Extended-duration thromboprophylaxis with enoxaparin after arthroscopic surgery of the anterior cruciate ligament: a prospective, randomized, placebo-controlled study

Abstract

Purpose: To compare the efficacy of extended-duration thromboprophylaxis with enoxaparin for 20 days in the outpatient setting with in-hospital thromboprophylaxis with enoxaparin (3 to 8 days) only in patients who had undergone arthroscopic surgery of the anterior cruciate ligament (ACL).

Methods: This was a single-center, randomized, double-blind, prospective trial investigating 175 ACL surgery patients. All patients received subcutaneous enoxaparin 40 mg once daily 12 to 18 hours presurgery and 3 to 8 days postsurgery during hospitalization. After discharge, patients were randomized to 40 mg enoxaparin (n = 87) or placebo (n = 88) self-administered once daily subcutaneously for 20 days. The primary efficacy end-points were the incidences of symptomatic and asymptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE). Primary safety endpoints were the incidences of major and minor bleeding.

Results: Thirty-five patients were excluded because of noncompliance with the predefined protocol. No patient had DVT confirmed by magnetic resonance venography (MRV) at discharge. Of 140 patients in the intention-to-treat population, 2 (2.8%) who received postdischarge enoxaparin (n = 72) and 28 (41.2%) who received placebo (n = 68) had DVT confirmed by MRV (P < .001). No patients were diagnosed with PE. No major bleeds occurred. Minor bleeding occurred in 13 (2.5%) out of 513 postdischarge enoxaparin injections and 10 (2.0%) out of 492 placebo injections (P = .595). Risk factors for DVT during the 20 days postdischarge were age >30 years (odds ratio [OR]: 3.241; 95% confidence interval [CI], 1.015 to 10.349) and immobilization before surgery (OR 18.195; 95% CI, 2.046 to 161.837).

Conclusions: Extended-duration postdischarge thromboprophylaxis for 20 days with enoxaparin in the outpatient setting significantly reduced the incidence of DVT in ACL surgery patients compared with enoxaparin limited to in-hospital thromboprophylaxis without increasing major or minor bleeding.

Level of evidence: Level I, high-quality randomized controlled trial.