Trial Comparing Impact of PENG Block on Quality of Recovery Compared to No-block for Primary Total Hip Arthroplasty

Total hip arthroplasty (THA) is now the second most common joint replacement surgery in the US due in part to an aging population. Opioid sparing analgesic treatments such as lumbar plexus and femoral nerve blocks are effective but they carry a high risk of undesirable lower limb motor or muscle weakness. Fascia iliaca block, on the other hand, does not consistently provide adequate pain relief. Today, early mobilization, rehabilitation and participation in physical therapy is an integral part of enhanced functional recovery program after THA. Because innervation of the hip joint is complex and preservation of lower extremity motor function is paramount, optimal regional analgesic intervention for THA has yet to be defined. The pericapsular nerve group (PENG) block is a novel regional anesthesia technique for providing analgesia after hip fractures and hip arthroplasties. Quality of recovery scores are patient reported outcome measures evaluating recovery after surgery and anesthesia. The quality of recovery-15 (QoR-15) is a validated questionnaire to assess postoperative recovery. The aim of this single center, double blind, randomized controlled trial is to confirm the efficacy of the PENG block for postoperative recovery after primary THA.

Methods: The participants will be randomly assigned to either PENG block group or "no Block" group using a random number generator. The patient will be blinded to the group allocated. The primary outcome will be the quality of recovery 15 score (QoR-15). The secondary outcomes will be visual analog scale score of pain postoperatively, opioid requirements in first 24 hours, ambulation distance on postoperative day1 and patient satisfaction. Statistical analysis will be performed using the student's t-test, Mann-Whitney U test, and Fisher's exact test as appropriate per sample. A p-value of less than 0.05 will be considered statistically significant.

As the practice of anesthesiology has grown increasingly safe, the focus has shifted to improving quality, as evidenced by the robust spread of Enhanced Recovery after Surgery protocols. The implications from poor quality recovery is vast, including prolonged stay in the recovery room or hospital. The Quality of Recovery (QoR-15) questionnaire is a method to measure five dimensions using 15 questions: physical independence, pain, comfort, patient support, emotional state. It is an extensively validated measure of patient-assessed quality of recovery after surgery, having been demonstrated over a variety of clinical settings. QoR-15 scores range from 0 (extremely poor quality of recovery) to 150 (excellent). Mean time to complete the 15-question survey is 3 minutes, a marker of its clinical utility. As we aim to improve our perioperative care and develop approaches to improve medicine in this regard, the QoR-15 provides a useful tool.

The effective postoperative analgesia is vital as acute surgical pain is a potential risk factor for future chronic pain. Persistent pain after THA (more than three months) is reported in 27% of patients and is reported to be correlated with the intensity of early postoperative pain rather than preoperative pain levels. Utilizing regional anesthesia helps to limit the use of opioids, however, which technique is best has yet to be determined. The lumbar plexus blocks, lumbar epidurals, and femoral nerve blocks have been associated with motor weakness. Fascia iliaca compartment block (FICB) has not been found to predictably decrease pain intensity or opioid use. Quadratus lumborum (QL) block is a relatively new regional block found to provide effective analgesia after primary THA, but it can indirectly block lumbar plexus branches and may cause some motor weakness. It is also a deep block and therefore contraindicated in patients on anticoagulation.

Recent anatomic studies confirmed the innervation of the anterior capsule of hip joint to be the obturator nerve, accessory obturator nerve, and femoral nerve. These studies also evaluated the relationship with these nerves and other bony or soft tissue landmarks visible by ultrasound guidance. Previous studies have found histologically that the anterior capsule has predominantly nociceptive fibers, while the posterior capsule is largely made up of mechanoreceptors. The pericapsular nerve group (PENG) block was introduced to target and block these articular branches providing innervation to the hip. Given the case reports showing the efficacy of PENG blocks for hip fracture surgeries, we sought to investigate the analgesic efficacy of PENG blocks for primary and revision THAs. The PENG block targets only the sensory branches and not the posterior mechanoreceptors; there is a potential motor-sparing effect which is desirable for early ambulation, better physical therapy, and earlier discharge. The effective analgesia and early ambulation provided by such regional anesthesia block may have positive impact on patient's mood, sleep, appetite and overall feeling of well-being. A similar postoperative recovery study protocol has been proposed for anterior quadratus lumborum blocks for THA. It remains unclear whether PENG block provides sufficient analgesia and improves the quality of post-operative recovery after primary THA.

The ideal regional anesthesia technique for THA will provide adequate postoperative analgesia, reduced opioid requirements, early ambulation and physical independence. The aim of this single center, double blind RCT is to confirm the efficacy of PENG block for postoperative recovery with respect to parameters mentioned above.

Eligibility Criteria:
Inclusion Criteria:

* Patients undergoing primary total hip arthroplasty
* Patients \>=18 years of age
* Patients with an American Society of Anesthesiology (ASA) physical status classification of I, II or III
* Primary THA (first THA operation in the patient's lifetime)

Exclusion Criteria:

* Patients with ASA physical status classification 4 or above
* Patients with allergies/intolerances to local anesthetic
* Patients with pre-existing neurologic or anatomic deficits in the lower extremity on the side of the surgical site
* Patients on chronic opioid use or opioid tolerant (The FDA defines a patient as opioid tolerant if for at least 1 week he or she has been receiving oral morphine 60 mg/day; transdermal fentanyl 25 mcg/hour; oral oxycodone 30 mg/day; oral hydromorphone 8 mg/day; oral oxymorphone 25 mg/day; or an equianalgesic dose of any other opioid)
* Poor understanding of English language.
* Patients with coexisting coagulopathy
* Patients that are pharmacologically anticoagulated will be excluded if placement of peripheral nerve block would be contraindicated according to ASRA (American Society for Regional Anesthesia) guidelines