Source: Europace  |  Posted 5 years ago

By W. A. Thomasson, PhD

CHICAGO, IL -- October 19, 2006 -- Patients given continuous lumbar plexus block after a total knee arthroplasty procedure have better walking speeds at 48 hours and 16 days, according to data presented at the American Society of Anesthesiologists (ASA) 2006 Annual Meeting.

"Total knee replacement is one of the most painful surgeries," Jian Hang, MD, PhD, assistant professor, Johns Hopkins Bayview Medical Center, Baltimore, Maryland, said in an interview, but patients with lumbar plexus block "actually don't have any pain."

Post-surgical pain can limit movement of the knee, thus hampering functional recovery. Previous studies have shown that lumbar plexus block can improve the knee's range of motion. This study is the first to show that self-selected walking speed -- a direct, quantitative measure of the patient's real-life functional capabilities -- is improved as well.

A total of 23 patients were randomly assigned to either lumbar plexus block with the local anesthetic ropivacaine or to sham block with administration of normal saline. Real or sham block was continued for 48 hours. All patients also had patient-controlled intravenous analgesia for 24 hours and oral analgesia as needed thereafter. Intraoperative management for all patients was with lumbar plexus block plus sciatic nerve block under sedation or general anesthesia at the discretion of the attending anesthesiologist.

There was no significant difference in preoperative walking speed between the real and sham groups (1.1 and 1.0 m/s, respectively). At 48 hours postsurgery, however -- shortly after withdrawal of the catheter delivering anesthetic or placebo -- patients who had received lumbar plexus block walked significantly faster than the sham control group (0.4 vs. 0.2 m/s, respectively; []P[] < .05). Day 16 saw a trend toward faster walking in the real-block group (0.8 vs. 0.9 m/s, respectively) but it did not reach statistical significance ([]P[] < .08).

"Many times I could tell these patients received real local anesthetic," Dr. Hang said. "They were all very happy and they used much less opioids." He then added,

"We hope for a long-lasting effect" from this short-term intervention, he said. Plans are under way to follow a larger group of patients for 1 or 2 yr.

"This study supports the notion that continuous peripheral nerve block not only is a superior analgesic technique but also improves functional restoration and outcome after [total knee arthroplasty]," the study authors concluded.

[Presentation title: Effects of Continuous Lumbar Plexus Nerve Block on Functional Outcome After Total Knee Arthroplasty. Abstract 1132]