Pain Treatment After Total Knee Replacement - Continuous Epidural Versus Intravenous Patient Controlled Analgesia With Morphine

Pain Treatment After Total Knee Replacement - Continuous Epidural Versus Intravenous Patient Controlled Analgesia With Morphine

The study purpose is to compare the effectiveness of different methods for post-operative pain treatment after total knee replacement.

Total knee replacement (TKR) is known to be one of the most painful surgical procedures. Many treatments have been used post TKR: IV opioids, epidural infusions, peripheral nerve blocks. No one method has been recognised as the best one.

In this study we will compare two well established methods of pain treatment:

1. continuous infusion of local anesthetics + opioids into the epidural space,
2. patient controlled analgesia with IV Morphine.

The study design is double blind.

Patients will have a combined spinal-epidural anesthesia for the operation and then will be connected to 2 different pumps, one to the epidural catheter and one to the intravenous catheter, for the first 24 hours post-operatively.

Pain scores, total analgesic medications other than study medications, adverse reactions to study medications, complications and patient satisfaction will be followed by blinded observers and compared between groups.

Inclusion Criteria:

• Informed consent
• Age: 55 to 85 years
• Osteoarthritis
• Primary unilateral total knee replacement
• American Society of Anesthesiologists (ASA) I-III
• Successful spinal epidural anesthesia for surgery

Exclusion Criteria:

• Any cause for knee replacement other than osteoarthritis
• Total knee revision (re-do)
• Any contraindication for regional anesthesia
• Abnormal coagulation studies
• Thrombocytopenia less than 100,000/cc
• Chronic renal failure (creatinine [cr] < 1.8)
• Neurological disease involving lower extremities
• Major surgery during the last 2 weeks pre-operatively
• Current or past drug or alcohol abuse
• Allergy to study medications
• Post-operative bleeding over 2000 cc/24 hours
• Postdural puncture headache after anesthesia performance