Evaluating the accuracy of Cuvis™ robot assisted total knee arthroplasty using offset type tensor system in ligament gap balancing.

Abstract

<h4>Background</h4>Conventional total knee arthroplasty (TKA) is a widely accepted and cost effective procedure for treating symptomatic knee osteoarthritis. Despite its success, patient satisfaction rates range from 82 % to 89 %, primarily due to suboptimal functional outcomes, reduced implant longevity, and the need for revision surgeries stemming from component malalignment or soft tissue instability. Robot-assisted total knee arthroplasty (RA-TKA) offers a promising approach to address these challenges.<h4>Aim</h4>This study aims to evaluate the accuracy of robot-assisted total knee arthroplasty in achieving optimal ligament gap balancing, based on 159 cases performed in 2023.<h4>Method</h4>A total of 159 RA-TKA procedures using the Cuvis™ robot were conducted in 2023, with 9 valgus knees and 150 varus knees. Ligament gaps were measured twice by the robotic system: initially before bone cuts and subsequently after bone cuts. During surgery, an off-set type tensor was used to reassess ligament gaps. Cases exhibiting a discrepancy greater than 3 mm between extension and flexion gaps, as measured by both the tensor and robot, were included for further analysis. Discrepancies between surgeon-measured values and robot-predicted values were also evaluated.<h4>Result</h4>Of the 159 cases, 35 demonstrated a ligament gap discrepancy of more than 3 mm, as measured by the tensor. Among these, 24 cases (15 %) exhibited discrepancies between robotic measurements and tensor assessments. All 9 valgus knee cases showed discrepancies, while 15 varus knee cases also displayed discrepancies. The robot recorded 20 errors in ligament gap measurement, 2 errors in balancing, and 2 cases with both errors.<h4>Conclusion</h4>While robot-assisted TKA excels in bone cutting accuracy, errors in predicting ligament balancing and gaps remain in some cases. Therefore, caution is advised when adapting surgical strategies intra-operatively, relying solely on the Cuvis™ robotic system's measurements.