Posterior Shoulder Dislocation- posterior dislocation is rare & should raise possibility of seizure as cause; other causes include an electric shock or ECT without muscle relaxants. Radiographs may reveal Reverse Hill Sach Lesion - compression fracture of the anteromedial portion of the humeral head is produced by the posterior cortical rim of the glenoid as in this case of 28 year old male, with posterior dislocation seen on 3D CT images.