Clinical question: Is DVT prophylaxis necessary with lower leg casting or after knee arthroscopy?
Background: Patients who undergo immobilization from casting or knee arthroscopic surgery are thought to be at increased risk for venous thromboembolism (VTE). Most patients who undergo orthopedic procedures receive thromboprophylaxis but controversy exists surrounding its use in low limb casting or knee arthroscopic surgery. Prior studies did not establish consensus because of methodologic weaknesses.
Study design: Two parallel randomized-controlled, open-label trials with blinded outcome (POD-KAST for knee arthroscopy and POD-CAST for casting lower leg.
Setting: International (32 pediatric intensive care units across Asia, Australia, Europe, and North America).
Synopsis: Patients were randomly assigned to receive either a prophylactic dose of low-molecular-weight heparin (either for the 8 days after arthroscopy or for the duration of casting-related immobilization) or no anticoagulant therapy. The primary outcomes were the cumulative incidences of symptomatic venous thromboembolism (VTE) and major bleeding within 3 months after the procedure. For the 1,543 patients undergoing knee arthroscopy, VTE occurred in 0.7% of the treatment group and 0.4% of the control group (relative risk, 1.6; 95% confidence interval [CI], 0.4-6.8; absolute difference in risk, 0.3 percentage points; 95% CI, −0.6 to 1.2) and major bleeding was seen in 0.1% of both groups.
For the 1,519 patients undergoing knee arthroscopy, VTE occurred in 1.4% of the treatment group and 1.8% of the control group (relative risk, 0.8; 95% CI, 0.3-1.7; absolute difference in risk, −0.4 percentage points; 95% CI, −1.8 to 1.0) and no episodes of major bleeding were reported in either group.
Bottom line: VTE prophylaxis either after arthroscopy or during immobilization from casting did not prevent DVT.
Citations: Van Adrichem RA, Nemeth B, Algra A, et al. Thromboprophylaxis after knee arthroscopy and low-leg casting. N Engl J Med. 2016 Dec 3. doi: 10.1056/NEJMoa1613303.
Dr. Cerceo is assistant professor in the division of hospital medicine, and associate director of the internal medicine residency program at Cooper Medical School of Rowan University, Camden, N.J.