The ‘‘Critical Thrombosis Period’’ in Major Orthopedic Surgery: When to Start and When to Stop Prophylaxis

Abstract

Patients undergoing major orthopedic surgery are at high venous thromboembolism (VTE) risk, with morbid and potentially fatal consequences. Anticoagulant VTE prophylaxis reduces rates of postoperative deep vein thrombosis by up to 60% to 70% in these patients. Therefore, pharmacological prophylaxis with low-molecular-weight heparins (LMWHs), vitamin K antagonists, or fondaparinux is recommended by current guidelines. However, there remains an ongoing debate regarding when to initiate and the optimal duration for prophylaxis. Here, we discuss the mechanisms underlying thrombus formation in patients undergoing major orthopedic surgery, and we review the current literature on the benefit-to-risk ratio associated with preoperative and postoperative initiation of thromboprophylaxis and also the benefit-to-risk ratio in cases of neuraxial anesthesia. We also discuss the duration of postoperative VTE risk following major orthopedic surgery and assess the ''critical thrombosis period'' when prophylaxis should be provided. Current literature reflects the need to balance the improved efficacy of initiating prophylaxis close to the surgery with increased risk of perioperative bleeding. Evidence from pathology, epidemiology, and clinical studies suggests the risk period for VTE begins at surgery and extends well beyond hospitalization-a crucial issue when considering how long to give prophylaxis-and, in the case of total hip arthroplasty, for at least 3 months after surgery. Literature supports the greater use of ''just-in-time'' thromboprophylaxis initiation and after-discharge continuation of optimal prophylaxis in orthopedic surgery patients. Providing optimal thromboprophylaxis throughout the critical thrombosis period where a patient is at VTE risk will ensure the best reductions in VTE-related morbidity and mortality.

Prevention of Venous Thromboembolism in Total Knee and Hip Replacement

“…13 Pharmacological prophylaxis can be started before surgery, but if too close there will be a risk of bleeding; if too far before surgery, the drug effect will have decayed before the thrombotic process commences. Preoperative administration is also compromised because an unexpected delay in surgery or an earlier than expected procedure will exacerbate these problems.…”

Coagulation and Fibrinolysis Markers and Their Use for the Prediction of High Risk Patients with Venous Thromboembolism Following Total Hip Arthroplasty

“…However, the optimal timing for the initiation of pharmaco-prophylaxis is one of the issues raised by thromboprophylaxis, and the administration of anticoagulant agents following this screening test might be regarded as being relatively late. There has been debate in the literature regarding the issue of how to maximize efficacy while minimizing bleeding risk [32] because the peak efficacy of anticoagulant agents depends on the timing of the first injection [33,34]. According to a systematic review [33], the incidence of DVT was 19% in patients to whom low-molecular-weight heparin (LMWH) was administered 12 hours before surgery, 12% in patients given LMWH during surgery, and 14% in those treated postoperatively.…”

Pre versus Post-Operative Initiation of Warfarin Therapy in Patients undergoing Total Hip and Knee Arthroplasty

“…It acts by preventing the carboxylation of Vitamin K dependent clotting factors in the liver; however, it first affects anti-coagulant Protein C and S, leading to an interval of transient hypercoagulability. While the risk of DVT formation may begin at the time of surgery or during the early postoperative period, patients are unprotected until their INRs reach appropriate levels [3]; thus, the optimal timing of warfarin treatment with respect to surgery remains unclear.…”