Comparison of postoperative alignment using fixed angle versus variable angle distal femoral resection in uncomplicated total knee replacement.

Abstract

This study aimed to compare the postoperative alignment of the lower limbs using fixed angle versus variable valgus angle distal femur resection in uncomplicated total knee replacement (TKR) and to determine the mean valgus correction angle (VCA) in the study population. This was a prospective comparative study conducted between July 2018 and December 2019 in patients with osteoarthritic knees who underwent primary TKR. Forty-nine patients with 54 knees completed the study. They were randomized into fixed valgus angle (group A) and variable valgus angle (group B) groups. Twenty-four patients with 26 knees were in group A who had distal femur resection with 5-degree valgus correction, while 25 patients with 28 knees were in group B who had distal femur resection with individualized valgus correction angle calculated from hip-knee-ankle scanogram. The demographic data were comparable in the two groups. There was no statistically significant difference between the groups in the mean preoperative mechanical femorotibial angle (MFTA). The fixed angle group had a mean postoperative MFTA of 2.0 ± 2.8°, while variable angle group had a mean of 1.6 ± 2.4°. However, the difference between the groups did not reach statistical significance (p = 0.60). The mean VCA in the study population was 5.8 ± 1.2° (Range 4-9°). Our study has shown that the use of variable valgus angle for distal femur resection in uncomplicated TKR did not significantly improve the accuracy of restoring the postoperative coronal alignment within 0 ± 3°.