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.