Robotic anatomo-functional alignment total knee arthroplasty accurately resurfaces the distal femur and preserves joint line obliquity: A prospective 3D modelling study.

Abstract

This study aims to evaluate the ability of a personalised robotic total knee arthroplasty (TKA) to accurately resurface the distal femur, maintain the native joint line obliquity (JLO), and optimise knee balancing, as measured on dedicated radiographs, with intraoperative measurement and CT scan 3D reconstruction. In this prospective study, 100 patients undergoing primary personalized robotic TKA were included using an anatomo-functional alignment. The ability of this technique to resurface the distal femur was assessed using CT scans by comparing 3D models of each patient pre- and postoperatively. Frontal alignment and JLO were compared on full-length radiographs pre- and postoperatively. The evolution of knee laxity was measured intraoperatively for each patient before and after TKA. The average difference between the distal femur articular surface before and after TKA was 2.27 mm. The JLO was preserved in 91% of cases (p < 0.05). The gap width target (2 ± 1 mm: medial and lateral femorotibial gap in extension, as well as the medial femorotibial gap in flexion) was achieved among 78% of the patients with varus deformity and 69% of patients with valgus deformity. The anatomo-functional alignment during TKA implantation, as described in this study, allows for resurfacing of the distal femur with millimetre precision, and the preservation of joint line orientation in most cases using robotic assistance. It also enables to restore a functionally optimal ligament tension both in extension and in flexion. Level III.