Glenohumeral Motion Related to the Glenoid Shape

Abstract

This study examines the glenoid cavity using three-dimensional MRI. Forty volunteers were enrolled in the study. Three-dimensional scapular images were reconstructed using an open MRI and computer software. The tilting angles of the glenoid bone were measured in five consecutive axial planes perpendicular to the glenoidal long axis. Cross sections were divided into three types (concave, flat, and convex)according to the shape on each plane.
The average tilting angles for the five planes from the bottom to the top were 3.3±4.1,1.4±3.8, -0.6±1.9, -1.4±3.3, -6.2±3.3 degrees anteriorly, indicating that the three-dimensional bony structure of the glenoid was twisted anteriorly to posteriorly. Images on the bottom plane consisted of 82.5% concave type,15% flat type, and 2.5% convex type, while only 3 cases (7.5%) showed a concave shape in the top plane. The shape of the glenoid cavity is thought to be conducive for glenohumeral motion and stability.