Adductor canal block with or without added magnesium sulfate following total knee arthroplasty: a multi-arm randomized controlled trial.

Purpose: Postoperative analgesia following total knee arthroplasty (TKA) often includes intrathecal opioids, periarticular injection (PAI) of local anesthetic, systemic multimodal analgesia, and/or peripheral nerve blockade. The adductor canal block (ACB) provides analgesia without muscle weakness and magnesium sulphate (MgSO) may extend its duration. The purpose of this trial was to compare the duration and quality of early post-TKA analgesia in patients receiving postoperative ACB (± MgSO) in addition to standard care.