Robotic‐assisted total knee arthroplasty reduces femoral notching and anterior flange lift‐off compared with navigation

PURPOSE: Accurate sagittal positioning of the femoral component is critical in total knee arthroplasty (TKA) to restore knee kinematics while avoiding anterior cortical violation and patellofemoral overstuffing. This study aimed to compare navigated and robotic-assisted TKA with respect to the incidence of femoral notching and anterior flange lift-off, and to evaluate their influence on anterior and posterior femoral offset (PFO) restoration. METHODS: This retrospective single-centre study included 400 consecutive primary TKAs. Robotic-assisted TKA was performed in 171 cases and navigated TKA in 229 cases. Femoral notching and anterior flange lift-off were assessed on postoperative true lateral radiographs as binary variables. Anterior femoral offset (AFO) and PFO were measured preoperatively and postoperatively and normalized as the anterior femoral offset ratio (AFOR) and posterior condylar offset ratio (PCOR). Variability was assessed using coefficients of variation. A multivariable logistic regression model adjusted for implant constraint, preoperative AFO, tibial slope, surgical approach and surgeon was used to adjust for potential confounders. RESULTS: Femoral notching occurred more frequently in the navigated group than in the robotic-assisted group (16.6% vs. 8.2%, p = 0.02). Anterior flange lift-off was also significantly more common with navigation (37.6% vs. 9.9%, p < 0.001). PFO restoration was comparable between techniques, with similar PCOR values (1.14 ± 0.17 vs. 1.11 ± 0.19, p = 0.079). In contrast, AFOR was significantly lower in the robotic-assisted group (0.736 ± 0.364 vs. 0.959 ± 0.583, p < 0.001), with reduced variability compared with navigation (coefficient of variation 49% vs. 61%). In the multivariable analysis, robotic assistance remained independently associated with lower odds of anterior flange lift-off (adjusted odds ratio [OR] 0.18, 95% confidence interval [CI] 0.095-0.324; p < 0.001). CONCLUSION: Robotic-assisted TKA significantly reduces femoral notching and anterior flange lift-off and demonstrates lower variability in AFO reconstruction. These findings reflect improved radiographic control of sagittal femoral positioning. LEVEL OF EVIDENCE: Level III, case-control retrospective analysis.