How much of the superolateral femoral neck should be removed in intramedullary nail fixation for intertrochanteric fracture?

The objective of this study was to measure how much of the superolateral femoral neck should be removed to reduce the incidence of wedge effect. Simulating surgery: Computed Tomography images of 131 intertrochanteric fracture patients were included, three-dimensionally reconstructed, virtually reduced and implanted with Proximal Femoral Nail Antirotation blade-II(PFNA-II) nail. The antero-posterior length and media-lateral width of the intersection between superolateral femoral neck and PFNA-II nail were measured. Retrospective study: The pre- and postoperative CT of 30 patients were collected. The average varus angle of the neck-shaft angle and the correlation between the angles and the difference in the actual and estimated width of the fragments removed were measured. Models of 108 patient were selected for analysis. The average antero-posterior length and media-lateral width were 14.46 mm (14.00-14.93 mm) and 9.33 mm (8.79-9.87 mm), respectively. The AO/OTA classification was not significantly associated with the outcome, but the gender was. In the retrospective study, the mean value of the varus angles was -4.58 degrees (SE = 6.85 degrees), and the difference of width was strongly positively correlated with the varus angle with a correlation coefficient of 0.698. Results obtained in this study can improve the understanding of this region and help surgeons to make appropriate preoperative planning to reduce the incidence of wedge effect. Retrospective study provided effective proof of the reliability of this study.