The indications for humeral head replacement in acute fractures and in chronic fracture problems have been studied over many decades and are reasonably well defined. Complications have probably been understudied. Many different complications occur, and their frequency and the need for reoperation is quite high. Because of the variety of complications that occur, familiarity with preventive measures and treatment options is important, not only to deal with complications arising from endoprostheses, but also to treat musculoskeletal infections, nerve injuries, fractures, instability, nonunion of tuberosities, malunion, and rotator cuff or capsule contracture or tearing. Physicians also must be able to integrate reparative/reconstructive surgery with a program of postoperative rehabilitation. The challenges are many. Treatment often provides considerable improvement for the patient, but often the extent of the improvement is somewhat less than optimal.