Shoulder function may not be fully restored after surgery

Shoulder motion after rotator cuff surgery remains “significantly different” when compared to the patient’s opposite shoulder, according to a Henry Ford Hospital study.

The findings were presented by Michael J. Bey, PhD, at the 2011 Orthopaedic Research Society’s annual meeting in Long Beach, Calif.

Patient satisfaction after the surgical repair of a torn rotator cuff is generally high, the study noted, but long-term shoulder function — specifically strength and dynamic joint stability — are reportedly not always restored.

The findings, Bey said, suggest that restoring normal joint mechanics may not be necessary to achieve a satisfactory clinical outcome.

“Our study suggests that surgery doesn’t necessarily restore normal shoulder strength or normal shoulder motion,” Bey stated in a release. “However, patient satisfaction is very high after surgery due in part because it relieves pain and discomfort.”

Twenty-two patients

Bey and his group compared motion in the shoulders of 22 patients who had arthroscopic surgical repair of tendon tears and no symptoms in their other shoulders. To do this, the investigators used high-speed bi-plane X-ray images that provided a 3D view of motion of the arm bone in relation to the shoulder blade. The system allows investigators to measure the position of bones and joints in the body during motion.

“The bi-plane X-ray system allows us to investigate subtle nuances of shoulder function that cannot be detected with conventional laboratory techniques,” Bey stated in the release.

The motion in both shoulders was analyzed at 3, 12 and 24 months after surgery, and the group was looking for changes in shoulder motion and shoulder strength. Conventional clinical outcomes were assessed using the Western Ontario Rotator Cuff (WORC) Index, where lower scores indicate a more satisfactory clinical outcome.

Complex relationships

The study found that an increase in superior translation of the humeral head was indicative of a less satisfactory clinical outcome. This could indicate that an increase superior translation of the humeral head “is related to not only the development of symptoms following a rotator cuff tear, but to a patient’s satisfactory clinical outcome following rotator cuff repair,” the authors wrote.

Furthermore, the authors noted, increased shoulder strength was shown in the study to be positively associated with improved clinical outcome. This factor is just one of many, they wrote, “complex relationships between [gleno-humeral head] mechanics, shoulder strength, and clinical outcome.”

“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,” Bey added in the release. “These clinical studies are aiding in our understanding of both the origin and treatment of rotator cuff tears.”

Reference:
Peltz, CD, et al. Clinical outcome after rotator cuff repair is related to dynamic joint mechanics and shoulder strength. Paper #0550. Presented at the 2011 Orthopaedic Research Society annual meeting. Jan. 13-16. Long Beach, Calif.
Disclosure: The study was supported by grant AR051912 from NIH/NIAMS.

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