Exparel and Zynrelef for Total Knee Replacement Recovery

This study looks at how three different numbing injections affect how quickly patients recover after knee replacement surgery (total knee arthroplasty, or TKA). Pain after knee replacement is common and can slow down how soon patients get moving again. Doctors often inject a numbing medication around the knee during surgery to help control this pain, but it is not clear which medication helps patients recover fastest in the first few days after surgery.

The study compares three injections that are all FDA approved and already used as part of routine knee replacement care: Exparel (liposomal bupivacaine), Zynrelef (bupivacaine with meloxicam), and Marcaine (bupivacaine). Exparel and Zynrelef are the two groups being studied, and Marcaine is the comparison (control) group.

Adults who are already planning to have a knee replacement may take part. People who join are placed into one of the three injection groups at random, so each person has a one in three chance of receiving each injection. Patients are not told which injection they received. Everything else about the surgery, anesthesia, and recovery care stays the same as usual.

The main goal is to see which injection helps patients recover best in the first three days after surgery. To measure recovery, the study team collects information on pain, pain-medication use, knee motion, activity level, and function. Patients complete short questionnaires about their activity, pain, and quality of life at their regular visits (before surgery and at 3 days, 1 week, 2 weeks, 6 weeks, 3 months, 1 year, and 2 years). A smart knee implant also records information about knee movement and motion at 3 and 7 days after surgery. About 200 people will take part. The study is considered minimal risk, meaning the risks are similar to those of having a knee replacement outside of the study.