Local and/or regional analgesia techniques are critical components of an optimal multimodal analgesia technique, as they have been shown to improve pain relief as well as reduce opioid requirements. Optimal pain management technique balances pain relief with concerns about safety and adverse effects associated with analgesic techniques. Periarticular infiltration (PAI) is increasingly included as a component of multimodal analgesia technique for patients undergoing THA, as it provides improved postoperative pain relief with no effects on quadriceps function. Recently, our group has developed a novel transmuscular quadratus lumborum and modified erector spinae plane (QLESP) block, which is characterized by simple operation, high efficiency, and wide dermatomal coverage of sensory block. Therefore, we designed a randomized controlled trial to compare ultrasound-guided QLESP with PAI as a component of non-opioid analgesic regimen in patients undergoing THA via posterior approach. We hypothesized that QLESP would provide superior analgesia when compared with PAI. The primary outcome of the study was postoperative opioid requirements within the initial 24-h postoperative period after THA. The secondary objectives were to compare pain scores, postoperative quadriceps strength, the time to first rescue analgesia, opioid-related adverse effects, time to ambulation, and the time to hospital discharge.

Inclusion Criteria:

1. Age 18-65 yrs
2. American Society of Anesthesiologists classification 1-3
3. Body mass index between 20 and 35 (kg/m2)
4. Undergo elective primary unilateral THA via a posterolateral approach
5. Informed consent

Exclusion Criteria:

1. A known allergy to the drugs being used
2. Pre-existing neuropsychiatric disorders or language barrier
3. Analgesics intake, history of substance abuse
4. Contraindications to peripheral nerve block
5. Acute cerebrovascular disease
6. Severe liver failure