Component Asymmetry in Robotic-Assisted Bilateral Total Knee Arthroplasty

Introduction Accurate sizing of femoral and tibial components is fundamental to achieving successful outcomes in total knee arthroplasty (TKA). Oversizing can increase patellofemoral contact forces and restrict flexion, whilst undersizing may result in instability. Although conventional TKA is well established, robotic-assisted systems provide enhanced alignment accuracy, individualised planning, and reduced periarticular soft-tissue injury. Bilateral TKA is increasingly performed in Middle Eastern populations, where knee anthropometry differs from Western cohorts. Previous studies in conventional bilateral TKA have demonstrated notable asymmetry between femoral and tibial components. The aim of this study was to determine the frequency of component asymmetry in simultaneous bilateral robotic-assisted TKA using the Navio robotic system in a Middle Eastern population. Methods A retrospective review was undertaken of all patients undergoing primary, uncomplicated simultaneous bilateral robotic-assisted TKA at Mediclinic City Hospital, Dubai, UAE, between January 2018 and January 2020. Only procedures performed by a single surgeon were included. Demographic data, body mass index (BMI), and component sizes were recorded. All procedures utilised implants from the Anthem Total Knee System (Smith & Nephew, London, UK), designed with standard and narrow femoral options to minimise medio-lateral overhang. Symmetry of femoral, tibial, polyethylene, and patellar components was assessed. Standard perioperative protocols for infection prevention, thromboprophylaxis, and enhanced recovery rehabilitation were employed. Results A total of 140 patients (78.6% female patients, mean age 70.4 ± 8.8 years) were included. The mean BMI fell within the overweight to obese range. Femoral components were identical in 132 patients (95%), with asymmetry present in eight patients (5%). Of these, six patients (4%) demonstrated a one-size difference, and eight exhibited variation in femoral component width (standard versus narrow). All tibial baseplates, polyethylene inserts, and patellar components were symmetrical across both knees (100%). Conclusion This is the largest series to date reporting on component symmetry in robotic-assisted bilateral TKA in a Middle Eastern population. The findings demonstrate a high degree of femoral and tibial component symmetry, with only 5% of patients requiring femoral asymmetry and none requiring tibial or patellar asymmetry. Compared with prior reports of conventional bilateral TKA in similar populations, robotic-assisted TKA showed markedly lower asymmetry rates. These results suggest that robotic technology improves the accuracy of component sizing and alignment, reduces mismatch rates, and may enhance long-term functional outcomes. Further prospective studies with functional and radiological endpoints are recommended to corroborate these findings and explore cost-effectiveness in the wider clinical practice.