Hip joint surgery for developmental dysplasia of the hip (DDH) in children is extremely painful and associated with considerable postoperative pain despite the use of systemic opioids. Caudal anesthesia and lumbar plexus block (LPB) were still the most common regional anesthesia techniques for perioperative analgesia in children undergoing this type of surgery. recently, pediatric anesthesiologists don't consider choosing both techniques because of potential complications such as intravascular and intrathecal injection, and urine retention. novel peripheral nerve blocks have been advocated in pediatrics to avoid the aforementioned complications such as PEricapsular Nerve Group (PENG) block, Quadratus Lumborum Block (QLB), and Fascia Transversalis Plane Block (FTPB) The objective of the current study is to assess the analgesic efficacy of ultrasound-guided FTPB versus ultrasound-guided PENG block in pediatric patients undergoing open hip surgery for DDH

During the pre-anesthesia check-up visit, the proposed intervention will be discussed with the eligible participant's parents or caregivers including data about the aim, the advantages, and the expected side effects, and then a detailed written informed consent will be obtained before recruitment and randomization.

All participants will be premedicated with 0.5mg/kg oral midazolam about 30min before being admitted to the operating room. The routine standard monitoring including electrocardiography (ECG), non-invasive blood pressure (NIBP), pulse oximetry for blood oxygen saturation (SpO2), temperature probe, and end-tidal CO2 (EtCO2) will be applied to all participants. Induction of general anesthesia (GA) will be performed using a face mask with sevoflurane inhalation in oxygen starting with 2% up to 8% till complete loss of consciousness after that peripheral intravenous (IV) line will be secured where fentanyl 1 μg/kg and followed by cisatracurium 0.15mg/kg to facilitate orotracheal intubation. Anesthesia will be maintained by using isoflurane 1.2-1.5% in oxygen air mixture 50%:50% in addition to incremental cisatracurium 0.03mg/kg.

After induction of GA, the eligible participants will be randomly assigned to one of two equal groups either FTPB or PENG block.

In both interventional group participants, the assigned block will be performed after induction of GA by the same investigator who will have no further role in the study. Surgery will be started about 15 minutes after performing the block.

Fentanyl 1μg/ kg will be administrated intraoperatively in the case of inadequate analgesia which is defined as an increase of heart rate (HR) and/or mean arterial blood pressure (MAP) more than 20% above the pre-operative values. At the end of the surgery, isoflurane will be switched off and extubation will be done after reversal of muscle relaxant with neostigmine 0.05 mg/kg and atropine 0.02 mg/kg where the participants will be transferred to the Post-Anesthesia Care Unit (PACU). Paracetamol (15 mg/kg) will be administered IV every 6 hours in all participants.

Inclusion Criteria:

• American society association (ASA) physical status class I - II.
• Participants who will be scheduled for an elective unilateral open hip surgery for correction of DDH under general anesthesia.

Exclusion Criteria:

• Participants with respiratory disease, renal or hepatic insufficiency.
• Infection of the skin in the puncture area.
• Coagulopathy.
• Allergy against any of the drugs to be used (bupivacaine).
• Neuromuscular disease.
• Obesity (body mass index, BMI >30).
• Bilateral hip surgery or previous hip surgery.
• Previous analgesic medication or chronic pain under treatment.
• previously known neurological pathologies or central nervous system disorders.