抄録
Background: In large and massive rotator cuff tears, the atrophy of teres minor muscle following rotator cuff tear was reported to be a prognostic factor postoperatively. However, the hypertrophy of teres minor muscle has not yet been reported. The purpose of this study was to examine the atrophy of infraspinatus muscle and the hypertrophy of teres minor muscle in patients of rotator cuff tears using MRI.
Methods: Forty-nine shoulders (28 males and 21 females, average age 65.1 years old) diagnosed with rotator cuff tear were investigated. We evaluated the infraspinatus muscle (tear; ISP(+), no tear; ISP(-)) and teres minor muscle on the most lateral side on which the scapular spine was in contact with the scapular body using the oblique sagittal image of MRI. Fatty infiltration of the infraspinatus muscle was evaluated according to the classification of modified Goutallier. We measured the ratio of TM / real ISP, and TM / anatomical ISP using the software Image J.
Results: There were 14 shoulders in ISP(+) and 35 shoulders in ISP(-). TM/anatomical ISP was statistically significant between ISP(+) and ISP(-). When the hypertrophy of TM was defined as TM/anatomical ISP>0.5 (hypertrophy; TM(+), no hypertrophy; TM(-), there were 12 shoulders in ISP(+)TM(+), 2 shoulders in ISP(+)TM(-), 0 shoulders in ISP(-)TM(+) and 35 shoulders in ISP(-)TM(-).
Conclusion: Our findings suggested that the hypertrophy of teres minor muscle may come from the tear and atrophy of the infraspinatus muscle.
