Quadratus lumborum block versus femoral nerve block in total hip arthroplasty: a randomized clinical trial

Abstract

Background

The innervation of the hip joint is complex, and multimodal analgesia enables optimal management of postoperative pain and early mobilization. This includes administration of regional anesthesia. Numerous blocks for total hip arthroplasty (THA) have been documented in the literature and recently the quadratus lumborum block (QLB) has been reported for use in hip replacement surgery.

In the present randomized controlled trial, a comparison was made between QLB and femoral nerve block (FNB) in patients undergoing THA. We selected morphine consumption in the first 24 hours after surgery as the primary outcome. We hypothesized that QLB would obtain better results than FNB.

Methods

We conducted a prospective, controlled, randomized, simple-blind trial at the University Hospital of Reims (France). Patients undergoing primary THA were included and were allocated to receive either QLB or FNB. Blinded observers recorded cumulative morphine consumption at 24 hours, pain scores at 1, 2, 6, 12 and 24 hours, use of other analgesics, and length of stay.

Results

There were 76 patients in the QLB group and 81 in the FNB group. There was no statistical difference in cumulative morphine consumption at 24h between both groups (14,6 +/- 12 mg vs 13,5 +/- 10,8 mg, p = 0.35, in the QLB and the FNB groups respectively). No clinically significant intergroup differences were found in terms of postoperative pain scores and length of hospital stay.

Conclusion

In THA, QLB is not associated with a significant change in postoperative morphine consumption in our study when compared with FNB.

Trial registration

ClinicatTrials.gov identifier: NCT: NCT03666260; Retrospectively registered, October 10, 2018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-025-03586-x.

Introduction

Total hip arthroplasty (THA) is one of the most common major orthopedic procedures designed to improve patient functional status and quality of life [1]. Its incidence is roughly 140,000 per year in France and is increasing every year due to the aging of the population. Early rehabilitation and mobilization after hip surgery improves outcomes [2, 3].

Physiotherapy when initiated on day one and when done three times per day is beneficial in terms of walking, muscle strength and length of hospital stay [4]. The postoperative period may involve severe pain that delays mobilization, affecting length of stay, risk of thromboembolic events, and costs [5].

Over the past decade, pain management has evolved. Analgesia is now described as multimodal, involving systematic use of analgesics and availability of regional anesthesia [6]. Use of peripheral nerve blocks as a pain management strategy has been recommended to restrict the use of opioid analgesics and their adverse effects (respiratory depression, nausea, vomiting, urinary retention and sedation).

Femoral nerve block (FNB) has historically been widely used for analgesia in total hip arthroplasty; however, it does not provide complete sensory coverage of the hip joint. Moreover, femoral nerve block is associated with quadriceps motor blockade, which may delay early mobilization and rehabilitation, as previously reported by Angers et al. in 2019 [7].

Quadratus lumborum block (QLB) may constitute an alternative to hip analgesia. QLB was first described by Blanco in 2007 [8]. It is an interfascial plane block of the posterior abdominal wall [9]. There are 3 QLB approaches: anterior, lateral, and posterior.

The anterior approach spreads the local anesthetic between the quadratus lumborum (QL) and the psoas major (PM) muscles [10, 11].

The hip is mainly innervated by the femoral and the obturator nerves (lumbar plexus). Given that the lumbar plexus nerves branches run between the PM and the QL, the anterior QLB could play a role in providing analgesia to the lower extremities and the trunk and is therefore an interesting option for posterior THA (PTHA) [12]. QLB can successfully manage post-operative pain in patients undergoing abdominal surgery, renal surgery, and cesarean Sect [13]. However, its efficacy in controlling pain following hip surgery is still unclear in the literature.

The purpose of the present study was to demonstrate the superiority of QLB over FNB, based on morphine consumption in the first 24 h after PTHA.

Methods

Study design

This simple-blind, prospective, randomized, controlled trial was conducted at the University Hospital of Reims (France) between October 2018 and July 2020 (ClinicatTrials.gov identifier: NCT: NCT03666260; registered October 10, 2018). Patients scheduled for PTHA were selected and randomized to one of two groups according to the regional block received: FNB group or QLB group. Randomization sequence was generated using the “Randomization” module of the Cleanweb^® software by the study designer. Randomization was performed on the day of surgery by the anesthesiologist investigator responsible for administering locoregional anesthesia. Allocation was implemented via the Cleanweb software and was stratified according to the type of anesthesia (spinal anesthesia or general anesthesia). Participants were randomly assigned in a 1:1 ratio using permuted blocks of four.

Patients

To be eligible, patients were required to undergo a total hip arthroplasty performed using a posterior approach (Moore approach) at the University Hospital of Reims. Exclusion criteria were allergy to local anesthetics; neuropathy; ASA score > 3; revision surgery; anterior THA; contraindication to regional anesthesia; patient refusal and patient subjected to protective legal measures.

Primary and secondary outcomes

The primary outcome was the cumulative morphine consumption in the first 24 h after surgery.

The secondary outcomes were pain score (VAS) at 1, 2, 6, 12, 24 h, at rest and on mobilization; use of other analgesics; length of surgery; length of stay in post anesthesia care unit (PACU).

Total participation time was 48 h. Motor function and early mobilization were not systematically assessed due to the absence of standardized early physiotherapy and formal motor testing, precluding reliable evaluation of motor outcomes.

Intervention

General anesthesia (using sufentanil, ketamine, propofol and cisatracurium) or spinal anesthesia (using bupivacaine and sufentanil without morphine) were administered. The dosage was left to the discretion of the attending anesthesiologist.

The FNB was administered prior to anesthesia taking strict aseptic precautions. Under the guidance of a high-frequency linear transducer (10–25 MHz) GE Logic e ultrasound device positioned horizontally in the inguinal area, 20 ml of levobupivacaine 0.25% was injected after negative aspiration with an 80-mm 21-G nerve block needle between the iliac fascia and the iliopsoas muscle using an in-plane technique (Supplementary material 1).

QLB was performed (after general or spinal anesthesia) under full aseptic conditions and under the guidance of a GE Logic e ultrasound low-frequency curvilinear transducer (2–5 MHz) with the patient placed in a lateral position. The transducer was placed transversely over the midaxillary line above the iliac crest. 20 mL of levobupivacaine 0.25% was diluted with 10 mL of normal saline, resulting in a final concentration of approximately 0.17%, in order to deliver the same total dose of local anesthetic as in the femoral nerve block group. Dilution was required because quadratus lumborum block is volume-dependent, and administering a higher undiluted dose could have introduced bias. 30 mL in total were injected after negative aspiration with an 80-mm, 21-G nerve block needle between the QL and the psoas muscle using an in-plane technique (Supplementary material 2).

Dexamethasone (8 mg) was administrated intravenously to patients from both groups.

Post-operative analgesia was paracetamol 1 g administered 4 times daily; ketoprofen 50 mg 4 times daily; PCA (patient-controlled analgesia) morphine; and, in the event of contraindications, 80 mg of nefopam per day + 1,25 mg of droperidol per day. Additional intravenous morphine was administered in 2 mg increments in the PACU to maintain a resting VAS score of < 4.

Data collection

Information was collected pertaining to age, sex, height, weight, ASA score, type of anesthesia, sufentanil dosage, use of other analgesics, number of comorbidities, visual analog scale (VAS) at rest and on mobilization, duration of surgery, length of PACU stay, and morphine use in the first 24 h.

Ethical considerations

This study was conducted in accordance with the Declaration of Helsinki and approved by the institutional review board (IRB) of the Sud-ouest et Outre-Mer II (Approval number: IRB 2018-A01119-46). CONSORT (Consolidated Standards of Reporting Trials) guidelines were thoroughly followed (Supplementary material 3).

Written informed consent was obtained from all participants prior to enrollment.

Sample size calculation and statistical analysis

The number of subjects for inclusion was calculated on the basis of the following hypothesis:

mean morphine consumption at 24 h of 16.96 ± 11.18 in the femoral group and 9.77 ± 7.07 in the QLB group based on a 2016 study by Parras et al. [14]

Given an alpha risk of 0.05 and a power of 90%, the inclusion of 80 patients per group was considered as sufficient for observing any significant difference between both groups.

Patients numbers were raised to 170 (85 participants per group) to compensate for possible dropouts (around 5%).

Firstly, a comparison was made between patient characteristics in the two groups, followed by analysis of the outcomes by means of various tests:

• Comparison of morphine consumption in the 24 h following surgery in the two groups using a parametric Student’s t test.

• Regarding the secondary outcomes, the parameters were compared using the parametric Student’s t test, the non-parametric Wilcoxon test, and the Chi2 test or Fisher’s exact test, as applicable.

Intention-to-treat analysis was applied.

With regard to missing data processing, the study was conducted in such a way as to minimize missing data.

The tests were bilateral, with an alpha risk of α = 0.05.

All statistical analyses were performed using SAS version 9.4 software (SAS Institute, Inc., Cary, NC, USA).

Results

A total of 160 patients were included but only 157 were analyzed as intention-to-treat since 3 patients were excluded for failing to meet the inclusion criteria.

Ultimately 81 patients were analyzed from the femoral nerve block group and 76 from the QLB group (Fig. 1).

Fig. 1.

Flow Chart

The population was predominantly female (58%; 91 patients), with a median age of 68 years (+/- 11.4).

Demographic data (age, sex, ASA score, weight/height, co-morbidities) were comparable in both groups (Table 1).

Table 1.

Baseline characteristics

	All n = 157	FNB N = 81	QLB N = 76
Age (years)	68.13 ± 11.41	68.16 ± 11.49	68.09 ± 11.39
Weight (kg)	79.20 ± 17.53	80 ± 17.89	78.27 ± 17.21
Height (cm)	166 ± 11	166 ± 11	166 ± 11
ASA	2 [1–3]	2 [1–3]	2 [1–3]
Sex female	91 (58)	43 (53.1)	48 (63.2)
Comorbidities	114 (72.6)	57 (70.4)	57 (75)
Diabetes mellitus	23 (14.6)	12 (14.8)	11 (14.5)
Hypertension	66 (42)	35 (43.2)	31 (40.8)
Obstructive sleep apnea	11 (7)	7 (8.6)	4 (5.3)
COPD	9 (5.7)	5 (6.2)	4 (5.3)
Ischemic heart disease	18 (11.5)	9 (11.1)	9 (11.8)
Systemic disease	74 (47.1)	34 (42)	40 (52.6)
Anesthesia
General	84 (53.5)	43 (53.1)	41 (53.9)
Spinal	71 (45.2)	37 (45.7)	34 (44.7)
Good echogenicity	48 (30.6)	28 (34.6)	20 (26.3)
Good needle visualization	44 (28)	27 (33.3)	17 (22.4)
Good diffusion visualization	53 (33.8)	31 (38.3)	22(28.9)

Data are expressed as medians [interquartile range], counts (percentages) or means ± standard deviation. FNB Femoral nerve block, QLB Quadratus lumborum block, ASA American Society of Anesthesiologists, COPD Chronic obstructive pulmonary disease

Surgical characteristics were also comparable in each group. The type of anesthesia administered was comparable between the two groups.

The groups were also compared for echogenicity, needle visualization and visualization of anesthetic diffusion. These data were reported by the attending anesthesiologist.

It is important to note that these data showed significant variation. Patient echogenicity was higher in the FNB group, as was needle and anesthetic diffusion visualization (Supplementary material 4).

Primary outcome

No difference in cumulative morphine consumption at 24 h was documented between the two groups (14.6 +/- 12 mg vs. 13.5 +/- 10.8 mg, p = 0.35, in the QLB and FNB groups respectively) (Table 2 and Fig. 2.)

Table 2.

Cumulative morphine consumption at 24 h

	FNB	QLB	p
Morphine consumption at 24 h in PACU (mg)	4.6 ± 5.8	4.9 ± 5.8	0.97
Morphine consumption at 24 h in recovery unit (mg)	8.8 ± 8.5	9.7 ± 8.5	0.17
Morphine consumption at 24 h (mg)	13.5 ± 10.8	14.6 ± 12	0.35

PACU Post-anesthesia care unit, FNB Femoral nerve block, QLB Quadratus lumborum block

Fig. 2.

Box plot comparing cumulative morphine consumption at 24h

Detailed opioids consumption figures are summarized in the supplementary material 5.

Secondary outcomes

Median intervention length was 2 h in both groups (p = 0.43).

No statistically significant difference was found in Post-anesthesia care unit (PACU) length of stay, which was 2.7 h (p = 0.71).

Time to first step was the same in both groups, namely 23.4 and 21.4 h in the FNB and the QLB groups respectively (p = 0.52).

There was no difference in postoperative pain measured by VAS between the two groups, irrespective of assessment time, at rest or on mobilization.

No statistically significant difference in the consumption of paracetamol, ketoprofen or nefopam in the surgical ward was found in either group (Table 3).

Table 3.

Secondary outcomes

	FNB	QLB	p
Intervention time (h)	2.1 ± 0.4	2 ± 0.4	0.43
Time in PACU (h)	2.7 ± 1.1	2.7 ± 1	0.71
VAS at rest
H1	0.7 ± 1.3	1.3 ± 1.8	0.20
H2	0.6 ± 1.4	0.9 ± 1.7	0.22
H6	2.3 ± 2.5	2.4 ± 2.6	0.98
H12	2.2 ± 2.7	2.1 ± 2.4	0.37
H24	2.7 ± 2.3	1.7 ± 2	0.44
VAS on mobilization
H1	2.5 ± 2.2	2.0 ± 2	0.65
H2	1.4 ± 1.6	1.6 ± 1.5	0.69
H6	2.4 ± 2	2.2 ± 2.1	0.85
H12	2.2 ± 2.5	2.4 ± 2.6	0.92
H24	2 ± 2	1.9 ± 1.8	0.48
Paracetamol use (No. of patients)	50	51	0.68
Ketoprofen use (No. of patients)	32	33	0.79
Nefopam use (No. of patients)	12	18	0.19

PACU Post-anesthesia care unit, VAS Visual Analogue Scale, FNB Femoral nerve block, QLB Quadratus lumborum block

Discussion

Present study findings demonstrate no anterior quadratus lumborum block superiority over femoral nerve block for postoperative pain control in scheduled posterior hip arthroplasty.

Indeed, no difference was observed in cumulative morphine consumption at 24 h between the two groups.

Morphine consumption at 24 h was approximately 14 mg in both groups. Our results are consistent with the hypothesis that was formulated to calculate the sample size, based on a study by Parras et al. [14]. Our findings are also consistent with mean morphine consumption documented in the literature [15].

Similarly, the secondary outcomes are comparable, and no difference was found in pain scores (VAS), length of stay and time to first step.

Regarding other analgesics used during the postoperative period (NSAIDs, nefopam, paracetamol), Thybo and al. showed that among patients undergoing THA, paracetamol plus ibuprofen significantly reduced morphine consumption compared with paracetamol alone in the first 24 h after surgery [16]. Karlsen also found that patients receiving NSAIDs had lower pain scores and required less opioids [17]. In our study, consumption of other analgesics, notably ketoprofen, was the same in both groups and therefore had no impact on morphine consumption.

Early mobilization and reduced opioid consumption are key elements in postoperative management of hip arthroplasty [2, 18]. An enhanced recovery protocol which includes multimodal analgesia and early physiotherapy has been shown to reduce the length of hospital stay and costs.

Many recent studies have demonstrated greater risk of mechanical falls due to quadriceps weakness after femoral nerve block [19], causing a delay in ambulation. Although risk of falling is the result of multiple factors such as age or BMI, there is a need for less invasive regional anesthetic techniques such as interfascial plane blocks.

Further studies should focus on the motor blocks and quadriceps weakness following QLB by measuring the effects of QLB.

Over the past decade, QLB has been used to provide analgesia after a number of surgical procedures, but its efficacy in hip surgery is still unclear. Several studies have been published over the past few years with conflicting results. He et al. conducted a study in 2018 that demonstrated a significant reduction in VAS at rest and on mobilization in the QLB group compared to patients who received no perineural anesthesia after THA [20]. Likewise, in a prospective randomized trial after elective THA, anterior QLB led to lower VAS scores and lower cumulative opioid consumption compared to the control group (without perineural anesthesia) [21]. By contrast, a study published in 2020 showed no significant difference in total 24 h morphine consumption between the QLB and the saline group. Pain scores were also comparable between the groups [15]. Our results contrast with those of certain studies in the literature. Aoyama et al. in 2020 showed that VAS scores at 6 h rose less with FNB than QLB after THA [22]. A randomized trial comparing lateral QLB to FNB revealed that QLB has a part to play in reducing pain scores and opioid use in patients undergoing hemiarthroplasty for femoral neck fracture [14].

We have made an attempt to understand this discrepancy in results in the literature. Firstly, it has been postulated that small changes in needle position and different QLB approaches can significantly alter the quality of the analgesia provided by the block [23]. In our study, there were significant differences in needle and anesthetic spread visualization as well as echogenicity. Furthermore, it is important to highlight the inter-operator variability of our study, thus potentially resulting in inconsistency in the efficacy of the block performed.

There is little available data in the literature to elucidate the true mechanism of action of these interfascial plane blocks. None of the above-mentioned studies have provided an assessment of local anesthetic diffusion or sensory/motor blockade to explain the mechanism of action.

Brixel et al. have demonstrated that even with tight control of the needle position when performing QLB, anesthetic solution spread was unpredictable [15]. Technically QLB is a difficult block to achieve, producing variable outcomes. Future studies could attempt to clarify the diffusion of local anesthetics during this procedure to make improvements on its execution and hence on outcomes.

More recently, the pericapsular nerve group block (PENG block) has been described for use in hip surgery [24, 25]. The PENG block is an ultrasound-guided regional anesthesia technique that aims to block the branches of the femoral, obturator, and accessory obturator nerves innervating the anterior hip capsule and diminishes quadriceps muscle block [26, 27]. A randomized clinical trial has shown that the PENG block improved postoperative analgesia after THA, by decreasing pain scores and opioid consumption during the first 48 h after surgery [26]. Studies have been conducted to compare femoral nerve blocks to PENG blocks. Allard et al. have demonstrated that the PENG block may yield equivalent postoperative morphine consumption, by comparison with FNB in patients operated for femoral neck fractures in whom postoperative quadricipital mobility was significantly preserved [28]. At the time of our study, this analgesic block had yet to be introduced into our operating rooms. This opens a pathway to research into the superiority of PENG in pain management after THA.

Limitations

Although the initial sample size calculation required 80 patients per group, only 76 patients were ultimately analyzed in the quadratus lumborum block group. This deviation may have reduced the statistical power of the study, particularly for detecting small between-group differences, and increases the risk of a type II error; therefore, the results should be interpreted with caution.

One limitation to this study is its single-center design. However, the population included in this study constitutes a satisfactory representation of the general population.

Another limitation is that we failed to collect certain information that might have been important to interpreting the results. Some elements such as previous morphine consumption [29], intensity of pre-operative pain and a depressive background are known to play a role in pain perception [30]. It would have been interesting to observe the results in these subgroups.

A major limitation of this study is the absence of standardized early physiotherapy and formal motor function assessment, which precluded a meaningful evaluation of early ambulation and motor-sparing effects of the regional blocks.

Conclusion

By way of conclusion, our study demonstrated no clinical superiority of QLB over femoral nerve block in posterior approach THA. French recommendations do not favor one technique of locoregional anesthesia over another or even over surgical site infiltration. According to our findings, QLB is possibly not a method of choice in hip surgery on account of its variability, its technical complexity and particularly its failure to achieve faster ambulation.

Authors’ contributions

S.A,J.C, A.B, M.R, MF.S,C.H,V.L, D.M, O.F, R.S: writing, literature review, data collection, figure generation, article drafting. S.A,J.C, A.B, M.R, MF.S, J-M.M, D.M, O.F: literature review, data collection, writing, critical revision. All authors: critical revision. A.T: data analysis, data interpretation. S.A,J.C, A.B, M.R, MF.S, D.M, O.F, R.S: literature review, study design, data collection, data analysis, data interpretation, writing, critical revision.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Data availability

The raw supporting the conclusion of this article will be made available by the authors upon reasonable request by sending an email to mriffault@chu-reims.fr.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki and approved by the institutional review board (IRB) of the Sud-ouest et Outre-Mer II (Approval number: IRB 2018-A01119-46). CONSORT (Consolidated Standards of Reporting Trials) guidelines were thoroughly followed (Supplementary material 1). Written informed consent was obtained from all participants prior to enrollment.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.