Abstract
BACKGROUND: Robotic-assisted total knee arthroplasty (RA-TKA) aims to improve surgical accuracy and reduce soft-tissue trauma. The bone-milling technique may further decrease mechanical stress during bone preparation. This study primarily compared systemic inflammatory biomarkers between bone-milling RA-TKA and conventional TKA (C-TKA), with secondary assessments of perioperative parameters, radiographic alignment, and early postoperative outcomes. METHODS: This prospective randomized controlled trial included 30 RA-TKAs and 30 C-TKAs performed between August 2023 and December 2024 in patients with Kellgren-Lawrence grade IV knee osteoarthritis. All RA-TKA procedures were conducted during the operating surgeon's early learning phase with the robotic platform. Serum interleukin (IL)-6, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), creatine kinase (CK), and lactate dehydrogenase (LDH) were measured preoperatively and at 6 h, 1 day, 3 days, 2 weeks, and 6 weeks postoperatively. Perioperative variables, radiographic alignment, and 6-week Knee Society Score (KSS) and visual analog scale (VAS) pain scores were compared. RESULTS: Postoperative inflammatory biomarkers did not differ significantly between groups at any time point, and the corresponding effect sizes were small, indicating minimal biological differences. Estimated blood loss was comparable (p = 0.753). RA-TKA demonstrated significantly improved postoperative mechanical alignment (mechanical axis [MA] deviation: 0.3 ± 2.4° versus 2.8 ± 3.4°; p = 0.002) but required longer tourniquet times (121.4 ± 15.3 min versus 95.0 ± 13.3 min; p < 0.001). Early functional outcomes were similar, with no significant differences in KSS (p = 0.114) or VAS pain scores at 6 weeks (p = 0.508). CONCLUSIONS: Bone-milling RA-TKA did not reduce systemic inflammatory responses compared with C-TKA, with small effect sizes confirming minimal biological differences. However, it provided superior radiographic alignment, while perioperative parameters and early postoperative recovery remained comparable except for longer tourniquet time.