This invention provides a device and treatment method for replacing the hip (in either a hemiarthroplasty or total hip arthroplasty), which protects the remainder of the femur from fracture. Such a device is highly applicable to the treatment of patients with current or impending fractures of the femur, particularly those with metastatic bone cancer, where there is concern for current or future metastatic disease of the femoral neck or head, which would necessitate hip replacement. The implant consists of a two-piece arrangement with a separate femoral component and a securing, intermedullary rod/nail that is received in a locking arrangement by a longitudinal fenestration of the femoral component.