Comparison of continuous transmuscular quadratus lumborum block and continuous psoas compartment block for posterior total hip arthroplasty: A randomised controlled trial

Background and Aims: Analgesia for hip surgery involves cutaneous anaesthesia at the site of the skin incision and the anterior hip capsule. This study aimed to compare continuous ultrasound (US)-guided transmuscular quadratus lumborum block (TQLB) with psoas compartment block (PCB) for analgesia in patients undergoing total hip arthroplasty (THA) under general anaesthesia (GA). Methods: This randomised, observer-blinded trial included 18-70-year-old American Society of Anesthesiologists physical status I-III patients undergoing THA under GA with either US-guided continuous TQLB or PCB. Primary objectives included a visual analogue scale (VAS; 0-100 mm) at rest and mobilisation at 6 h postoperatively (analysed by intention to treat and per protocol) using a non-inferiority margin of 20 mm. Secondary objectives included VAS at other time points, 24-h fentanyl consumption (analysed using the Wilcoxon rank-sum test), sensory dermatomes anaesthetised, motor weakness 30 min after block, and haemodynamic response to skin incision (analysed using the Chi-squared or Fisher's exact test). A P value less than 0.05 was considered statistically significant. Results: VAS (0-100 mm) score at 6 h on rest was 25.34 +/- 14.25 and 27.3 +/- 9.6, mean difference (MD) was 1.9 [-3.3, 7.1] and at movement was 35.1 +/- 23.0 and 38.6 +/- 17.0, MD was 3.5 [-5.2, 12.2], in the PCB (n = 29) and QLB (n = 30) groups, respectively (i.e. less than the non-inferiority margin). However, VAS (rest) at 1, 12, and 24 h postoperatively and median (IQR) 24-h fentanyl consumption was significantly higher in the QLB group (1212.5 [300-2345] mu g] when compared to the PCB group (635 [100-1645] mu g; P = 0.0004). Conclusion: Though statistically, continuous QLB was non-inferior to continuous PCB for pain at rest and mobilisation at 6-hours postoperatively, a higher 24-hour perioperative fentanyl consumption and VAS show that QLB was clinically inferior to PCB.