The relationship of glenoid and humeral version with supraspinatus tendon tears.

The aim of this study was to investigate the relationship of glenohumeral anatomic measurements on MR imaging with supraspinatus tendon tears. The study was approved by the institutional review board and informed consent was obtained from each subject. Forty-two patients (mean age 55.5 years; age range 40-73 years) with supraspinatus tendon tears and 50 asymptomatic shoulders of 32 controls (mean age 43 years; age range 17-69 years) without rotator cuff tears were included. The acromio-glenoid and supraspinatus-glenoid angles were measured on coronal images, the glenoid and humeral head version as well as the bicipital-humeral distance on axial images. Significant differences were found between the patients and controls for both glenoid version and bicipital-humeral distance, which are considered to influence the distribution of forces placed on the cuff (p < 0.05). The patients had a decreased glenoid version by an average of 2.3 degrees (-7.1 +/- 7.8 degrees vs. -4.8 +/- 5.6 degrees), and a decreased bicipital-humeral distance by an average of 2.7 mm (12.1 +/- 3.7 mm vs. 14.8 +/- 4.1 mm). No significant differences were found between these groups for humeral head version and the acromio-glenoid and supraspinatus-glenoid angles, which might contribute to extrinsic impingement by narrowing the supraspinatus tendon outlet. Differences in glenoid and humeral version may be responsible for RC tears by changing the orientation of the rotator cuff and thus increasing shearing stress.