Fluoroscopic landmarks to recognize iatrogenic varus displacement (wedge effect) during cephalomedullary nailing of intertrochanteric fractures.

Abstract

Iatrogenic varus malreduction after intramedullary nailing of intertrochanteric fractures (wedge effect) may be more common than previously reported. The aim of study is to determine its incidence and to define easy fluoroscopic landmarks to recognize it intraoperatively. We included surgical procedures with residual varus malreduction and sufficient intraoperative fluoroscopy images to assess an intraoperative anatomical reduction at the beginning of the procedure. Two intraoperative fluoroscopic landmarks were defined to assess varus in the anteroposterior view: the position of the greater trochanter (GT) related to the femoral shaft (medialized GT sign), and the position (superior, centre or inferior) of the guide wire in both the neck and the head of the femur (cross wire sign). We describe our current method of treatment to avoid this complication. A total of 369 extracapsular hip fractures were treated using PFNA and Gamma 3 systems. We found 55 (14.9%) fractures with a varus malreduction. Six were underreduced and fixed in varus. Thirty-five (9.48%) were well reduced by closed reduction but suffered a iatrogenic varus displacement when introducing the nail. 31 were female; mean age was 86.6 (range 70-97). Mean postoperative head-shaft angle was 119,2° range (113°-123°). Mean TAD was 24,37 range (14-36 mm). Wedge effect (iatrogenic varus displacement of a well reduced intertrochanteric fracture when introducing the nail) could occur in at least 10% of intertrochanteric fractures. The medialized GT and the "crossing wire sign" seem to be good predictors of iatrogenic varus malalignement.