This research study is attempting to answer the question of whether 81 mg aspirin once daily is as effective as 81 mg aspirin twice daily in preventing blood clots after total joint replacement surgery.

Inclusion criteria:

• > 18 years of age
• Planning to undergo a primary total hip or knee arthroplasty

Exclusion Criteria:

• High risk patients for VTE as defined by:

  • History of venous thromboembolism
  • Active malignancy
  • Known pro thrombotic condition

• BMI > 40

• Patients requiring anticoagulation for pre-existing conditions

• Patients with the contraindication for use of aspirin or nonsteroidal antiinflammatory drugs for reasons such as peptic ulcer disease, intolerance, others.

• Patients not fluent in the language of the informed consent form

• Prisoners

• Pregnancy

• Reported to have mental illness or belonging to a vulnerable population