Three-dimensional analysis of the proximal humeral and glenoid geometry using MicroScribe 3D digitizer.

PURPOSE: To understand the geometry of the proximal humerus and glenoid fossa to facilitate the design of components used in shoulder arthroplasty. The aim is to evaluate the geometry of the proximal humerus and glenoid fossa and their relationship using a MicroScribe 3D digitizer.

METHODS: Scans and measurements were obtained from 20 pairs of dry proximal humeri and scapulae [10 female and 10 male cadavers: median age 81 years (range 70-94 years)] using a MicroScribe 3D digitizer and Rhinoceros software.

RESULTS: Means (±SD) of humeral inclination, medial wall angle of the bicipital groove, and radius of the humeral head values were 135 ± 11°, 39 ± 19°, and 14 ± 3 mm, respectively. Means (±SD) of glenoid height and width were 35 ± 4 and 26 ± 4 mm, while the means (±SD) of the angles of glenoid inclination, retroversion, and rotation were 87 ± 32°, 96 ± 10°, and 9 ± 6°, respectively. A significant difference in glenoid height (P ≤ 0.002) and width (P ≤ 0.0001) was observed between males and females, despite them having almost an identical radius of the humeral head, glenoid inclination, retroversion, and angle of rotation. There was also a significant difference (P ≤ 0.01) in the angle of glenoid retroversion between the right and left sides.

CONCLUSIONS: Using a MicroScribe 3D digitizer, the glenoid fossa was observed to be significantly smaller in females than males; furthermore, there was a difference in glenoid retroversion between the right and left sides.