Prophylaxis with Enoxaparin After Total Knee or Hip Replacement

Risks of Thromboembolic Disease

The highest risk of venous thromboembolism (VTE) is generally among orthopedic patients, and VTE represents a significant complication after lower limb joint replacement surgery. Deep vein thrombosis occurs in 50–70% of patients undergoing knee replacement if thromboprophylaxis is not prescribed. VTE can occur up to 3 months after total knee replacement (TKR) or hip replacement (THR) and is the most common cause of rehospitalization after total hip joint replacement. Approximately 2/3 of patients with VTE related to orthopedic surgery experience deep vein thrombosis, with 1/3 additionally suffering from pulmonary embolism.

ACCP Recommendations

Thanks to the introduction of routine prophylaxis – based on the most commonly applied guidelines by the American College of Chest Physicians (ACCP) – in patients undergoing total hip or knee joint replacement, the incidence of fatal pulmonary embolism (PE) is rare. The incidence of symptomatic VTE within 3 months after surgery has decreased to 1.3–10% compared to the high incidence (50–70%) before the introduction of prophylactic treatment. ACCP guidelines recommend the administration of LMWH for a minimum of 10–14 days and up to 35 days, starting therapy ≥ 12 hours before or ≥ 12 hours after the procedure. Alternatively, other agents such as fondaparinux, apixaban, dabigatran, rivaroxaban, low-dose unfractionated heparin (UFH), vitamin K antagonists (VKA), or acetylsalicylic acid (ASA) can be used.

Portuguese Study and Its Findings

The Portuguese retrospective observational study focused on evaluating prophylaxis and the incidence of venous thromboembolism in patients who underwent THR or TKR between March 2019 and February 2020. Patients included in the study were those medicated with enoxaparin at a dose of 40 mg once daily for the specified indication. The analyzed data were extracted from the national electronic medication prescribing system.

The study included 483 patients, with 66.25% being women, and the median age was 68.3 years. The age of individuals undergoing TKR was significantly higher. Of all the study participants, 39.75% (n = 192) underwent elective THR, and 60.25% (n = 291) underwent TKR. The THR group stayed in hospital care about 1 day longer on average compared to the TKR patients (6.20 ± 5.00 vs. 5.21 ± 2.91 days; p < 0.001).

Enoxaparin was administered for approximately the same duration in both cohorts, averaging 31.86 ± 5.98 days in the THR group and 30.28 ± 5.97 days in the TKR group (p = 0.005). Treatment adherence was assessed as good, with patients completing an average of 29.38 ± 8.12 days (THR group) and 28.20 ± 7.32 days (TKR group) of VTE prophylaxis with enoxaparin (p = 0.098). The incidence of VTE was higher in the THR group (3.13% vs. 0.69% in the TKR group; p = 0.064).

Conclusion

The commonly prescribed dose of enoxaparin 40 mg once daily for up to 35 days post-procedure was effective in the cited study for VTE prophylaxis. The treatment, well-tolerated by patients, exhibited only a very small number of adverse events, contributing to very good compliance.

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Sources:
1. Nóbrega Catelas D., Cordeiro F., Loureiro L. et al. Effective VTE prophylaxis with enoxaparin after elective THR or TKR: a retrospective observational study. Porto Biomed J 2023 Aug 3; 8 (4): e222, doi: 10.1097/j.pbj.0000000000000222.
2: Gumulec J. Prevention of venous thromboembolism. Internal Medicine 2009; 11 (10): 458-462.