Bilateral Femoral Neck Fractures in A Young Patient Suffering from Hypophosphatasia, Due to A First Time Epileptic Seizure

INTRODUCTION: We report a case of an adolescent sustaining bilateral femoral neck fractures due to a first time epileptic seizure, as a result of expansion of his known syrinx. CASE REPORT: A 19-year-old patient suffering from hypophosphatasia (HPP), Arnold-Chiari malformation, and a ventriculoperitoneal shunt sustained a trivial fall with profound pain and an inability to mobilize. Radiographs demonstrated a right-sided Garden-4 femoral neck and left-sided multi-fragmentary intracapsular/extracapsular fractures. The patient had previously suffered bilateral proximal femoral shaft fractures, treated with intramedullary unlocked nail fixation that was still in situ. Operative treatment with an exchange to Synthes Adolescent Lateral Recon nail was performed on the right with two Recon screws inserted into the femoral head. On the left, the existing Pedinail was preserved with an additional single screw inserted into the femoral head. In addition, 3 months of non-mobilization was required for adequate bone healing. After 1-year from time of injury, there is no avascular necrosis on radiographs and the patient is mobilizing pain-free. CONCLUSION: Patients with hypophosphatasia have delayed bone healing. We recommend surgical fixation with an intramedullary device and periods of non-mobilization until there is radiographical evidence of adequate bone healing.