Researchers Pitch Rapid Rotator Cuff Repair

NEW YORK, May 9 -- Rapid repair of a torn rotator cuff is the best guarantee of a return to full mobility with minimal loss of arm strength, orthopedic researchers reported.

The reason is that the degree of atrophy and fatty infiltration of the shoulder muscles - factors that progress over time -- predicts how well the shoulder will perform after surgery, said James Gladstone, M.D., of Mount Sinai Medical Center here.

Indeed, in a small cohort study, atrophy and fatty infiltration were the only independent predictors of how well the shoulder worked following surgery, Dr. Gladstone and colleagues reported online and in the May issue of the American Journal of Sports Medicine.

And, regardless of how soon the surgery was performed or how well the repair lasted, the atrophy and fatty infiltration did not improve over time, they noted.

"Our study suggests there may be a 'point of no return' at which time the muscles undergo irreversible change," Dr. Gladstone said in a statement.

"A clearer understanding of these factors would allow for better preoperative counseling and decision-making as to the most appropriate treatment plan," he said.

The prevalence of rotator cuff injury, an occupational hazard for baseball pitchers, is estimated to be as high as 30% in the general population over the age of 45 who complain of shoulder pain, but the true rate is unknown because many people are asymptomatic and others just don't visit a doctor.

In general, rotator cuff repair - whether performed as open or arthroscopic surgery - is a successful procedure, but the role of muscle quality on the functional outcome and the structural integrity of the tear hasn't been clear, the researchers said.

To shed some light on the issue, they enrolled 38 patients (part of a larger study using MRI to evaluate rotator cuff integrity a year after the procedure) and used regression analyses to correlate factors such as tear size and muscle atrophy to the overall clinical outcome.

The patients (mean age, 62) were evaluated using pre-operative and post-operative MRI scans, and their scores on American Shoulder and Elbow Society, Constant , and pain scales.

The investigators found that rotator cuff repair led to significant improvements (at P<0.0001) in the American Shoulder and Elbow Society, Constant, and pain scores.

The multivariate regression analysis showed:

• The degree of atrophy of the infraspinatus muscle was significantly and negatively correlated with the American Shoulder and Elbow Society score (at P=0.001), the Constant score (at P=0.033) and forward elevation strength (at P=0.04).
• The degree of fatty infiltration of the infraspinatus was significantly and negatively correlated with the American Shoulder and Elbow Society score (at P=0.01) and with external rotation strength (at P=0.004).
• Atrophy of the supraspinatus was significantly and negatively correlated with forward elevation strength (at P=0.013), and fatty infiltration of the muscle was significantly and negatively correlated with external rotation strength (at P=0.04).
• Tear size and the integrity of the repair at one year were not independent predictors of functional outcome. Tear size was, however, the only independent predictor of ultimate cuff integrity.

At the one-year follow-up, rotator cuffs had re-torn in 39% of the patients, the researchers said, and the pre-operative degrees of atrophy and fatty infiltration of the infraspinatus and the supraspinatus were linked to the risk of re-injury.

For example, among those whose rotator cuff remained intact, infraspinatus atrophy averaged 0.30, while among those who suffered a re-tear, the rate was 0.87 - a difference that was significant at P=0.012.

Importantly, Dr. Gladstone and colleagues found, the degree of atrophy and fatty infiltration of the muscle did not improve over time - except in one case, it either was stable or had worsened.

The researchers said the progression was significant for both muscle atrophy and fatty infiltration. All told, 23 patients had mild atrophy or none at all and eight (35%) saw atrophy progress. Of the 15 patients who had moderate to severe atrophy, 10 (67%) progressed.

The study is limited by the small number of patients and the lack of a control group, the researchers acknowledged. They also noted that the natural history of atrophy and fatty infiltration is not well understood, so that the one-year follow-up may be too short.