Posterior shoulder fracture-dislocation. A) Anteroposterior radiograph of the right shoulder showing the internally rotated humerus and the characteristic "lightbulb sign" of its proximal part. Both tuberosities have been detached from their anatomic position. B) Transthoracic lateral radiograph of the right shoulder demonstrates the posterior dislocation of the humeral head. C) Axial computed tomography (CT) scan of the right shoulder. A locked posterior fracture-dislocation is recognised. The anteromedial defect is close to 50% of the articular surface. Fracture comminution of both tuberosities and low bone density of the humeral head are also visible.