Continuous Femoral Versus Posterior Lumbar Plexus Nerve Blocks for Analgesia After Hip Arthroplasty: A Randomized, Controlled Study
Brian M. Ilfeld, MD, MS, Edward R. Mariano, MD, MAS, Sarah J. Madison, MD, Vanessa J. Loland, MD, NavParkash S. Sandhu, MD, Preetham J. Suresh, MD, Michael L. Bishop, MD, T. Edward Kim, MD, Michael C. Donohue, PhD, Anna A. Kulidjian, MD, and Scott T. Ball, MDHip
BACKGROUND
Hip arthroplasty frequently requires potent postoperative analgesia, often provided with an epidural or posterior lumbar plexus local anesthetic infusion. However, American Society of Regional Anesthesia guidelines now recommend against epidural and continuous posterior lumbar plexus blocks during administration of various perioperative anticoagulants often administered after hip arthroplasty. A continuous femoral nerve block is a possible analgesic alternative, but whether it provides comparable analgesia to a continuous posterior lumbar plexus block after hip arthroplasty remains unclear. We therefore tested the hypothesis that differing the catheter insertion site (femoral versus posterior lumbar plexus) after hip arthroplasty has no impact on postoperative analgesia.
METHODS
Preoperatively, subjects undergoing hip arthroplasty were randomly assigned to receive either a femoral or posterior lumbar plexus stimulating catheter inserted 5 to 15 cm or 0 to 1 cm past the needletip, respectively. Postoperatively, patients received perineural ropivacaine, 0.2% (basal 6 mL/hour, bolus 4 mL, 30 min lockout) for at least two days. The primary end point was the average daily pain scores as measured with a numeric rating scale (0–10) recorded in the 24-h period beginning at 07:30 the morning after surgery, excluding twice-daily physical therapy sessions. Secondary end points included pain during physical therapy, ambulatory distance, and supplemental analgesic requirements during the same 24-h period, as well as satisfaction with analgesia during hospitalization.
RESULTS
The mean (SD) pain scores for subjects receiving a femoral infusion (n = 25) were 3.6 (1.8) versus 3.5 (1.8) for patients receiving a posterior lumbar plexus infusion (n = 22) resulting in a group difference of 0.1 (95% confidence interval −0.9 to 1.2; P = 0.78). Because the confidence interval was within a prespecified −1.6 to 1.6 range, we conclude that the effect of the two analgesic techniques on postoperative pain was equivalent. Similarly, we detected no differences between the two treatments with respect to the secondary end points, with one exception: subjects with a femoral catheter ambulated a median (10th–90th percentiles) 2 (0–17) m the morning after surgery, compared with 11 (0–31) m for subjects with a posterior lumbar plexus catheter (data nonparametric; P = 0.02).
CONCLUSIONS
After hip arthroplasty, a continuous femoral nerve block is an acceptable analgesic alternative to a continuous posterior lumbar plexus block when using a stimulating perineural catheter. However, early ambulatory ability suffers with a femoral infusion.
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