Reverse coronal deformity does not adversely affect clinical outcomes or early survivorship following image‐based robotic total knee arthroplasty performed under functional alignment

PURPOSE: Reverse coronal deformity (RCD) is characterized by a ≥2° reversal of coronal alignment between knee extension and 90° of flexion. This study evaluated clinical outcomes, intraoperative alignment characteristics, and early revision rates in patients with RCD undergoing image-based robotic-assisted total knee arthroplasty (TKA) using functional alignment (FA) principles. METHODS: A retrospective comparative study of 204 consecutive robotic-assisted TKAs performed under FA with ≥2.5-year follow-up was conducted. RCD was defined intraoperatively as ≥2° varus in extension reversing to ≥2° valgus at 90° flexion, or vice versa. Twenty-two knees (10.8%) met criteria for RCD. Median follow-up was 39 months (interquartile range [IQR] = 36-46). Alignment parameters were obtained from robotic measurements. Clinical outcomes included Knee Society Score (KSS) and Forgotten Joint Score (FJS). Kaplan-Meier analysis assessed implant survivorship. RESULTS: Preoperatively, the RCD group demonstrated median 2.5° varus (IQR: 2-4) in extension and -2° valgus (IQR: -5 to -2) in flexion, compared with 7.5° varus (IQR: 5-12) and 5° varus (IQR: 3-8) in controls (p < 0.0001). Intraoperatively, tibial alignment differed slightly between groups (0° varus vs. 1° varus; p = 0.0002), while other parameters were comparable (all p > 0.05). At final follow-up, KSS-knee was 95 (IQR 90-100) in RCD versus 94 (IQR: 90-100) in controls (p = 0.36); KSS-function was 90 (IQR: 90-100) in both groups (p = 0.92); and FJS was 82.5 (IQR: 63-90) versus 86 (IQR: 67-94) (p = 0.48). No aseptic revisions occurred; two revisions (1.1%) in controls were due to infection. Kaplan-Meier analysis demonstrated no difference in revision risk between groups (p = 0.62). CONCLUSION: RCD was present in 10.8% of knees. When managed under FA principles, only minor implant adjustments were required to achieve balanced gaps, with comparable clinical outcomes and early survivorship to non-RCD knees. LEVEL OF EVIDENCE: Level III, retrospective comparative study.