Anterior Quadratus Lumborum Block Does Not Provide Superior Pain Control After Hip Arthroscopy

A Double-Blinded Randomized Controlled Trial

Stephen C. Haskins, M.D.; Audrey Tseng, B.A.; Haoyan Zhong, M.P.A.; Marko Mamic, M.D.; Stephanie I. Cheng, M.D.; Jemiel A. Nejim, M.D.; Douglas S. Wetmore, M.D.; Struan H. Coleman, M.D.; Anil S. Ranawat, M.D.; Danyal H. Nawabi, M.D.; Bryan T. Kelly, M.D.; Stavros G. Memtsoudis, M.D., Ph.D., M.B.A.

Disclosures

Anesthesiology. 2021;135(3):433-441. 

In This Article

Discussion

This prospective double-blinded randomized controlled trial assessed the clinically analgesic effect of anterior quadratus lumborum block with multimodal analgesia compared to multimodal analgesia alone in hip arthroscopy. The only benefit in the anterior quadratus lumborum block intervention was at the 30-min point after PACU arrival. However, while statistically significant, a 1.1 difference in pain score may not represent a clinically meaningful difference. There was no difference found in secondary outcomes regarding opioid use, nausea/vomiting, antiemetic use, the incidence of hospital admission, time to discharge from PACU, patient satisfaction with pain management, change in quadriceps strength, or incidence of urinary retention and hypotension. In sum, these findings suggest that anterior quadratus lumborum block, in addition to multimodal analgesia, may have limited value in the setting of hip arthroscopy.

This study demonstrated that the anterior quadratus lumborum block did not cause a significant motor deficit despite previous reports suggesting up to 90% of quadriceps weakness after the anterior quadratus lumborum block.[20] A retrospective study by Ueshima and Hiroshi reported that 65 out of 81 patients receiving anterior quadratus lumborum block experienced quadriceps weakness after performing bilateral anterior quadratus lumborum block with a total of 40 cc of 0.375% levobupivacaine.[20] Quadriceps weakness caused by blockade of the lumbar plexus can impede early mobilization and physical therapy and cause falls, all of which delay PACU discharge.[2] Despite the anterior quadratus lumborum block's proximity to the lumbar plexus, the local anesthetic is injected posterior to the psoas major muscle. In contrast, the lumbar plexus is encased within the psoas major muscle. The cadaveric study by Dam et al. demonstrated that out of 10 anterior quadratus lumborum block injections, no dye surrounded the lumbar plexus block, suggesting that the lumbar plexus is not affected.[21] Changes in quadriceps strength were common in both of our groups, likely due to pain or surgical swelling limiting quadricep firing. Without a control group, it is possible that other retrospective reports misinterpreted standard surgery-related postoperative weakness as the direct result of the anterior quadratus lumborum block. Finally, although our study was not powered to assess this outcome, the addition of anterior quadratus lumborum block to multimodal analgesia did not provide superior pain control for patients with intra-abdominal fluid extravasation.

Contrary to the retrospective study by McCrum et al.,[8] our analysis suggests that for hip arthroscopy, the addition of anterior quadratus lumborum block to multimodal analgesia is not superior to multimodal analgesia alone for postoperative pain control, reducing opioid or antiemetic consumption, and patient satisfaction. Similar to the study by Brixel et al. evaluating posterior quadratus lumborum block for elective total hip arthroplasty, we also found that this block is not a good clinically analgesic option.[7] These findings are meaningful as the anterior quadratus lumborum block is relatively new. There are many hypotheses regarding the surgical procedures that might benefit from the performance of this block. However, the lack of treatment effect with performing anterior quadratus lumborum block for hip arthroscopy in addition to multimodal analgesia helps to identify the surgical procedures that do not benefit clinically from these novel blocks, particularly given that many of these blocks are deep, challenging to perform, and associated with potential complications. Additionally, the publication of prospective randomized studies with a lack of treatment effect ensures increased accuracy of future meta-analyses investigating the block's clinical analgesic effect.

The limitations of this study include the single-institutional nature, which limits external validity. We did not control for the type of hip arthroscopy performed. A sham block was not performed; however, we felt a sham block was not appropriate. The quadratus lumborum block is deep, and we did not want to risk potential violation of the peritoneum or kidney without the benefit of the postoperative analgesia. Further, we excluded patients with chronic pain or opioid dependence, who may have benefitted from additional analgesia from a regional technique.

There may be an analgesic role for the quadratus lumborum block as a rescue block for patients in severe postoperative pain. The quadratus lumborum block is performed far from the surgical site and is motor sparing; therefore, it can be performed easily without removing the surgical dressing. Also, the postprocedural analgesia might decrease the need for hospital admission for pain control while simultaneously enabling ambulation, unlike the lumbar plexus block. Additionally, patients with a history of chronic pain or high opioid dependence may benefit, no matter how marginally, from any supplemental analgesic to decrease the need for high-dose opioids postoperatively. However, despite these potential indications, our findings conclude that it does not seem prudent to routinely perform the anterior quadratus lumborum block on patients undergoing hip arthroscopy if multimodal analgesia is provided in the perioperative setting.

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