All subjects scheduled to receive a unilateral, primary total knee replacement were evaluated for eligibility in the preoperative anesthesia center. Adults, older than 18 years of age, ASA I-III were included in the study. Subjects who were either pregnant, on anticoagulant therapy, allergic to opioids, local anesthetics, chronic pain patients, history of traumatic lower extremity injury, or had a body mass index of greater than 35 kg/m2 were excluded from the study.
