The main objective of this study is to evaluate the effectiveness of the association of PENG and LFCN blocks on the quality of recovery 24 hours after total hip replacement surgery.

Total hip replacement is a frequent procedure in the geriatric population associated with moderate post-operative pain. It is known that a sub-optimal analgesia is associated with a delayed mobilization leading to a longer hospital stay, poor functional recovery and increased thromboembolic complications. Moreover, opioid analgesia, especially in the geriatric population, increases the incidence of delirium.

Multimodal analgesia, combining different analgesic classes and regional anesthesia, is preferable than relying mainly on opioids, improving the outcomes in the post-operative period. Until now, no regional anesthesia technique has proven itself to be better than the others, each having its limitations. While the local anesthetic doses are high with the peri-articular infiltration under direct visualisation, the epidural is associated with bilateral block and sympathetic block. Also, the lumbar plexus block is a technically difficult block and is associated with a motor block. Finally, other blocks such as the femoral, 3:1 or fascia iliaca are not blocking the totality of the nerves involved in the post-operative pain pathways.

A recent anatomic study from Short et al. demonstrated a greater implication than what was previously known of the accessory obturator nerve and the femoral nerve in the etiology of the post-operative pain. Regarding the incision, it is generally located in the lateral femoral cutaneous nerve territory. Recently published as case reports, the PENG block is a new regional anesthesia technique that has emerged for hip surgeries. It consists of injecting local anesthetics in the myofascial plan between the psoas anteriorly and the pubic ramus posteriorly.

With this prospective randomized trial, the investigators aim to investigate whether a PENG block combined with the LFCN block provides a superior analgesia compared to multimodal analgesia alone and improves the outcomes of the patients in the post-operative phase.

Methods:

The PENG and LFCN blocks will be performed with the patients in a dorsal decubitus position, using a high frequency linear ultrasound probe (Sonosite HFL50 6-15 MHz) in the inguinal area, with an insulated hyperechoic needle (50-80 mm, 22 gauge, Pajunk) placed in plane in relation to the ultrasound beam. The myofascial plane between the psoas anteriorly and the pubic ramus posteriorly will be targeted. The anesthesiologist will confirm the correct position of the needle by injecting 1 ml of 5% dextrose.

For the group A, after negative aspiration, 20 ml of a solution of ropivacaine 0,5% with epinephrine 2,5 mcg/ml will be injected in 5 ml aliquots. Then, the lateral femoral cutaneous nerve will be localized, infero-medially to the antero-superior iliac spine, superficially to the sartorius muscle and 5 ml of the same solution will be injected with the same needle. For group B, the technique of the blocks will be identical to group A, but 20 ml and 5 ml of a sterile saline solution will be used instead.

Patients will then be taken to the operating room where a spinal anesthesia will be performed using 12 mg of iso or hyperbaric bupivacaine (at the discretion of the anesthesiologist) with the addition of 15 mcg of fentanyl. A dose of 8 mg of dexamethasone will be administered intravenously over 10 minutes. In case of failed spinal anesthesia, patient will be excluded from the study.

For hospitalized patients:

In the absence of contraindication, patient controlled analgesia (PCA) with hydromorphone will be prescribed post-operatively, until 8h on post-operative day 1. Patients will thus have the possibility to self-administer 0,2 mg of hydromorphone every 5 minutes, for a maximum of 10 doses per hour. In case of contraindications, subcutaneous or per os hydromorphone will be prescribed to these patients. Multimodal analgesia with acetaminophen and celecoxib (in absence of contraindication) will be continued as per protocol.

For patients treated on an outpatient trajectory:

Patients will benefit from medical prescriptions for total hip replacement, including hydromorphone or oxycodone, celecoxib and acetaminophen.

Inclusion Criteria:

• Patients over 18 years old undergoing a total hip replacement surgery

Exclusion Criteria:

• Contraindication to regional anesthesia (allergy to local anesthetics, severe coagulopathy, infection in the designated area, pre-existing neuropathy in the obturator or femoral territory)
• Contraindication to spinal anesthesia
• Patient's refusal or inability to consent
• Opioid use on a regular basis pre-operatively
• Inability to communicate with medical team or research team
• Inability to understand the items of the multiple forms

triple blind