Cadaveric study (n=9 shoulders) mapping where the glenoid rim contacts the posterior humeral head during the apprehension position. Tested at maximum external rotation, horizontal extension, and 0°, 30°, and 60° abduction to define the anatomic zone at risk for Hill-Sachs engagement. Introduces the glenoid track concept as a measurable framework for surgical decision-making in anterior instability.
Before this framework, Hill-Sachs lesions were assessed by size and depth alone — thresholds like '>20% of humeral head' or '>1000 mm³ volume' guided treatment without a biomechanical rationale linking lesion location to actual engagement risk.
The glenoid track gives you a concrete decision rule: measure the Hill-Sachs lesion from the rotator cuff footprint on CT. If its medial margin falls within 84% of glenoid width (adjusted downward for any glenoid defect), the lesion is on-track and a Bankart repair alone is appropriate.
If the medial margin exceeds that boundary, the lesion is off-track. A standard Bankart repair will not prevent re-dislocation, and bone augmentation (Latarjet) or remplissage should be added.
This paper is the anatomic foundation for the on-track/off-track classification now used routinely in instability workup. Knowing the formula (glenoid track = 0.84 × glenoid width minus any defect) is directly testable on the OITE.
Cadaveric study (n=9 shoulders) mapping where the glenoid rim contacts the posterior humeral head during the apprehension position. Tested at maximum external rotation, horizontal extension, and 0°, 30°, and 60° abduction to define the anatomic zone at risk for Hill-Sachs engagement. Introduces the glenoid track concept as a measurable framework for surgical decision-making in anterior instability.
Before this framework, Hill-Sachs lesions were assessed by size and depth alone — thresholds like '>20% of humeral head' or '>1000 mm³ volume' guided treatment without a biomechanical rationale linking lesion location to actual engagement risk.
The glenoid track gives you a concrete decision rule: measure the Hill-Sachs lesion from the rotator cuff footprint on CT. If its medial margin falls within 84% of glenoid width (adjusted downward for any glenoid defect), the lesion is on-track and a Bankart repair alone is appropriate.
If the medial margin exceeds that boundary, the lesion is off-track. A standard Bankart repair will not prevent re-dislocation, and bone augmentation (Latarjet) or remplissage should be added.
This paper is the anatomic foundation for the on-track/off-track classification now used routinely in instability workup. Knowing the formula (glenoid track = 0.84 × glenoid width minus any defect) is directly testable on the OITE.