# Comparison of serum systemic inflammatory biomarkers in bone-milling robotic-assisted total knee arthroplasty and conventional total knee arthroplasty: a prospective randomized controlled trial

## TL;DR

This study compares robotic-assisted and conventional knee replacement surgeries, finding no significant difference in inflammation but better alignment with the robotic method.

## Contribution

The novel contribution is the direct comparison of systemic inflammatory biomarkers between bone-milling robotic-assisted and conventional TKA in a prospective randomized trial.

## Key findings

- No significant differences in systemic inflammatory biomarkers between RA-TKA and C-TKA.
- RA-TKA showed significantly improved postoperative mechanical alignment compared to C-TKA.
- Early functional outcomes and recovery were comparable between the two groups.

## Abstract

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.

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.

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).

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.