Single Injection Adductor Canal Block Versus Continuous Adductor Canal Infusion for Total Knee Arthroplasty

The objective of this study is to determine if a single shot multimodal peripheral nerve block containing bupivacaine, dexamethasone, buprenorphine, clonidine, and epinephrine will provide comparable (equivalent) analgesic control when compared to an adductor catheter. The primary end point will be pain scores at 30 hours post block initiation. Secondary end points will include, opioid consumption, time to first analgesic request; pain scores; binary patient satisfaction (yes/no); likeliness to recommend their analgesic regimen, straight leg raise test on post-operative day (POD) number 1; adverse events, incidence of post-operative nausea, and vomiting.

Methods and Measures Design The study will be a randomized, double-blind, sham catheter study. Patients will be recruited and randomized to one of two groups: The "Treatment Arm" receive a single shot adductor canal block containing 20 milliliters (ml) of solution including 0.25% bupivacaine, 150 mcg of buprenorphine, 2 mg of dexamethasone, 1.67 mcg/ml of clonidine, and 1:400,000 epinephrine with sham catheter. The sham catheter will be placed in the Sartorius muscle in the same sterile, aseptic fashion as patient's in the control arm. The pump will be set at the lowest possible volume per hour of normal saline (0.1 ml/hour in the current pump in use at our hospital). An opaque bag will be placed over the pump for blinding purposes. The "Control Arm" will receive an adductor canal catheter through which they will receive a 20 ml bolus of 0.25% bupivacaine with 1:400,000 epinephrine followed by an adductor canal catheter infusion of 0.125% bupivacaine at 10 ml/hour. An opaque bag will be placed over the control arm pumps in similar fashion. For all patients, the order in the electronic medical record will be per research pharmacy protocol. For their primary anesthetic, patients in both arms will then receive either a subarachnoid (spinal) anesthetic or general anesthetic per the anesthesiologist in the operating room.

Inclusion criteria

Patients will be eligible for inclusion in the study if they are:

• Age of 18 years old or older
• Scheduled to primary unilateral total knee arthroplasty.
• Patients must give written informed consent for anesthesia including continuous adductor canal block for postoperative analgesia prior to recruitment

Exclusion criteria

Patients will be excluded if they have:

• A contraindication to an adductor canal block or catheter placement including, but not limited to site infection, irritation, or refusal.
• Poorly controlled diabetes (A1C >8.0)
• Allergy to medications involves in this study (opioids, bupivacaine, buprenorphine, clonidine, or dexamethasone)
• Opioid use >40 mg of oxycodone daily, long-acting opioids.