Simultaneous Total Hip Arthroplasty and Plate Fixation for Ipsilateral Subtrochanteric Fracture Following Femoral Neck Osteosynthesis.

Background: Subtrochanteric fracture is a recognized complication following osteosynthesis for femoral neck fractures, typically occurring within 1-2 months postoperatively. At the time of onset, incomplete healing of the femoral neck fracture often results in a complex fracture configuration that poses challenges for management. Case Presentation: A 60-year-old woman with schizophrenia sustained a Garden Type I femoral neck fracture after a fall and underwent osteosynthesis with three sliding hip screws. Three months later, she developed marked hip pain without any new trauma. Radiographs revealed a displaced ipsilateral subtrochanteric fracture originating from the distal screw insertion site. The patient was treated with simultaneous open reduction and internal fixation (ORIF) using a polyaxial locking plate and total hip arthroplasty (THA). The postoperative course was uneventful, and the patient regained independent ambulation. Conclusion: Although intramedullary nailing remains a common option for such fractures, selecting the optimal treatment can be challenging, particularly when fixation stability and femoral head viability are in question. In selected middle-aged or elderly patients, combining joint replacement with fracture fixation can provide both reliable mechanical stability and early functional recovery. This case underscores the importance of considering simultaneous arthroplasty and plate fixation in patients with poor bone quality, incomplete femoral neck healing, or a high risk of avascular necrosis, when revision osteosynthesis alone cannot provide sufficient mechanical stability.