Rockwood Adults CH34

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SECTION TWO • Upper Extremity

a forward flexed and internally rotated arm can also result in a posteriorly directed force, which creates a posterior force vector of the humeral head relative to the glenoid (Fig. 34-1C). Lux- atio erecta, or inferior shoulder dislocation, occurs with forced hyperabduction of the arm and a levering of the humeral head against the acromion. 53,272

but, in reality, a spectrum of injuries occurs with instabil- ity events. 12 Depending on the direction and degree of force applied to the limb, a variety of injuries can occur to the cap- sule, ligaments, labrum, articular cartilage, rotator cuff, neuro- logic structures, and bone. Bony injuries include fractures to the glenoid and humeral head known as bony Bankart (Fig. 34-2B) or Hill–Sachs lesions (Fig. 34-2C), respectively. A Hill–Sachs lesion represents an impaction fracture of the posterior humeral head against the firmer glenoid rim. 89 Less frequently, coracoid fractures, greater tuberosity fractures, and lesser tuberosity fractures are seen with higher energy injuries. 240 Capsular and ligamentous injuries include stretching and rupture along with avulsion from the humeral side known as humeral avulsion of

INJURIES ASSOCIATED WITH GLENOHUMERAL INSTABILITY

Glenohumeral instability typically results in an injury to the capsule and labrum. Bankart originally identified the labral tear as the essential lesion creating shoulder instability (Fig. 34-2A),

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Figure 34-2.  A: Axial T2-weighted magnetic resonance image with arthrogram (MRA) demonstrates ante- rior inferior labral tear or “Bankart” lesion. B: CT image with 3D reconstruction of the glenoid shows “bony Bankart” lesion on the anterior inferior glenoid. C: Axial T1-weighted MRA image shows “Hill–Sachs” lesion on the posterior humeral head. D: Coronal T2 MRA image shows humeral avulsion of glenohumeral ligament (HAGL) lesion.