A Hill Sachs Lesion or Hill Sachs Fracture is a dent or a compression injury to the posterolateral part of the humeral head created by the glenoid rim during dislocation. It occurs when the humeral bone pops out of the socket, its relatively soft head impacts against the anterior edge of the glenoid.
Shoulder can dislocate forward, backward or downward. A Hill-Sachs injury occurs only when there is a forward dislocation of the shoulder.
Hill Sachs Lesion is named after two American radiologists Harold Hill and Maurice Sachs – who in 1940, popularized the injury, provided radiographic evidence and determined a link between the lesion and recurrent instability.