Revision with Locking Plate and Sliding Inlay Bone Graft for Hypertrophic Nonunion after Combined Treatment of Ender Nails and Teriparatide for Atypical Femoral Stress Fracture A Unique Case Report

Introduction: Atypical femoral fractures (AFFs), whose characteristic radiograph patterns include beaking and the dreaded black line, are uncommon in elderly patients with osteoporosis. Bisphosphonates (BPs) are commonly prescribed for prevention of osteoporosis-related fractures. However, the long-term use of BPs has been linked to the occurrence of AFFs. Here, we report a rare case of multiple incomplete atypical stress fractures of the lateral femoral cortex with endosteal marrow edema in a patient with no history of antiresorptive treatment. Case presentation: A 74-year-old Japanese woman sought care for severe pain in her right thigh and difficulty with ambulation. A review of the patient's past radiograph series revealed multiple incomplete stress fractures of the lateral mid-shaft femur that had existed for at least 3 years. After progression to complete fracture induced by lowenergy trauma, we performed flexible intramedullary Ender nailing and prescribed the patient teriparatide. A positron emission tomography (PET)/computerized tomography (CT) scan with 18F-NaF revealed faint radio tracer uptake around five incomplete fracture lines in addition to marked uptake at the complete fracture site. Four months after the Ender nailing fixation operation, radiographs showed a displaced femoral stress fracture associated with breakage of three Ender nails due to hypertrophic nonunion. The patient was treated with a sliding full cortical thickness inlay bone graft combined with cancellous bone grafting and a locking plate. Conclusion: It is important to evaluate the risk of progression from atypical stress fracture to complete fracture and to consider alternative treatment options, including surgery, in addition to conservative management with teriparatide. If standard conservative treatment following a correct diagnosis fails to produce a good outcome, a sliding full cortical thickness inlay bone graft technique with locking plate is an effective method for the difficult-to-manage AFFs.