PURPOSE: Existing evidence estimates a twofold risk of venous thromboembolisms (VTEs) if tourniquet is applied during total knee arthroplasties (TKAs). However, this estimate relies on multiple trials with a low number of patients analyzing VTEs as a secondary outcome. We hypothesized that tourniquet-use increases the risk of symptomatic VTE within 90 days of contemporary primary TKA and aimed to use the extensive Danish healthcare registries to quantify this risk.
METHODS: Prospectively collected registry data from Danish patients receiving primary TKAs between 2014 and 2018 were included in the study. Patients were divided by tourniquet-use during surgery. By merging information from four nationwide registries, the study included 44 baseline characteristics with the potential to confound the association between tourniquet-use and VTE. Incidence rate and odds ratios were used to compare the risk of VTE within 90 days of surgery.
RESULTS: 19,804 patients of whom 10,111 (51%) were operated with tourniquet and 9693 (49%) without were included. The mean age (SD) was 70 (9) in both groups and 62% were females in the tourniquet group compared with 61% in the no tourniquet group. The groups were similarly comparable across all other baseline characteristics except type of post-operative thromboprophylaxis, type of anaesthesia, implant fixation, and year of surgery. The 90-days incidence of VTE was 0.77% (95% CI 0.60-0.94) in the tourniquet group compared with 1.10% (95% CI 0.90-1.31) in the no tourniquet group. Following adjustment for the unbalanced confounders, the odds ratio for VTE was 0.77 (95% CI 0.54-1.10) associated with tourniquet-use.
CONCLUSION: In contemporary TKAs the rate of VTE within 90 days is low and not significant altered by tourniquet-use. Thus, tourniquet can safely be applied during primary TKA-surgery without jeopardizing the risk of postoperative VTE.
LEVEL OF EVIDENCE: II-prospective cohort study.