Our aim was to describe the atypical pattern of increased fatty
degeneration in the infraspinatus muscle compared with the supraspinatus
in patients with a massive rotator cuff tear. We also wished to
describe the nerve conduction and electromyography findings in these
patients. A cohort of patients undergoing surgery for a massive rotator
cuff tear was identified and their clinical records obtained. Their
MRI images were reviewed to ascertain the degree of retraction of
the torn infraspinatus and supraspinatus muscles, and the degree
of fatty degeneration in both muscles was recorded. Nerve conduction studies
were also performed in those patients who showed more degeneration
in the infraspinatus than in the supraspinatus.Aims
Patients and Methods
This study examined the role of vitamin D as a factor accounting for fatty degeneration and muscle function in the rotator cuff. There were 366 patients with disorders of the shoulder. A total of 228 patients had a full-thickness tear (group 1) and 138 patients had no tear (group 2). All underwent magnetic resonance arthrography and an isokinetic muscle performance test. The serum concentrations of vitamin D (25(OH)D3) were measured. In general, a lower serum level of vitamin D was related to higher fatty degeneration in the muscles of the cuff. Spearman’s correlation coefficients were 0.173 (p = 0.001), −0.181 (p = 0.001), and −0.117 (p = 0.026) for supraspinatus, infraspinatus and subscapularis, respectively. In group 1, multivariate linear regression analysis revealed that the serum level of vitamin D was an independent variable for fatty degeneration of the supraspinatus and infraspinatus. The serum vitamin D level has a significant negative correlation with the fatty degeneration of the cuff muscle and a positive correlation with isokinetic muscle torque.
