Pain control following total hip arthroplasty: a prospective randomized controlled trial comparing spinal anaesthesia without adjuncts versus fascia iliaca block versus pericapsular nerve group block versus local anaesthetic infiltration.

Aims: Postoperative pain management for total hip arthroplasty (THA) remains an area for improvement. This study compared the impact of suprainguinal fascia iliaca block (FIB) versus local anaesthetic infiltration (LAI), versus pericapsular nerve group (PENG) block, and versus spinal anaesthesia alone, on early postoperative pain in patients who underwent inpatient primary THA.

Methods: This was a single-centre, assessor- and participant-blinded randomized controlled trial. A total of 240 patients undergoing THA under spinal anaesthesia were randomized to LAI, FIB, PENG block, or control in a 1:1:1:1 ratio. The primary outcome was pain at four hours postoperatively (visual analogue scale (VAS)). Secondary outcomes included VAS at other timepoints, opioid consumption, patient satisfaction, and length of hospital stay (LOS). A VAS difference of 2 cm was considered clinically significant.

Results: A total of 240 participants were randomized, with 222 in the final analysis. Only LAI (mean VAS 1.6 (SD 2.2)) significantly decreased postoperative pain compared with the control group (mean VAS 3.0 (SD 2.7); p = 0.004) at four hours. VAS at four hours was not significantly different between LAI, FIB, and PENG block groups in direct comparisons. FIB (23.3 mg morphine equivalents (MEQ) (SD 18.4), p = 0.001) and LAI (22.2 mg MEQ (SD 18.7), p = 0.001) significantly decreased opioid consumption compared with the control group (36.7 mg MEQ (SD 24.5)) at 24 hours postoperatively. The same was found at 48 hours postoperatively. LAI significantly improved patient satisfaction scores at four hours compared with the control group (1.3 (SD 0.6) vs 1.9 (SD 1.2), p = 0.043). There was no difference in LOS between study groups. One patient had femoral nerve motor deficit following PENG block, with full recovery at six months postoperatively.

Conclusion: LAI combined with spinal anaesthesia reduced early postoperative pain and improved patient satisfaction with pain control compared with spinal anaesthesia alone. LAI and FIB both decreased opioid consumption in the first 24 and 48 hours.