Variation in the glenoid origin of the anteroinferior glenohumeral capsulolabrum.

Restoration of the anteroinferior capsulolabrum, including the labrum and origin of the anterior band of the inferior glenohumeral ligament is crucial during Bankart repair. The purpose of the current study was to describe variations in this anatomy near the glenoid. The histologic and gross anatomy were studied in 10 fresh-frozen glenohumeral joints from adult cadavers. Each joint was placed in the apprehension position of abduction, external rotation, and horizontal abduction because anterior dislocation occurs in this shoulder position. The joints then were sectioned serially in the transverse plane from cephalad to caudad. Three glenohumeral joints were embedded in Techovit 7200 resin, polymerized, and then mounted onto an acrylic slide. Ground sections were prepared by attaching a microscope slide to the face of each and cutting 200 microm-thick sections. The thin sections were ground to a thickness of 30 microm. Finally, sections were stained with 1% toluidine blue zero in 1% sodium tetraborate for light microscopic examination. The other seven glenohumeral joints were frozen in the apprehension position and held with a custom jig while sectioned serially at 3-mm intervals. The surfaces then were recorded with a tabletop computer and a scanning device. Two distinct patterns of the anteroinferior capsulolabrum attachment to the glenoid were identified. In eight joints (80%) it had its major origin from the labrum with some fibers extending onto the glenoid neck, a Type I origin. In two joints (20%), it emanated solely from the glenoid neck, a Type II origin. Failure to repair the glenoid origin of the anteroinferior capsulolabrum, the location of the anterior band of the inferior glenohumeral ligament, because of variations in its anatomy may be a reason for failure after Bankart repair.