Glenohumeral Joint Morphology in
Traumatic Anterior Shoulder Instability

Abstract

The purpose of this study is to clarify the relationship between glenohumeral joint morphology and characteristic features of traumatic anterior shoulder instability. We examined 30 shoulders of 30 patients who had computed tomography before their operations. There were 24 males and 6 females. The mean age was 24 years old. Twenty-three were dislocations and 7 were subluxations. The mechanism of injury was classified into two groups, traumatic group (fall or direct injury) and minor injury group (overhead activity). The traumatic group consisted of 16 shoulders and the minor injury group consisted of 14 shoulders. We measured the maximum transverse diameters of the articular surface of the glenoid and the maximum diameters of the humeral head in uninjured shoulder and calculated the glenoid-head ratio. We also examined glenoid rim morphology by three-dimensional CT in the injured shoulderr. Glenoid rim morphology was classified into three groups, bony Bankart lesion, morphologic abnormality and normal. We investigated the relationship between glenoid-head ratio and gender, dislocation or subluxation and the mechanism of injury. We also investigated the relationship between the mechanism of injury and glenoid rim morphology. The mean of the glenoid-head ratio was 65.3%. There was no difference in gender, dislocation or subluxation and the mechanism of injury. But glenoid-head ratio tended to be smaller in females and the minor injury group. In glenoid rim morphology, sixteen males had bony Bankart lesion and four females had normal glenoid rim morphology. Also seventy-five percent of the traumatic group had bony Bankart lesion and fifty percent of minor injury had normal glenoid rim morphology. Bony Bankart lesions were much seen in males and the traumatic group, and morphologic abnormality or normal glenoid rim were much seen in females and the minor traumatic group.