Perineural versus Intravenous Dexamethasone for Prolongation of Multiple Nerve Blocks for Pain Relief after Total Knee Arthroplasty

Abstract

Background: Multiple nerve blocks (MNB) provide excellent time-limited perioperative analgesia following total knee arthroplasty. Both perineural and systemic use of dexamethasone (DXM) as an adjuvant to local anesthetic prolong the duration of single-shot MNB. We hypothesized that preoperative perineural injection of DXM prolongs analgesia after MNB more than the same dose of intravenous (IV) DXM injection due to direct action on the nerves and not only by a systemic action mechanism. Methods: This is a prospective, randomized, controlled and observer-blinded study. One hundred and nine patients were randomly assigned to one of three groups: Group (Gr) 1-perineural DXM+MNB, Gr 2-systemic IV DXM +MNB, Gr 3-control group, MNB without DXM. Postoperative variables including intensity of pain at rest and during motion, grade of sensory and motor block, opioid consumption, comfort time (the first analgesic request) were the primary end-points of investigation. Results: Ninety patients completed the study protocol. Very low parameters of intensity of pain at rest and during motion, high grade of sensory and motor block were observed up to 12 hours after MNB performance in all three groups. Patients who received MNB with DXM perineurally or systemically, experienced superior pain relief and had reduced opioid consumption 24 hours post-block compared to the control group without differences between the two