Position of the humeral head and rotator cuff tear: an anatomical observation in cadavers.

Abstract

Background: The relationship between the humeral head position and rotator cuff tears is not well described.

Material and methods: We performed an anatomical study of 22 cadaveric shoulders to find out the relationship between the normal anatomical position of the humeral head and tears of the rotator cuff. After dissection, the rotator cuff pathology was documented. The position of the humeral head was noted in relation to the acromion. The humeral head with intact acromion and articulated shoulder joint was photographed from the superior aspect of the joint and the area of the humeral head outside the acromion was measured, i.e. the part of the humeral head lateral to the lateral border of the acromion process. The relationship between rotator cuff pathology and uncovering of the humeral head was determined.

Results: 9 specimens had a partial cuff tear, while 4 had a complete tear. Those specimens with a rotator cuff tear had a mean area of 83% of the humeral head under the acromion. The specimens that did not show a rotator cuff tear had a mean area of 61% of the humeral head under the acromion.

Interpretation: We suggest that there is individual variation in anatomical position of the humeral head in relation to the acromion and that this position correlates with the occurrence of rotator cuff pathology.