Dynamic Stress Fluoroscopy for Evaluation of the Femoral Neck After Intramedullary Nails: Improved Sensitivity for Identifying Occult Fractures.

OBJECTIVES: To report on the use of dynamic stress fluoroscopy (DSF) for detection of occult fractures of the femoral neck associated with femoral shaft fractures. To compare DSF with a fully static imaging protocol in detecting occult femoral neck fractures.

DESIGN: Multicenter retrospective cohort study.

SETTING: Two urban level I trauma centers.

PARTICIPANTS/INTERVENTION: A consecutive series of 1273 femoral shaft fractures were included. Inclusion criteria were patients treated with an intramedullary rod (antegrade/retrograde), age ≥18 years, a fine-cut (2 mm) preoperative computed tomography and hip radiographs, intraoperative anteroposterior (AP)/lateral fluoroscopic view of the femoral neck before femoral nailing, and a minimum follow-up of 3 months. Patients were divided into 2 groups based on the technique used to identify the presence of a femoral neck fracture after intramedullary fixation of the femoral shaft: DSF or static intraoperative radiographs.

MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS: Both the static imaging protocol and DSF had high specificity (100%; 100%), positive predictive value (100%; 100%), and negative predictive value (99.5%; 99.6%). Sensitivity was poor (73.7%) for the static protocol group versus high (92.3%) for the DSF group.

CONCLUSIONS: Compared with a fully static imaging protocol, DSF is a more sensitive and highly specific technique, enabling intraoperative detection of occult fractures of the femoral neck.

LEVEL OF EVIDENCE: Diagnostic Level III. See Instructions for Authors for complete description of levels of evidence.