Intra-articular adductor canal block has equivalent analgesic effect to traditional ultrasound-guided adductor canal block after total knee arthroplasty: a prospective randomized controlled trial.

Introduction: An adductor canal block (ACB) is widely accepted as a regional nerve block for pain management following total knee arthroplasty (TKA). However, no consensus exists concerning whether the analgesic effect is greater when joint surgeons perform intra-articular ACBs (IA-ACBs) or when anesthesiologists perform ultrasound-guided ACBs (UG-ACBs). We hypothesized that intra-articular ACBs (IA-ACBs) performed by joint surgeons and UG-ACBs performed by anesthesiologists based on peri-articular injections (PAI) would yield equivalent analgesic effects.

Material and methods: This prospective randomized controlled trial included 61 patients who underwent IA-ACBs and 56 patients who received UG-ACB with additional PAI for post-TKA pain management. The primary outcome was postoperative pain assessed using numeric rating scale scores （NRS） at rest and during exercise. Secondary outcomes included opioid consumption and functional recovery. We also investigated local and systemic adverse events, including nausea, vomiting, and wound complications.

Results: Both groups of patients experienced comparable analgesic effects for both IA-ACB and UG-ACB pain management; however, those who received IA-ACBs were prescribed more opioid equivalents than those in the UG-ACB group on postoperative day 1 (P = 0.048). No differences between the groups were observed regarding local or systemic adverse events.

Conclusions: IA-ACBs performed by joint surgeons provided equivalent analgesic effects to UG-ACBs performed by anesthesiologists. However, IA-ACBs may lead to a higher postoperative requirement for opioid analgesics.