Incidence of Venous Thromboembolism in Orthopaedic Foot and Ankle Surgeries

Abstract

Category: Other Introduction/Purpose: Venous thromboembolism (VTE) is a rare but potentially lethal complication following orthopaedic foot and ankle surgery. Surgeons continue to debate the types of patients and procedures in which it is appropriate to use chemical thromboprophylaxis. A recent meta-analysis concluded that patients at high risk for VTE after foot and ankle surgery should receive prophylaxis, but there remains a paucity of data to elucidate which demographic or comorbidity variables are most strongly associated with development of VTE. The incidence of VTE after orthopaedic foot and ankle surgery stratified by specific procedure has yet to be examined. The purpose of this study is to report the incidence of and identify risk factors for VTE in a large sample of patients receiving orthopaedic foot and ankle surgery. Methods: In this study, we retrospectively analyzed prospectively-collected data from the National Surgical Quality Improvement Program (NSQIP) 2006 to 2015 data files. The incidence of VTE was calculated for 30 specific orthopaedic foot and ankle surgeries and for four broad types of foot and ankle surgery. A total of 23,212 patients were identified and grouped by current procedures terminology (CPT) codes. Demographic, comorbidity, and complication variables were analyzed to determine associations with development of VTE. Pearson’s chi-squared test was used to compare categorical variables and Student t test was used to compare continuous variables. P-values of p<0.05 were considered statistically significant. Multivariable modelling was not possible due to the very low number of VTE cases relative to non-VTE cases. Results: The mean age at the time of surgery was 52.7±17.8 years. VTE events were documented 142 times in our sample, yielding an overall sample VTE incidence of 0.6%. The types of procedures with the highest frequency of VTE were ankle fractures (105/15,302 cases, 0.7%), foot pathologies (28/5,466, 0.6%), and arthroscopy (2/398, 0.5%). Female sex, increasing age, obesity level, inpatient status, and non-elective surgery were all significantly associated with VTE events. Postoperative pneumonia was significantly associated with VTE development. Patients who developed a VTE stayed at the hospital after surgery significantly longer than patients without VTE (6.2 vs. 3.1 days). Patients who developed VTE also had significantly higher estimated probability of morbidity (8.0% vs. 6.0%) and mortality (2.0% vs. 1.0%) when compared to patients without VTE. Conclusion: The present study confirms that VTE events after foot and ankle procedures are rare. The data presented suggest that female sex, increasing age, higher BMI, inpatient status, and non-elective procedures are associated with increased risk for VTE after orthopaedic foot and ankle surgery. Prospective, randomized, controlled trials are necessary to definitively determine the efficacy of chemoprophylaxis and to develop evidence-based clinical practice guidelines to minimize VTE after foot and ankle procedures.