Coagulation and Inflammatory Responses After Tourniquet Release in Total Knee Arthroplasty: Association with Hemodynamic Instability.

Background

Tourniquet use during total knee arthroplasty (TKA) improves surgical visualization and limits blood loss but may also trigger ischemia-reperfusion-related hemodynamic instability. This study investigated coagulation and inflammatory responses after tourniquet release and their association with perioperative hemodynamic instability.

Methods

This prospective observational cohort study included 22 patients aged 65-90 years undergoing unilateral TKA. Hemodynamic parameters, coagulation markers (D-dimer, INR, APTT), and inflammatory markers were measured at predefined perioperative time points. Hemodynamic instability was assessed using the modified shock index (MSI = HR/MAP). Non-parametric statistical analyses were performed.

Results

The D-dimer and INR increased significantly after tourniquet release and remained elevated at 24 h (p < 0.001). APTT prolongation was transient (p = 0.001). The NLR and SII increased both early and late, whereas CRP showed a delayed rise. Δ analysis demonstrated temporal changes in coagulation parameters; however, no significant between-group differences according to MSI status were identified. Although ΔPeak IL-6 was higher in the unstable group, the difference was not statistically significant (p = 0.097). ROC analysis demonstrated moderate discriminative performance for ΔPeak IL-6 (AUC = 0.747), whereas the NLR (AUC = 0.471), SII (AUC = 0.529), and CAI (AUC = 0.482) showed poor predictive performance for hemodynamic instability.

Conclusions

Tourniquet release induces significant coagulation and inflammatory responses following total knee arthroplasty. Although no definitive biomarker of hemodynamic instability was identified, ΔPeak IL-6 showed a trend toward association with instability and may merit further investigation. These findings suggest a possible interaction between inflammatory and coagulation pathways after tourniquet release and should be validated in larger prospective studies.