Quadratus lumborum block is a newly developed block with good performance in lower abdominal surgery. In a cadaveric study, the spread of local anesthetic in the anterior approach of QL block (QL3) was reported to cover nerve roots from T10 to L3. Thus, it was hypothesized that this approach could be used in hip surgeries with minimal motor affection.

This study aims to compare QL3 block and suprainguinal Fascia Iliaca block in the duration of postoperative analgesia, pain scores, motor power in quadriceps muscle, and side effects.

A randomized, controlled, double blinded, trial will be conducted in Cairo university hospital. Written informed consent will be obtained from all participants. Randomization will be achieved using a computer-generated sequence. Concealment will be achieved using opaque envelopes. Patients scheduled for hip replacement surgeries under subarachnoid block (SAB). e.g. hip hemiarthroplasty, total hip arthroplasty.

On arrival of the patients to regional anesthesia room, patients will be secured with 18-gauge intravenous cannula, and will receive ondansetron (4 mg), and dexamethasone (8 mg IV). Monitoring will include Electrocardiography, non-invasive arterial blood pressure, and pulse oximetry.

Before receiving subarachinoid block, patients will be randomly assigned into one of the two study groups:

QLB Group (n=17): this group will receive ultrasound-guided transmuscular quadratus lumborum block; (Anterior QLB or QLB III) FIB Group (n=17): this group will receive suprainguinal fascia iliaca block To achieve double blinding, patients will receive the block with 30 mL bupivacaine (0.25%) by the anesthetist. Another doctor not involved in the block procedure will evaluate the patients postoperative.

After finishing the block & assessment of motor power of quadriceps femoris muscle , patient will receive midazolam (2mg intravenous), and then transferred to operation room.

Postoperatively, all patients will receive 1 g paracetamol every 6 hours and 30 mg ketorolac every 12 hours.

If the visual analogue scale (VAS) is 4 or more, a 2 mg morphine increment will be added per time to maintain a resting VAS at <3 with maximum total 24-hours morphine 10 mg.

Inclusion Criteria:

• Patients scheduled for hip replacement surgeries under subarachnoid block (SAB). e.g. hip hemiarthroplasty, total hip arthroplasty.

Exclusion Criteria:

• Coagulopathy, infection at the injection site,.
• Allergy to local anesthetics.
• Severe cardiopulmonary disease (≥ASA IV),.
• Diabetic or other neuropathies.
• Patients receiving opioids for chronic analgesic therapy.
• Contraindication to spinal anesthesia.
• Inability to comprehend visual analogue scale (VAS).