Liposomal Bupivacaine vs Perineural Adjuvants in Adductor Canalf and iPACK Blocks in Total Knee Arthroplasty

The purpose of this research study is to compare two different combinations of anesthetic medications to see which works the best in providing the longest lasting pain relief for total knee arthroplasty surgery. The drugs being used are liposomal bupivacaine compared to a combination of bupivacaine, clonidine, epinephrine, buprenorphine, and dexamethasone. Pain scores will be collected at different intervals during study participation.

This double-blinded prospective randomized control trial will evaluate analgesia following total knee arthroplasty for patients who receive an adductor canal block and infiltration between the popliteal artery and condyles of the knee (iPACK) block utilizing bupivacaine with the adjuvants clonidine, epinephrine, buprenorphine and dexamethasone (BPV-CEBD), as compared to patients who receive liposomal bupivacaine (LB) for both blocks. All patients will receive a spinal anesthetic with ropivacaine (17.5 mg) and fentanyl (10 mcg), and an adductor canal and iPACK block for analgesia. Patients randomized to the LB group will receive 10 ml of 0.25% bupivacaine expanded with 133 mg (10 ml volume) of LB into both the adductor canal and iPACK blocks (total of 40 ml). The BPV-CEBD group will receive a 20 ml of solution consisting of 0.25% bupivacaine, 1.667mcg/ml of clonidine, 1:400,000 epinephrine, 0.15 mg total of buprenorphine, and 2 mg total of preservative free dexamethasone - which will be used in both the adductor canal block and iPACK block (total of 40 ml). On post-operative day (POD) 0, rest and movement pain scores will be collected at 4 hours and 8 hours with time "zero" being the time of the final block placement. On POD 1 and 2, questionnaires will be collected for pain scores at 0700, 1200 and 1700. Participants will be called once daily on days 3 through 7 to collect remaining secondary data, including sleep score, quality of recovery, worst daily pain score, and patient satisfaction (POD 7 only).

Inclusion Criteria: * 18-80 years of age * Receiving primary total knee arthroplasty * Patients receiving a spinal anesthetic with ropivacaine and fentanyl * American Society of Anesthesiology (ASA) category 1 to 3 Exclusion Criteria: * Revision of Total Knee Arthroplasty * Opioid use in the prior 6 months \> 40 mg oxycodone equivalents per day or long-acting opioids as determined by the Prescription Drug Monitoring Program (PDMP) * Patients planned to receive general anesthesia * Patients planned to receive a spinal other than ropivacaine * History of peripheral neuropathy * Poorly controlled diabetes (Hgb A1C \>8) * Allergies or contraindications to study medications: acetaminophen, celecoxib (including sulfa), methocarbamol, midazolam, fentanyl, bupivacaine, dexamethasone, acetaminophen, buprenorphine, NSAIDs, clonidine, epinephrine, and liposomal bupivacaine. * Unable to provide informed consent