Effect of Different Truncal Blocks Under Ultrasound-Guidance on Pain Management After Open Reduction of Pediatric Developmental Dysplasia of the Hip: a Randomized Trial

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.