MRI Tear Characteristics as a risk factor for Rotator Cuff Repair

Rotator cuff muscle quality has been implicated as having a direct effect on the ability of a repair to heal and the functional outcome after a repair. Both fatty degeneration (comparative amount of muscle tissue to fat as determined by MRI or CT scan) and muscle atrophy (volume of rotator cuff muscle as determined by MRI or CT scan) have been evaluated in regards to their effects on tendon repair healing and outcomes. Based upon six Level IV studies^{48, 47, 49, 50, 51, 52} it is an option for a surgeon to advise a patient undergoing rotator cuff repair about the negative affects of supraspinatus and infraspinatus muscle atrophy and fatty degeneration on both tendon healing and clinical outcomes.

One study⁴⁸ evaluated 38 patients prospectively who underwent a rotator cuff repair with MRI and outcome scores (ASES score, Constant-Murley score) at baseline and at 1 year postoperative. The authors reported that worse infraspinatus muscle atrophy and fatty degeneration were correlated with worse ASES and Constant-Murley scores. Also, worse fatty degeneration correlated with poorer infraspinatus healing. Worse supraspinatus atrophy correlated with worse ASES scores, Constant-Murley scores and tendon healing. Finally, worse supraspinatus fatty degeneration correlated with worse tendon healing.

A second study⁵⁰ evaluated twenty-eight patients who underwent repair of a massive rotator cuff tear at 44 months postoperative with UCLA scores. Preoperative fatty degeneration of the infraspinatus correlated with inferior postoperative UCLA scores.

Several authors focused their evaluation on the correlation of just supraspinatus muscle quality to tendon healing and outcomes. One study evaluated twenty-seven⁴⁷ patients after a mini open rotator cuff repair for an isolated supraspinatus tear with an MRI and Constant- Murley score at an average of 67 months postoperative. This study determined that preoperative supraspinatus muscle atrophy correlated negatively with postoperative Constant-Murley scores. Another study⁴⁹ evaluated 53 patients after isolated arthroscopic supraspinatus repair with Constant-Murley scores and MRI at an average of 26 months postoperative. Preoperative supraspinatus fatty degeneration and muscle atrophy correlated with worse healing rates. A final study⁵¹ prospectively evaluated 30 chronic rotator cuff tears of varying sizes, which underwent an open rotator cuff repair, with an MRI at an average of 21 months postoperative. The authors determined that preoperative supraspinatus muscle atrophy correlated with poorer healing rates.

Based upon these studies, preoperative infraspinatus fatty degeneration and muscle atrophy correlated with worse outcomes and healing. Preoperative supraspinatus muscle atrophy correlated with worse outcomes and healing. Finally, preoperative supraspinatus fatty degeneration was correlated with worse healing, but not necessarily worse outcomes.