Impact of Adding iPACK Block With Dexamethasone to Existing APS Multimodal Analgesia Protocol for Patients Undergoing Total Knee Arthroplasty

This will be a single-center (UCSD), randomized blinded investigation.

Enrollment. Consenting adults undergoing TKA will be offered enrollment. Study inclusion will be proposed to eligible patients prior to surgery. If a patient desires study participation, written, informed consent will be obtained using a current UCSD IRB-approved ICF.

Preoperative Procedures. Following written, informed consent, we will record baseline anthropomorphic information (age, sex, height, and weight) that is already provided by all patients having surgery. After consenting and prior to surgery, patients will be randomized (utilizing sealed envelopes with 1:1 ratio) to either single-shot adductor canal block with sham iPACK block or single-shot adductor canal block with local anesthetic + dexamethasone iPACK block. A regional anesthesia fellow, not participating in the study, will open the sealed envelope and prepare the iPACK solution to be used accordingly.

Current Standard Care: Currently, all patients undergoing TKA receive preoperative adductor canal block as well as multimodal pain regimen managed by APS. They all receive intraoperative intraarticular injections by the surgical team. Spinal vs general anesthesia is decided at the discretion of the intraoperative anesthesiologist along with patient preferences and relevant contraindications. The only difference for subjects participating in the study (vs those not participating) will be that they will be randomized to receive an additional nerve block for posterior knee pain.

Adductor canal single shot block + Sham group: In the preoperative holding area, all subjects in this cohort will have a peripheral intravenous (IV) catheter inserted, standard noninvasive monitors applied, supplemental oxygen administered via a nasal cannula or face mask, and positioned supine. Midazolam and fentanyl (IV) will be titrated for patient comfort, while ensuring that patients remain responsive to verbal cues. The area of insertion will be cleaned with chlorhexidine gluconate and isopropyl alcohol (ChloraPrep One-Step, Medi-Flex Hospital Products, Inc., Overland Park, KS, USA). A single shot adductor canal block will be performed under ultrasound guidance with 20 mls of 0.25% ropivacaine with 1:400,000 epinephrine. A sensory level to ice will be confirmed and decided to be adequate if positive based on the discretion of the attending anesthesiologist. A Sham iPACK block will then be performed under ultrasound guidance, where 20 mls of 0.9% normal saline with 1:400,000 epi (as a vascular marker) is injected between the popliteal artery and the posterior aspect of the femoral condyle. As is standard for all TKA at our institution, all patients will additionally receive an intraoperative intraarticular injection by the surgical team of 50 mls 0.25% bupivacaine + 30 mg Ketorolac + 0.25mg epinephrine, which will occur at least 60 minutes after preoperative perineural injections.