Ultrasound-guided Pericapsular Nerve Group (PENG) Block vs. Intraoperative Local Anesthetic Infiltration (ILAI) for Total Hip Arthroplasty (THA): a Single Center, Non-inferiority Randomized Control Trial Pilot Study.

Traditionally, the most common ultrasound-guided nerve blocks utilized for hip analgesia during THA are the Femoral Nerve Block and the Fascia Iliaca Block. Despite the analgesia component of both techniques, they can cause quadriceps weakness1-2, which is an unwanted side effect for this patient population as it interferes with surgical recovery, physical therapy, and increases the risk of fall. For these reasons, these types of blocks are not performed for patients undergoing THA at our center (London Health Science Centre).

In 2018, a cadaveric study performed by Short et al. demonstrated that the hip capsule is innervated by sensory branches of the Femoral Nerve and Accessory Obturator Nerves.3 An ultrasound-guided technique for the blockade of the articular branches of the hip was first described by Giron-Arango et al.4 The major benefit of using this approach is the possible motor-sparing effect, capable of maintaining the quadriceps muscle force as the technique aims only at sensory articular branches.

The current standard care for postoperative analgesia for THA is intraoperative infiltration with a solution containing ropivacaine 0.25% (local anesthetic), morphine (opioid), and ketorolac (NSAID). Patients with any contra-indication for the administration of opioids, or nonsteroidal anti-inflammatories receive intraoperative infiltration with plain local anesthetic.

The efficacy of ILAI for THA remains inconclusive. While some studies validated the benefit of this technique5-9, others were not able to confirm improvements in pain control.10-15 As it is a simple technique based on the injection of analgesic solution in the tissue surrounding the surgical field, it has become a popular intervention.

Similarly, the analgesic efficacy of the PENG block for THA remains unclear. As the PENG block involves sensory articular nerves of the anterior hip capsule, the benefit for the patients lies in the possibility of having a good analgesic response along with no motor leg weakness. This will improve patient care during the postoperative period with early mobilization and adequate pain control. There is limited information in the literature available regarding the use of the PENG block as part of the postoperative analgesia plan for THA. Thus, we have identified a need to conduct a trial that aims to investigate if the ultrasound-guided PENG block can provide non-inferior postoperative analgesia compared to local intraoperative anesthetic infiltration (ILAI).