The purpose of this study is to compare the effectiveness of three analgesia techniques on pain relief and functional recovery after knee replacement: continuous femoral nerve block vs single-injection femoral nerve block with intravenous patient controlled analgesia vs intravenous patient controlled analgesia.

Primary Outcome Measures:

• Incidence of patients with significant pain on movement on day 1 post surgery
• Range of knee flexion

Secondary Outcome Measures:

• Pain intensity (rest/movement)
• Functional recovery
• Knee Injury and Osteoarthritis Score
• Side effects/ Adverse outcomes
• SF12 Quality of Life Questionnaire
• Length of stay

Inclusion Criteria:

• 40 years and above
• Osteoarthritis
• Primary unilateral total knee replacement
• No other lower extremity joint disease
• ASA I-III
• Body mass index < 35
• No severe cardiac or pulmonary diseases
• No chronic narcotic therapy or illicit drug use
• Mentally competent to understand study procedures and use of pain scales
• Able to provide informed consent

Exclusion Criteria:

• Any cause for knee replacement other than osteoarthritis
• Total knee revision
• Any contraindication for femoral block
• Abnormal coagulation studies
• Thrombocytopenia less than 100,000/cc
• Known hepatic or renal insufficiency
• Neurological disease involving lower extremities
• Major surgery during the last 2 weeks pre-operatively
• History of allergy to study medications
• History of post-operative bleeding over 2000 cc/24 hours
• History of opioid or alcohol abuse
• Currently taking or has taken opioid > 30 consecutive days of daily use at a daily dose > 15mg morphine, within the past 2 weeks prior to surgery
• Previously has not responded to opioid analgesics for treatment of pain
• Pregnancy or breastfeeding