{'fraction_non_alphanumeric': 0.020721686316541622, 'fraction_numerical': 0.0021436227224008574, 'mean_word_length': 5.422018348623853, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Femoral Nerve Block for Anterior Cruciate Ligament Reconstruction—Do We Have the Information We Need? Response

Dear Editor: In a recent study, Luo and colleagues found a negative relationship between a femoral nerve block (FNB) and 6month recovery of select measures of muscle strength in adolescent patients after undergoing anterior cruciate ligament reconstruction. While the use of an FNB for painful knee procedures confers effective pain control, known negative impacts on long-term recovery need to be carefully considered. The report by Luo et al continues an appropriate discussion but, unfortunately, does not yet provide the information that we need. There are several methodological issues in this study that potentially limit the conclusions. A retrospective methodology can produce bias. The overrepresentation of one surgeon in the control group and another in the FNB group prompts the question of the impact of variable surgical techniques. Did one surgeon favor a 2-incision approach? Was the graft fixation technique standardized? The significantly different tourniquet times and operative times suggest disparate surgical techniques. How were the 2 groups matched for baseline flexion/extension? Likewise, details of the FNB are lacking. What type, concentration, and volume of local anesthetic was used? Were these single-injection blocks, continuous catheter infusions, or a combination of both? Short-term and long-term dysfunctions may be related to a higher dose/concentration and/or longer duration of exposure. In the meantime, how was the nerve located? While ultrasound nerve localization gives the benefit of decreasing the negative impact on nerves, the timeline of this study suggests that the blocks may have been performed before ultrasound guidance. The more fundamental concern is the lack of defined/ precise metrics. Are we even looking at the right outcomes? In 2 published reports evaluating the effect of FNBs, measured deficiencies of strength did not translate into functional compromise. Also concerning is the assignment of a causal relationship between FNBs and sciatic nerve– mediated deficiencies such as slow and rapid knee flexion, which constituted 2 of the 3 indicators preventing a return to sports as determined by Luo et al. The lack of data and defined metrics related to longterm functional recovery makes postoperative variations and associations with FNBs difficult to interpret. This leaves surgeons, anesthesiologists, and patients in the uncomfortable position of making decisions with imperfect and conflicting information. A prospective, randomized, double-blinded, placebo-controlled study involving both anesthesiologists and surgeons is long overdue and would put to rest many of the questions raised by this study and this letter.