Patients are painful after total hip arthroplasty. These patients have significant co-morbidities. Analgesics cause significant side effects in this population. Locoregional analgesia is therefore an effective means of reducing the consumption of opioids in this surgery.

The "gold standard" of locoregional analgesia after Total Hip Arthroplasty is the femoral block. However, a new technique has recently been described: the Quadratus Lumborum Block.

The comparison of these two techniques is lacking in the literature. The comparison of the Quadratus Lumborum Block to the femoral block in Total Hip arthroplasty is important in the analgesic strategy of patients undergoing this surgery.

The aim of this study is to compare the clinical efficacy of two regional locoregional analgesia strategies in total hip replacement surgery: the ultrasound-guided Quadratus Lumborum Block and the ultrasound-guided femoral block.

This is a double-blind, randomized study in prospective inclusion with a superiority test. Two groups of patients will be compared: a group of patients with a quadratus lumborum block and a group of patients with a femoral block.

Management (quadratus lumborum block or femoral block) will be randomized. The randomization will be stratified on the type of anesthesia (spinal anesthesia and general anesthesia). Randomization will be done on the day of surgery to determine the patient's treatment group. The surgical procedure will not be modified by the participation of the patent in the study.

Patients who would benefit from total hip replacement surgery in the Reims University Hospital and who agreed to participate in the study were included.

Inclusion Criteria:

• Patients eligible for total hip replacement surgery in Reims University Hospital
• Patients agreeing to participate in the research and having signed informed consent
• between 18 yo and 95 yo
• Patients affiliated to a social security system

Exclusion Criteria:

• Patients with allergy to local anesthetics
• Patients with neuropathy
• Patients with an ASA score of 4
• Patients undergoing revision surgery for total hip arthroplasty
• Patients receiving anterior hip total hip replacement surgery
• Patients with a contraindication to the realization of the quadratus lumborum block, femoral block or spinal anesthesia (clinical coagulopathy, infection at the point of puncture ...)
• Patients refusing the proposed techniques