The Cortical Step Sign Fails to Prevent Malrotation of a Nailed Femoral Shaft Fracture: A Case Report

Intramedullary nailing has become the treatment of choice for diaphyseal femur fractures. Malrotation is a well-recognized complication of femoral nailing. Various techniques including the cortical step sign (CSS) have been described to minimize iatrogenic rotational deformity during femoral nailing. We present a case in which the use of the CSS resulted in a clinically significant malrotation requiring revision. 1. Introduction Incidence of clinically significant rotational malalignment (≥15 degrees) [1, 2] following intramedullary nailing of femoral shaft fractures is reported in up to 28% of cases [3]. To minimize this iatrogenic rotational deformity, various techniques have been described to assess and correct intraoperative femoral rotation during intramedullary fixation of femur fractures [4–8]. More recently, the significance of the cortical step sign (CSS) in assessing femoral rotation in noncomminuted femur fractures was analyzed in cadaveric specimens [9]. Although avoidance of the CSS in comminuted femur fractures is recommended, its use in cases where one cortex is noncomminuted, as in Winquist and Hansen type II fractures, is not known. We present a case in which the CSS failed to detect a 15° malrotation during antegrade nailing of one such fracture. The patient has provided informed written consent for print and electronic publication of this case report. 2. Case Report This is the case of an 18-year-old male who was ejected from his Ski-Doo when it collided with a rock. He presented to our facility with an isolated, closed, right diaphyseal femur fracture. The fracture had a small lateral butterfly fragment, with otherwise a simple transverse fracture through the medial cortex, Winquist and Hansen Type II fracture (Figure 1) [10]. After an informed consent the patient was positioned supine on a radiolucent operating table for intramedullary nailing of his femur. Reduction was acquired with manual traction. An antegrade reamed nail (Synthes, Mississauga, Ontario) with a piriformis start point was inserted. The nail was locked proximally. The cortical step sign (CSS), using the non-comminuted medial cortex, was employed to assess intraoperative femoral rotation. When the medial cortical widths of the proximal and distal fragments were noted to be equal on an anteroposterior (AP) fluoroscopic image, the intramedullary nail was locked distally using the free-hand technique. Figure 1: Preoperative images of the right diaphyseal Winquist and Hansen type II femur fracture. Note the lateral butterfly fragment, and the relatively transverse