Scapular morphological variations and sex-related and generational differences in global scapular shape: three-dimensional morphometric analysis using a homologous model

Background: The objectives of the present study were to perform a three-dimensional morphometric analysis of global scapular shape in 500 individuals using homologous modeling and to examine sex-related and generational differences in global scapular shape. Methods: Computed tomography images of the scapulae of 500 individuals were obtained. A homologous model of the scapula, comprising 19,563 vertices, was created based on 40 landmarks. Principal component analysis of the three-dimensional coordinates of all vertices was performed. The morphological variation represented by each principal component (PC) was interpreted based on the virtual shape of each loading score, a 2-way analysis of variance of PC scores was conducted to assess sex-related and generational differences. Results: Men had the following characteristics compared with women, the scapular body was longitudinally longer than transversely (PC1); the lateral morphology was posteriorly inclined, and the scapular body was anteriorly inclined (PC2); the acromion was anteriorly oriented, and anteroposterior diameters of the scapular body and supraspinous fossa were increased (PC5); the acromion and coracoid process were anteriorly oriented, and the width of the scapular body was increased medially and laterally (PC6). The older age group showed a tendency toward having a posterior tilt of the lateral morphology and an anterior tilt of the scapular body (PC2), a medial orientation of the acromion, and increased anteroposterior diameter of the supraspinatus fossa (PC3) compared with the younger age group. Conclusion: We observed several variations in the global shape of the scapula. Sex-related and generational differences in global scapular shape were clarified. These differences may be considered when analyzing scapular morphology.