Health-related quality of life after tricompartment knee arthroplasty with and without an extended-duration continuous femoral nerve block: a prospective, 1-year follow-up of a randomized, triple-masked, placebo-controlled study

Abstract

Background: We previously provided evidence that extending an overnight continuous femoral nerve block to 4 days after tricompartment knee arthroplasty (TKA) provides clear benefits during the perineural infusion in the immediate postoperative period. However, it remains unknown if the extended infusion improves subsequent health-related quality of life between 7 days and 12 mo.

Methods: Patients undergoing TKA received a femoral perineural infusion of ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to either continue perineural ropivacaine (n = 25) or normal saline (n = 25) in a double-masked fashion. 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 mo after surgery. The WOMAC evaluates three dimensions of health-related quality of life: 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 mo 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] = 1.2, 95% confidence interval: -5.6 to +8.0; P = 0.72) and at all individual time points (P > 0.05).

Conclusions: We found no evidence that extending an overnight continuous femoral nerve block to 4 days improves (or worsens) subsequent health-related quality of life between 7 days and 12 mo after TKA. (ClinicalTrials.gov number, NCT00135889.).

Conflict of interest statement

Conflict of Interest: Arrow International (Reading, Pennsylvania, United States) and Stryker Instruments (Kalamazoo, Michigan, United States) provided funding and donated portable infusion pumps and perineural catheters for the original investigation. These two companies had absolutely no input into any aspect of study conceptualization, design, and implementation; data collection, analysis and interpretation; or manuscript preparation of the previous or current studies. Drs. Mariano and Enneking conduct continuous peripheral nerve block workshops for Stryker Instruments (Kalamazoo, Michigan, United States). None of the other authors has any personal financial interest in this research.

Figures

Figure 1

Effect of an extended femoral perineural ropivacaine infusion on health-related quality of life following tricompartment knee arthroplasty, as measured with the Western Ontario and McMaster Universities Osteoarthritis Index. Data are expressed means for patients randomly assigned to an extended continuous femoral nerve block (perineural ropivacaine from surgery through postoperative day 4) or overnight continuous femoral nerve block (perineural ropivacaine from surgery through 06:00 postoperative day 1 followed by perineural normal saline through postoperative day 4). The two treatment groups had similar 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]=1.2, 95% confidence interval:−5.6 to +8.0; p=0.72) and at all individual time points (p>0.05).

Figure 2

Effect of an extended femoral perineural ropivacaine infusion on improvement from preoperative baseline of health-related quality of life following tricompartment knee arthroplasty, as measured with the Western Ontario and McMaster Universities Osteoarthritis Index. Data are expressed as mean for patients randomly assigned to an extended continuous femoral nerve block (perineural ropivacaine from surgery through postoperative day 4) or overnight continuous femoral nerve block (perineural ropivacaine from surgery through 06:00 postoperative day 1 followed by perineural normal saline through postoperative day 4). The two treatment groups had similar scores at all individual time points (p>0.05).