Background and objectives: Continuous lumbar plexus infusion of local anesthetic after total knee arthroplasty has been shown to improve analgesia and early recovery as compared with patient-controlled analgesia (PCA) morphine. Any benefit of an infusion over a single-injection lumbar plexus block has not been directly shown however.
Methods: In a double-blind, randomized, controlled trial, 32 patients undergoing total knee arthroplasty were randomly allocated to 1 of 2 groups: 0.1% levobupivacaine infusion or saline infusion. Preoperatively, all patients received a lumbar plexus block with 25 mL 0.5% levobupivacaine using a posterior approach with a catheter left in situ, a sciatic nerve block with 15 mL 0.5% levobupivacaine, and a spinal anesthetic. At the end of surgery, 0.1% levobupivacaine or saline was infused into the catheter at 10 mL/h for 48 hours. All patients also received PCA morphine. The primary endpoint was morphine use from the PCA machine. Secondary endpoints included pain scores, day of first postoperative mobilization, and nausea.
Results: Patients receiving the levobupivacaine infusion used significantly less morphine than those receiving saline (19 mg [interquartile range (IQR) 8.5-29.5] vs 32 mg [IQR 23.5-53.0], P = .04) and also mobilized earlier postoperatively (day 1 or 2 [levobupivacaine] vs day 2 or 3 [saline], P = .001). Pain scores were similar.
Conclusion: Postoperative infusion of local anesthetic around the lumbar plexus reduces morphine requirement and improves early recovery after total knee arthroplasty as compared with a single-injection block.