Case Report of Femoral Neck Stress Fracture in X-linked Hypophosphatemic Rachitis Patient Treated with Mechanical Axis Correction and a Literature Review.

Introduction: X-linked hypophosphatemic rachitis (XLHR) is the most common cause of hereditary rickets that can lead to long bone deformities requiring multiple surgical correction procedures. In addition, high rates of fractures are reported in adult XLHR patients. This study aimed to report a case of femoral neck stress fracture in XLHR patient treated with mechanical axis correction. No previous studies demonstrating a combined valgus correction and cephalomedullary nail fixation were identified in the literature. Case Report: A 47-year-old male patient with XLHR attended the outpatient clinic with severe left hip pain. X-rays revealed a left proximal femoral varus deformity and a femoral neck stress fracture. After 1 month without improvement of pain, and no radiographic sign of healing, correction of the proximal femoral varus deformity and fixation of the cervical neck fracture was achieved by a cephalomedullary nail. At 8 months follow-up, hip pain relief was achieved with radiographic healing of the femoral neck stress fracture and the proximal femoral osteotomy. Conclusion: A review of the literature was performed to identify any case report of femoral neck fractures fixation due to coxa vara in an adult. Both coxa vara and XLHR can cause femoral neck stress fracture. This study presented the surgical technique for treating a rare case of femoral neck stress fracture in a XLHR patient with coxa vara. Pain relief and bone healing were achieved by combined deformity correction and fracture fixation with a femoral cephalomedullary nail. The technique for deformity correction and cephalomedullary nail insertion in the patient with coxa vara is shown.