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Ultrasound-guided infrapatellar nerve block for anterior cruciate ligament repair: a prospective, randomised, double-blind, placebo-controlled clinical trial

Background and objectives We have previously described an ultrasonography-guided technique to block the infrapatellar nerve that is associated with an extended duration of anaesthesia. The aim of the present study was to investigate the clinical usefulness of this new technique in patients undergoing arthroscopy-assisted anterior cruciate ligament repair. Methods Using a prospective, double-blind and placebo-controlled study design, 64 patients were randomised to get an active infrapatellar nerve block (IPNB; 10 ml levobupivacaine 0.5%; n = 31) or a sham block with isotonic saline (n = 33) as a complement to a standardised anaesthetic and analgesic regimen. Pain was recorded hourly and the proportion of patients with a pain intensity of more than 3 (numeric rating scale 0–10) during 12–24 postoperative hours was chosen as the primary end-point of the study. Duration of the block, numbers of hours spent sleeping and other secondary parameters were also recorded. Results The proportion of patients with a pain score of higher than 3 at rest was significantly lower in patients receiving an IPNB during postoperative hours 16–24 (P = 0.0117) as well as on muscular activity during postoperative hours 16–24 (P = 0.0039). Median block duration was 23 h (95% confidence interval 19–24 h). A significantly larger proportion of patients were asleep during the time period 13–24 h after surgery in patients given active treatment as compared to sham block (P < 0.0269). Conclusion Adjunct use of an ultrasound-guided block of the infrapatellar nerve is associated with improved pain relief and an increased number of sleep hours after arthroscopy-assisted anterior cruciate ligament repair.