A reduced concentration femoral nerve block is effective for perioperative pain control following ACL reconstruction: a retrospective review.

INTRODUCTION: Femoral nerve block (FNB) is a routinely used regional analgesic technique for anterior cruciate ligament (ACL) reconstruction. One method to balance the analgesic effect and functional impairment of FNBs may be to control the concentration of local anesthetics utilized for the block. MATERIALS AND METHODS: Retrospective chart review was performed on 390 consecutive patients who underwent ACL reconstruction between June 2014 and May 2017. Patients were divided into those who received a standard (0.5%-bupivacaine) or low (0.1-0.125%-bupivacaine) concentration single-shot FNB performed with ultrasound guidance. Maximum postoperative VAS, Post-Anaesthesia Care Unit (PACU) time prior to discharge, need for additional 'rescue' block, and intravenous postoperative narcotic requirements were recorded. RESULTS: A total of 268 patients (28.4 ± 11.9 years) were included for final analysis, with 72 patients in the low-concentration FNB group and 196 patients receiving the standard concentration. There were no differences in the maximum postoperative VAS between the low (6.4 ± 2.5) and standard (5.7 ± 2.9) concentration groups (P = 0.08). Similarly, the time from PACU arrival to discharge was not different between groups (P = 0.64). A sciatic rescue block was needed in 22% of patients with standard-dose FNB compared to 30% of patients receiving the low-concentration FNB (P = 0.20). Patients with a hamstring autograft harvest were more likely to undergo a postoperative sciatic rescue block compared to a bone-patellar tendon autograft (P = 0.005), regardless of preoperative block concentration. Quadriceps activation was preserved with low-concentration blocks. CONCLUSIONS: Using 1/5th to 1/4th the standard local anesthetic concentration for preoperative femoral nerve block in ACL reconstruction did not significantly differ in peri-operative outcomes, PACU time, need for rescue blockade, or additional immediate opioid requirements. LEVEL OF EVIDENCE: III.

Ultrasound-guided sciatic neuroma block for treatment of intractable stump pain.

A 61-year-old patient with severe stump pain required hospitalization and intravenous opioids for pain control. After evaluation by our anesthesia pain management service, we concluded that the patient had a neuroma at the site of sciatic nerve transection and that injection of a mixture of local anesthetic and corticosteroid at the site of the neuroma was the most appropriate management. Because the alternative methods of nerve localization (eg, motor stimulation, paresthesia) were unlikely to be successful, we felt that the most reliable way to accomplish this task was to use live ultrasound guidance. After a series of 4 ultrasound-guided blocks with bupivacaine and methylprednisolone acetate, the patient's pain was alleviated to the point at which it was managed with occasional doses of oral opioids.