Shoulder dislocation (instability)

Accurate assessment of bipolar lesions—those involving both the glenoid and the humeral head—is critical in preventing treatment failure. Glenoid bone loss is typically expressed as a percentage of the glenoid width, while Hill-Sachs lesions are measured for depth, width, and engagement potential. CT with 3D reconstruction is the imaging modality of choice. Quantifying bone loss guides treatment decisions: minimal loss may only need soft tissue repair, while significant loss (>20% glenoid or large engaging Hill-Sachs) requires bony augmentation. Accurate calculation allows surgeons to predict stability and reduce the risk of postoperative recurrence.

The concept of on-track vs off-track lesions, based on the glenoid track theory, helps determine whether a Hill-Sachs lesion is likely to engage with the anterior glenoid rim. An off-track lesion extends beyond the glenoid track and increases the risk of recurrent dislocation. Determining this preoperatively, using imaging and calculations, allows surgeons to plan a combined approach—typically Bankart repair plus remplissage or Latarjet procedure. This classification system has revolutionized how bipolar bone loss is managed, ensuring targeted, anatomy-specific solutions and reducing the incidence of failure following arthroscopic stabilization.

Management of bipolar bone loss requires individualized treatment based on lesion size, interaction, and shoulder function. For on-track lesions with minimal glenoid loss, a standard Bankart repair may suffice. In off-track lesions, a combined approach—such as Bankart plus remplissage, DAS plus remplissage, Latarjet, or bone block—is required. In cases of significant humeral head damage, bone grafting or partial resurfacing may be necessary. The treatment goal is to restore stable, functional range of motion without compromising the anatomy. Patient activity level, sport demands, and previous surgeries also influence the final decision, making precise planning essential.