Lumbar erector spinae plane block (ESPB) has been proposed to relieve pain after total hip replacement (THR), but high-quality evidence is scarce.
This double-blinded (patient and assessor) randomized clinical trial, performed in 2 tertiary centers in Hong Kong, recruited patients undergoing primary unilateral THR under general anesthesia (GA) who received either single-shot ESPB at L1 (treatment arm) or no block (control arm). Patients were followed up on the first day postoperatively. We hypothesized that compared to no block, a single-shot lumbar ESPB at L1 would reduce postoperative fentanyl use and postoperative pain scores. Primary outcomes were intravenous fentanyl use at 12 and 24 hours postoperatively, along with pain intensity in numeric rating scale (0–10) at rest and upon movement on the first day postoperatively. Per-protocol analysis was performed. Mann-Whitney U test was used to compare the outcomes between both groups, and median difference was derived from the Hodges-Lehmann estimator.
Seventy-one patients were randomized (n = 36 in treatment arm, n = 35 in control arm). The median amount of fentanyl consumed at 12 hours postoperatively was 210 (quartiles, 140.5–363) μg for the ESPB group and 165 (quartiles, 77.5–330.5) μg for the control group, while at 24 hours postoperatively, it was 409 (quartiles, 221–636.5) μg for the former and 349 (quartiles, 114–626.5) μg for the latter. The median differences in fentanyl consumption 12 and 24 hours postoperatively were 39 μg (95% confidence interval [CI], −40 to 116; P = .463) and 41 μg, respectively (95% CI, −83.5 to 199.5; P = .474), which were statistically insignificant. The median pain score at rest was 3 for both the ESPB group (quartiles, 0–5) and the control group (quartiles, 0–4.5), while upon movement, it was 7 for both the former (quartiles, 6–8) and the latter (quartiles, 4.5–8.5). The median difference in pain scores between both groups was 0 at rest (95% CI, −1 to 1; P = .890) and upon movement (95% CI, −1 to 1; P = .509).
This trial did not demonstrate that ESPB at L1 improved analgesia following THR.