Safe zone for the superficial femoral artery demonstrated on computed tomography angiography

Internal or external fixation of the femur is common following trauma. Neurovascular structures around the shaft of the femur are at risk, particularly the superficial femoral artery (SFA). Damage to this structure, when it is medial to the femur, can occur during the lateral approach, when drills, pins or screws are inserted. This anatomical study aims to delineate a safe zone for operative intervention to the shaft of the femur with respect to the SFA, and describe the relationship between this zone and the width and length of the femur.

41 limbs from 22 patients were examined using Computed Tomography Angiography to determine the relationship between the SFA and the medial shaft of the femur. The danger zone where the SFA lies medial to the shaft of the femur in the sagittal plane was identified and measured, and the width and length of the femur were measured for reference points.

The SFA begins anterior to the shaft of the femur proximally and passes posteriorly, crossing the shaft of the femur in the sagittal plane at points 239.6±39.8mm and 172.5±40.9mm proximal to the adductor tubercle (AT). The width of the femur correlates to the inferior crossing point of the SFA on the femur with a mean ratio of 1:2.05, p=0.000, the length of the femur correlates to the mid crossing point of the SFA on the femur with a ratio of 2.00:1, p=0.000.

There is a safe zone along the medial shaft of the femur, which can be estimated intraoperatively using anatomical reference points.