Secondary hip fractures (SHFs) rarely occur after intramedullary nailing (IMN) fixation without femoral neck fixation for atypical femoral fractures (AFFs). We report three cases of older Japanese women who sustained SHFs presumably caused by osteoporosis and peri-implant stress concentration around the femoral neck after undergoing IMN without femoral neck fixation for AFF. All cases were fixed with malalignment. In AFF patients, postoperative changes due to postoperative femoral bone malalignment may affect the peri-implant mechanical environment around the femoral neck, which can result in insufficiency fractures. At the first AFF surgery, we recommend femoral neck fixation after adequate reduction is achieved.
Keywords: atypical femoral fracture; bone malalignment; femoral neck fracture; hip fracture; intramedullary nail.