Comparison of Clinical Outcomes and Soft Tissue Laxity Between Robot-Assisted Functionally and Mechanically Aligned Total Knee Arthroplasty

Purpose This study aimed to compare postoperative clinical outcomes and soft tissue laxity between functional alignment (FA) and mechanical alignment (MA) in robot-assisted total knee arthroplasty (TKA). Methods Thirty-one FA and 31 MA TKAs performed using a robotic system were included in this retrospective study. Range of motion (ROM), the 2011 Knee Society Score (2011 KSS), and the Forgotten Joint Score-12 (FJS-12) at 6 weeks, 3 months, and 6 months after TKA, respectively, were compared between the two groups. Intraoperative laxities were compared between the two groups. Results Although no significant differences were noted in postoperative ROM and the 2011 KSS, the FJS-12 scores at 3 and 6 months after TKA were significantly higher in the FA group (64.4 and 68.4) than those in the MA group (51.9 and 57.0) (p<0.05 and p<0.05). At 90° flexion, the medial laxity of 1.1 mm in the FA group was significantly lower than that of 2.3 mm in the MA group (p < 0.001). Conclusion FA TKA was superior to MA TKA in achieving better FJS-12 and greater medial stability at 90° flexion.