If placing groceries on your kitchen countertop makes your shoulder ache or you've been in pain since that wicked backhand you tried in tennis, a rotator cuff injury might be the culprit. The good news is that doctors now can turn to a faster, cheaper way to confirm that hunch and decide whether surgical treatment would help.
High-resolution ultrasonography, which bounces sound waves off objects to image them, can visualize the rotator cuff that stabilizes and coordinates shoulder movements. However, this advanced variation of ultrasonography (US) has not been widely used to evaluate cuff tears.
Researchers at Washington University School of Medicine in St. Louis now have compared high-resolution US images taken before shoulder surgery to surgical findings in 98 patients. They found that US images of 100 shoulders were sharp enough to detect completely torn tendons of the rotator cuff.
"Ultrasound provides an excellent way to look at rotator cuff injuries, and also at dislocations of the tendon of the biceps muscle," says William D. Middleton, M.D. Middleton, a professor of radiology, co-authored an article on the study, which was published in the April 2000 issue of The Journal of Bone and Joint Surgery.
'Extremely accurate'
Doctors often order noninvasive images to evaluate whether a shoulder injury would benefit from surgery. This approach might help if a patient has completely torn part of the rotator cuff, for example.
The rotator cuff consists of four muscles and their associated tendons. These components cover the front, top and back of the shoulder joint, and are subject to wear and tear. The cuff supports the large ball that is the top of the long bone of the arm as it rests in a shallow socket, an arrangement that allows for excellent range of motion, but is structurally unstable and injury-prone. Traditionally, doctors have ordered magnetic resonance imaging (MRI) to evaluate a shoulder for a rotator cuff tear. To assess the value of US, the researchers conducted a study on patients who underwent US and arthroscopic shoulder surgery between January 1996 and September 1997. Arthroscopy is a surgical technique that involves inserting a pencil-thin tube with a lens at its end into the shoulder. The arthroscopic images are projected onto a television screen to guide surgery.
During surgery, Ken Yamaguchi, M.D., an assistant professor of orthopedic surgery and chief of the medical school's Shoulder and Elbow Service, identified 65 full tears of tendons that connect rotator cuff muscles to bones. All of these tears also were correctly identified by US before surgery. In addition, five of six dislocated tendons of biceps were identified by US. The imaging technique also permitted identification of the majority of partially torn rotator cuff tendons. "For imaging the rotator cuff, ultrasound is extremely accurate -- as accurate as MRI," Yamaguchi says.
Comparing US to MRI
To image deep tissues, US technologists and radiologists place a probe directly on a patient's shoulder and move the probe to different locations. The shoulder is moved to expose portions of the rotator cuff that normally lie beneath bone because US can't travel through bone. This repositioning can be uncomfortable for patients with shoulder pain. However, the researchers found that shoulder injuries assessed using MRI produced similar amounts of pain.
This finding comes from a separate study of 80 patients who had been imaged using both techniques. The study, performed by Middelton, Yamaguchi and Sharlene A. Teefey, M.D., associate professor of radiology and chief of Diagnostic Ultrasound at the School of Medicine's Mallinckrodt Institute of Radiology, also revealed that the majority of the patients preferred US over MRI.
During MRI, patients lie on a table for about an hour while a series of scans are taken. Any movement by the patient can blur the images. Therefore, patients have to remain motionless for 10 or more minutes at a time, which can produce shoulder pain. Because US produces images immediately, movement doesn't ruin the results. "People tolerate ultrasound extremely well because they can modify any uncomfortable position," Middleton says.
Patients also get US exam results immediately, and it provides other benefits. "It's an easier, quicker, less expensive test," Teefey says. US exams of the shoulder usually take less than 15 minutes and cost only one-fourth as much as MRI examinations, which typically run about $1,600.
However, Middleton and Teefey note that MRI remains a valuable technique for imaging many shoulder injuries. It can visualize the entire shoulder -- including bones, ligaments, cartilage and the rotator cuff. Therefore, it provides a more global assessment of the shoulder than US can.
They add that US still has its place, though. "Ultrasound is a very attractive way to image the shoulder, given its ease, tolerance by patients, low cost and excellent accuracy," Teefey says. "We now use it routinely instead of MRI to evaluate rotator cuff tears."
Note: Teefey SA, Hasan SA, Middleton WD, Patel M, Wright RW, Yamaguchi K,"Ultrasonography of the Rotator Cuff: A Comparison of Ultrasonographic and Arthroscopic Findings in One Hundred Consecutive Cases," The Journal of Bone and Joint Surgery, 82-A (4): 498-504, April 2000.
Journal
Journal of Bone and Joint Surgery