Does Liposomal Bupivacaine Provide Superior Postoperative Analgesia Compared With Ropivacaine With Dexamethasone in Suprainguinal Fascia Iliaca Compartment Block for THA? A Randomized Controlled Trial

Background Choosing the most effective pain management is important for enhancing functional recovery after surgery. The fascia iliaca compartment block (FICB) is recommended for analgesia after THA, but whether liposomal bupivacaine is more effective for this application remains uncertain. Questions/purposes (1) Did a single-injection suprainguinal FICB using liposomal bupivacaine provide superior pain control by a clinically important margin? (2) What was the effect of liposomal bupivacaine on perioperative opioid consumption? (3) How did liposomal bupivacaine affect the duration of the sensory block and quadriceps motor weakness in the operated limb? Methods This was a prospective, parallel-group, assessor-blinded, single-center, randomized controlled clinical trial. Patients who underwent unilateral primary THA via the posterolateral approach were included in the study. Exclusion criteria included a BMI of > 32.5 kg/m 2 (which is the diagnostic criterion for moderate obesity in China), contraindications to peripheral nerve block, known allergy to study medications, psychiatric or cognitive disorders that could interfere with pain assessment, severe hepatic or renal dysfunction, and chronic pain necessitating long-term opioid therapy. According to these criteria, 76% (60 of 79) of screened patients met eligibility requirements and were subsequently randomized into either the liposomal bupivacaine group or the control group. All patients received an ultrasound-guided, single-injection, suprainguinal FICB. The patients in the liposomal bupivacaine group were administered a solution consisting of 10 mL of 1.33% liposomal bupivacaine combined with 20 mL of 0.25% bupivacaine hydrochloride, whereas the control group received 30 mL of 0.5% ropivacaine with the addition of 5 mg dexamethasone. There were no dropouts, and all patients were analyzed in the groups to which they were assigned. The groups did not differ in important ways with respect to baseline characteristics or relevant surgical and anesthesia parameters. The outcomes were (1) static (at rest) and dynamic (during passive hip flexion to 45°) numeric rating scale (NRS) scores measured at 6, 12, 24, 48, and 72 hours postoperatively, (2) cumulative opioid consumption expressed as intravenous morphine equivalents intraoperatively and within 72 hours postoperatively, and (3) sensory block duration and quadriceps motor weakness in the operated limb assessed at 24 and 48 hours postoperatively. Postoperative rebound pain, rescue analgesia, and adverse events were also recorded. The minimum clinically important difference was predefined as 1.5 for static NRS scores, 1.8 for dynamic NRS scores, and 10 mg of intravenous morphine equivalents for opioid consumption. Results Although we found no clinically important between-group differences in either static or dynamic NRS scores at any time point, we found that the group treated with liposomal bupivacaine consumed fewer morphine equivalents in the first 72 hours after surgery than did patients treated without liposomal bupivacaine in the block (median IQR 10 mg 7 to 16 versus 24 mg 20 to 28, difference of medians -12; p < 0.001). Likewise, the sensory block lasted longer in the liposomal bupivacaine group (median IQR 71 hours 66 to 77 versus 12 hours 10 to 17, difference of medians 58; p < 0.001). However, there were no differences in the number of patients with quadriceps motor weakness at 24 hours and 48 hours after surgery between the two groups. Postoperative rebound pain, rescue analgesia, and adverse events likewise did not differ between the groups. Conclusion In this randomized trial, we found a clinically relevant reduction in opioid consumption within the first 72 hours after posterolateral THA with the use of liposomal bupivacaine in a single-injection suprainguinal FICB. Furthermore, the prolonged block duration with liposomal bupivacaine was not associated with an increased risk of quadriceps motor weakness. Based on these findings, we recommend the routine use of liposomal bupivacaine for this application. Future trials should focus on the use of liposomal bupivacaine in combined regional anesthesia methods. Level of Evidence Level I, therapeutic study.