Less Pain, Opioid Use With Liposomal Bupivacaine Via Adductor Canal Block

Originally published by our sister publication Anesthesiology News

HOLLYWOOD, Fla.—The administration of liposomal bupivacaine (LB) via adductor canal block (ACB) can significantly reduce pain and opioid use among patients undergoing total knee arthroplasty (TKA), according to data presented at the 2023 spring meeting of the American Society of Regional Anesthesia and Pain Medicine (abstract 4381).

“As same-day total joint surgery becomes the norm, we need to ensure that our patients leave the hospital comfortable and stay comfortable,” said Jeff Gadsden, MD, a professor of anesthesiology and the chief of the Division of Orthopaedic, Plastic and Regional Anesthesiology at Duke University Medical Center, in Durham, N.C. “It does little good to have 12 hours of excellent pain control, only to have it wear off on the drive home.”

While continuous catheters are one way to extend the duration of analgesia following knee surgery, this study shows that an alternative, single-injection technique can provide sustained quality pain relief in this population, Gadsden said.

The phase 3, multicenter, randomized, double-blind, active-controlled study compared the postoperative analgesic effect between two cohorts of patients undergoing primary unilateral TKA who received their analgesics via ACB. One group received 133 mg of LB admixed with 50 mg of bupivacaine hydrochloride (LB133-ADMIX group), and the other group was given 50 mg of bupivacaine hydrochloride (BUP50 group).

“In this study of ACB in TKA patients, we used an active comparator, bupivacaine, and a technique that employed both nerve stimulation and ultrasound guidance to ensure the drug was immediately next to each nerve,” said Gadsden, who is a member of the Anesthesiology News editorial advisory board.

A total of 166 patients were treated: 45 in the LB133-ADMIX group and 121 in the BUP50 group.

Results showed that pain intensity scores were generally lower in the LB133-ADMIX group than the BUP50 group, particularly from 30 to 96 hours, and total opioid consumption was significantly lower in the LB133-ADMIX group from 0 to 96 hours after surgery.

“Many studies show a reduction in pain scores with an intervention, but often at the cost of higher opioid consumption,” Gadsden said. “We were able to achieve both, which shows a robust analgesic effect.”

Additionally, LB at 133 mg was well tolerated, with both groups showing similar rates of adverse events, most of which were mild to moderate in intensity.

Future study hopefully will clarify existing concerns about LB and investigate the efficacy of other nerve block approaches.

“There has been some confusion about the role of LB and the degree to which it extends analgesia postoperatively,” Gadsden said. “Part of this has been related to study design issues, lack of active comparators, but primarily the inherent difficulty in studying liposomal products which must be placed with the utmost of precision next to the nerve or plexus. Unlike regular local anesthetics, the liposomes do not diffuse across fascial planes. We have seen in other models (e.g., transversus abdominis plane [or TAP] blocks) that a sloppy block with LB is likely to fail, whereas the blocks that were placed in the correct plane do indeed show an expected and extended effect.”

Gadsden noted that “ACB is just one of several motor-sparing peripheral nerve blocks that are used for TKA. Further work is indicated to explore the use of long-acting local anesthetics in blockade of, for example, the genicular nerves and posterior capsule.”

By Ethan Covey

This study was sponsored by Pacira BioSciences. Assistance with poster preparation was provided under the authors’ direction by Emma Hinkle, PhD, and David Boffa, ELS, of MedThink SciCom, and funded by Pacira BioSciences.