Fatty replacement of rotator cuff in brain-injured patients is associated with hemiplegic arm function, but not with tendon tear: A multicenter study.

Background: The association between fatty replacement of rotator cuff and hemiplegic upper extremity function has not been defined yet. Moreover, the relationships among rotator cuff tears, shoulder pain, spasticity, and fatty replacement were not clearly studied.

Objective: We investigated the association of fatty replacement of the supraspinatus and infraspinatus muscles with tendon tear in stroke or brain-injured patients.

Methods: A total of 72 hemiplegic patients were enrolled in 3 hospitals, and ultrasonography of both shoulders was performed once. Fatty replacement of the supraspinatus and infraspinatus was graded by the visibility of outer contours, pennate pattern, central tendon, and echogenicity.

Results: Fatty replacement was observed in 22 (30.6%) out of the 72 patients (in 18 supraspinatus muscles and 12 infraspinatus). Inter-rater agreement (kappa value) between the 2 physiatrists was 0.530 for the supraspinatus, and 0.411 for the infraspinatus. The Fugl-Meyer assessment score, Brunnstrom stage, and modified Barthel index were significantly lower in patients with fatty replacement of the supraspinatus or infraspinatus (group 1) than in those without (group 2). The motor power of both shoulders, the pain-free range of motion, spasticity, and hemiplegic shoulder pain were comparable between the two groups. The tear rate of the supraspinatus, infraspinatus, or subscapularis tendon at the hemiplegic side was higher than that at the contralesional side in each group, although there was no significant difference between group 1 and group 2.

Conclusion: Disuse leading to muscle atrophy rather than rotator cuff tear might be the cause of fatty replacement of these muscles, which may be associated with decreased function of the hemiplegic upper extremities.