Prophylactic Enoxaparin Reduces Symptomatic Venous Thromboembolism Compared With No Chemoprophylaxis Within 95 Days After Knee Arthroscopy

PURPOSE: To investigate whether prophylactic use of low-molecular-weight heparin (enoxaparin) after knee arthroscopy reduces the incidence of symptomatic venous thromboembolism (VTE) compared with no postoperative pharmacological prophylaxis. METHODS: We conducted a population-based cohort study using linked national insurance and hospital data from January 1, 2016, to December 31, 2023. Adults undergoing standard knee arthroscopy were identified and included, and those with prior VTE, coagulation disorders, recent cancer, preoperative anticoagulation, septic arthritis, or extended hospital stay were excluded. Patients filling a prophylactic enoxaparin prescription within 5 days of discharge comprised the enoxaparin group; all others formed the control group. The primary outcome was symptomatic VTE (combined deep vein thrombosis and pulmonary embolism) within 90 days after group allocation. Secondary safety outcomes included wound infection, septic arthritis, heparin-induced thrombocytopenia, intracranial hemorrhage, gastrointestinal bleeding, epistaxis, and surgery-related bleeding leading to hospitalization. RESULTS: Of 181,135 knee arthroscopies identified, 99,916 patients met the inclusion criteria. Among them, 67,108 (67%) received enoxaparin and 32,808 (33%) did not. Symptomatic VTE occurred in 380 patients (0.57%) in the enoxaparin group and 293 patients (0.89%) in the control group. Enoxaparin prophylaxis was associated with a significantly lower incidence of symptomatic VTE (hazard ratio: 0.64; 95% confidence interval: 0.55-0.74; P = .0003), corresponding to a number needed to treat of 310 to prevent 1 symptomatic event. Adverse events were rare in both groups. CONCLUSIONS: Prophylactic enoxaparin after knee arthroscopy was associated with a significantly reduced risk of symptomatic VTE within 95 days of discharge compared with no pharmacological prophylaxis. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.