ORLANDO, Florida—An overnight femoral nerve block works just as well as a 4-day continuous femoral nerve block following total knee arthroplasty (TKA), but the 4-day continuous nerve block may improve immediate functional recovery and reduce pain, according to new research presented at the 2008 annual meeting of the American Society of Anesthesiologists in Orlando, Florida.1

“Immediate functional recovery was distinctly quicker in the blocked patients—and those patients experienced much less pain. [That’s] reason enough to use continuous femoral nerve blocks!”—Daniel I. Sessler, MD
“This investigation found little evidence that, compared with an overnight continuous femoral nerve block, a 4-day continuous femoral nerve block improves health-related quality of life between 7 days and 12 months following TKA, despite providing clear benefits during the perineural infusion in the immediate postoperative period,” report the researchers who were led by Brian M. Ilfeld, MD, an anesthesiologist at the University of California at San Diego.

In the new study, patients received a femoral perineural catheter followed by ropivacaine 0.2% delivered via portable infusion pump after knee replacement surgery until the following morning. Then, patients were randomized to either continue perineural ropivacaine or switched to normal saline until the evening of postoperative day 4.

Researchers assessed health-related quality of life with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) preoperatively and at 1 week as well as 1, 2, 3, 6, and 12 months after surgery. The two treatment groups had similar WOMAC scores at all time points (P >.05), the study showed.

Overnight vs 4-day Femoral Nerve Blocks Effects on WOMAC Scores (Median Values)
  Preop 7 Days 1 Month 2 Months 3 Months 6 Months 12 Months
PAIN
Ropivacaine 10 6 6 2 2 0 1
Normal Saline 10 9 5 4 4 1 1
STIFFNESS
Ropivacaine 5 4 3 3 2 1 1
Normal Saline 4 4 3 2 2 2 1
FUNCTIONING
Ropivacaine 35 21 17 9 5 2 2
Normal Saline 32 24 13 9 7 4 3
TOTAL
Ropivacaine 49 33 27 14 11 5 4
Normal Saline 46 37 22 15 12 7 4


Translating research into practice

“The study showed that measures of long-term quality-of-life were comparable in patients who were and were not given continuous femoral nerve blocks,” said researcher Daniel I. Sessler, MD, chairman of the department of outcomes research at the Cleveland Clinic in Ohio. “There was thus no evidence that overall function, especially related to arthritis, was improved,” he told MSKreport.com. “But that said, immediate functional recovery was distinctly quicker in the blocked patients—and those patients experienced much less pain. [That’s] reason enough to use continuous femoral nerve blocks!”

Reference
1. Ilfeld BM, Le LT, Mariano ER, et al. Postoperative continuous femoral nerve blocks after TKA and subsequent health-related quality-of-life, Presented at:  2008 Annual Meeting of the American Society of Anesthesiologists; October 18-22, 2008; Orlando, Fla. Presentation No. A390