Morphological analysis of the glenoid version in the axial plane according to age

Total shoulder arthroplasty planning requires a preoperative assessment of the glenoid version. This study aimed to determine the morphologic profile of the glenoid cavity and our null hypothesis was that age may affect the spiraling aspect.

114 CT arthrographies of patients from 15 to 78 years old were included. Four groups were defined according to age: 15-29, 30-44, 45-59 years old, and over 60. The version of the glenoid was measured in the axial plane according to the most common method: a line is drawn between the osseous anterior and posterior margins of the glenoid and the version corresponds to the angle between this line and the transverse axis of the glenoid. The transverse axis of the scapula is determined by a line drawn from the center of the glenoid fossa to the medial border of the scapula. The axial plane (perpendicular to the supero-inferior axis of the glenoid cavity) was defined by multiplanar reconstruction. The measurements were performed at three regions of interest: the level of the coracoid process (region A), the level of the notch on the anterior border of the glenoid (region B), and the region of the greater antero-posterior diameter (region C).

96 % of the glenoid cavities included were retroverted. The mean version in region A was 11.9° (0-24.3, S-D 5.2), in region B 6.85° (-5.2 to 12.1, S-D 4.13) and in region C 4.04° (-7.7 to 11.1, S-D 4.04). The difference between the mean version of region A and region B was 5.02° and the difference between the mean version of the region B and the mean version of the region C was 2.81°. When considering the rate of change of the mean version between two adjacent regions, no difference was observed between the four groups of age.

The analysis showed the importance of the axial reconstruction plan chosen to allow interpretable and reproducible measures. A decreasing version of the glenoid superior-to-inferior was observed, presenting a spiraling twist as described in previous studies. The profile of variation does not change in the four groups of patients included. The reconstruction of an articular surface as close to the anatomy as possible would also participate in establishing the muscular balance and the constraints on implants. Up to now, implants do not take into account this cranio-caudal twisting.