An Ultrasound Study of the Anatomical Position of the Femoral Nerve in Patients with a Fractured Neck of Femur

Introduction: Femoral nerve blockade is commonly used as analgesia in patients with a fractured neck of femur. The relationship of the femoral nerve in relation to the femoral artery is thought to change after a fractured neck of femur. We hypothesised that a fracture of the femoral neck would result in an increase in the distance from the mid-point of the femoral nerve to the mid-point of the femoral artery, due to lateral displacement of the femoral nerve. Materials and methods: We conducted an assessor-blinded observational study to investigate the position of the femoral nerve in relation to the femoral artery and skin in 27 patients with fractured neck of femur, using the non-fractured side as a within subject control. Results: There were no statistically significant differences between the fractured and non-fractured sides with regard to artery-nerve distance [18.0 mm (0.4) on the side of the fracture and 16.7 mm (0.4) on the non-fractured side (p = 0.255)] or distance from the mid-point of the femoral nerve to the skin surface [16.6 mm (0.5) on the fractured side and 16.9 mm (0.5) on the non-fractured side (p = 0.802) (mean (SD)]. Conclusion: There appear to be no clinically relevant changes in landmark position of the femoral nerve, at the level of the inguinal ligament, following hip fracture.