Study protocol
iliac muscle
ANTERIOR, DECUBITUS, MOORE
After entering the room, electrocardiography, pulse oximetry, and Invasive arterial blood pressure were applied. All blocks were performed by two anesthesiologists experienced in ultrasound-guided S-FICB with the patient in the supine position. After skin disinfection and draping, a high-frequency (13–6 MHz) linear ultrasound transducer (SonoSite M Turbo; Secma, Amsterdam, The Netherlands) was positioned longitudinally at the level of the anterior superior iliac spine (ASIS). The iliac muscle (IM) and fascia iliaca (FI) were identified by sliding the ultrasound transducer in a medial and caudal direction. To obtain a ‘bow-tie sign’ the transducer was rotated slightly so that the cranial end of the transducer points to the umbilicus and the caudal end pointed at the ASIS. The transducer was positioned in the parasagittal plane, and the deep circumflex iliac artery (DCIA) was identified, which is a vital ultrasound landmark. In this position, a needle was introduced at the transducer caudal edge. Using the in-plane approach, the fascia iliaca was penetrated and hydro-dissected, separating the fascia iliaca from the iliac muscle. The predetermined volume of 0.33% ropivacaine was injected (Fig. 
Ultrasound image of supra-inguinal fascia iliaca compartment block. ASIS Anterior superior iliac spine, IM iliacus muscle, AM abdominal muscles, LA local anestheticReferring to the previous study [
Flow diagram of studyExperienced surgeons performed all operations. The surgical approach was posterior total hip arthroplasty (Moore approach). The patient was in a lateral decubitus position, and the fixation was placed at the sacrum and pubic symphysis. And during the operation, the pelvis and trunk are perpendicular to the operating table, which is parallel to the floor. The incision ran from the distal side 10 cm of the posterior superior iliac spine to the posterior edge of the greater trochanter, parallel to the gluteus maximus muscle fibers. And then, it extended 10 ~ 13 cm distally along the femoral shaft.All patients were sent to the resuscitation room after the operation. The tracheal tube was extubated after spontaneous breathing recovery, consciousness recovery, and muscle strength recovery. Send patients back to the ward when the steward score exceeds 4.