Muscle atrophy and fatty infiltration predict arthroscopic rotator cuff repair outcome

Patients with retears after cuff repair had more muscle atrophy than those with intact cuffs.

Issue: September 2006

HOLLYWOOD, Fla. — When treating patients with arthroscopic rotator cuff repair, surgeons may be able to predict the likelihood of a retear based on preoperative and postoperative MRIs.

At the University Clinic of Münster in Germany, researchers found that high degrees of atrophy and fatty infiltration in the supraspinatus were predictive of a retear. Regardless of cuff integrity, muscle atrophy and fatty infiltration also influenced postop abduction strength and total Constant score, according to study author Dennis Liem, MD.

Liem and his colleagues prospectively evaluated 32 patients with isolated supraspinatus tendon tears and found a 19.6% retear rate, equivalent to retear rates found with open and minimally invasive arthroscopic rotator cuff repair, he said.

Researchers compared the preoperative and postoperative MRIs for these patients to those with intact cuff repairs. "[For intact cuffs] we found no indication that ... structural changes could be reversed," Liem said at the Arthroscopy Association of North America 25th Annual Meeting. "And for the retears we found progressional fatty infiltration and atrophy [correlated] with an inferior clinical outcome."

Clinical and MRI evaluations

All patients had isolated supraspinatus tendon tears, ranging from small to medium sized, and all previously failed conservative treatment. Average age was 60 years. From 2002 to 2003, surgeons treated these patients using the arthroscopic Mason-Allen technique and single-row bioabsorbable anchors, Liem said.

Researchers used the Constant score to clinically evaluate patients at an average 26.5-month follow-up. Two independent examiners, blinded to outcomes, evaluated the pre- and postoperative MRIs, which were all performed on the same MRI machines.

"We used established criteria to evaluate tendon integrity," Liem said. "We used a prestaged grading system, based on the supraspinatus muscle position towards the tangent sign, to evaluate the supraspinatus atrophy. As for fatty infiltration, we used the Goutallier classification from Grade 0 to Grade 4."

MRI comparison findings

Surgeons found that the patients with retears showed significantly lower abduction strength and overall Constant score.

"When comparing the preoperative MRIs of the retears and the intact tendons, we found that the retears had a significantly higher muscle atrophy of the supraspinatus," Liem said. All retear patients had an atrophy score of at least Grade 2.

Comparing postoperative MRIs, the researchers again found significantly higher supraspinatus atrophy in the retear patients. They also found a significantly higher degree of fatty infiltration in the supraspinatus and infraspinatus muscles, Liem said. When the researchers evaluated the structural changes, they found no difference between pre- and postoperative MRIs for the intact cuff repair patients. In other words, they found no significant reversal of fatty infiltration or muscle atrophy in the retear patients. In contrast, between pre- and postoperative MRIs, patients with retears had a significant increase in fatty infiltration for the supraspinatus and infraspinatus, Liem said.

"Regardless of tendon integrity, the grades for fatty infiltration and also the grades for supraspinatus atrophy were predictive of a retear and showed significantly higher retear percentages," Liem said. "Looking at these postoperative MRIs, we found that the fatty infiltration of the supraspinatus and also the atrophy of the supraspinatus were correlated with an inferior clinical result, regarding strength and also overall Constant score."

For more information:
Liem D, Magosch P, Lichtenberg S, et al. MRI examination of arthroscopic rotator cuff repair — Influence of cuff integrity, atrophy and fatty infiltration on the clinical result. #SS-27. Presented at the Arthroscopy Association of North America 25th Annual Meeting. May 18-21, 2006. Hollywood, Fla.