Timing of tourniquet release in knee arthroplasty - Meta-analysis of randomized, controlled trials

Background: Some surgeons release the tourniquet before closing the wound to secure hemostasis during knee arthroplasty. We examined whether early tourniquet release could reduce the perioperative blood loss and whether not releasing the tourniquet until after wound closure would increase the risk of early postoperative complications. Methods: We searched electronic databases and reference lists of relevant articles, retrieved all of the published randomized controlled trials designed to address these issues, and performed a meta-analysis. Results: Eleven studies involving a total of 872 patients and 893 primary knee arthroplasties were analyzed systematically. The studies showed considerable clinical and methodological diversity. Early release of the tourniquet increased the total measured blood loss (weighted mean difference = 228.7 mL; 95% confidence interval = 168.3 to 289.1; p < 0.00001). Early release also increased blood loss as calculated on the basis of the maximum decrease in hemoglobin concentration (weighted mean difference = 320.7 mL; 95% confidence interval = 204.3 to 437.1; p < 0.00001). The rate of reoperations due to postoperative complications was 3.1% (nine of 290) in the group with late tourniquet release compared with 0.3% (one of 290) in the group with early tourniquet release; the risk difference was 3% (95% confidence interval, 0.1% to 5%), which was significant (p = 0.04). Conclusions: Early tourniquet release for hemostasis increases the blood loss associated with primary knee arthroplasty. However, tourniquet release after wound closure can increase the risk of early postoperative complications requiring another operation. Well-conducted large studies are needed to further explore the risk of early postoperative complications associated with late tourniquet release in knee arthroplasty. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.