Inclusion Criteria:  Patients undergoing unilateral primary total knee arthroplasty with spinal anesthetic and MAC followed by a unilateral adductor canal block with ultrasound guidance.  Exclusion Criteria:  Patients on chronic anticoagulation upon admission Patients with significant genetic or acquired clotting/bleeding disorders (hemophilia, DIC, etc.) or significant platelet dysfunction Patients with prior back surgery or leg surgery that precludes spinal or regional anesthesia Infection at sites for regional/spinal anesthesia Allergy to local anesthetics