinations in the clinic. Interpretation of RUSI images requires two things. One is a thorough knowledge of the anatomy being studied. The second is a thorough knowledge of neuromuscular and musculoskeletal disorders. Not only do PTs have both, but their knowledge is significantly greater than that of a radiologist when it comes to superficial joints and surrounding tissues. Giving PTs this ability would also be cost effective.
The argument has already been made that direct access would be cost effective as would permitting us to order X-rays. The same argument applies to RUSI with an additional bonus. A PT who is able to perform RUSI could do so at the initial visit and diagnosis a rotator cuff tear the same visit. That patient could then be referred to a physician for medical management minus the expense of multiple x-rays and other studies, a few weeks of pain and ineffective therapy and with a diagnostic image that reveals the injury. The same PT could then use RUSI post-operatively for muscle re-education by showing the patient in real-time what happened when he or she contracted a muscle.
Other than lacking true direct access, the biggest drawback to RUSI is the long learning curve. All the literature I reviewed talked about introductory courses of 3 to 5 days followed by up to 2 years of supervised study, including performing up to 50 or 60 one-on-one scans. Completion of the programs results in certification to perform the examinations. Currently the courses are open to MDs, MDs in training and retired MDs. I saw one course open to sonographers. That certification means the person is competent to perform RUSI of any structure, not just the superficial joints that would interest a PT. A PT would need much less training to perform scans of the shoulder, hips, knees and ankles.
For anyone interested, here are some articles to reference. I found these using CINHAL which can be accessed through Open Door on the APTA Website.
Robertson, D., Brown, J. (2007) An introduction to musculoskeletal ultrasound in sports and exercise medicine. Sportex Medicine, 33, pgs. 20-26.
Robertson, D. (2007) The clinical applications of musculoskeletal ultrasound in primary care. Sportex Medicine, 34, pgs. 21-26.
Sullivan, O., Bentman, S, Bennett, K., Stokes, M. (2007) Rehabilitative ultrasound imaging of the lower trapezius muscle: Technical description and reliability. Journal of Orthopedic & Sports Physical Therapy, 37, pg. 620-626.
Whitake, S., Teyhan, D., Elliot, J., Cook, K., Languin, H. Dahl, H., Stokes, M. (2007) Rehabilitative ultrasound imaging. Understanding the tecnnology and its applications. Journal of Orthopedic & Sports Physical Therapy, 37, pgs 434-449.