Posterior fracture-dislocations of the shoulder are uncommon and challenging lesions. We present the case of a 76-year-old male patient who sustained a locked posterior humeral head fracture-dislocation during a convulsion. Because more than 40% of the articular surface was involved, preserving the head was not possible. We treated the fracture with a cemented humeral surface replacement. The patient demonstrated good shoulder function and no instability on short-term follow-up. Surface replacement may be a valuable treatment option for fracture-dislocations of the shoulder with articular surface involvement.