Influence of limb positioning during image acquisition on femoral torsion measurements: implications for surgical planning

Femoral torsion is an important parameter to accurately quantify when planning for the correction of structural pathomorphology. The purpose of this study was to quantify the influence of limb positioning during image acquisition and of alignment techniques on femoral torsion measurements, by measuring the change in femoral torsion angle, upon digital rotations that simulate flexion/extension and adduction/abduction positions of the femur. Femoral torsion measurements were reduced up to 1 degrees and increased up to 0.35 degrees per each degree of flexion and abduction, respectively. The estimation of femoral torsion measurements yielded a difference up to 5.8 degrees between the aligned and non-aligned cases.