The femoral trochlear anterior line is a better alternative intra-operative reference compared to femoral anterior tangent line for femoral rotation in both genders in total knee arthroplasty

Abstract Purpose To determine the most reliable reference axis for the femoral component rotation in TKA patients by comparing the trochlear anterior line (TAL) and the femoral anterior tangent line (FAT). To evaluate the variability of each anatomic parameter in a Korean population. Methods Magnetic resonance images (MRIs) were taken for 500 patients (400 females and 100 males) with knee joint osteoarthritis who had Kellgren and Lawrence grade 3 and 4 prior to TKA in our institution between February 2016 and September 2017. It was investigated that whether significant differences in variance and gender exist for TAL and FAT. Results TAL and the FAT were internally rotated by 5.1° ± 3.1° and 6.8° ± 6.1°, respectively, about the Transepicondylar axis (TEA). Although no gender-related differences were found for the TAL, they were found for the FAT. The variance of the TAL with respect to the TEA was significantly smaller compared with that for the FAT and thus exhibited a more consistent distribution. In addition, such a trend was found for both genders. Conclusions The results show that the TAL is a favorable index for appropriate rotational alignment of the femoral component in TKA.