The pourpose of this study was to investigate the variability of the posterior condylar angle and the whiteside’s angle to establish if three degrees of external rotation of the femoral component produce the correct rotational alignment, in varus knee

33 patients (33 knee) affected by varus osteoarthritic knee (5°–30°)underwent a preoperative CT scan examination of the knee and the hip. On the axial views, we have evaluated the femoral anteversion, the posterior condylar angle and the whitesiede’s angle.

The mean femoral anteversion angle was 5.5°±13.7° (−24°;33°). The mean posterior condylar angle was 6.1°±2.5° (1°;14°). The mean intraobserver error was 0.9°. In 60.6% of the cases the angle was greater than 5°. The mean Witheside’s angle was 6°±3.5° (1°;16.5°). The mean intraobserver error was 0.8°. In 51.5% of the cases the angle was greater than 5°.

Both the posterior condylar angle and the Whiteside’s angle showed values almost double than three degrees proposed as standard rotation for the femoral component. The method of three degrees standard of external rotation lead to relative internal rotation of the femoral component in TKR also for varus knee.