A Comparative Analysis of Robotic-Assisted and Manual Techniques for Unicondylar Knee Arthroplasty Conversion to Total Knee Arthroplasty: Revision Component Use, Surgical Time, and Cost.

Abstract

Unicondylar knee arthroplasty (UKA) conversion to total knee arthroplasty (TKA) is more complex than primary TKA, requiring additional time, effort, and occasionally revision components. Robotic assistance may alleviate the additional time and complexity when converting UKA to TKA. The aim of this study was to compare the use of revision components (e.g., stems, cones, augments), polyethylene characteristics, time, and cost between manual versus robotic UKA conversion to TKA. This is an Institutional Review Board (IRB)-approved, retrospective study of consecutive patients who underwent UKA conversion to TKA at a single institution from 2015 to 2025. Data extracted included surgical technique, reason for UKA failure, type of UKA and TKA implants, type of robot, use of revision components, polyethylene characteristics, surgical time, cost of implants, and postoperative complications. There were 62 UKA conversions to TKA identified, with 35 (56.5%) using robotic assistance. Statistical analyses were performed using Fisher's exact tests or Chi-square tests for categorical variables and Student's t-tests for continuous variables. Significance was set at P < 0.05. Robotic-assisted cases used fewer stems (11.4 versus 40.2%, P = 0.02) and less mid-level constrained polyethylene than manual cases (0 versus 14.8%, P = 0.04). Robotic conversion used significantly less costly implants than manual ($6,149.79 versus $7,185.42, P = 0.02), which included disposable robot costs. Robotic surgery resulted in shorter surgical time (109.9 versus 123.0 minutes, P = 0.028), reflecting an additional $490.6 in savings for the robotic group. Conclusion Robotic-assisted UKA conversion to TKA was associated with fewer revision stems, less mid-level constraint, and lower direct and indirect costs. There was no difference in use of cones or augments. These results may support robotic assistance, reducing the complexity, cost, and time for UKA conversion to TKA.