Total hip arthroplasty (THA) is associated with blood loss ranging from 300 to 2000 mL. Tranexamic acid (TXA) is frequently administered prophylactically during this procedure to reduce blood loss by inhibiting fibrinolysis or by stopping naturally occurring clot resolution. TXA is employed currently based on a surgeon's preference. The objective of this study is to quantitate the degree of fibrinolysis using rotational thromboelastometry (ROTEM) and investigate the role of TXA prophylaxis on blood loss in patients undergoing THA in a double-blind fashion. Our hypothesis is that fibrinolysis is minimal at most and TXA prophylaxis is not necessary during THA. All patients, whether they receive TXA or normal saline, will not be at risk, as at this time no data exists to determine which approach is safer or more effective. This is the first study to compare TXA vs. placebo in a double-blinded, randomized controlled trial.

Total hip arthroplasty (THA) is associated with moderate blood loss ranging from 300 to 2000 mL. Tranexamic acid (TXA) is frequently administered prophylactically during this procedure to reduce blood loss by inhibiting fibrinolysis. Most clinical studies reported potential benefit of the treatment demonstrated by less estimated blood loss (EBL), reduced hemoglobin/hematocrit (HH) change, and reduced transfused packed red blood cells (PRBC). However, bleeding complication may be affected more significantly by the degree of surgical trauma and comorbidity of patients than coagulation abnormality. Further, the frequency and severity of fibrinolysis during these procedures have not been well studied. Additionally, TXA administration may increase the tendency of postoperative venous thrombosis by inhibiting fibrinolysis in already prothrombotic patients. The objective of this study is to quantitate the degree of fibrinolysis using rotational thromboelastometry (ROTEM) and investigate the role of TXA prophylaxis on clinical outcome in patients undergoing THA in a double-blind fashion. Our hypothesis is that fibrinolysis is minimal at most and TXA prophylaxis is not necessary during primary THA.

Inclusion Criteria:

• The study population will include total of 200 adults (age range of 18 - 85 years) who are in the American Society of Anesthesiologists (ASA) Physical Status (PS) 1-3. Inclusion criteria are patients undergoing unilateral, primary, total hip arthroplasty.

Exclusion Criteria:

• Exclusion criteria include patient's refusal, patients with history of significant coagulopathy or on anticoagulation therapy. Female patients who are pregnant or nursing will be excluded. In addition, patients with anemia (Hb < 8 g/dL) or who received blood transfusion within one week before surgery will be excluded. Patient receiving subcutaneous heparin on the same day prior to surgery will be also excluded.