Comparison of early postoperative inflammatory response, blood-loss burden, and functional outcomes after robot-assisted and conventional total knee arthroplasty

This study compared early inflammation, hemoglobin (Hb)-based estimated total blood loss, lower-limb alignment, and early recovery between robot-assisted total knee arthroplasty (RA-TKA) and conventional manual TKA (CM-TKA). We reviewed 106 patients with knee osteoarthritis who underwent primary unilateral TKA. There were 48 patients in the RA-TKA group and 58 in the CM-TKA group. We recorded operative time, tourniquet time, hip-knee-ankle angle (HKA), C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), hemoglobin (Hb), visual analogue scale (VAS) score, and knee range of motion (ROM). Total blood loss was estimated using the Nadler and Gross formulas. Multivariable regression and stabilized inverse probability of treatment weighting were used. RA-TKA required longer operative and tourniquet times. However, estimated blood loss was lower in the RA-TKA group than in the CM-TKA group. Postoperative HKA was closer to 180°, and HKA deviation was smaller. HKA correction and alignment outlier rates were similar. RA-TKA also showed lower postoperative day (POD) 3 CRP, lower POD3 VAS, and higher POD3 ROM. POD1 and POD3 NLR were higher. After pretreatment adjustment, RA-TKA remained associated with smaller HKA deviation, lower POD3 CRP, less estimated blood loss, lower POD3 VAS, higher POD3 ROM, and higher POD3 NLR. RA-TKA was associated with lower POD3 CRP, less estimated blood loss, and differences in early postoperative pain and ROM measurements, although it required longer operative and tourniquet times. Postoperative NLR and CRP showed discordant patterns, and the clinical significance of the higher NLR remains uncertain.