LAUSR

Background Ultrasound-guided, supra-inguinal fascia iliaca block (FIB) provides effective analgesia after total hip arthroplasty (THA), but is complicated by high rates of motor block. The erector spinae plane block (ESPB) is a promising motor-sparing technique. In this study, we test the analgesic superiority of FIB over ESPB, while also comparing motor impairment. Methods In this randomized, observer-blinded clinical trial, patients scheduled for THA with spinal anesthesia were randomly assigned to receive either ultrasound-guided FIB or ESPB preoperatively. Primary outcome was morphine consumption at 24 hours after surgery. Secondary outcomes were: pain scores; assessment of sensory and motor block; incidence of postoperative nausea and vomiting and other complications; and development of chronic post-surgical pain. Results Sixty patients completed the study. There were no statistically-significant differences in morphine consumption at 24 hours (p = 0.68) or pain scores at any time point. FIB produced more reliable sensory block in the femoral nerve (p = 0.001) and lateral femoral cutaneous nerve (p = 0.018) distributions. However, quadriceps motor strength was better preserved in the ESPB group when compared to the FIB group (p = 0.002). No differences were observed for hip adduction motor strength (p = 0.253). No differences between groups were observed in terms of side effects or chronic pain incidence. Consclusions ESPB may represent a promising alternative to FIB for postoperative analgesia after THA. ESPB and FIB offer similar opioid-sparing benefits within the first day after surgery, but ESPB results in less quadriceps motor impairment.