Introduction: Numerous anatomic studies of the shoulder have quantified the size, shape, and variability of either the humerus or scapula individually. However, few have attempted to quantify the relationship of the humerus to the scapula to better understand the spatial variation of these bones in both male and female shoulders.
Methods: Seventy-four cadaveric shoulder CT scans (37 males and 37 females with statistically equivalent age and BMI) were reconstructed using Mimics ® to create 3D models of the humerus and scapula. After 3D reconstruction, each CT bone model was analyzed in Rapidform® to quantify the morphology of the humerus, scapula, and the spatial relationship between the two to better understand the role of gender on the morphological variability of the glenohumeral joint.
Results: Spatial glenohumeral relationships of male shoulders were significantly larger than female shoulders in 13 of 16 measurements; morphology of male humeri were significantly larger than female humeri in 17 of 24 measurements, and scapula and glenoid morphology of male shoulders were significantly larger than female scapula and glenoids in 11 of 22 measurements.
Discussion: Numerous significant gender differences in spatial relationships and morphology were identified in this anatomic study of the glenohumeral joint. An improved understanding of these observed binomial distributions has utility for shoulder arthroplasty prosthesis design, computer navigation, and may also be useful to the orthopaedic surgeon during surgical preoperative planning.