Evaluation of bone loss and the glenoid track

Glenohumeral bone loss (e.g., bony Bankart and Hill-Sachs lesions) is a common sequela of shoulder dislocation and is frequently implicated in recurrent instability. Performing surgical repair of soft tissue structures without addressing glenohumeral bone deficiency may predispose patients to repeated instability. Accurate diagnosis and quantification of glenohumeral bone loss is critical to guide surgical management of these lesions. In this chapter, we first describe the anatomic and biomechanical basis of shoulder stability and how disruption of normal shoulder anatomy, either from soft tissue injury or glenohumeral bone deficiency, can lead to recurrent instability. We next discuss the epidemiology and types of glenoid and humeral head lesions. An emerging concept in humeral bone loss is the notion of "engaging Hill-Sachs lesions," and we present the techniques described that may help predict which Hill-Sachs lesions engage with the glenoid rim and must be surgically addressed. We conclude with a description of how glenohumeral deficiency can be identified and quantified on arthroscopy as well as on imaging studies, including X-rays, computed tomography, and magnetic resonance imaging.