Background: Previously, we have demonstrated that extending a continuous femoral nerve block (cFNB) from overnight to 4 days after total knee arthroplasty (TKA) provides clear benefits during the infusion, but not subsequent to catheter removal. However, there were major limitations in generalizing the results of that investigation, and we subsequently performed a very similar study using a multicenter format, with many health care providers, in patients on general orthopedic wards, thus greatly improving inference of the results to the general population. Not surprisingly, the perioperative/short-term outcomes differed greatly from the first, more limited study. We now present a prospective follow-up study of the previously published, multicenter, randomized controlled clinical trial to investigate the possibility that an extended ambulatory cFNB decreases long-term pain, stiffness, and functional disability after TKA, which greatly improves inference of the results to the general population.
Methods: Subjects undergoing TKA received a cFNB with ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to continue either perineural ropivacaine (n = 28) or normal saline (n = 26). Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months after surgery. This index evaluates pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of 4 of the 6 time points, including day 7 and at least 2 of months 3, 6, and 12.
Results: The 2 treatment groups had similar Western Ontario and McMaster Universities Osteoarthritis scores for the mean area-under-the-curve calculations (point estimate for the difference in mean area under the curve for the 2 groups [overnight infusion group − extended infusion group] = 3.8; 95% confidence interval, −3.8 to +11.3; P = 0.32) and at all individual time points (P > 0.05).
Conclusions: This investigation found no evidence that extending an overnight cFNB to 4 days improves (or worsens) subsequent pain, stiffness, or physical function after TKA in patients of multiple centers convalescing on general orthopedic wards.
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Funding for this project was provided by the National Institutes of Health grant GM077026 from the National Institute of General Medical Sciences (Bethesda, MD); National Institutes of Health grants RR00082, RR000827, and RR025208 from the National Center for Research Resources (Bethesda, MD); the Department of Anesthesiology, University of California San Diego (San Diego, CA); Stryker Instruments (Kalamazoo, MI); and Teleflex Medical (Research Triangle Park, NC). The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of these entities.
Teleflex Medical and Stryker Instruments provided funding for this investigation; these 2 companies had absolutely no input into any aspect of study conceptualization, design, and implementation; data collection, analysis, and interpretation; or manuscript preparation. The funding from these companies was used by each institution to help defray research coordinator expenses for the original randomized clinical trial. Drs. Mariano and Loland previously conducted continuous peripheral nerve block workshops for Stryker Instruments. No other author has a personal financial interest in this research.