Shoulder function not fully restored after surgery

In the study, researchers used X-rays providing a 3D view of motion of the arm bone in relation to the shoulder blade, to compared motion in the shoulders of 14 patients who had arthroscopic surgical repair of tendon tears and no symptoms in their other shoulders.

Researchers analyzed the motion of both shoulders at three, 12 and 24 months after surgery, looking at changes in shoulder motion and shoulder strength.

“Although patient satisfaction is generally very high after surgical repair of a torn rotator cuff, the data suggest that long-term shoulder function – in particular, shoulder strength and dynamic joint stability – may not be fully restored in every patient,” says Michael Bey, Ph.D., director of the 3,000-sq.-ft. Herrick Davis Motion Analysis Lab at Henry Ford Hospital.

Dr. Bey will present the results Saturday at the Orthopaedic Research Society's annual meeting in New Orleans.

“We found that the motion pattern of the repaired shoulder is significantly different than the patient's opposite shoulder,” says Dr. Bey. “These differences in shoulder motion seem to persist over time in some patients.”

According to the American Academy of Orthopaedic Surgeons, rotator cuff tears are a common cause of pain and disability among adults, especially among those over age 40. The rotator cuff is comprised of four muscles and several tendons that create a covering around the top of the upper arm bone. The rotator cuff holds the bone in and enables the arm to rotate.

The rotator cuff can be torn from a single injury but most tears result from overuse of the muscles and tendons over years. Those at especially high risk are those who engage in repetitive overhead motions. Common treatments include anti-inflammatory medication, steroid injections, physical therapy and surgery.

Dr. Bey explains that the study findings suggest that restoring normal joint mechanics may not be necessary in order to achieve a satisfactory clinical outcome.

“Our study suggests that surgery may restore normal shoulder strength but doesn't necessarily restore normal shoulder motion,” says Dr. Bey. “It could be, however, because the shoulder pain goes away, there is value in surgery.”

The study was done using a high-speed biplane X-ray system, one of only three in the country, which allows researchers to measure the position of bones and joints in the body during motion to within half a millimeter.

“The biplane X-ray system allows us to investigate subtle nuances of shoulder function that cannot be detected with conventional laboratory techniques,” explains Dr. Bey.

Next steps for Henry Ford researchers include looking at physical therapy vs. surgery, and investigating improved or different techniques for treating rotator cuff tears.

Dr. Bey is also presenting results from another study at the conference which looks at the condition of the shoulder prior to surgery.

“What further complicates our understanding of rotator cuff tears is that we have also shown that there are subtle yet important differences in shoulder function between the dominant and non-dominant shoulder of healthy volunteers,” says Dr. Bey. “These ongoing studies are aiding in our understanding of both the origin and treatment of rotator cuff tears.”

Funding: National Institutes of Health and Henry Ford Hospital.