To determine the incidence of femoral neck fractures with high-energy shaft fractures and to determine whether there was a correlation of neck fractures with antegrade or retrograde intramedullary nailing. We also evaluated the timing of diagnosis and the treatment options and outcomes.

A retrospective review of patients with femoral shaft fractures treated at 8 level 1 trauma centers from 2001 to 2005. Two thousand eight hundred ninety-seven fractures were identified, and 89 patients had 91 femoral neck-shaft combinations (3.2%).

Average age: 36 years (15-72 years) and average Injury Severity Score: 18 (9-66). Seventy-eight patients had associated injuries; 67 of 91 femoral neck fractures were discovered before nailing.

There were 24 missed femoral neck fractures, 11 discovered intraoperatively and 13 postoperatively. Of these 24 patients, 15 had retrograde fixation and 9 had antegrade femoral shaft fixation. There was a high rate of open femur fractures (34%) and an increased incidence of associated injuries (88%) with neck-shaft combinations. In 12 of 67 patients with a preoperative computed tomography scan, the scan did not demonstrate a femoral neck fracture.

This study found a similar rate of neck-shaft combinations (3.2%), a higher rate of open fractures, and increased incidence of associated injuries compared with the literature. Most importantly, our data indicate that even with a negative preoperative computed tomography scan, a femoral neck fracture can be present. A trend also indicated more missed femoral neck fractures with retrograde nailing, which may be attributed to less fluoroscopic imaging of the hip with this technique. Patients with femoral shaft fractures should have good quality radiographs after femoral nailing to minimize the risk of missed femoral neck fractures.