Comparison Between Pericapsular Nerve Group Block (PENG) and Morphine Infusion

The pericapsular nerve group block (PENG) is a regional anaesthetic technique that was developed in 2018, primarily for total hip arthroplasties (THA) as a postoperative analgesia modality with motor sparing benefits.

The block is thought to provide more complete analgesia to the hip by depositing local anaesthetic within the myofascial plane of the psoas muscle and superior pubic ramus.

The indications for THA often include degenerative hip disease and traumatic hip fractures. These indications for surgery are relatively common in the elderly population and are associated with significant morbidity and mortality.

Operative intervention, such as THA, has also been associated with significant pain.

Historically, the most commonly performed peripheral nerve blocks include a lumbar plexus block, a femoral nerve block, or a fascia iliaca compartment block to manage post-operative analgesia.

With the understanding that additional articular branches (i.e., from the sciatic nerve) these blocks will provide incomplete analgesia to the hip and may also predispose the patient to fall due to weakness of the quadriceps muscles.

Therefore the ideal block technique should provide complete analgesia of the hip joint and without muscle weakness.

The PENG has been described for postoperative pain control for surgery at the hip joint or the management of post-traumatic pain associated with fractures of the proximal femur/ femoral head.

There are currently no unique contraindications that are specific to the PENG block. Therefore, similar guidelines applicable to most peripheral nerve blocks would apply and include:

• Lack of patient consent
• Skin infection at the site of injection
• Systemic bacteremia or sepsis
• Anticoagulation and antithrombotic medications precautions as detailed by the American society of regional anaesthesia for peripheral nerve blocks The hip joint has a complex innervation, and the pain following hip fractures or total hip arthroplasties is particularly severe. An appropriate plan for perioperative analgesia is challenging, but a multimodal approach including acetaminophen, cox-2 selective NSAIDs, regional anaesthesia, and periarticular infiltration techniques improves patient outcomes.

The ultrasound-guided PENG block allows for coverage of the hip joint, targeting the proximal articular branches that innervate the joint capsule. This proximal approach via ultrasound guidance can confer several advantages over a femoral nerve block by providing more complete analgesia to the hip joint. Additionally, the motor function of the involved extremity should be spared. The PENG block can be used alone as a primary analgesic or in conjunction with other forms of anaesthesia during surgery or in the perioperative period. For lateral surgical incisions, a supplemental lateral femoral cutaneous nerve block provides additional coverage.

With the patient in the supine position, the ultrasound probe is placed on a transverse plane over the anterior superior iliac spine (ASIS). Once the ASIS is identified, the transducer is aligned with the pubic ramus and rotated at approximately 45 degrees, parallel to the inguinal crease. The transducer is then slid medially along this axis until the anterior inferior iliac spine (AIIS), iliopubic eminence (IPE), and the psoas tendon is identified, serving as anatomic landmarks.

Sliding the probe distally or gently tilting the caudal will expose the head of the femur. Returning to the initial starting position, a standard 20-22 gauge 100mm needle is inserted in-plane, from lateral to medial, in the plane between the psoas tendon and the pubic ramus. 15-20ml of a long-lasting local anaesthetic ((i.e., 0.5% ropivacaine) is then deposited in this plane, lifting the psoas tendon. Care should be taken to avoid puncturing the psoas tendon. In this study, the investigators will assess the effect of pericapsular nerve group (PENG) block on pain control in patients with proximal femur fracture in the emergency department.

The Control group will receive morphine as regular patient control analgesia (PCA) The interventional group will receive PENG block before being attached to regular morphine PCA