Abstract
<title>Abstract</title> <p>Background Appropriate soft-tissue balancing is critical for successful total knee arthroplasty (TKA). Although robotic systems enable intraoperative assessment of joint laxity (JL) through manual varus–valgus stress testing, the clinical validity of this technique remains unclear. This study investigated whether robot-assisted manual stress assessment accurately reflects quantitative ligament balancing and predicts postoperative soft-tissue balance and clinical outcomes. Methods Fifty knees that underwent robot-assisted TKA were retrospectively evaluated. Following implant placement, intraoperative JL in extension was measured using robot-assisted manual stress assessment (JLR) and a tensioner device (JLT), with a distraction force of 80 N applied to both compartments. Postoperative JL in extension was assessed by measuring the medial opening angle (MOA) and lateral opening angle (LOA) on stress radiographs. Correlations between intraoperative and postoperative JL measurements, as well as clinical outcomes assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS) and the 2011 Knee Society Score at 1 year postoperatively, were analyzed. Results No significant differences were observed between JLR and JLT in either the medial or lateral compartment. Medial JLR demonstrated a significant positive correlation with MOA and lateral JLR demonstrated a significant positive correlation with LOA. Greater lateral JLR was significantly associated with lower KOOS Sports and Quality of Life scores. Conclusions Robot-assisted intraoperative manual stress assessment in knee extension showed good agreement with quantitative tensioner measurements and predicted postoperative JL and clinical outcomes. These findings suggest that robot-assisted manual stress assessment in extension is a reliable and clinically useful method for evaluating soft-tissue balance during TKA.</p>