Venous thromboembolism after fast-track unicompartmental knee arthroplasty - A prospective multicentre cohort study of 3927 procedures

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) has increased due to potential favourable complication rates when compared to total knee arthroplasty (TKA). Although venous thromboembolism (VTE) is a well-documented complication after TKA limited data is available after UKA and mostly presented as secondary findings in observational comparisons to TKA. There is a lack of fast-track UKA VTE studies and no guidelines on thromboprophylaxis. Consequently, we described the 90-day incidence of VTE after UKA within a multicentre fast-track collaboration.

MATERIALS AND METHODS: We used an observational cohort study design from 8 dedicated fast-track centres with prospective collection of preoperative risk-factors, complete follow-up on length of stay (LOS), 90-day readmissions and mortality from the Danish National Patient Registry and analysis of health records if LOS > 2 days or an ICD-10 code of VTE. Due to limited events we refrained from analysis of independent risk-factors.

RESULTS: In 3927 procedures (46.1% males, mean age 66.2 (SD 9.4) years) median LOS was 1 [IQR 0-1] day and 7.5% had LOS > 2 days. The 90-day incidence of VTE was 16 (0.41%) and 14 (0.37%) when excluding preoperatively anticoagulated patients. There were 5 (0.13%) pulmonary embolisms and 11 (0.28%) deep-vein thrombosis after median 18 [11.75-35.25] days. 90-day mortality was 3 (0.08%) with no fatal PE or initial postoperative VTE.

CONCLUSIONS: The 90-day incidence of VTE after fast-track UKA was 0.41% (0.37% when excluding preoperatively anticoagulated patients), which is comparable to reports of 0.39% VTEs after fast-track TKA in the same departments. Investigations on risk-factors are needed for optimizing thromboprophylaxis.