Shoulder Dislocation on X-ray: Imaging Findings

A Hill-Sachs lesion is a posterosuperior impaction fracture of the humeral head created when it engages the anterior glenoid rim during anterior dislocation. It appears on axial MRI or CT as a wedge-shaped cortical depression at the posterosuperior humeral head and is best seen on axial T2-FS images or CT with 3D reconstruction. A Bankart lesion is the complementary injury — an anteroinferior labral avulsion, with or without an attached osseous fragment (bony Bankart). MR arthrogram best demonstrates the soft-tissue Bankart lesion as contrast tracking into the labral detachment on axial images. The combination of a large engaging Hill-Sachs lesion and a significant bony Bankart defect increases recurrent instability risk and influences surgical planning.

Recurrence risk after a first-time anterior shoulder dislocation is strongly age-dependent. Patients younger than 20 years have recurrence rates approaching 80–90%, while those over 40 years have rates below 15%, partly due to concurrent rotator cuff tears that stabilize the joint. High-demand athletes and military personnel have similarly elevated recurrence risks. MRI findings that predict recurrence include large Hill-Sachs lesions, significant Bankart labral damage, capsular laxity, and anterior glenoid bone loss. Early surgical stabilization with arthroscopic Bankart repair is increasingly recommended for young active individuals after a first-time dislocation to reduce the cumulative damage caused by recurrent episodes.

The Latarjet procedure — transfer of the coracoid process with its attached conjoint tendon to the anterior glenoid — is preferred when anterior glenoid bone loss exceeds approximately 20–25% of the glenoid surface, or when an engaging Hill-Sachs lesion creates an off-track bipolar lesion that puts an arthroscopic soft-tissue repair at unacceptably high risk of failure. CT with 3D surface subtraction reconstruction or MRI best quantifies glenoid bone loss. The Latarjet provides a triple stabilizing effect: bony augmentation of the glenoid arc, the sling effect of the conjoint tendon, and the capsulorrhaphy. Recurrence rates with the Latarjet are lower than with soft-tissue repair in high-risk instability cases.