Periprosthetic fractures of the humerus.

Periprosthetic humeral fractures present a treatment challenge for the orthopedic surgeon. The overall incidence of fracture is between 0.5% and 3%, with the majority of fractures occurring intraoperatively and involving the humeral diaphysis. Excess torque produced during surgery is usually responsible for intraoperative fractures. Improper canal preparation or prosthetic placement may also increase the chance of sustaining a fracture. Postoperative fractures are most commonly caused by minor trauma, such as a fall. Poor bone quality, female sex, advanced age, and history of rheumatoid arthritis are the risk factors most commonly associated with periprosthetic fractures. All 4 systems used to describe periprosthetic humeral shaft fractures classify fracture patterns according to the anatomic relation of the fracture to the prosthetic stem. Treatment decisions should be made with respect to obtaining fracture stability, initiating early gleno-humeral motion, and restoring shoulder function. Intraoperative fractures and any postoperative fracture resulting in prosthetic instability should be treated with a long-stem prosthesis extending at least 2 to 3 cortical diameters past the fracture site with consideration for rigid plate fixation. Short oblique or transverse postoperative fractures should be managed with early stable fixation. There has been some support for conservative treatment of long oblique or spiral postoperative fractures. Postoperative diaphyseal fractures distal to the stem generally are well maintained with standard fracture management.