Long-Term Pain, Stiffness, and Functional Disability Following Total Knee Arthroplasty With and Without an Extended Ambulatory Continuous Femoral Nerve Block: A Prospective, One-Year Follow-Up of a Multicenter, Randomized, Triple-Masked, Placebo-Controlled Trial
Brian M. Ilfeld, MD, MS,1 Jonathan J. Shuster, PhD,2 Douglas W. Theriaque, MS,3 Edward R. Mariano, MD, MAS,4 Paul J. Girard, MD,5 Vanessa J. Loland, MD,6 R. Scott Meyer, MD,7 John F. Donovan, MD,8 George A. Pugh, MD,9 Linda T. Le, MD,10 Daniel I. Sessler, MD,11 and Scott T. Ball, MD12Knee
Background
Previously, we have demonstrated that extending a continuous femoral nerve block from overnight to four days following total knee arthroplasty 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 healthcare 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 continuous femoral nerve block decreases long-term pain, stiffness, and functional disability following total knee arthroplasty; which greatly improves inference of the results to the general population.
Methods
Subjects undergoing total knee arthroplasty received a continuous femoral nerve block with ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to either continue 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 (WOMAC) Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months following surgery. This index evaluates pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of four of the six time points, including day 7 and at least two of months 3, 6, and 12.
Results
The two treatment groups had similar WOMAC scores for the mean area under the curve calculations (point estimate for the difference in mean area under the curve for the two 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 continuous femoral nerve block to four days improves (or worsens) subsequent pain, stiffness, or physical function following TKA in patients of multiple centers convalescing on general orthopedic wards.
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