Abstract
Atrophy of rotator cuff muscles is an important factor influencing the outcome of rotator cuff repair. Accurate evaluation of the muscular volume was essential for good shoulder reconstruction. However, the relationship between the muscular volume evaluated with MRI and the rotator cuff tear size was not well determined. The aim of this study was to evaluate the comparison between these two parameters. We retrospectively evaluated MR images of 38 shoulders with surgically treated full thickness supraspinatus tendon tears, and 12 shoulders without a rotator cuff tear as control. Muscle volume was evaluated with oblique sagittal images in the 25 mm medial plane parallel to the glenoid fossa. Standardized cross-sectional areas (each rotator cuff muscle area divided by the area of the supraspinatus fossa (SF)) were measured as an indicator of the muscular volume according to the method of Zanetti et al. Supraspinatus (SSP/SF), infraspinatus and teres minor (ISP+TM/SF)and subscapularis (SBS/SF) were measured respectively. We compared these measurements between the tear group and the control group. We also analysed the correlation between these measurements and the tear sizes: longitudinal and transversal sizes. SSP/SF, ISP+TM/SF, and SBS/TM in the control group were 134±41,257±103,391±137, respectively. The measurements in the tear group were 100±29,226±80,345±128, respectively and SSF/SF was significantly decreased compared to the control. SSP/SF in the tear group was inversely proportional to the longitudinal tear size (r=-0.377) and the transversal size (r=-0.452) in a linear relationship. Shoulder muscular atrophy Was more correlated to the transversal rotator cuff tear size compared to the longitudinal tear size.
