By Rick Weber
You’ve likely had an MRI at some point in your life. But you probably haven’t experienced musculoskeletal (MSK) ultrasound imaging.
MSK ultrasound imaging was first used in the United States in the 1970s for investigating the rotator cuff, then the Achilles tendon in the 1980s. Its popularity plateaued, likely because of the lack of physicians and sonographers trained in its use, lower reimbursement rates and the advent of the MRI.
Although it remains a specialized service that is more commonly available in large hospitals, ultrasound imaging is gaining traction and popularity, and is becoming more widely available.
“It was initially used for research purposes, but it became clear that it could be used for diagnostic and treatment purposes,” says Arie van Duijn, a professor of Physical Therapy in the Department of Rehabilitation Sciences at Florida Gulf Coast University’s Marieb College of Health & Human Services. “Research started to show that the reliability and validity for diagnosing common superficial structures was in many cases comparable to the MRI, and with the rapid decline of the cost of ultrasound imaging equipment, this led to the gradual increase in use of this technology.
“Portable ultrasound imaging units can now be bought for as low as $5,000, making it accessible to many healthcare providers, and this has led to a rapid increase in its use, especially in the last five years. Equipment manufacturers have also started to develop specialized MSK software for their units, also making it easier for providers to start using it in practice.”
Van Duijn says MSK ultrasound imaging provides a low-cost, high-quality, reliable alternative to traditional imaging modalities such as MRI and CT for MSK health care providers to examine superficial MSK structures that can show these structures moving in real time.
It can assist providers when targeting structures for injections or dry needling by visualizing needle placement, and can provide information about effectiveness of treatment. It can be used for biofeedback purposes, such as allowing patients to learn how to
contract muscles that they can’t see with the naked eye. And because it is a very safe imaging modality that does not require radiation, it is used in obstetrics (OB) for visualizing fetuses.
There are some downsides to MSK ultrasound imaging:
• Only superficial structures can be seen. Since sound waves cannot penetrate bone, structures that are covered by bone cannot be seen by ultrasound imaging (for instance the ACL or meniscus in the knee are both deep structures largely covered by bone so are difficult to visualize with ultrasound imaging).
• There is a learning curve for providers, so continuing education is needed to teach the technical skills needed.
• Unit cost can be a barrier, but the cost is coming down rapidly.
Facilities such as emergency rooms already had the equipment that was used for other diagnostics (such as OB and vascular), so there was early adoption there for MSK purposes. There is a rapid increase in the equipment in orthopedic physician offices and physical therapy practices now that the cost of the equipment is coming down.
Hand-held portable units are now starting to be used outside the office at what is referred to as POCUS (point-of-care ultrasound), such as in athletics, where athletic trainers, physical therapists and/or physicians use it on the sidelines. Those portable units are simply probes that connect to a phone or tablet that has the image-display app.
Van Duijn, along with FGCU Doctor of Physical Therapy (DPT) program faculty and graduate students, has been using MSK ultrasound imaging in ongoing projects with FGCU athletics to evaluate how tendon and ligament structures behave during the course of a season in various sports and identify tissue changes that may indicate a higher injury risk.
They have measured the thickness of tendons and ligaments of baseball players and golfers at multiple times throughout the season to understand how those tissues change, and also looked at the presence of fluid in the tendon/ligament to determine what is normal.
“Once we understand the normal course that can be expected, we hopefully can identify if an athlete has abnormal changes that may indicate an increased risk for injury such as a rotator cuff or elbow ligament tear,” he says. “We recently acquired the technology to also measure tissue stiffness—called shear wave elastography—that may show abnormal tissue changes that are not yet showing in a change in thickness.
“Decreased tendon or ligament stiffness means that those tissues are less able to withstand the high forces placed on those tissues by overhead throwing, etc., and may also indicate an increased injury risk. Once an athlete tears a tendon or ligament, they are usually looking at surgery (Tommy John elbow surgery) and a good number of those athletes will never be able to come back to the level they were before the injury, so it is important to try to prevent these devastating injuries.
“We are also using ultrasound measurements to evaluate other injuries such as fractures, and to evaluate to outcomes of physical therapy interventions such as manual therapy, exercise, cold water immersion, etc.
“We now are starting to understand what we can normally expect throughout the season. The next phase of these projects is to identify what kinds of deviations from those normals are associated with increased injury risk.”
Florida Gulf Coast University
Marieb College of Health & Human Services
10501 FGCU Boulevard South
Fort Myers, FL 33965
(239) 590-1000 | fgcu.edu