Hybrid Fixation Utilizing a Custom Stem Extension for the Treatment of Periprosthetic Femoral Nonunions Around Well-Fixed Cylindrical Femoral Stems

Abstract

Periprosthetic femoral nonunion associated with total hip arthroplasty is an infrequent complication1. However, the increasing worldwide incidence of periprosthetic fractures2 is expected to result in a higher number of complications, including fracture nonunion. A periprosthetic fracture around a well-fixed stem (e.g., Vancouver type B1)3 is a difficult complication to manage4, and it often requires both an arthroplasty and the skills of a trauma surgeon5. Nonunited fractures are even more challenging; they have a high rate of complications and relatively poor functional outcomes1. We present two cases of periprosthetic femoral nonunion around a stable cylindrical stem. The first nonunion occurred following an intraoperative periprosthetic fracture, and the second nonunion occurred following a postoperative fracture, after which a custom stem extension had been added to the conventional fixation method. After this combination of intramedullary and extramedullary or hybrid fixation, stability was achieved at the nonunion site, and healing was obtained in both patients. To our knowledge, the use of this type of custom-made porous-coated prosthesis has not been previously reported. The patients were informed that data concerning their cases would be submitted for publication, and they provided consent. Case 1. A sixty-six-year-old woman with a history of polymyalgia rheumatica (treated with corticosteroid therapy) and left hip osteoarthritis underwent simultaneous removal of previous fixation hardware and a cementless left total hip arthroplasty. The components included a Duraloc cup and a cylindrical-type Prodigy stem (DePuy Synthes, Warsaw, Indiana). During the procedure, the patient sustained a long spiral femoral fracture extending around and distal to the stem. Because the stem was stable, the fracture was reduced and fixed with a Dall-Miles cable and plate system and multiple lag screws. Six months postoperatively, radiographs showed a well-ingrown femoral stem; however, the fracture had failed to …