SSSI Efficacy With iACB and PC-LIA in TKA Pain Management

This prospective, two-armed, triple-blinded, sham-controlled randomized controlled trial investigates the additive effect of Supra-Sartorial Subcutaneous Infiltration (SSSI) to intermittent adductor canal block (iACB) and posterior capsule local infiltration analgesia (PC-LIA) in multimodal pain management for total knee arthroplasty (TKA). SSSI is a peripheral nerve block technique the investigators devised as a simpler alternative to targeted anterior femoral cutaneous nerve (AFCN) block, which is technically more demanding and time-consuming. Based on the investigators' preliminary study (in publication) where SSSI combined with PC-LIA provided clinically meaningful analgesia in \~58% of patients, and drawing from previous studies on AFCN blocks, the trial compares: Arm 1 (all active SSSI + active iACB + active PC-LIA) versus Arm 2 (sham SSSI + active iACB + active PC-LIA). Adults (45-90 years) undergoing unilateral primary TKA (n=90, 45/arm) will be randomized 1:1, stratified by age, preoperative pain levels (in Numerical Rating Scale) and functional status (WOMAC Index or Knee Society Score). Interventions use 0.3% ropivacaine or saline shams, with SSSI and ACB catheterization performed in the post-anesthesia care unit by anesthesiologists and PC-LIA performed intraoperatively by surgeons. Primary outcome: Numerical Rating Scale pain scores at rest and during continuous passive motion at 9:00 PM on postoperative day (POD) 0, focusing on anteromedial knee pain. Secondary outcomes include daily pain scores, rescue ACB doses, additional opioid use, functional recovery (quadriceps strength, timed up and go \[TUG\] test), and complications over POD 0-3. With \~96% power for a 2-point NRS difference, this trial evaluates SSSI's role in enhancing motor-sparing analgesia.