Robotic arm-assisted total knee arthroplasty reduces postoperative inflammatory response and blood loss compared to manual total knee arthroplasty: A matched-pairs analysis of 688 patients.

Abstract

Purpose: Robotic arm-assisted total knee arthroplasty (raTKA) has demonstrated several advantages over manual TKA (mTKA), including enhanced early recovery. Reduced soft tissue trauma and avoidance of femoral intramedullary canal opening have been hypothesised to lower the systemic inflammatory response. However, findings from previous small-cohort studies have been inconsistent. This study aimed to evaluate postoperative systemic inflammation in a large patient cohort.

Methods: Patients who underwent raTKA using the Mako® system were matched with patients who received mTKA based on gender, American Society of Anesthesiologists score, age and body mass index. This matching process resulted in two comparable cohorts, each comprising 344 patients. Blood samples were collected preoperatively, 6 h postoperatively, and on postoperative Days 3 and 5. Measurements included C-reactive protein (CRP), white blood cell count (WBC) and calculated blood loss.

Results: The highest CRP levels were observed on postoperative Day 3 in both groups. The median CRP increase was significantly lower in the raTKA group compared with the mTKA group on Day 3 (4.4 vs. 5.3 mg/dL; p = 0.002) and slightly lower on Day 5 (3.5 vs. 3.8 mg/dL; p = 0.349). The WBC count peaked at 6 h postoperatively in both groups before steadily declining, with no significant difference between groups. The median operation time was significantly longer in the raTKA group (92 vs. 86 min; p < 0.001). Despite a longer surgical duration, the median blood loss was significantly lower in the raTKA group (653 vs. 729 mL; p = 0.005).

Conclusion: In the largest comparative analysis to date, raTKA was linked to significantly lower postoperative CRP levels than mTKA. Reduced soft tissue trauma, avoidance of femoral intramedullary canal violation and significantly lower blood loss may all contribute to a diminished systemic inflammatory response, potentially explaining the improved early functional outcomes observed with raTKA.

Level of evidence: Level III, retrospective comparative study.