The Shape of the Acromion in Subjects of 20 Years Old or Less by Computed Tomography, Particularly the Undersurface of the Antero-lateral Part

Abstract

Few studies have been conducted regarding the acromial morphology in young subjects by computed tomography(CT). The purpose of this study is to evaluate the shape of acromions in subjects of 20 years old or less by CT including multi planer reconstruction(MPR) and three dimensional(3D)images, and to refer to these results for judging the presence of acromial spurs in rotator cuff patients. Thirty-six shoulders of 23 patients of 20 years old or less with recurrent shoulder dislocations who underwent surgery were evaluated. Acromial tilt angles were significantly different among lateral, middle, and medial part(97.4°, 105.0°, and 117.9°, respectively, p<0.001). The proportion of the shapes of acromions classified into three types; flat, curved, and convex were significantly different between in 3D images and sagittal images (p<0.001). Convex architectures at the lateral edges of acromial undersurfaces were detected in 20 shoulders in 3D images. The thickness of the acromion at the lateral part was significantly thinner than that at the medial part (p<0.001). These data suggest that it is difficult to judge the acromial shape by radiography or one-dimensional images, and the convex architectures at the lateral edges of acromial undersurfaces in 3DCT images might be normal structures, so it is important to check the convex structures and the thickness of acromions in coronal images for judging the presence of spurs.