PRIMARY OBJECTIVE: Compare the effect of usual care with an adductor canal catheter (ACC) containing ropivacaine to the effect of usual care without an ACC on the second-postoperative-day pain levels among patients undergoing elective primary unilateral total knee arthroplasty (TKA)

SECONDARY OBJECTIVES: Among a sample of patients undergoing elective primary unilateral TKA who receive peri-articular anesthetic injections:

1. To compare the overall two-week levels of postoperative pain between those participants randomized to ACCs containing ropivacaine and those participants randomized to usual care without an ACC
2. To compare the use of opioid medications (in mean total morphine milligram equivalents) between those participants randomized to ACCs containing ropivacaine and those participants randomized to usual care without an ACC over the two-week postoperative period
3. To describe the incidence of complications related to ACC placement including infection, displacement, ACC-related clinic or emergency department (ED) visits
4. To conduct exploratory analyses to identify candidate predictors of differential response to the ACC

DESIGN: Randomized, open-label, two-arm, parallel-comparison noninferiority trial

POPULATION: Adults aged >18 years intending to undergo elective primary unilateral TKA at the Kaiser Permanente Northern California (KPNC), San Leandro Medical Center

INTERVENTION: Participants will be randomized to one of two treatment arms:

1. Adductor canal catheter placement in the pre-operative area immediately prior to TKA surgery OR
2. No adductor canal catheter placement

DURATION: The intervention phase will occur between randomization and three days postoperatively (or until the ACC is removed by the participant or the ACC falls out spontaneously among ACC-randomized participants); the primary outcome will be measured on postoperative day 2, secondary pain and medication outcomes will be collected for two weeks postoperatively and the electronic medical record (EMR) will be examined for evidence of adverse events at 30 days postoperatively

SAMPLE SIZE: 118 participants randomized using balanced allocation to the two study arms

Inclusion Criteria:

• Intending to undergo elective primary unilateral TKA at the Kaiser Permanente Northern California, San Leandro Medical Center
• Patient ambulates independently

Exclusion Criteria:

• Patient declines use of ACC
• Surgeon decides that an ACC will not be placed for any reason
• Known hypersensitivity to ropivacaine or any alternative anesthetic for ACC use
• Hypersensitivity or inability to tolerate peri-articular injections of clonidine, epinephrine, bupivacaine and ketorolac
• Any evidence of substance-use disorder in past year
• Non-English speaking
• Failure to complete all baseline study instruments prior to surgery
• Requires secondary procedure at time of TKA (e.g., removal of hardware)
• Not intending to use spinal anesthesia for TKA procedure
• Actively enrolled in KPNC chronic-pain program
• Having been prescribed long-acting opioid (e.g., Oxycontin, MS Contin) within 90 days prior to enrollment
• Inability to tolerate any oral NSAID or acetaminophen or any short-acting opioid

Consideration for sharing patient-level data will be made on case-by-case basis via contact with the study PI

30 days postoperatively