Only High Risk Patients May Require Anticoagulation After Arthroscopic Knee Surgery Interview with:

Suzanne C. Cannegieter, M.D., Ph.D. Einthoven Laboratory  Leiden University Medical Center  The Netherlands

Dr. Suzanne Cannegieter,

Suzanne C. Cannegieter, M.D., Ph.D.
Einthoven Laboratory
Leiden University Medical Center
The Netherlands What is the background for this study? What are the main findings?

Response: Patients who undergo arthroscopic knee surgery and patients who are treated with casting of the lower leg are at increased risk for venous thromboembolism (VTE). It is uncertain whether thromboprophylaxis is effective in these situations to prevent VTE. For both indications, several trials have been performed to evaluate the effectiveness of anticoagulant prophylaxis. However, an overall risk–benefit balance could not be established because of methodologic shortcomings; hence, there has been reluctance to establish international guidelines regarding the use of anticoagulant therapy for either of these indications.

For both indications about 1500 patients were randomised for either anticoagulant treatment with low molecular weight heparin (LMWH) or no treatment. In the knee arthroscopy trial  venous thromboembolism occurred in 5 of the 731 patients (0.7%) in the treatment group and in 3 of the 720 patients (0.4%) in the control group (relative risk, 1.6; 95% confidence interval [CI], 0.4 to 6.8; absolute difference in risk, 0.3 percentage points; 95% CI, −0.6 to 1.2). In the plaster cast trial VTE occurred in 10 of the 719 patients (1.4%) in the treatment group and in 13 of the 716 patients (1.8%) in the control group (relative risk, 0.8; 95% CI, 0.3 to 1.7; absolute difference in risk, −0.4 percentage points; 95% CI, −1.8 to 1.0).

Major and clinically relevant non major bleeding was rare and occurred at the same rate in both treatment groups in both trials. What should readers take away from your report?

Response: Thromboprophylaxis with low-molecular-weight heparin for the 8 days after knee arthroscopy or during the full period of immobilization due to casting is not effective for the prevention of symptomatic VTE. It is therefore not advisable to treat all patients routinely with low molecular weight heparin . What recommendations do you have for future research as a result of this study?

Response: Particularly in patients with plaster cast, VTE is not rare (about 1.6%) so in absolute terms VTE will remain to occur. It is likely that these patients have other underlying risk factors. When these are known, it would make sense to target only such high risk patients with higher intensity or longer duration anticoagulant treatment. Future research should focus on this topic. Thank you for your contribution to the community.


Thromboprophylaxis after Knee Arthroscopy and Lower-Leg Casting

Raymond A. van Adrichem, M.D., Banne Nemeth, M.D., Ale Algra, M.D., Ph.D., Saskia le Cessie, Ph.D., Frits R. Rosendaal, M.D., Ph.D., Inger B. Schipper, M.D., Ph.D., Rob G.H.H. Nelissen, M.D., Ph.D., and Suzanne C. Cannegieter, M.D., Ph.D.

December 3, 2016DOI: 10.1056/NEJMoa1613303

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on December 6, 2016 by Marie Benz MD FAAD