Three-dimensional analysis of the orientation and the inclination of the rotator cuff footprint.

Abstract

The tuberosities of the proximal humerus relate geometrically to the humeral head in an anteroposterior symmetry. Twenty-eight cadaveric shoulders were scanned with computed tomography and reconstructed digitally in 3 dimensions. On both tuberosities, 5 facets were identified. An orthogonal planar system using the center of the humeral head as its origin was created to calculate the coordinates of the centre of each facet. The angular position of the center of each facet was measured with reference to the sagittal plane. The inclination of each facet was measured to the axial plane. The presence of 5 distinct facets with a different inclination was confirmed (lesser tuberosity: inferior facet: 77.8° [sd 7.8°]; superior facet: 50.3° [sd 9.3°] - greater tuberosity: superior facet: 20.4° (sd 5.6°); middle facet: 48.6° (sd 5.2°); inferior facet: 92.7° [sd 7.7°]). The angular position of the centers of the facets was less variable (lesser tuberosity: inferior facet: 22.6° [sd 4.3°]; superior facet: 39.2° [sd 4.4°] - greater tuberosity: superior facet: 89.9° [sd 5.9°]; middle facet: 131.6° [sd 6.1°]; inferior facet: 155.1° [sd 6.8°]). Our study contributes to the knowledge of the anatomy of the proximal humerus, more specifically of the position of the rotator cuff insertion in relation to the humeral head. These insights are useful in the development of shoulder trauma prostheses.