Comparison of two peripheral regional analgesic techniques for primary elective total hip arthroplasty: a randomised clinical trial

Introduction: Several regional anaesthesia techniques have been used in the peri-operative pain management of patients who undergo primary elective total hip arthroplasty. The erector spinae plane, pericapsular nerve group and lateral femoral cutaneous nerve blocks offer motor-sparing analgesia of the hip region but target different areas. We designed this study to compare the pericapsular nerve group block combined with lateral femoral cutaneous nerve block with the erector spinae plane block in terms of postoperative analgesia and motor impairment. Methods: Our study involved patients undergoing primary elective unilateral total hip arthroplasty. All patients received spinal anaesthesia and standardised peri-operative multimodal analgesia. Patients were assigned at random to either pericapsular nerve group and lateral femoral cutaneous nerve blocks (‘anterior’ block group) or erector spinae plane block (‘posterior’ block group). The primary outcome was intravenous morphine consumption within the first 24 h postoperatively. Secondary outcomes included: pain scores; assessment of sensory and motor block; incidence of complications; and incidence of chronic postsurgical pain. Results: Sixty-two patients completed the study. The study groups were comparable in baseline characteristics. There was no difference in morphine consumption at 24 h between patients allocated to the anterior and posterior block groups (median (IQR [range]) 5 (1–10 [0–22]) mg vs. 5 (2–8.5 [0–20]) mg, respectively; p > 0.99). Incidence of motor block was 1/31 for patients allocated to the anterior block group compared with 5/31 for those allocated to the posterior block group (p = 0.09). There were no differences in any of the secondary outcome measures between groups. Discussion: We found no statistically or clinically relevant difference between two motor-sparing peripheral regional analgesic techniques among patients undergoing primary elective total hip arthroplasty with multimodal analgesia. Appropriate choice of block may be situation-dependent, and physicians should consider patient and system factors when selecting a technique.