Fig. (8) A: The “Hill-Sachs Interval” (HSI) is the distance from the footprint of the sleeve to the medial margin of the lesion of Hill-Sachs. In a normal shoulder 83% of the diameter of the glenoid (D) corresponds to the distance between the cuff footprint and the medial margin of the glenoid, this distance is the “glenoid track”. If there is a glenoid defect (d), the defect must be subtracted form 83% of the glenoid width to get the true Glenoid track (GT=(D*.83)-d). B: An engaging lesion combination or injury “off-track”. The HSI is greater than the GT, the medial margin of Hill-Sachs is located medial to the projection area of ​​the glenoid rim glenoid producing engagement. C: Non engaging lesion combination or injury “on-track”. With no glenoid defect, the HSI will be smaller than the GT, the Hill-Sachs will be covered by the glenoid at all times and there is no risk of engaging.