Individualized Functional Knee Alignment in Total Knee Arthroplasty: A Robotic-assisted Technique

Introduction: The use of robotic technology is becoming a well-recognized alternative to conventional total knee arthroplasty (TKA). The quantitative soft tissue information generated in robotic surgery can be used to balance the knee and achieve functional alignment (FA) of the components. This paper describes a novel FA technique using an individualized preoperative plan that is then adjusted to achieve soft tissue balance. Materials and Methods: We report on surgical technique, indications, considerations, and complications after our experience of performing 650 functionally aligned TKAs. We collected 2-year patient reported outcomes on 165 TKAs in this series (165 of 193 TKAs have reached 2 years follow-up in the series of 650 TKAs; 85% follow-up rate). Results: We found significant postoperative improvements with few infections and no revisions for mechanical reasons 2 years after surgery with this technique. Patients had improved knee range-of-motion (105 degrees degrees flexion preoperatively vs. 125 degrees flexion postoperatively; P < 0.001), higher Forgotten Joint Scores (17 preoperatively vs. 77 postoperatively; P < 0.001), improved Oxford Knee Scores (22 preoperatively vs. 43 postoperatively; P < 0.001), higher KOOS Jr scores (48 preoperatively vs. 88 postoperatively; P < 0.001) and lower visual analogue score pain scores (70 preoperatively vs. 12 postoperatively; P < 0.001) 2 years postoperatively. Discussion: The described surgical technique is a promising method for conducting a robotic TKA. Benefits of FA include improved efficiency with preresection balancing, reduced soft tissue releases compared with a mechanical alignment technique, and accurate bony cuts with robotic assistance. Further studies are required to compare this technique with established methods to determine any differences in outcomes.