Bipolar bone defect in the shoulder anterior dislocation.

In the anterior shoulder instability with glenoid bone loss among 25 % or more of the inferior glenoid diameter (inverted-pear glenoid), the consensus of recent authors is that glenoid bone grafting (Latarjet procedure) should be performed. The engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior shoulder instability. We have developed a method using radiographic and arthroscopic studies and the concept of the glenoid track to determine whether a Hill-Sachs lesion will engage the anterior glenoid rim, whether or not there is concomitant anterior glenoid bone loss. If the Hill-Sachs lesion engages, it is called an "off-track" Hill-Sachs lesion; if it does not engage, it is an "on-track" lesion. On the basis of our quantitative method, we have developed a treatment paradigm with specific surgical criteria for all patients with anterior shoulder instability (first dislocation or recurrent dislocation), both with and without bipolar bone loss.