Description
Objectives: The rotational alignment of the femoral component impacts directly on knee kinematics in terms of knee flexion stability, patellar tracking, and range of motion. This study aims to conduct an intraoperative quantitative evaluation, as its primary objective, to analyze the relation between femoral rotation and frontal alignment in TKA procedures employing two distinct techniques: navigation-assisted (NA) and traditional guide-based methods. Additionally, the study addresses a secondary objective by evaluating the clinical outcomes associated with these two techniques.
Methods: A total of 100 patients undergoing TKA with the gap-balance technique were prospectively, comparative and randomly analyzed. Conventional and NA instruments were used.
Results: The femoral rotation cut in the conventional TKA group was balanced within a half-degree difference to the NA TKA group (p-value = 0.02), and had a smaller range [NA TKA group rotation cut = 3.5º (-5.5º to 3.5º), Conventional TKA rotation cut = 3.0º (0.0º to 3.0º)]. The concordance as a positive correlation between condylar posterior line and tibial cut was significant (R 0.45, p= 0.002). Non-significant differences were found between groups based on clinical measures, such as VAS, ROM, Flexion, Extension, KSS, OKS, and HSS.
Conclusions: This study presents the biomechanical differences between the conventional TKA and NA TKA using the gap balancing technique and showed minimal intraoperative differences of the femoral rotation cut. It has also highlighted the results in the coronal axis where the HKA angle was within 3º of varus for the two groups. Both conventional and NA instruments in gap balance TKA implemented with force tensor can lead to good results at 1-year postoperative.
Level of evidence: I
