Perioperative anticoagulation for patients undergoing orthopaedic surgery remains a challenge. Currently, there is insufficient evidence to provide definitive recommendations for care. Recent estimates suggest that, in the U.S. alone, there are over two million patients with atrial fibrillation who receive warfarin each year. Moreover, >100,000 heart valve replacements are performed annually.
In the September 2015 issue of JBJS Reviews, Dundon et al. review current recommendations for perioperative management of patients on existing anticoagulation therapy. They note that cessation of warfarin is based on risk stratification for thromboembolic events and bleeding risk, with cessation and bridging therapy being recommended if patients are at high risk for thromboembolic events or bleeding. On the basis of their assessment of published reports, they recommend that warfarin should be withdrawn and that bridging therapy should be instituted five days prior to surgery. Cessation and regular dosing should be resumed twelve to twenty-four hours after the operation.
However, the issue of perioperative bridging is currently under debate. The authors of this article could find no double-blind, randomized, controlled trials in which patients undergoing vitamin-K antagonist therapy who had received bridging with low-molecular-weight heparin or unfractionated heparin were compared with patients undergoing vitamin-K antagonist therapy who had received no bridging therapy. Bridging therapy with therapeutic-dose intravenous unfractionated heparin should be stopped four to six hours before surgery, but patients receiving therapeutic-dose subcutaneous low-molecular-weight heparin should take the last dose approximately twenty-four hours prior to surgery.
The authors recommended that patients in high cerebrovascular and cardiovascular risk groups should maintain aspirin with bridging therapy and may also maintain clopidogrel in emergencies as long as they are not undergoing a high-risk procedure. For patients who take rivaroxaban or dabigatran, emergency surgery is permissible as long as levels of the drug are ≤30 ng/mL at the time of admission.
These recommendations are based on careful and critical analyses of available data; however, as noted above, there are no critical evidence-based studies in the area of perioperative management of anticoagulation in patients who are undergoing orthopaedic surgery. The concepts and ideas presented in this article should be considered as recommendations at best.
Thomas Einhorn, Editor
The overall rate of symptomatic lower-extremity deep vein thrombosis (DVT) following arthroscopic ACL procedures is reported to be <0.3%, and guidelines from the American College of Chest Physicians recommend against DVT prophylaxis prior to arthroscopic knee surgery, unless a patient has risk factors for blood clots. But some patients are unknowingly at high risk for clots, as a case report by Ackerman et al. in the June 10, 2105 JBJS Case Connector shows.
A 45-year-old woman presented for arthroscopic ACL reconstruction in her left knee. Unbeknownst to her or her surgeons, the patient had asymptomatic May-Thurner syndrome—an anatomic variant of the iliac blood vessels in which the right common iliac artery crosses over the left common iliac vein, compressing the vein against the lumbar spine.
Nine days after ACL surgery, the patient showed up in the ED with pain and swelling in the operative leg. Ultrasound revealed an extensive DVT extending distally from the common femoral vein. Imaging of the chest and cardiac workups were negative for heart or lung thromboembolism.
A heparin drip was started, and a vascular surgeon ordered a left-leg venograph, which revealed a large clot extending from the origin of the left common iliac vein to the insertion site of the catheter in the popliteal vein. Severe stenosis of the left common iliac vein confirmed May-Thurner syndrome (see image below).
Treatment consisted of an infusion of tissue plasminogen activator (Alteplase) directly to the clot, continued intravenous heparin, and an angioplasty with stents to open the stenosed left common iliac vein. Mechanical thrombolysis and aspiration of a residual femoral vein thrombus was accomplished with a Trellis device.
Postoperatively the patient was transitioned to therapeutic warfarin for six months and instructed to wear compression stockings. She completed her ACL physical therapy protocol uneventfully, and one year after the ACL reconstruction, the knee graft was stable and there was no evidence of post-thrombotic syndrome.
The authors remind orthopaedists that May-Thurner syndrome, which is more common in women than men, should be suspected in the presence of an extensive iliofemoral DVT. They emphasize that multimodal and aggressive treatment, in consultation with a vascular specialist, should be initiated to bust the clot and reduce the risk of post-thrombotic syndrome. Post-clot, such patients should be maintained on warfarin for a minimum of six months, and patients with stents often require lifelong aspirin therapy.