Continuous Femoral Nerve Analgesia After Unilateral Total Knee Arthroplasty: Stimulating Versus Nonstimulating Catheters

Continuous femoral analgesia provides extended pain relief and improved functional recovery for total knee arthroplasty (TKA). Stimulating catheters may allow more accurate placement of catheters. We performed a randomized prospective study to investigate the use of stimulating catheters versus nonstimulating catheters in 41 patients undergoing TKA. All patients received i.v. patient-controlled anesthesia for supplementary pain relief. The principal aim of the trial was to examine whether a stimulating catheter allowed the use of lesser amounts of local anesthetics than a nonstimulating catheter. The additional variables we examined included postoperative pain scores, opioid use, side effects, and acute functional orthopedic outcomes. Analgesia was satisfactory in both groups, but there were no statistically significant differences in the amount of ropivacaine administered; the median amount of ropivacaine given to patients in the stimulating catheter group was 8.2 mL/h vs 8.8 mL/h for patients with nonstimulating catheters, P = 0.26 (median difference -0.6; 95% confidence interval, -2.3 to 0.6). No significant differences between the treatment groups were noted for the amount of fentanyl dispensed by the i.v. patient-controlled anesthesia, numeric pain rating scale scores, acute functional orthopedic outcomes, side effects, or amounts of oral opioids consumed. The use of stimulating catheters in continuous femoral nerve blocks for TKA does not offer significant benefits over traditional nonstimulating catheters.