Abstract
The shapes of the glenoid were analyzed in this study. The subjects were fifty healthy right shoulders of males aged between 19 and 39 years ( mean 28.1 ). They were supined on a table with their arms at a 90 degree-abducted-position, and the shape of the glenoid was photographed by rotating a fluoroscope around the humeral axis in a 180-degree-arc and recorded on a video tape three dimensionally. The relationships between the images and the angles were recorded on an NAC SELGRAPH 2D SYSTEM. Thirty six images at intervals of five degrees were sampled and each image was analyzed by a PIAS LA500 image analyzing system. Assuming that the surface of the glenoid is an ellipsoid, its approximate equations were calculated. Furthermore, the approximate equations in specific areas of the glenoid were also calculated.
The humeral head has a similar shape to a spheroid with its rotational axis on the long diameter, while no tendency was observed in the whole zone of the glenoid. However, the superior and the anteroinferior portion of the glenoid showed a similar shape to a spheroid. Moreover, the central area of the glenoid showed a larger curvature then did the other areas. This study reveals that the shape of both the superior portion of the glenoid and the humeral head have similar congruities. Actually they fit well into an arm elevated position. This suggests that this relationship is significant for getting stability of the shoulder in a joint needing support.
