Glenoid shape is sexually dimorphic

Abstract

Uniform assessment of the glenoid anatomy is fundamental in establishing uniform standards of care. Subjectivity in classification inherent in the absence of quantification permits deficiency in glenoid assessment methods (e.g., Walch classifications). Therefore, this report aims to objectively quantify the variance of glenoid fossa contours in both sexes via geometric morphometric techniques. A total of 135 glenoid fossae from 135 adult Mexican individuals, who had undergone CT scanning for non-shoulder-related reasons, were randomly selected for this study. Geometric morphometric analysis, including principal component analysis, canonical variate analysis, and two-block partial least squares analysis, was performed on glenoid contours in coronal and axial planes among males and females of varied age groups. The canonical variate analysis of the glenoid revealed sexual dimorphism in both the coronal and axial glenoid contours. Males tend to have a move concave glenoid contour than females, especially in the axial plane. Partial least squares analysis revealed a shape-relationship between coronal and axial contours— when coronal contours are relatively concave, axial contours also exhibit concavity; conversely, when there is minimal concavity in one dimension, there tends to be minimal concavity in the other. This manuscript establishes a novel means of assessing the glenoid cavity through geometric morphometrics; in doing so, the objective and quantifiable methods can be an important supplement to evolving glenoid assessments such as the Walch classification system. The novel approach used in this research revealed sexual dimorphism in the shape of the glenoid cavity as well as a relationship between coronal and axial contours.

Sexual dimorphism and allometry in human scapular morphology

“…Scapular morphology is highly variable across the human population (Dwight, 1887;Graves, 1921). The multi-factorial sources of scapular shape variation are unclear; however, previous work has revealed significant differences in scapular shape between males and females (Maranho et al, 2022;Scholtz et al, 2010;Zdilla and Guzmán-López, 2023). Understanding sexual dimorphism in scapular morphology is important for contextualizing scapula features that are correlated with injury risk (Lee et al, 2020), developing personalized treatments, identifying relevant shape traits for classifying sex in forensic analyses (Atamtürk et al, 2019;Dabbs and Moore-Jansen, 2010;Di Vella et al, 1994;Er et al, 2020;Peckmann et al, 2016), and providing insights into the role of sexual selection in human evolution (Puts, 2010).…”

“…Previous geometric morphometric studies of the scapula have quantified morphology using 2D projections. These studies have found that the male scapula tends to have more pronounced curvature on the medial and lateral borders, a more projected inferior angle, and a more concave glenoid compared to the female scapula (Maranho et al, 2022;Scholtz et al, 2010;Zdilla and Guzmán-López, 2023). However, the 2D approach could be missing important sexually dimorphic 3D features.…”