The main purpose of this study is to determine if there is improvement in pain and other patient outcomes when using a continuous wound analgesia system after total knee replacement, compared to usual methods of pain control. Another purpose is to determine if the system makes it easier for nurses to care for these patients.

Continuous local wound infusion analgesia is a relatively new way of managing post-operative pain, whereby a local anesthetic is continuously infused into the surgical area. Some studies and users have reported decreased pain, decreased opioid use, decreased post-operative nausea and vomiting, decreased length of stay, and improved patient and caregiver satisfaction with the use of continuous local wound infusion analgesia, when compared to placebo, or usual care, in arthroplasty and other surgical interventions.

Hypotheses:

Primary:

The On-Q PainBuster (continuous wound infusion analgesia) in TKA will result in improved patient pain control, compared to usual care.

Secondary:

• Pain scores post-operatively will be better than usual care.
• Fewer narcotics will be ingested post-operatively than with usual care.
• Post-op nausea and vomiting will be less than usual care.
• Length of stay will be shorter compared to usual care.
• Patient satisfaction will be greater than satisfaction with usual care.
• Post-operative infection rates will be no different between groups.
• Fall rates will be no different between groups.
• Subjects will participate in physical therapy the day of surgery.
• Nursing Intensity requirements will be less with the wound infusion due to fewer requests for pain medication.

Inclusion Criteria:

• Scheduled for TKA at the Royal Alexandra Hospital
• Patient of Dr. Arnett
• Deemed fit for continuous wound infusion (no allergies to Bupivacaine or related medications) by anesthesia
• Cognitively aware, and provides informed consent
• Elective (not trauma-related) surgery
• Able to read, speak and understand English
• Adult < 70 years of age
• Intra-operative spinal anaesthesia
• Reside within metropolitan Edmonton, in a bungalow
• Have a caregiver at home
• ASA risk classification of 1 or 2
• Do not regularly use opioid medication pre-operatively
• Have preoperative knee range of motion > 90 degrees
• Body Mass Index < 40
• No known hepatic or liver insufficiency

Exclusion Criteria:

• Deemed unfit for continuous wound infusion due to allergies
• Other exclusion criteria to be determined