A secondary atypical diaphyseal femoral fracture after intramedullary nailing for an atypical subtrochanteric femoral fracture: A case report.

Intramedullary nailing is the gold standard of treatment for atypical femoral fractures, with a few reports of secondary atypical subtrochanteric femoral fractures following intramedullary nailing for atypical diaphyseal femoral fractures. However, there are no reports of secondary atypical diaphyseal femoral fractures following intramedullary nailing for atypical subtrochanteric femoral fractures. A 71-year-old woman with adult-onset Still's disease sustained a right atypical subtrochanteric femoral fracture and was treated with a mid-length intramedullary nail. One year after the surgery, the patient sustained a contralateral atypical diaphyseal femoral fracture and was treated with a long-length intramedullary nail. Moreover, 6 months after the second surgery, the patient complained of right-thigh pain, and a radiograph of the lateral view of the femur revealed a diaphyseal femoral fracture at the distal screw-insertion site. Revision surgery was performed using a long-length nail and screws directed toward the femoral head. Bony union of the bilateral diaphyseal femoral lesion was obtained, but the subtrochanteric lesion remained unhealed 1.5 years postoperatively. Mid-length intramedullary nailing for atypical subtrochanteric femoral fractures can cause secondary atypical diaphyseal fractures because of stress concentration at the distal screw-insertion site. For atypical subtrochanteric femoral fractures, the use of long-length nails and proximal screws directed toward the femoral head may be important to prevent secondary atypical diaphyseal femoral fractures.