Patients undergoing total hip arthroplasty are randomly assigned to two groups (fascia iliaca compartement block [FICB] group or quadratus lumborum block [QLB] group). In the FICB group, ultrasound-guided suprainguinal FICB (30 ml of 0.375% ropivacaine with 75 µg of epinephrine) is performed on the ipsilateral surgical side at the end of surgery. In the QLB group, ultrasound-guided anterior QLB (30 ml of 0.375% ropivacaine with 75 µg of epinephrine) is done on the ipsilateral surgical side at the end of surgery. A standardized multimodal analgesic regimen is used for postoperative pain control. The total use of opioids including patient-controlled analgesia and rescue analgesics is compared in both groups for 24 hours after surgery. The amount of opioids used is compared by conversion to oral morphine equivalent dose. Pain score at rest and movement during postoperative 24 hours, time to first request for analgesics, the incidence of side effects, patient satisfaction for pain control at postoperative 24 hours, quality of recovery at postoperative 24 hours, time to discharge readiness, and hospital length of stay are compared.

Inclusion Criteria:

• Adult patients between the ages of 19 and 70 undergoing total hip arthroplasty under spinal anesthesia
• Be able to provide written consent to participate in clinical trials, understand the procedures of this clinical trial, and be able to properly fill out patient-reported questionnaires
• ASA physical status classification 1-2

Exclusion Criteria:

• ASA physical status classification 3-4
• Patients who are contraindicated to nerve blocks (hypersensitivity to local anesthetics, infection at the injection site, etc.)
• Patients with chronic pain and taking pain medications, antidepressants, and anticonvulsants
• Other major medical or psychiatric conditions that will affect response to treatment
• Refusal of intravenous patient-controlled analgesia
• Patients determined to be unsuitable for this clinical trial by the researchers