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.

The femoral anterior tangent line could serve as a reliable alternative reference axis for distal femoral rotational alignment in total knee arthroplasty: an MRI-based study

“…However, Ji’s study only included women patients who underwent TKA, and there was no data on the men. In another similar comparative study carried out by Nam et al, the TAL/cTEA angle was −5.1° ± 3.1° and the FAT/cTEA angle was −6.8° ± 6.1°, the mean value of the FAT/cTEA angle was significantly smaller than in other comparable studies, and the standard deviation was considerably larger ( 34 ). These differences might be attributed to their special measurement methods, which involved three-dimensional (3D) MR reconstruction and remodeling.…”

“…Most of our results were similar to the previously published CT-based studies, but there was some disparity in terms of certain indicators; Further study directly comparing the differences between the MRI and the CT scans is recommended. Finally, our study did not include some newly invented distal femoral rotational reference axes such as the TAL and the posterior cortical axis ( 34 , 36 , 37 ). Because these axes are still in the primitive stage of research and have not been widely used in practice, further comparative analysis would be appropriate when there is enough clinical application experience.…”