Uncoupling of the Helical Blade in a Proximal Femoral Nail - A Novel Mechanical Failure.

INTRODUCTION: Intertrochanteric fractures are increasingly common in the elderly, and intramedullary fixation with a proximal femoral nail antirotation (PFNA) is widely preferred due to its biomechanical advantages. The helical blade improves cancellous bone purchase, yet complications such as cut-out, cut-in, and excessive sliding remain concerns. Mechanical uncoupling of the helical blade from the nail is extremely rare. We report an unusual case of spontaneous helical blade disengagement following PFNA fixation of a stable fracture.

CASE REPORT: An 85-year-old male sustained a stable intertrochanteric femur fracture following a road traffic accident and underwent closed reduction with a long PFNA fixation, achieving good reduction and implant placement. Early recovery was uneventful. At 8 weeks, he developed proximal thigh pain and a firm mass. Imaging showed subcutaneous migration of the uncoupled distal helical blade without additional trauma. The component was removed under local anesthesia, and weight-bearing was deferred. Alignment remained stable, and at 12 months, a painless fibrous non-union allowed continued conservative management.

CONCLUSION: Helical blade uncoupling is an exceptionally rare PFNA failure mode. In elderly, low-demand patients with stable alignment and minimal symptoms, conservative treatment after such mechanical failure can provide satisfactory outcomes without revision surgery.