Pain Relief after Hip Fracture Repair Surgery: Options and Outcomes

Hip fracture is common among the older surgical patients and is one of the leading causes of morbidity and mortality.[1] Early surgery has been recommended to decrease the overall mortality and morbidity associated with the hip fracture.[2] The road to recovery in these patients, however, is long and may continue for several months after surgery. Effective postoperative pain management and early mobilization have been recognized among the critical modifiable factors that can affect the patient’s postoperative functional recovery.[3] Adequate pain relief after hip fracture surgery enables early ambulation and initiation of physical therapy and reduces postoperative complications and the length of hospital stay. Conventionally, for anesthesiologists, the modalities available for postoperative analgesia were limited to epidural analgesia, femoral nerve block, and parenteral opioid medications.[4] On one hand, these modalities provided analgesia, but on the other hand, they paradoxically resulted in undesirable side effects such as motor weakness, nausea and vomiting, sedation, and urinary retention. Hence, the role of anesthesiologists was far from enhancing the overall postoperative functional recovery in patients undergoing surgery for hip fracture. With the advent of ultrasound (USG) machines in the anesthesiology practice, various nerve block techniques have emerged for postoperative analgesia, such as the suprainguinal fascia iliaca block, quadratus lumborum block, and pericapsular nerve block group (PENG) block.[5] With so many available options, it is vital for an anesthesiologist to know which among these is best for postoperative analgesia after the hip fracture surgery. In this issue of JICA, Rurhia et al. presented an interesting study comparing the continuous USG-guided PENG block to the continuous USG-guided lumbar plexus block (LPB) for postoperative pain relief after hip fracture surgeries.[6] Their study interventions were aimed at blocking the nerve supplying the hip joint at two opposite sides of the road. The PENG block targets the specific articular branches of the femoral, obturator, and accessory obturator nerves innervating the anterior hip capsule.[7] In contrast, an LPB is a more proximal block targeting the main trunks of the lumbar plexus (L1-L4), covering the nerves supplying the hip and the thigh.[8] The choice between the various nerve blocks for postoperative analgesia following hip fracture surgery depends on several factors, such as the primary goal in the postoperative period, the type of the hip repair surgical procedure, and the operator’s experience. The nerve blocks targeting the lumbar plexus at the proximal locations result in quadriceps muscle weakness, which affects the ability of the patient to ambulate after surgery. The PENG block is, therefore, the preferred choice when the primary goal is early mobilization and rehabilitation for a patient with a hip fracture. Its motor-sparing effect is a key advantage for facilitating physical therapy and reducing the risk of falls in elderly or frail patients. The LPB may be considered if emphasis is purely on comprehensive short-term pain reduction and immediate postoperative fentanyl consumption, and temporary motor weakness is less of a concern. The choice of the nerve block also depends on the type of surgery for hip fracture. Surgery for hip fracture is an umbrella term, as there are varied surgical procedures undertaken depending on the site of fracture, displacement of the fractured bone fragments, and the age of the patient.[9] The PENG block primarily targets the sensory branches that innervate the anterior capsule of the hip joint. This makes it particularly effective for intracapsular hip fractures. For extracapsular fractures, while useful, the PENG block alone may not provide complete coverage (such as intertrochanteric fractures) because some pain fibers in the posterior or lateral aspects might not be fully blocked. The lateral aspect of the thigh is supplied by the lateral femoral cutaneous nerve (LFCN) of the thigh, which is a direct branch of the lumbar plexus. The LPB (or a fascia iliaca compartment block) may be a better option when pain from the lateral thigh is a significant issue, as it provides broader sensory coverage. For facilitating early ambulation of patients along with adequate analgesic coverage, the PENG block has been combined with the block of the LFCN in some studies.[10,11] Another important factor determining the preference of a particular nerve block is the expertise of the anesthesiologist. Of all the blocks available for hip surgery, USG-guided LPB requires advanced skills due to the deep location of the lumbar plexus, complex sonoanatomy, and high risks of complications such as hematoma and spread of local anesthetic drugs to the epidural space. Therefore, LPB is a demanding procedure, best attempted by an experienced and skilled operator, and often requires a combination of USG and nerve stimulation for safety and efficacy. On the other hand, the PENG block is comparatively less technically challenging and relatively safer. In the study by Rurhia et al., it was observed that the postoperative pain control in the patient receiving the PENG block compared to the LPB was better. There was one previous study that compared the PENG block with the LPB and reported lower postoperative pain scores with the latter.[12] The authors attributed the difference in the findings to the different regimens of local anesthetics (LA) used. For the PENG and the LPB block, Rurhia et al. used 0.5% ropivacaine along with 2 µg/ml of fentanyl, followed by an infusion of 0.2% ropivacaine and 2 µg/ml of fentanyl for 48 h. Despite this explanation, in the LPB block, the deposition of LA drugs occurs at the anatomical location that will invariably block the sensory and the motor fibers of mixed nerves such as femoral, obturator, and accessory obturator nerves. Therefore, the LPB block theoretically should result in a denser block compared to the PENG block. The LPB is performed within the psoas muscle compartment, which is a relatively vascular site. It is plausible that in the LPB, there is rapid absorption of LA drugs from the block site and distribution into the circulation compared to the PENG block. This could have resulted in lower efficacy of the LPB block in comparison to the PENG block. Furthermore, the volume of LA given was lower than the practice of administering an initial bolus of 20–30 ml followed by infusion at 8–10 ml/h followed in other studies on continuous LPB.[13,14] Nevertheless, this study contributes to growing evidence on the efficacy of two different nerve blocks for the postoperative analgesia following hip fracture surgery. As one of the “USPs” of the PENG block is its ability to spare the motor blockade of the thigh muscles, it has provided anesthesiologists an opportunity to positively contribute to the postoperative functional recovery of patients with hip fracture. Future studies comparing the PENG block with other nerve blocks for patients undergoing hip fracture surgery should focus on the outcomes related to the postoperative functional recovery of patients, such as time to ambulation and occurrence of postoperative complications such as postoperative delirium, postoperative cognitive dysfunction, and pulmonary complications.