Opioid-free analgesia by continuous psoas compartment block after total hip arthroplasty. A randomized study.

Background And Objective: Adequate analgesia is needed after total hip arthroplasty to control pain at rest and during rehabilitation. Our aim was to compare, in a randomized study, the efficacy of two analgesia regimens in control of postoperative pain after total hip arthroplasty: opioid-free continuous psoas compartment block vs. an opioid/non-steroidal anti-inflammatory drugs continuous intravenous infusion.

Methods: In all, 73 patients (ASA I-III), aged 61-82 yr, undergoing total hip arthroplasty were prospectively enrolled in a single-blind randomized trial. Patients were allocated either to the study group (Group A, n = 37) or to the control group (Group B, n = 36). Patients in Group A underwent preoperative placement of a catheter in the psoas compartment and, 30 min before the end of surgery, the catheter was primed with a loading dose of 0.75% ropivacaine (0.4 mL kg(-1)) followed by a continuous infusion of 10 mL h(-1) ropivacaine 0.2% for 48 h. Patients in Group B received, from 1 h before the end of surgery, a continuous intravenous infusion of 0.1% morphine and 0.12% ketorolac at 2 mL h(-1) for 48 h. Both groups received spinal anaesthesia for surgery. Pain scores at rest and after mobilization, amount of rescue analgesia, nausea/vomiting and haemodynamic parameters were recorded.

Results: In Group A, median pain scores were very low during the whole study duration both at rest and during physiotherapy in comparison to Group B. Less rescue analgesia was needed and less nausea and vomiting was observed in Group A.

Conclusions: Opioid-free continuous psoas compartment block seems to be an appropriate and reliable technique in providing effective postoperative analgesia at rest and during physiotherapy after total hip arthroplasty when compared to intravenous morphine/ketorolac infusion.