The aim of the study is to evaluate the effectiveness of ultrasound-guided transversalis fascia plane block (TFPB) and quadratus lumborum block (QLB) on post-operative analgesia in pediatric patients with Developmental Dysplasia of the Hip (DDH)under going open reduction surgeries（Salter acetabular osteotomy，combined with proximal femoral rotation osteotomy）.The effectiveness of TFPB/QLB for perioperative analgesia in lumbar nerves (L1) innervated surgery have been demonstrated in recent studies. However, this regional technique rarely applied to children.The objective of our research is to assess the quality of postoperative analgesia in pediatric patients who had received a preoperative TFPB/QLB for hip surgery.

90 pediatric patients(age 2-10years) in the BeiJing Ji Shui Tan Hospital and The Second Affiliated Hospital of Wen Zhou Medical University with American Society of Anesthesiologists (ASA) physical status I or II, who are scheduled to undergo open reduction surgeries （Salter acetabular osteotomy，combined with proximal femoral rotation osteotomy）are selected and divided into 3 equal groups with 30 subjects.The consent forms are approved by the institutional Ethics Committee.

Inclusion Criteria: Pediatric patients between 2 years to 10 years with DDH, scheduled for unilateral open reduction surgeries（Salter acetabular osteotomy，combined with proximal femoral rotation osteotomy）.

Exclusion Criteria:Patients will be excluded if participants meet any of the following criteria:patients with known allergy to local anaesthetics, mental disability, peripheral neuropathy, a coagulopathy disorder,localized infection in the area, and any reason cause reoperation.

Electrocardiogram, non-invasive blood pressure, pulse oximetry, temperature,capnography, and end tidal anesthetic concentration values are monitored in patients Parental presence will be allowed if requested for the induction of anesthesia. Pediatrics without vein access will receive general anesthesia which induces with 8% sevoflurane in 70% nitrous oxide and 30% oxygen, via a facemask. When loss of consciousness is achieved,investigators need to establish vein access routinely.Intravenous induction for general anesthesia with endotracheal intubation is commenced using intravenous propofol 3 mg/kg, cis-atracurium 0.2 mg/kg,fentanyl 2. ug/kg. Anesthesia will be maintained using remifentanyl, and a volatile anesthetic(sevoflurane). The inhaled concentration of sevoflurane will be adjusted to maintain hemodynamic stability, which is defined as a change in systolic blood pressure and heart rate of no more than 20% of baseline parameters. The use of opioids during the perioperative periods at the discretion of the anesthetist. Some anesthetists administer opioids preemptively, however, in the majority of cases the decision is based on the cardiovascular response to stimulation; an increase in heart rate of 10% from baseline is usually interpreted as insufficient analgesia and is treated with opioids. Patients will be given either fentanyl in doses of 1-2mcg/kg, remifentanil as continuous infusion 0.01-0.03 mcg/ (kg.min) or a combination of these.

TFPB group Patients in transversalis fascia plane block group(Group T) will receive ultrasound-guided transversalis fascia plane block using0.3% ropivacaine(0.8 ml/kg) after general anesthesia. A high-frequency probe (Sono-Site HFL50x, 15- 6 MHz, 55-mm broadband linear array) connected to an S-nerve ultrasound machine((Sonosite Inc,Bothell, WA, USA) was positioned with a transverse orientation, between iliac crest and costal margin.With the patient in a supine position, the needle is advanced from the anterior using an in-plane technique. A linear ultrasound probe is orientated transversely over the lateral abdomen between the iliac crest and the costal margin. The external oblique, internal oblique,and transversus abdominis muscles are imaged, and the more posterior transversus aponeurosis is isolated from these muscles.The reflection of the peritoneum curving away from the muscles from anterior to posterior, and the perinephric fat, which lies behind the peritoneum and deep to the transversalis fascia, are both identified. The perinephric fat is generally more prominent closer to the iliac crest. The quadratus lumborum is identified medial to the aponeurosis of the transversus abdominis. The end point is more visible if the needle is passed through the posterior''tail'' of the transversus muscle, as the transversus aponeurosis is thinner and less distinct as a separate layer. After passing through the deep surface of transversus abdominis muscle, local anesthetic is injected to separate the transversalis fascia from the transversus muscle. The correct needle position was confirmed by injection of 2 ml of normal saline solution that was spreading anterio-posteriorly between the anterior border of QLM and its fascia, in addition to a minimal anterior spread in TAP plane. After negative aspiration, 0.8 ml/Kg of ropivacaine 0.3%was injected.

QLB group Patients in quadratus lumborum block group（Group Q） will receive ultrasound-guided quadratus lumborum block using 0.3% ropivacaine(0.8 ml/kg).after general anesthesia.The TFPB is performed with the patient in the lateral position using a curvilinear low-frequency ultrasound probe.This is orientated transversely at the posterior axillary line between the iliac crest and the costal margin using a 22G 100-mm needle.The needle is directed in the posterior to anterior orientation with the practitioner standing behind the patient. The triangular quadratus lumborum (QL) muscle is adherent to the apex of the transverse process of L3 vertebra.Using the Shamrock method, a new transmuscular quadrates lumborum block technique, developed by Børglum (British Journal of Anaesthesia, 2013), the needle penetrates the QL muscle with an in-plane approach from the posterior side of the ultrasound probe. The target point is the interfascial plane between the QL and the psoas major muscle just deep to the transversalis fascia, in order to lessen the risk of unintentional penetration of the peritoneal cavity contrary to the technique. The correct needle position was confirmed by injection of 2 ml of normal saline solution that was spreading antero-posteriorly between the QL and the psoas major muscle. After negative aspiration, 0.8 ml/Kg of ropivacaine 0.3%was injected.

Control group Patients in the third group as control (Group C) receive no nerve block.Patients will be extubated based on clinical criteria.

Patients will then be transported to the post-operative anesthesia care unit (PACU) after extubation.All pediatric patients will receive 6-hourly paracetamol post-operatively for two days and receive sufentanyl via nurse-controlled analgesia (NCA) or patient-controlled analgesia (PCA). The prescription of post-operative NCA/PCA is also at the discretion of the anesthetist. Children under the age of 6 years will receive sufentanyl via NCA continuously at a rate of 2 mcg/(kg.48h) with a bolus option of 0.01 mcg/kg every 15 minutes.Older children will receive sufentanyl via PCA continuously at a rate of 2 mcg/( kg.48h) with a bolus option of 0.01 mcg/kg every 15 minutes.

Data collection will include the type of procedure, age, weight, type of truncal block (QLB group vs TFPB vs control).Primary outcome was the FLACC (ie, the Face, Legs, Activity, Consolability Scale) score of patients in the PACU and at 2h, 4h, 8h, 12h, 24h, 48h postoperatively. Secondary outcomes included intraoperative MBP and HR at the endpoints of Salter acetabular osteotomy(T1), femoral rotation osteotomy (T2), and anterior superior iliac spine osteotomy (T3) during the surgery; intraoperative opioid consumption (i.e., fentanyl and remifentanil); duration of the surgery; postoperative fentanyl consumption in the PACU, postoperative morphine consumption in the ward; the length of PACU stay; the time until first press of NCA/PCA pump and the total counts number of pressing the pump; length of hospital stay; complications (e.g., immediate complications such as vessel puncture and possible undesirable effects such as hypotension, bradycardia, epidural local anesthetic spread, or postoperative nausea and vomiting). The number of doses of rescue analgesics (morphine 0.05 mg/kg) in the postoperative period (48 h) will be recorded. Rescue treatment of postoperative nausea and vomiting,will be treated with ondansetron (0.1 mg/kg) if needed.Side effects such as pruritus will also be noted.

Inclusion Criteria:

• Pediatric patients aged between 2 years and 10 years with DDH,
• scheduled for unilateral open reduction surgeries（Salter acetabular osteotomy，combined with proximal femoral rotation osteotomy）

Exclusion Criteria:

Patients will be excluded if they meet any of the following criteria:

• patients with known allergy to local anaesthetics,
• mental disability,
• peripheral neuropathy,
• a coagulopathy disorder,
• localized infection in the area,
• any reason cause reoperation.