Total hip replacement is one of major orthopedic surgery which result in severe postoperative pain especially at first 24 hours. Ultrasound guided regional anesthesia has become a part of multimodal analgesia.Ultrasound guided supra-inguinal fascia iliaca block is a new technique which can consistently cover femoral and lateral femoral cutaneous nerve. And with large volume (40ml), it may cover obturator nerve. This technique already proved to be useful for acute pain control in hip fracture or postoperative control in dynamic hip screw or nail insertion operation. However, it has not been compared with intrathecal morphine for total hip replacement yet.

By using combine ultrasound guided supra-inguinal fascia iliaca block with periarticular infiltration with mutimodal analgesic drugs will have longer duration time to first rescue analgesic drug compared with combine intrathecal morphine with periarticular infiltration with multimodal analgesic drugs.

Inclusion Criteria:

• elective surgery of primary total hip replacement, body weight ≥40kg and BMI ≤35 kg/m2, competence to consent

Exclusion Criteria:

• contraindication to regional anesthesia, allergy to study drugs, skin infection at supra-inguinal fascia iliaca injection point, neurological deficit affecting the lower extremities, inability to use patient-controlled analgesia, GFR <50 mL/min