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Saturday, March 13, 2004

Rotator repair won't reverse muscle atrophy

By Mary Ann Porucznik

Rotator cuff repair can relieve pain but does not result in a reversal of fatty infiltration or muscle atrophy according to the presenters of Scientific Paper 217. Both fatty infiltration and muscle atrophy are often seen in large tears of the rotator cuff.

Investigators wanted to analyze the efffect of these conditions on clincial outcome and postoperative repair integrity. As part of a prospective outcome study of rotator cuff repair, they compared fatty infiltration and muscle atrophy using both preoperative and postoperative magnetic resonance images (MRI).

The study focused on 39 patients (mean age of 62 years; minimum follow-up of 1 year) with full-thickness rotator cuff tears. After rotator cuff repair, clinical outcomes were determined based on American Shoulder and Elbow Surgeons (ASES) and Constant scores. Both preoperative and postoperative MRIs were examined. The degree of fatty infiltration was graded using a 5-point scale; muscle atrophy was graded using a 4-point scale.

Researchers found that rotator cuff repair, whether open or arthroscopic, significantly reduced pain and improved function, ASES and Constant scores (p < 0.05). There was a postive correlation between both fatty infiltration and muscle atrophy and tear size (p < 0.0001, r = 0.712), and an inverse correlation between both fatty infiltration and muscle atrophy and ASES scores, Constant scores and strength measurements (p < 0.03).

Fatty infiltration in the infraspinatus had a greater impact on strength in forward elevation and external rotation than similar levels of infiltration in the supraspinatus. Patients with greater degrees of fatty infiltration in the supraspinatus, however, were more likely to experience a retear of the rotator cuff (p < 0.001, r = 0.745). Pain relief was independent of the severity of both fatty infiltration and muscle atrophy.

"Overall, the amounts of fatty infiltration and muscular atrophy progressed regardless of cuff integrity," noted the researchers. Only one patient improved from moderate to mild muscle atrophy; in 18 patients, muscle atrophy and fatty infiltration remained unchanged and in 21 patients, muscle atrophy and/or fatty infiltration actually worsened.

"The fact that...there is no reversal of the changes, even with successful maintenance of the rotator cuff repair, may portend the functional ability of the muscles to act in an appropriate biomechanical fashion. A better understanding of these factors may allow better preoperative counseling of patients as to expected functional results, and perhaps a clearer indication as to which severely involved tendons should have a repair attempt,"reported the researchers. If muscle degeneration is present before the surgery, patients should be counseled not to expect reversal of the damage.

Investigators included Julie Bishop, MD, of Columbus, Ohio; Ian Lo, MD, of Calgary, Alberta, Canada; and James N. Gladstone, MD, and Evan L. Flatow, MD, both of New York City.

  Preop tear of supraspinatus.
  One-year postop showing repair intact but no improvement of fatty infiltration.

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Last modified 20/February/2004