Robotic-assisted bone cuts guided by intraoperative load sensors for ligament balancing in restricted kinematic alignment total knee arthroplasty: A retrospective study with 2-year follow-up.

Abstract

Achieving optimal ligament balance during total knee arthroplasty (TKA) improves patient satisfaction. While kinematic alignment enhances ligament balance compared to mechanical alignment, soft tissue releases are sometimes necessary. However, soft tissue releases lack consistency and reproducibility, contributing to suboptimal outcomes despite the use of intraoperative load sensors. Recent studies suggest tibial recuts as an alternative method for ligament balance. This study investigates the feasibility and efficacy of robotic-assisted bone recuts for achieving ligament balance, with a secondary aim of determining a force threshold correlating with negative clinical outcomes. A retrospective study of 109 patients undergoing TKA between February 2020 and February 2021 was conducted. All surgeries used Stryker Triathlon implants with no soft tissue releases. Bone recuts, in 0.5-mm increments, were performed at the tibia or femur based on intraoperative load sensor feedback. Clinical outcomes were assessed using the Forgotten Joint Score 12 (FJS-12) and the Knee Injury and Osteoarthritis Outcome Score 12 at 2 years. Eight patients were lost to follow-up at 2 years. At the end of the procedure, 92% of knees were balanced at 10° of flexion, and 85% were balanced at 90° of flexion. After tibial recuts, the medial femorotibial force decreased by an average of 33.6 lbf at 10° of flexion and 30.1 lbf at 90° of flexion. At 2 years, the mean FJS-12 score was 78.94, with 65% of patients achieving a score above 77.1. No significant correlation was found between intraoperative ligament balance and clinical outcomes. Robotic-assisted ligament balancing using bone recuts is a feasible and reproducible technique to achieve intraoperative balance without soft tissue releases. However, improved ligament balance did not result in superior clinical outcomes at 2 years. Level III, retrospective comparative study.