Robotic-assisted total knee arthroplasty achieves superior early postoperative outcomes compared to conventional techniques in patients with severe varus.

Purpose: This study aimed to compare the clinical efficacy of robot-assisted total knee arthroplasty (RATKA) and conventional total knee arthroplasty (CTKA) in patients with varying degrees of varus, and to determine the indications and advantages of RATKA. Methods: A retrospective analysis was conducted on clinical data from patients with knee osteoarthritis who underwent either RATKA or CTKA. Univariate and multivariate linear regression analyses were performed to identify factors influencing postoperative hip-knee-ankle (HKA) angle deviation. Based on the degree of preoperative HKA angle deviation, patients were grouped into mild varus (HKA angle deviation <10°) and severe varus groups (HKA angle deviation ≥10°). Postoperative outcomes of the two surgical techniques were compared in patients with varying degrees of varus. These included lower limb alignment parameters such as HKA, posterior slope angle (PSA), medial proximal tibial angle (MPTA), and femoral distal lateral angle (FDLA); clinical functional scores including Hospital for Special Surgery score (HSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), visual analog scale for pain (VAS), and range of motion (ROM); as well as operative time and the proportion of cases requiring soft tissue release. Alignment parameters and functional scores were assessed 1 week before surgery and 3 months postoperatively. Results: A total of 218 patients were included. The mean ages of the RATKA and CTKA groups were 64.9 ± 6.5 years and 65.1 ± 5.7 years, respectively. The RATKA group included 15 males and 69 females, while the CTKA group included 29 males and 105 females. Multivariate analysis identified preoperative HKA angle deviation as the most important predictor of postoperative HKA alignment, with each 1° increase in preoperative deviation associated with an approximate 0.150° increase postoperatively. In patients with mild varus, there were no significant differences in alignment restoration or clinical scores between RATKA and CTKA. However, in the severe varus groups, RATKA demonstrated significantly better outcomes in terms of HKA, PSA, MPTA and FDLA alignment parameters, lower radiographic outlier rates, reduced need for soft tissue release, and superior HSS, WOMAC and VAS scores (p < 0.05). Conclusion: RATKA provides greater clinical benefits in patients with severe varus, offering more accurate limb alignment, improved implant positioning, and better short-term functional outcomes. RATKA should be preferentially considered for patients with substantial preoperative HKA angle deviation. Level of Evidence: Level Ⅲ, retrospective cohort study.