Evidence Basis for Regional Anesthesia in Ambulatory Anterior Cruciate Ligament Reconstruction: Part I-Femoral Nerve Block.

The optimal management of pain after ambulatory anterior cruciate ligament reconstruction (ACLR) is unclear. Femoral nerve block (FNB) is purported to enhance postoperative analgesia, but its effectiveness in the setting of modern multimodal analgesia is unclear. This systematic review examines the effect of adding FNB to multimodal analgesia on analgesic outcomes after ACLR, whether or not the analgesic regimen used included local instillation analgesia (LIA). We retrieved randomized controlled trials evaluating the effects of adding FNB to multimodal analgesia on analgesic outcomes after ACLR, compared to multimodal analgesia alone (control). We designated postoperative opioid consumption at 24 hours as our primary outcome. Secondary outcomes included postoperative opioid consumption at 24-48 hours, rest, and dynamic pain severity between 0 and 48 hours, time to analgesic request, postanesthesia care unit and hospital stay durations, patient satisfaction, postoperative nausea and vomiting, functional outcomes, and long-term (>1 month) quadriceps strength. Eight randomized controlled trials (716 patients) were identified. Five trials compared FNB administration to control, and another 3 compared the combination of FNB and LIA to LIA alone. Compared to control, adding FNB resulted in modest reductions in 24-hour opioid consumption in 2 of 3 trials, and improvements in rest pain at 1 hour in 1 trial and up to 24 hours in another. In contrast, the combination of FNB and LIA, compared to LIA alone, did not reduce opioid consumption in any of the trials, but it did improve pain scores at 20 minutes only in 1 trial. The effect of FNB on long-term quadriceps strength or function after ACLR was not evaluated in the reviewed trials. Contemporary evidence suggests that the benefits of adding FNB to multimodal analgesia for ACLR are modest and conflicting, but there is no incremental analgesic benefit if the multimodal analgesic regimen included LIA. Our findings do not support the routine use of FNB for analgesia in patients having ACLR.