Rotational alignment of the distal femur: a literature review

Rotational malalignment still accounts for an unacceptable number of failures in total knee arthroplasty (TKA). This paper presents a literature review of previously published papers describing rotational alignment of the distal femur and discussing different techniques in obtaining correct rotational alignment of the femoral component in TKA. Based on the published values, the following mean angular relationships between the rotation axes of the distal femur in the axial plane can be calculated: the posterior condylar line is on average 3 degrees internally rotated relative to the surgical transepicondylar axis (TEA), 5 degrees relative to the anatomical TEA and 4 degrees relative to the perpendicular to the trochlear anteroposterior axis. The greatest interindividual variability is described for the trochlear AP axis. The worst track record regarding inter- and intraobserver variability is for the TEA. Given the large ranges and standard deviations of all reference axes, and the important inter- and intraobserver variability in the surgical location of the TEA, the use of a preoperative CT scan is recommended.