Stability of the Glenohumeral Joint With Combined Humeral Head and Glenoid Defects A Cadaveric Study

Background:Shoulders with recurrent anterior instability often have combined bony defects of the humeral head and glenoid. Previous studies have looked at only isolated humeral head or glenoid defects.Purpose/Hypothesis:The aim of this study was to define the relationship of combined humeral head and glenoid defects on anterior shoulder instability. Combined bony defects will lead to increased instability compared with an isolated defect, and the “critical” size of humeral head and glenoid defects that need to be addressed to restore stability will be smaller when combined rather than isolated.Study Design:Controlled laboratory study.Methods:Eighteen shoulder specimens were tested at 60° of glenohumeral abduction and 80° of glenohumeral external rotation. Humeral head defect sizes included 6%, 19%, 31%, and 44% of the humeral head diameter. Glenoid defect sizes included 10%, 20%, and 30% of the glenoid width. Outcome measures included percentage of intact stability ratio (%ISR; the stability ratio for a g...