Total knee replacement is often associated with severe postoperative pain, especially in the first 24 hours. Patient controlled analgesia (PCA) and continuous femoral block with PCA are commonly used to treat postoperative pain after total knee arthroplasty. However, PCAs use opioids. Opioids are excellent painkillers but their use is hampered by side effects such as nausea, vomiting, bowel dysfunction, urinary retention, pruritus, sedation and respiratory depression. We propose to test the hypothesis that adding a low dose lidocaine infusion to PCAs will lower the amount of opioids that these patients receive, thereby improving patient safety while still providing adequate analgesia. In addition, continuous femoral block has been shown to provide superior postoperative pain control when compared to morphine PCA. Therefore, postoperative pain levels of study subjects will be compared to those subjects who receive a combination of a continuous femoral block catheter with a PCA.

• Procedure: Continuous femoral catheter block
• Drug: Lidocaine
• Other: Preservative free normal saline

• Active Comparator: Group A subjects will receive a continuous femoral block catheter and a Patient Controlled Analgesia (PCA).
• Experimental: Group B subjects will receive a low dose lidocaine (1.33 mg/kg/hr) infusion and a Patient Controlled Analgesia.
• Placebo Comparator: Group C subjects will receive placebo (preservative free normal saline) infusion and a Patient Controlled Analgesia.

Inclusion Criteria:

1. Undergoing a total knee arthroplasty
2. Be American Society of Anesthesiologist physical status 1,2, or 3
3. Be willing and capable of providing informed consent
4. Be English speaking

Exclusion Criteria:

1. Age greater than 80 years old or younger than 18 years old
2. Congestive hear failure
3. Hepatic insufficiency
4. Neurological disorders
5. Psychiatric disorders
6. Steroid treatment
7. History of atrial fibrillation
8. Chronic pain disorder with opioid treatment