Does the use of periarticular Exparel in total knee arthroplasty prove to more effectively manage post operative pain control than another local analgesic, Ropivacaine, when both are used as part of a multimodal pain management approach?

The investigators hypothesize that Exparel, a bupivacaine liposomal injectable suspension, will improve total knee arthroplasty postoperative pain with significant improvement of early function outcomes.

The investigators use a double blind, controlled, randomized study to examine the effectiveness of periarticular Exparel in total knee arthroplasty postoperative pain control as well as effect on early mobilization and length of hospital stay when compared to another local analgesic (Ropivacaine) when both are used as part of a multimodal pain management approach.

Inclusion Criteria:

• Patient undergoing Total Knee Arthroplasty with Dr. J.H. DeClaire
• 18 years of age or older
• Primary diagnosis of osteoarthritis of the knee
• Opioid naïve patient (according to FDA guidelines)

Exclusion Criteria:

• Prior knee replacement
• Prior use of narcotics for chronic pain management
• Inflammatory arthritis (Rheumatoid arthritis, Lupus, etc.)
• Unicompartmental knee replacement
• Bilateral Total Knee Arthroplasty
• Opioid Tolerant as defined by the FDA: Patients who are taking, for one week or longer, at least:

> 60 mg oral morphine/day > 25μg transdermal fentanyl/hour > 30 mg oral oxycodone/day > 8 mg oral hydromorphone/day > 25 mg oral oxymorphone/day