Prevention of Venous Thromboembolism after Arthroscopic Knee Surgery in a Low-Risk Population with the Use of Aspirin. A Randomized Trial.

Introduction: Historically, venous thromboembolism (VTE) in the setting of elective knee arthroscopy has been considered rare. However, more recently, the rate of deep vein thrombosis (DVT) has been reported to be approximately 10%. With increasing recognition of the potential for the development of thromboembolic events, several randomized trials have evaluated the efficacy of chemoprophylaxis in reducing the risk of VTE following knee arthroscopy. However, all of these studies have evaluated the efficacy of low molecular weight heparins (LMWH), with reductions in the risk of DVT ranging from 65% to 93%, but with the potential side effect of bleeding. At the present time, there have been no randomized studies reported evaluating the utility of aspirin, an agent with a reportedly lower bleeding risk than LMWH, as pharmacologic prophylaxis against VTE after arthroscopic knee surgery.

Methods: In a single-center, randomized, single-blind prospective trial, the efficacy of aspirin as postoperative pharmacologic VTE prophylaxis was evaluated in a low risk population undergoing knee arthroscopy. One hundred seventy patients were randomized to a treatment group of 325 mg of aspirin daily for 14 days postoperatively (66 patients) or to the control group with no intervention (104 patients). Bilateral, whole leg, compression venous duplex ultrasonography was performed 10 to 14 days postoperatively to document the incidence of DVT. The primary endpoint of the current study was the development of DVT or pulmonary embolism (PE), and the secondary endpoint was the development of a postoperative complication.

Results: The study cohort was comprised of 104 males (61%) and 66 females (39%) with a mean age of 44.4 ± 14.4 years (range: 18 to 75 years). Within both the aspirin treatment and control groups, the surgical procedures included meniscectomy, ACL reconstruction, chondroplasty, and meniscus repair. No cases of postoperative deep vein thrombosis (DVT) or pulmonary embolism (PE) were identified in either arm of the study during the observation period. Twenty-three patients experienced a complication, including pain or swelling (9%), residual joint line tenderness (3%), arthrofibrosis (0.6%), and instability after a fall (0.6%). Three patients developed knee swelling, two of them in the aspirin group and one of whom required a knee aspiration. However, there was no difference in the development of complications between the two patient populations (p = 0.76, odds ratio [OR] 1.14, 95% confidence interval [CI] 0.5-2.56).

Conclusions: With no cases of VTE identified in our patient population, the use of aspirin in a low-risk population undergoing arthroscopic knee surgery is not warranted.