Incidence, Impact, and Complications of Short Cephalomedullary Nail Toggling in Patients with Wide Femoral Medullary Canal

Abstract

Background: Toggling of the short cephalomedullary nail is an understudied phenomenon characterized by a change in the longitudinal axis of the nail in relation to the longitudinal axis of the femoral medullary canal, with subsequent potential loss of reduction. This retrospective study aims to examine the incidence and impact of toggling of short cephalomedullary nails in cases with wide femoral canals. Methods: One thousand two hundred fifty-six (1256) cases that received short proximal femoral nails for intertrochanteric fractures were reviewed. Of them, 101 cases that had wide femoral canals (≥15 mm) and a minimum radiographic follow-up of 6 weeks were included in this study. Outcome measures included nail toggling, varus malunion and revision surgery. Results: After a mean radiographic follow-up of 53.5 weeks, sixteen cases (15.8%) showed significant nail toggling of more than 4 degrees and had subsequent varus displacement of the fracture. In all 16 cases, there was deficient proximal nail fixation, in the form of either a lag device not engaging the lateral wall (2 cases), lateral proximal femoral wall fracture/incompetency (7 cases), or a combination of the two factors (7 cases). Despite this, all sixteen cases achieved fracture union. Five additional cases had complications related to poor initial reduction (four cases) or femoral head avascular necrosis (one case). The other 80 cases had minimal (0-4 degrees) nail toggling and healed without varus malunion, and none of them required revision surgery. Conclusions: Short cephalomedullary nails may toggle in patients with wide femoral canals. The effect of femoral canal width on nail movement and subsequent varus malunion may be abolished when the lag device engages the lateral proximal femoral cortex, and the lateral cortical bone is intact. In patients with wide femoral medullary canals or cases with proximal lateral femoral cortical fracture, the utilization of long or intermediate length cephalomedullary nails may be a more viable option.

Keywords: intertrochanteric femur fracture; short PFN; short cephalomedullary nail; toggle; trochanteric fracture.

Figure 1

(A) Immediate post. (B) 3-month postoperative radiographs of an 81-year-old female with intertrochanteric fractures with improper proximal fixation (lag device not engaging an incompetent lateral femoral cortex) of a short cephalomedullary nail. The last radiograph (B) shows varus fracture displacement and lag screw articular penetration. The patient declined further interventions and expired 5 months later due to heart disease.

Figure 2

(A) Preoperative, (B) Immediate postoperative plain radiographs of 1 95-year-old male with an intertrochanteric fracture. Note the fractured/incompetent lateral wall. Note also that the lag device does not perfectly engage the lateral wall. (C) 8-week and (D) 16-week follow-up radiographs showing nail toggling and varus fracture collapse.

Figure 3

(A,B) Intraoperative and Immediate post. (C) 71-week postoperative radiographs of a 91.8-year-old female with a wide medullary canal and uneventful fracture healing without nail toggling despite a proximal lateral wall fracture.