TOPLINE

Among patients who underwent total knee arthroplasty, opioid use 24 hours after surgery was similar between those who received an intravenous (IV) infusion of lidocaine and those who received an adductor canal block, although the block provided better immediate pain relief.

METHODOLOGY

• Researchers conducted a randomized, double-blind, noninferiority trial to assess whether IV lidocaine worked as well as a nerve block for pain relief after knee replacement surgery.
• They included 120 adults aged 18-80 years who underwent total knee arthroplasty at a US hospital between April 2021 and July 2024. Patients were randomly assigned to receive either an adductor canal block (n = 60; median age, 71 years; 63% women) or an IV lidocaine infusion (n = 60; median age, 68.5 years; 58% women).
• Patients in the block group received a single 30-mL injection of 0.5% ropivacaine and a saline infusion. Those in the lidocaine group received a sham block and IV lidocaine (an initial dose of 1.5 mg/kg followed by an infusion of 1.5 mg/kg/h) until about 2 hours after admission to the postanesthesia care unit (PACU); all patients received standard multimodal pain medicines.
• The primary outcome was total consumption of opioids 24 hours after surgery, converted to oral morphine equivalents (OME). Lidocaine was deemed noninferior if the upper limit of the 95% CI for the median difference between groups did not exceed 30 mg.
• Secondary outcomes included time to first analgesic request, pain scores at various intervals, quality of recovery at 24 hours, and patient satisfaction.

TAKEAWAY

• At 24 hours, median opioid use was 57.5 mg OME in the lidocaine group and 52.5 mg OME in the block group. The median difference was 5 mg, which met the noninferiority criteria.
• In the PACU, patients in the block group had lower median opioid consumption than those in the lidocaine group (7.5 vs 17.5 mg OME), with a median difference of 10 mg OME (P = .02).
• Median pain scores at discharge from the PACU were lower in the block group than in the lidocaine group, with a median difference of 2 points (P = .02). Both groups reported similar scores for quality of recovery, time to first request for pain medicine, and satisfaction with their pain control at 24 hours.
• No study-related side effects or safety issues were reported in either group.

IN PRACTICE

The findings “suggest that intravenous lidocaine may serve as a practical alternative in multimodal analgesia when adductor canal block is not feasible,” the researchers reported.

SOURCE

The study was led by Vendhan Ramanujam, MD, of the Warren Alpert Medical School of Brown University in Providence, Rhode Island. It was published online on July 28 in Regional Anesthesia & Pain Medicine.

LIMITATIONS

Lidocaine was infused only for a few perioperative hours rather than continuing for up to 24 hours. The follow-up period was short and did not track long-term recovery or pain during activity. Both groups also received multiple pain-relief treatments; thus, the individual effects could not be isolated. 

DISCLOSURES

The authors reported no funding sources or competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.