Quadratus Lumborum Block versus Fascia Iliaca Compartment Block for Acetabular Fracture Surgery by Stoppa Method: A Double-Blind, Randomized, Noninferiority Trial

Background Acetabular fracture surgeries are frequently accompanied by protracted and severe perioperative pain, and there is no consensus on optimal pain relief management. Aim This study aimed at comparing the analgesic efficacy of fascia iliaca compartment block (FICB) and quadratus lumborum block (QLB) in patients with acetabular fractures undergoing surgery using the Stoppa method. Methods In this double-blind, randomized, noninferiority clinical trial, adult patients undergoing spinal anesthesia for acetabular fracture surgery, in Imam Hossein Hospital, Tehran, Iran (IRCT20191114045435N1), were randomly divided into two groups: FICB (n = 22) and QLB (n = 24). The visual analog scale (VAS) was used to assess the pain intensity at different times for all participants. In addition, the dose of fentanyl required to induce the patient to sit for spinal anesthesia and the pain intensity were evaluated. Moreover, the duration of analgesia and the total amount of morphine consumed in the first 24 h following surgery were evaluated, analyzed, and compared between the two study groups. Results FICB and QLB demonstrated effective comparative postoperative analgesic profiles following acetabular fracture surgery; however, no significant differences in VAS values were observed between the two groups during the study. FICB experienced reduced cumulative fentanyl consumption during spinal anesthetic placement, whereas QLB had a significantly lower total morphine demand in the initial postoperative 24 h period. Conclusion The lateral QLB and FICB can be introduced as effective routes for analgesia in acetabular fracture surgery using the Stoppa method. Clinical Trial Registration. The study was prospectively registered in the clinical trials registry system, on 2021-02-17, with registration number: IRCT20191114045435N1.


Background
Hip fractures are painful orthopedic emergencies [1].A relatively uncommon type of hip fracture, acetabular fracture (AF), afects approximately three per 100,000 patients annually [2].Tis fracture frequently results from highenergy injuries, including falls from height or a road traffc collision, and requires surgery to stabilize the hip joint and restore hip anatomy [3].AF is commonly associated with protracted and severe postoperative pain; however, no consensus exists on pain management.On the other hand, uncontrolled pain can raise the risk of delirium, anxiety, and fear; thus, pain management is essential for optimal care in these patients [4].
Pain control in these patients is traditionally based on systemic opioids [4,5].Although the use of opioids has been a signifcant revolution in anesthesia and postoperative pain management, evidence suggests that they can not only produce a variety of adverse efects during the perioperative period but also alter long-term outcomes and have a signifcant impact on patient's lives, such as the development of opioid dependence or opioid-induced hyperalgesia [6].Consequently, it is necessary to limit the use of opioids and substitute them with safer and more efective alternatives, such as peripheral nerve block [7].
Te pain associated with acetabular fracture surgeries can be managed with regional anesthesia methods such as fascia iliaca compartment block (FICB) or the pericapsular nerve group (PENG) block.Tese blocks have been noted for their low risk and moderate analgesic efcacy [8,9].Furthermore, the quadratus lumborum block (QLB) is a novel plane block that provides satisfactory analgesia after abdominal surgeries such as inguinal hernia repair, laparotomy, and cesarean section [7].
Te QLB, initially introduced by Blanco in 2007, is an interfacial plane block situated in the posterior abdominal wall [10].Te pivotal anatomical structures associated with this block are the quadratus lumborum muscle and the thoracolumbar fascia (TLF) [11].QLB, as a novel truncal regional block technique, shows promise in alleviating both somatic and visceral pain following abdominal surgery [12].Tis fascial plane block targets the thoracolumbar nerves by administering local anesthetics around the quadratus lumborum muscle [7].Various approaches exist for the QL block, including lateral, posterior, and anterior QLB, each applied based on the injection site and with distinct mechanisms tailored to specifc operations.Recent case studies have highlighted QLB's analgesic impact on the hip joint [13], confrming its efcacy [14].Te injectate pathway of anterior (or transmuscular) QLB may extend to the paravertebral (PVB) space, providing sensory innervation coverage to the hip nerves [7].In addition, this block ofers the advantage of minimizing quadriceps weakness [15].
Another case study has recently shown that QLB can provide efective analgesia following total hip arthroplasty [13].To our knowledge, however, no study has investigated the possible analgesic efects of QLB block in acetabular fracture surgery using the Stoppa method.
To this end, in this study, the efects of QLB and FICB on the amount of fentanyl consumed for painless positioning to perform spinal anesthesia in a seated position, the total amount of morphine supplied in 24 h, and the pain VAS score in patients after acetabular fracture surgery utilizing the Stoppa method were evaluated.Te null hypothesis was that there were no diferences in analgesic efcacy between fascia iliaca compartment block (FICB) and quadratus lumborum block (QLB) in patients with acetabular fractures undergoing surgery.

Patients and Study
Design.Tis double-blind, randomized, noninferiority trial was registered with registration number IRCT20191114045435N1 on the clinical trials registry system on February 17, 2021.Tis research was conducted between August 2020 and March 2021 at Imam Hossein Hospital, Tehran, Iran.Patients eligible for acetabular fracture surgery between the ages of 20 and 70 with ASA classes I and II met the inclusion criteria.Tis study excluded patients with a history of psychiatric illness, drug addiction, or a body mass index (BMI) of greater than 30 kg/m 2 .In addition, patients were excluded from the study if the plan for spinal anesthesia was changed to general anesthesia during surgery, if they bled more than 1 liter, if the surgery lasted more than 3 hours, if they experienced orthopedic complications during surgery, or if the surgical plan changed.Before the commencement of the study, all patients provided written consent to participate in the survey and to have the results made public.Tis research was approved by the Shahid Beheshti University of Medical Sciences Ethics Committee and adhered to the ethical principles of the Declaration of Helsinki [16].
Forty-six patients with acetabular fractures were randomly divided into groups A (patients who received FICB) and B (patients who received QLB).A blind anesthesia assistant utilized a computerized random number generator to conduct randomization.Randomization sequences were delivered to the anesthesiologist, who performed the blocks in opaque, sealed envelopes.Based on our previous research, the minimum sample size for each group was 18, with a confdence level of 0.05, a standard deviation (SD) of 55, and a statistical power of 90%.A 30% diference was assumed in average analgesia duration between the two groups [17].

Preparing the Patient before Performing the Block.
Before blocking, patients were moved to the block room.After administering 5 ml/kg of intravenous crystalloid liquid, 1 μg/kg of fentanyl, 0.02 mg/kg of midazolam, and 7 L/ min of oxygen through a face mask, they were ready to perform the block under standard monitoring.

Fascia Iliaca Compartment Block
Procedure.FICB was performed after topical anesthesia with 2 mL of 1% lidocaine infltration when the skin was sterilized with chlorhexidine.Under the direction of a high-frequency linear probe (6-15 MHz/linear array/6 cm scan dept FUJIFILM SonoSite Inc., Tokyo, Japan) ultrasound device (S-nerve; FUJIFILM SonoSite Inc., Tokyo, Japan) that was horizontally aligned in the inguinal region, 0.3 mL/kg of 0.5% ropivacaine was injected by in-plane technique between the iliopsoas muscle and iliac fascia using a needle (B.Braun needle, 22 G, 80 mm, Stimuplex Ultra 360) (Figure 1).

Quadratus Lumborum Block Procedure.
A pillow was placed under the lumbar region in the supine position for quadratus lumborum 1 (QL1) or lateral quadratus lumborum block (QLB).After sterilizing the skin, 2 mL of 1% lidocaine was subcutaneously infltrated to provide topical anesthesia.Te same device was used to perform a long-axis in-plane ultrasound at the level of the anterior axillary line between the costal margin and the iliac crest.Te transversus abdominis muscle (TAM), internal oblique muscle (IOM), and external oblique muscle (EOM) were the three  If VAS was >4 in this position, 1 μg/kg of fentanyl was administered intravenously and repeated every 5 min if required.Te total dose of fentanyl consumed until the appropriate time for spinal anesthesia was recorded.For postoperative analgesia, intravenous patient-controlled analgesia (IV-PCA) containing 40 mg of morphine in 40 mL of normal saline was administered.Each time the patient pushed the button, 0.5 mg of morphine was delivered (with a 15 min lockout time).If the VAS was >4 or higher within the frst 24 h after surgery, 2 mg of intravenous morphine was administered as rescue therapy, and the total amount of morphine was also calculated.Te primary outcome was the analgesia duration (the time since the patient's frst request for postoperative analgesia).Other variables included VAS scores at baseline (before the block procedure), in the recovery room (15 min after block performance), and 6, 12, and 24 h after surgery.In addition, the total dose of fentanyl for painless placement in the sitting position and the total amount of morphine administered in the frst 24 h after surgery were evaluated.Moreover, blood pressure and heart rate were recorded at baseline and 15 minutes after the block procedure.
Te patients, the block quality assessor, the anesthesia assistant responsible for intraoperative data collection, and the statistician were blinded to the block type.We utilized the Stoppa method as one of the standard surgical procedures for acetabular fractures.

Statistical Analysis.
Te chi-square test was used to evaluate categorical data, which were then expressed as frequency (percentage).Te Kolmogorov-Smirnov test was utilized to demonstrate the normality of continuous data, and the data were expressed as the mean ± SD.Te Mann-Whitney U test or independent-sample t-test was employed to compare continuous data between two study groups.Repeated-measures analysis of variance (ANOVA) was performed to analyze VAS at various times and block types (within-groups factor).Multiple comparisons (VAS) were corrected using the Bonferroni method.P values below 0.05 were considered statistically signifcant.SPSS software (v.16.0) was utilized for data analysis.

Results
Tis project enrolled 54 patients with acetabular fractures between August 2020 and March 2021.Eight patients were excluded from this study: two did not participate, fve had a history of psychiatric illness, and one was addicted to multiple drugs.Te remaining 46 subjects eventually completed the study and were analyzed.Te remaining 46 patients were randomly divided into two groups (group FICB, n � 22; group QLB, n � 24) and underwent surgery using the Stoppa method (Figure 3).Te patient demographics are shown in Table 1.
Our results indicated that both FICB and QLB led to signifcant reductions in blood pressure compared to baseline 20 min after administration (P < 0.001 and P � 0.019, respectively).In addition, 20 minutes after QLB, the heart rate was signifcantly lower than at baseline (P < 0.001), whereas there was no signifcant diference in this variable between the QLB and FICB groups (P � 0.89).A repeated-measures ANOVA with a Greenhouse-Geisser correction showed that the mean VAS scores signifcantly decreased compared to baseline in both FICB (F (3.37, 77.43) � 22.49, P < 0.001) and QLB groups (F (3.37, 77.43) � 22.49, P < 0.001).Bonferroni adjustment revealed that VAS scores decreased signifcantly in both groups compared to baseline, at recovery, and 6 h, 12 h, and 24 h following surgery (Tables 2 and 3).At any point during the trial, there was no signifcant diference between the two groups' VAS scores (Table 4).As shown in Table 5, total morphine requirements during the frst 24 hours after surgery were signifcantly lower in the QLB group than in the FICB group.In contrast, total fentanyl consumption during spinal positioning was signifcantly higher in the QLB group than in the FICB group.

Discussion
Te current study found no signifcant diference in VAS values between the two groups at any point during the study, and both FICB and QLB had a relatively similar postoperative analgesic profle after acetabular fracture surgery using the Stoppa method.Typically, each block ofers an additional beneft.While the QLB group used signifcantly less morphine during the frst 24 h after surgery than the FICB group, the FICB group had a lower cumulative fentanyl intake while positioned for spinal anesthesia.Nevertheless, in both methods, pain reduction occurred before surgery and during the positioning of the patient for spinal anesthesia, which is supposed to be due to the nerve blocks and fentanyl pretreatment.FICB is already reported to provide perioperative analgesia after femoral neck fracture, total hip arthroplasty, and hip and knee surgery [6].According to most existing studies and meta-analyses, FICB reduces pain intensity, the demand for opioids, and the rates of problems associated with their systemic use in these procedures [18][19][20].Vergari et al. concur with our conclusion that FICB is a safe and efective option for postoperative analgesia following acetabular surgery [9].As the lumbar plexus (LP) innervates the acetabular region, LP blocks provide analgesia in patients undergoing acetabular fracture surgery [9,21].Te lumbar plexus comprises the obturator nerve (ON), lateral femoral cutaneous nerve, ilioinguinal nerve, iliohypogastric nerve, genitofemoral nerve, and femoral nerve (FN), as well as the lumbosacral trunk [22].Teoretically, the possible mechanism of FICB block is blocking the femoral nerve, the lateral femoral cutaneous nerve, and the ON [9].
To our knowledge, no research has documented the analgesic efcacy of lateral QLB in acetabular fractures.Our results revealed that QLB decreased pain VAS scores and the need for opioids in the frst postoperative 24 h.Nassar et al. found comparable outcomes, reporting that QLB can decrease the VAS score throughout spinal block positioning and increase postoperative motor power after THA [31].Kukreja et al. observed that QLB could decrease pain intensity and the demand for analgesic medications 24 h following THA surgery [32].However, using the same approach, Aoyama et al. were unable to detect sensory blockage of the lumbar nerves following transmuscular QLB [33].
As stated previously, systemic opioid administration has historically been used to treat pain after acetabular fracture procedures.Tis method has several disadvantages, including postoperative nausea, vomiting, oversedation, apnea, respiratory issues, and altered gastrointestinal function [4].Consequently, utilizing analgesic techniques such as QLB that lessen the requirement for opioids can result in fewer side efects, early involvement in physical therapy, and quicker recovery and discharge [5,7].
Te precise mechanism of the analgesic efect of QLB remains unknown.Nonetheless, several potential mechanisms may be involved, including (a) medial distribution of the local anesthetic drug to the paravertebral spaces of the thoracolumbar region; (b) direct spread of local anesthetics to the lumbar plexus nerve roots and branches, such as the lateral femoral cutaneous, ilioinguinal, superior cluneal, and iliohypogastric nerves; inconsistent anesthetization of the femoral nerve, obturator nerve, and lumbar sympathetic trunk; and (c) the possibility of lumbar plexus block by spreading through the fascial layer between the psoas muscle [31].

Conclusion
In conclusion, our paper described the lateral QLB and FICB as efective analgesic techniques for acetabular fracture surgery utilizing the Stoppa approach, which exhibited a virtually identical analgesic profle.However, large-scale clinical studies must confrm these pilot clinical data to exclude local factors that could infuence the fnal results.

Data Availability
Te CONSORT and raw datasets used during the current study were uploaded as supplemental fles alongside the manuscript submission.Also, they would be available from the corresponding author upon reasonable request.

Additional Points
Strengths and Limitations.Te current study was the frst to evaluate the potential analgesic efect of QLB in acetabular fracture surgeries using the Stoppa approach, providing a basis for future research in this feld.However, this study has some limitations.First, we did not consider all the important parameters for evaluating the efcacy of enhanced recovery after surgery (ERAS), such as the time to frst ambulation, length of hospitalization, and patient satisfaction.Second is the failure to evaluate the long-term side efects of the blocks, such as the development of chronic pain in the study groups.Tird, the data from this study are insufcient to draw robust conclusions, and a larger sample size of randomized controlled trials is required to validate our results.

2
Pain Research and Management abdominal anterolateral muscles that required localization.Te quadratus lumborum muscle (QLM), characterized by a hypoechogenic region, can be located by moving the probe posterolaterally where the disappearance of the TAM can be witnessed in the anatomical axillary posterior line.Using the same needle type, 0.3 mL/kg of 0.5% ropivacaine was injected into the lateral terminal site of the transverse abdominis muscle through hydrodissection (Figure2).

2. 5 .
Patient Care after Block.Patients were instructed to assume a seated position 20-30 minutes after block administration.

Table 2 :
VAS score changes at diferent times of the study compared to the baseline in the FICB group.

Table 3 :
VAS score changes at diferent times of the study compared to the baseline in the QLB group.
Pain Research and Management