Periarticular injection versus placebo in total knee arthroplasty with intrathecal morphine.

Introduction: Periarticular injection (PAI) is one part of total knee arthroplasty (TKA) multimodal analgesia protocols. PAI combined with neuraxial anesthesia including intrathecal morphine (ITM) has not been previously investigated. This study prospectively compares PAI to placebo injection in patients undergoing TKA under spinal anesthesia with ITM.