Does PAI Reduce Pain After TKA Among Knee Arthroplasty Patients Receiving ACB & IPACK?

Does Periarticular Injection (PAI) Reduce Pain After TKA Among Knee Arthroplasty Patients Receiving Adductor Canal Block and Infiltration Between the Popliteal Artery and the Capsule of the Posterior Knee (ACB&IPACK)? A Blinded, Randomized Controlled Trial.

The goal of this clinical trial is to determine whether Periarticular Injection (PAI) alongside Adductor Canal Block (ACB) and Infiltration between the Popliteal Artery and Capsule of the Knee (IPACK) block can decrease post-operative pain in patients undergoing primary total knee arthroplasty. The main question it aims to answer is:

• Is ACB/IPACK without PAI as effective as ACB/IPACK with PAI for TKA patients?

Participants will be assigned to one of the following groups at random:

• ACB/PACK with PAI
• ACB/IPACK with saline injection

Participants will also be asked to complete pre- and post-operative questionnaires.

Kim et al (2019) have shown that addition of ACB/IPACK to PAI improves analgesic outcomes (the nerve blocks reduced pain with ambulation and reduced opioid consumption). TKA patients receiving PAI + ACB/IPACK (along with a comprehensive multimodal analgesic program) had low pain scores with ambulation on POD1: 1.7 +/- 1.4 (mean +/- SD, NRS, 0-10 scale). The opioid consumption in the first 24 hours was 40.6 +/- 32.1 (mg oral morphine equivalents).

It is not clear if the PAI component is necessary, given the theoretically nearly complete analgesic effects of the ACB/IPACK block. Additionally, anecdotal evidence indicates that some surgeons at HSS routinely use the PAI and some do not, without obvious large differences in analgesic outcomes. While there may be a 'belt and suspenders' advantage to using PAI in addition to ACB/IPACK, it is not desirable to perform unnecessary procedures.

In this study, we seek to compare the efficacy of ACB/IPACK with and without PAI in TKA patients.

Inclusion Criteria:

• Planned use of regional anesthesia
• Ability to follow the major components of the study protocol
• English speaking (Secondary outcomes include questionnaires validated in English only)

Exclusion Criteria:

• Patients younger than 25 years old and older than 80
• Non-English speaking
• Patients intending to receive general anesthesia
• Contraindication to nerve blocks or peri-articular injection
• Patients with an ASA of IV or higher
• Renal insufficiency (ESRD, HD, estimated creatinine clearance < 30 ml/min)
• Patients with major prior ipsilateral open knee surgery
• Chronic gabapentin/pregabalin use (regular use for longer than 3 months)
• Chronic opioid use (taking opioids for longer than 3 months)