Modified radiographic views to prevent the anterosuperior and posterosuperior bony violation during screw fixation of femoral neck fractures.

Abstract

The standard anteroposterior and lateral fluoroscopic projections used during femoral neck fracture fixation provide a two-dimensional representation of the cephalocaudal and anteroposterior extents of the femoral neck. The radiographic representation differs from the actual extent of the femoral neck. The anterosuperior (AS) and posterosuperior (PS) surfaces of the femoral neck are at risk of bony breach by the fixation screws and that may get easily missed with standard fluoroscopic views. The current study aims at investigating the special fluoroscopy views, based on the orientation of the AS and PS surface of the femoral neck, that can help in the safe placement of screws near these surfaces without bony breach. A computed tomography-based analysis of fifty intact proximal femora was performed. The longitudinal axis of the proximal femoral shaft and the center of the femoral head were aligned along a common horizontal plane. The cephalocaudally constricted zone of the femoral neck was identified along its axis. The surface inclinations of the AS surface and the PS surface at the constricted zone of the femoral neck were measured in relation to the horizontal plane. The mean, standard deviation, overall range, interquartile ranges and gender-based variation of each of the two surface inclinations were measured. The mean surface inclinations of the AS surface and the PS surface with reference to the horizontal plane were 55° ± 7.76° and 123.32° ± 7.88°, respectively. There were no significant side to side and male to female differences. The modified radiographic views based on the surface inclinations of the AS and the PS surfaces can help in the localization of the critical zones of these surfaces which are at risk of bony breach with screw placement close to the surface. A prior fluoroscopic evaluation of these surfaces before guidewire placement can help in preventing the surface violation.