Anterior Quadratus Lumborum Block with Liposomal Bupivacaine versus Ropivacaine for Postoperative Recovery in Laparoscopic Colorectal Surgery: A Randomized Controlled Trial

Introduction

Laparoscopic colorectal surgery is a cornerstone of modern Enhanced Recovery After Surgery pathways. Despite the significant reduction in surgical trauma afforded by minimally invasive techniques pain management during the first 48 to 72 hours postoperatively remains a major clinical challenge. Inadequate analgesia during this period can lead to poor pain control delay early mobilization slow bowel function recovery and reduce overall subjective well being which collectively reduce the clinical efficacy of the Enhanced Recovery After Surgery pathways.

Within regional anesthesia strategies, the quadratus lumborum block (QLB) has been widely adopted as a key component of multimodal analgesia for abdominal procedures. Evidence suggests that QLB achieves extensive sensory blockade by injecting local anesthetics into the thoracolumbar fascial planes, making it particularly suitable for laparoscopic colorectal surgery.^1–3 In this study, we specifically selected the transmuscular approach (QLB-3) because the plane between the quadratus lumborum and psoas major muscles facilitates cephalad anesthetic spread toward the thoracic paravertebral space and rami communicantes. This anatomical pathway targets the sympathetic chain and visceral afferent fibers more effectively than superficial variants, providing a comprehensive blockade of both deep visceral nociception and somatic sensory loss. However, the duration of conventional long-acting local anesthetics, such as ropivacaine, is typically limited to 18–24 hours.^4,5 This failure to cover the high-incidence pain window of 48–72 hours creates a period of inadequate pain control, restricting the patient’s ability to transition smoothly from the acute postoperative phase to functional independence.

To address this limitation in duration liposomal bupivacaine (LB) has been introduced into regional anesthesia as a sustained-release formulation.^6,7 Its multivesicular liposome structure extends drug release up to 72 hours, which theoretically makes it ideal for injection into fascial planes like the QLB.^6–8 Through its extended release formulation within the fascial plane liposomal bupivacaine aims to provide continuous analgesia during the waning effect of conventional anesthetics and the peak of postoperative inflammatory pain thereby potentially enhancing the overall Quality of Recovery.⁹

Despite the theoretical potential of the quadratus lumborum block (QLB) combined with liposomal bupivacaine (LB) to provide extended analgesia in laparoscopic colorectal surgery, current clinical evidence remains highly controversial.^8,10–14 While the extended duration of liposomal bupivacaine is theoretically advantageous its higher acquisition cost compared to standard local anesthetics remains a practical concern in clinical decision making. Recent studies and meta-analyses on abdominal fascial plane blocks, such as the TAP block, have frequently failed to demonstrate a consistent opioid-sparing effect or superior pain control for LB over conventional local anesthetics.^7,15,16 Furthermore while liposomal bupivacaine has shown promise in specific anatomical depots like the rectus sheath its efficacy appears highly dependent on the specific surgical procedure and its economic benefit in routine quadratus lumborum blocks remains unproven.^13,17 Crucially, while many studies focus solely on pain scores, we identified the Quality of Recovery-15 (QoR-15) at 48 hours as our primary endpoint. This timing was considered most clinically relevant because it represents the pharmacological peak of LB’s extended-release effect while coinciding with the critical transition period in ERAS pathways, such as early mobilization and the return of bowel function, where the patient’s subjective well-being is most vulnerable. Furthermore interpreting the clinical significance of any surgical intervention requires referencing the minimal clinically important difference. For the QoR-15 scale an 6.0 point change is widely established as the minimal clinically important difference.

The objective of this randomized controlled trial was to evaluate whether the addition of liposomal bupivacaine to a transmuscular quadratus lumborum block (QLB) improves the QoR-15 score within 48 hours postoperatively, compared to a standard ropivacaine regimen, in patients undergoing laparoscopic colorectal surgery.

Methods

Study Design, Participants and Ethical Approval

This single-center, prospective, randomized, double-blind, superiority trial was conducted at Neijiang First People’s Hospital (Sichuan, China) in accordance with the Declaration of Helsinki and the CONSORT guidelines between May 12, 2025, and December 25, 2025. The study protocol was approved by the Ethics Committee of Neijiang First People’s Hospital (Approval No. 2024-lun-57) and registered at the Chinese Clinical Trial Registry (Registration No. ChiCTR2500097657) prior to patient enrollment. Patient recruitment and follow-up were performed between May 12, 2025, and December 25, 2025 (Figure 1).Written informed consent was obtained from all participating patients prior to any study specific procedures, following a detailed explanation of the trial protocols, potential risks, and benefits.

Figure 1 CONSORT flow diagram of the study. The flowchart details the enrollment, randomization, allocation, follow-up, and data analysis of patients undergoing laparoscopic colorectal surgery. Abbreviations: LB, liposomal bupivacaine; QLB, quadratus lumborum block.

Patients eligible for the study were those aged 18 to 80 years with an American Society of Anesthesiologists physical status of I to III, scheduled for elective laparoscopic colorectal resection, and capable of using a patient controlled intravenous analgesia device while completing the QoR 15 questionnaire. Exclusion criteria included chronic preoperative opioid use for more than 3 months, known allergy to local anesthetics, severe hepatic, renal, or cardiovascular dysfunction, a history of major abdominal wall surgery, emergency surgery, severe cognitive impairment, and a body mass index exceeding 35 kg per square meter. All statistical analyses were strictly conducted following the intention to treat principle, meaning all randomized patients were included in the final analysis according to their originally assigned groups, regardless of protocol deviations such as intraoperative conversion to open surgery. A superiority trial was designed to determine if the higher cost of liposomal bupivacaine is justified by distinct statistical and clinical advantages over standard ropivacaine.

Randomization and Strict Blinding

Patients were randomly allocated in a 1 to 1 ratio into either the Liposomal Bupivacaine group or the Ropivacaine group. The randomization sequence was generated by an independent statistician using computer software with block randomization. Allocation concealment was strictly maintained using sequentially numbered opaque sealed envelopes which were only opened by the independent anesthesia nurse immediately prior to block execution. To facilitate blinding, this nurse prepared the medications in identical 20 mL syringes wrapped in opaque tape. We acknowledge that the distinct sonographic echogenicity of the milky white liposomal bupivacaine suspension compared to the clear ropivacaine solution during fascial hydrodissection presents a potential risk of unblinding for the clinician performing the block. To mitigate this performance bias, the study maintained a strict separation of clinical roles. The senior anesthesiologist who performed the ultrasound guided block and witnessed the injectate appearance was not involved in any subsequent aspects of the study, including data collection or patient care. Most importantly, the patients, the surgical team, and the dedicated postoperative investigators responsible for assessing the primary and secondary outcomes such as the QoR 15 scores and the Barthel Index remained strictly blinded to the group allocation until the final data analysis.

Ultrasound-Guided Quadratus Lumborum Block and Interventions

Following anesthesia induction, all bilateral anterior quadratus lumborum blocks (QLB-3) were performed by the same senior anesthesiologist (Figure 1). A portable ultrasound system (Wisonic; Shenzhen Wisonic Medical Technology Co., Ltd., Shenzhen, China) equipped with a 2–5 MHz curved array transducer was utilized. With the patient in the lateral decubitus position and under strict aseptic conditions, the transducer was placed in the mid-axillary line at the L3-L4 level to identify the shamrock sign (psoas major, erector spinae, and quadratus lumborum muscles).

An in plane needle trajectory was used using a 21 gauge 100 mm stimulating needle. The needle was advanced until it penetrated through the quadratus lumborum muscle. Upon confirmation of the needle tip reaching the correct fascial plane located between the anterior aspect of the quadratus lumborum and the posterior aspect of the psoas major muscle via hydrodissection, the designated local anesthetic was injected Figure 2.

Figure 2 Ultrasound anatomy and needle trajectory for the anterior quadratus lumborum block (QLB-3). The image demonstrates the fascial plane between the anterior aspect of the quadratus lumborum (QL) muscle and the psoas major (PM) muscle. The needle is advanced from anterior to posterior in-plane to target this fascial injection plane. Abbreviations: ESM, erector spinae muscle; PM, psoas major muscle; QL, quadratus lumborum muscle.

Experimental Group (LB Group)

Patients received 1.3% liposomal bupivacaine (Jiangsu Hengrui Pharmaceuticals Co., Ltd., Lianyungang, China; 266 mg/20 mL). The medication was diluted with 20 mL of 0.9% normal saline to achieve a total volume of 40 mL (20 mL injected per side).

Control Group (Control Group)

Patients received 0.33% ropivacaine hydrochloride injection (Jiangsu Hengrui Pharmaceuticals Co., Ltd., Lianyungang, China). The total volume administered was 40 mL (20 mL injected per side).

Perioperative Management and Anesthesia Protocol

All patients received standardized perioperative care according to our institutional Enhanced Recovery After Surgery protocol, beginning with detailed preoperative counseling to set expectations for recovery. Upon entering the operating room, standard physiological and Bispectral Index monitoring were established. General anesthesia was induced using midazolam (0.05 mg/kg), sufentanil (0.4 µg/kg), propofol (1.5 to 2.0 mg/kg), and cisatracurium (0.15 mg/kg), followed by endotracheal intubation. Anesthesia was maintained with sevoflurane (1.0 to 2.0%) inhalation and a continuous intravenous infusion of remifentanil (0.1 to 0.2 µg/kg/min). The target was to maintain a Bispectral Index value between 40 and 60 while keeping hemodynamic fluctuations within 20% of baseline values, and muscle relaxation was maintained with intermittent boluses of cisatracurium as clinically indicated.

Intraoperatively, a goal directed fluid therapy strategy was implemented to maintain normovolemia, and standardized antiemetic prophylaxis was administered to prevent postoperative nausea and vomiting. During the surgery, additional doses of long acting opioids, such as sufentanil, were administered intermittently based on hemodynamic responses and clinical requirements. Postoperatively, early oral feeding and early mobilization were strongly encouraged to facilitate rapid functional recovery and minimize complications.

Postoperative Analgesia and Rescue

Postoperatively, all patients were equipped with a patient-controlled intravenous analgesia (PCIA) pump containing sufentanil (1 µg/mL). The PCIA device was programmed with a background infusion rate of 1 mL/h, a bolus dose of 2 mL, and a 15-minute lockout interval. Rescue analgesia was strictly defined: if a patient reported a resting Visual Analog Scale (VAS) pain score > 4 despite effective utilization of the PCIA, intravenous flurbiprofen axetil (50 mg) was administered as a rescue analgesic.

The primary outcome was the overall Quality of Recovery (QoR-15) score assessed at 48 hours postoperatively (POD 2). Secondary outcomes included the QoR-15 score at 24 hours (POD 1) and postoperative physical independence evaluated by the Barthel Index at POD 1. Postoperatively, all patients received a standardized patient-controlled intravenous analgesia (PCIA) pump containing sufentanil. Rescue analgesia (intravenous flurbiprofen axetil 50 mg) was administered if a patient reported a resting Visual Analog Scale (VAS) pain score > 4 despite PCIA utilization.

The consumption of postoperative opioids was converted to intravenous morphine milligram equivalents to facilitate standardized comparison between groups. The conversion factor used in this study was 1 microgram of intravenous sufentanil being equal to 1 milligram of intravenous morphine.

Sample Size Calculation

The sample size was calculated based on the primary outcome, the global QoR-15 score at POD 2. Based on recent consensus in perioperative medicine, a minimal clinically important difference (MCID) of 6.0 points is widely accepted for the QoR-15 scale in major abdominal surgeries. Assuming an expected mean difference of 6.0 points with a standard deviation (SD) of 11.0, an α error of 0.05, and a statistical power of 80%, 53 patients per group were required. To account for a potential dropout rate of approximately 15%, we planned to enroll a total of 120 patients (60 per group).

Statistical Analysis

Statistical analyses were performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA) and R software version 4.1.0 (R Foundation for Statistical Computing, Vienna, Austria). Continuous variables were assessed for normality using the Shapiro–Wilk test. Normally distributed data are presented as mean ± SD and were compared using the independent-samples t-test. Non-normally distributed data are expressed as median (interquartile range) and analyzed via the Mann–Whitney U-test. Categorical variables were compared using Pearson’s chi-square test or Fisher’s exact test, as appropriate. For the analysis of repeated measurements across multiple postoperative time points, such as the QoR-15 scores, a linear mixed-effects model was employed. In this model, the treatment group, time point, and the interaction between group and time were treated as fixed effects, while the individual subject was included as a random effect to account for intra-subject correlation. To identify independent predictors associated with recovery quality at postoperative day 2, a pre-planned multivariable linear regression model was constructed, adjusting for baseline covariates. Furthermore, an exploratory subgroup analysis based on the surgical site (colon versus rectum) was performed. A formal interaction test was conducted to determine if the treatment effect differed by surgical site. These subgroup findings were considered hypothesis-generating, as the study was powered for the overall cohort. A two-sided P < 0.05 was considered statistically significant.

Results

Baseline Characteristics

A total of 120 patients were enrolled and randomized into two groups (n = 60 per group). The baseline demographic and clinical characteristics were well-balanced between the Liposomal Bupivacaine (LB) group and the control group (Table 1). There were no significant differences in age (65.88±4.98 vs 66.78±4.28 years, P = 0.290), BMI (23.07±1.57 vs. 23.30±1.48 kg/m2, P = 0.404), or preoperative albumin levels (36.01±2.82 vs. 38.99±2.70 g/L, P = 0.055). Surgical factors, including the site of surgery (P = 1.000) and the duration of surgery (168.33±29.73 vs. 167.47±28.35 min, P = 0.870), were also comparable between the two groups. Other variables such as gender, ASA classification, and CCI scores showed no statistically significant differences (P > 0.05).The detailed screening, enrollment, and randomization process of the study patients is illustrated in the CONSORT flow diagram (Figure 2).

Table 1 Baseline Demographic and Clinical Characteristics of the Study Patients

Postoperative Quality of Recovery and Analgesic Efficacy

Analyzed using a linear mixed-effects model, the overall QoR-15 scores were significantly higher in the LB group compared to the control group (P_group= 0.008). While scores at postoperative day 1 (POD 1) were marginally higher in the LB group (110.68 ± 8.21 vs. 107.81 ± 9.42), a significant group-by-time interaction was observed (P_interaction= 0.042). This indicates a significantly steeper trajectory of recovery in the LB group, culminating in substantially superior recovery quality by POD 2 (118.93 ± 7.45 vs. 114.55 ± 9.12, Figure 3). This divergence underscores the extended analgesic window provided by LB, which significantly enhanced patient comfort during the critical 48-hour recovery phase.

Figure 3 Comparison of postoperative quality of recovery (QoR-15 scores) over time between the Liposomal Bupivacaine (LB) and Control groups. The QoR-15 scores were assessed at 24 hours (POD 1) and 48 hours (POD 2) postoperatively. Data are presented as mean ± standard deviation (SD). Analyzed using a linear mixed-effects model, a significant group-by-time interaction was observed (P = 0.042), indicating a superior and extended trajectory of recovery in the LB group by POD 2. Abbreviations: LB, liposomal bupivacaine; POD, postoperative day; QoR-15, 15-item Quality of Recovery scale.**P < 0.01 compared with the control group.

Similarly, the longitudinal analysis of opioid consumption revealed a highly significant group-by-time interaction (P_interaction< 0.001). Although cumulative opioid consumption (MME) was comparable between groups during the initial 24 hours (8.6 ± 4.1 mg vs. 8.8 ± 4.6 mg), consumption in the LB group was drastically reduced during the 24–48 hour interval (7.2 ± 2.1 mg vs. 12.5 ± 3.4 mg). Consequently, the total 48-hour MME was significantly lower in the LB group (15.8 ± 4.5 mg vs. 21.3 ± 5.8 mg, P = 0.012). Consistent with these findings, significantly fewer patients in the LB group required rescue analgesia beyond 24 hours (15.0% vs. 31.7%, P = 0.028).

To further explore the potential impact of surgical site on recovery, an exploratory subgroup analysis of QoR-15 scores at POD 2 was performed (Table 2). Crucially, the formal group-by-surgical site interaction test was non-significant (P_interaction= 0.745), confirming that the treatment effect of LB was consistent across different surgical procedures. Within the exploratory subsets, the colon surgery subgroup showed that the LB group had significantly higher QoR-15 scores compared to the control group (119.16 ± 6.84 vs. 114.36 ± 8.56, P = 0.027). In the rectal surgery subgroup, although the numerical difference favored the LB group (118.61 ± 8.24 vs. 114.82 ± 9.87), this did not reach statistical significance (P = 0.104), likely due to the limited sample size.

Table 2 Postoperative Recovery Quality, Analgesic Outcomes, and Subgroup Analysis

Postoperative Physical Independence and Safety Profile

Regarding early functional return, physical independence was evaluated using the Barthel Index on POD 1. The Barthel Index scores were 29.88 ± 4.52 in the LB group and 29.12 ± 5.14 in the control group, with no statistically significant difference observed between the cohorts (P = 0.3889). These results suggest that while LB improves subjective recovery quality by 48 hours, the immediate impact on objective physical independence within the first 24 hours is comparable to that of conventional ropivacaine.

Regarding the overall safety profile, both regional anesthesia regimens were well-tolerated. The incidence of postoperative nausea and vomiting (PONV) was lower in the LB Group, although this reduction did not reach statistical significance (13.3% vs. 20.0%, P = 0.156). Crucially, there were no reported cases of Local Anesthetic Systemic Toxicity (LAST), such as cardiac arrhythmias or neurological symptoms (seizures, perioral numbness), in either group. Furthermore, we actively monitored for specific block related complications, and there were no cases of clinically significant local hematoma, severe puncture site pain, or lower extremity motor weakness observed in either cohort. Other adverse events, including pruritus, dizziness, and urinary retention, were infrequent and their incidences were comparable between the two groups (all P > 0.05; see Table 3). No study related serious adverse events or wound healing complications were observed during the follow up period.

Table 3 Postoperative Adverse Events and Safety Profile

Independent Predictors of Recovery Quality

A multivariable linear regression analysis was conducted to identify independent factors associated with recovery quality at POD 2 (Table 4 and Figure 4). After adjusting for potential confounders including age, BMI, preoperative albumin, surgery duration, blood loss, and CCI score, the administration of Liposomal Bupivacaine (Group) remained an independent predictor of improved QoR-15 scores (β= 4.18, 95% CI: 0.94 to 7.43, P = 0.012). Other clinical variables, including age (P = 0.504), BMI (P = 0.748), and blood loss (P = 0.792), did not significantly influence the recovery trajectory at this time point.

Table 4 Multivariable Linear Regression Analysis of Independent Factors Associated with Recovery Quality (QoR-15 Scores) at POD 2

Figure 4 Forest plot illustrating the independent predictors for recovery quality (QoR-15 scores) at 48 hours postoperatively (POD 2). The plot summarizes the results of the multivariable linear regression analysis. Squares represent the regression coefficient (β), and horizontal error bars represent the 95% confidence intervals (CIs). A β value to the right of the vertical reference line (zero) indicates a positive association with recovery quality. After adjusting for age, BMI, preoperative albumin, surgery duration, blood loss, and CCI score, the administration of Liposomal Bupivacaine (LB) remained the only independent factor significantly associated with improved QoR-15 scores at POD 2 (β = 4.18, P = 0.012). The bold P value indicates statistical significance (P < 0.05). Abbreviations: LB, liposomal bupivacaine; BMI, body mass index; CCI, Charlson Comorbidity Index; CI, confidence interval; POD, postoperative day.

Discussion

In this randomized trial, liposomal bupivacaine (LB) for quadratus lumborum block significantly improved the overall trajectory of postoperative recovery. Although early recovery (POD 1) was comparable to conventional ropivacaine, LB yielded superior recovery quality by 48 hours (POD 2) and independently predicted higher QoR-15 scores (β = 4.18, P = 0.012). Subgroup interaction testing confirmed this sustained benefit was consistent across colon and rectal surgeries, indicating the rectal cohort’s non-significance likely resulted from limited statistical power. Collectively, LB provides robust 48-hour analgesia, effectively bridging the gap as conventional local anesthetics decline.

A primary observation of our study is the extended therapeutic benefit of liposomal bupivacaine which effectively addresses the temporal mismatch commonly observed in regional anesthesia. While conventional ropivacaine provides peak analgesia within the first 24 hours its efficacy inevitably wanes leaving patients vulnerable to rebound pain.^18,19 We postulate that the thoracolumbar fascia targeted in our quadratus lumborum block acts as a relatively avascular pharmacological reservoir. Unlike highly vascularized intraarticular spaces where drugs are rapidly cleared a factor that may explain the limited benefits reported in some orthopedic trials the dense connective tissue of the thoracolumbar fascia prevents rapid systemic absorption and optimizes the multivesicular liposome delivery system.^15,20,21 This hypothesis aligns with existing pharmacological principles suggesting that dense and relatively avascular fascial planes are highly conducive to the prolonged action of liposomal formulations. This provides a sustained release of bupivacaine facilitating a smoother transition to functional independence at 48 hours.

Our results provide crucial context to the ongoing and highly controversial debate regarding the clinical utility of LB. Multiple randomized controlled trials and meta-analyses have questioned LB’s superiority, particularly in superficial fascial plane blocks like the TAP block, frequently reporting no significant reduction in pain scores or opioid consumption.^6,8,22–24 However, our study establishes its unique value by addressing two major limitations of previous research: the reliance on unidimensional endpoints and the short observation window. Recent studies on QLB in other surgical populations (eg., cesarean sections, THA) have noted that while cumulative opioid consumption may not differ significantly, the quality of recovery (QoR) can still be meaningfully improved.^3,22,25–27 By extending our evaluation to 48 hours and utilizing the multidimensional, patient-centered QoR-15 scale, we captured a significant recovery benefit that would have remained hidden under traditional metrics. This suggests that LB’s efficacy is dependent on both the depth of the anatomical plane (deep QLB vs. superficial TAP) and the longitudinality of the assessment.

The selection of 266 mg for the liposomal bupivacaine group and 132 mg for the ropivacaine group was designed as a pragmatic comparison of standard clinical protocols. These doses reflect the typical applications in colorectal surgery rather than a strict equianalgesic pharmacologic match. The pharmacokinetic profile of liposomal bupivacaine is characterized by a bimodal release that maintains local concentrations over an extended timeframe, which necessitates a higher total dose compared to the rapid peak and decay of standard ropivacaine. Crucially, the advanced liposomal formulation serves as a safety vehicle, allowing a 266 reservoir to be safely deposited in the fascial plane without reaching the threshold for systemic toxicity. Consequently, the clinical outcomes observed in this study represent the combined effect of the sustained release technology and the increased total drug volume it facilitates.

An observation emerged from our exploratory subgroup analysis, where LB’s benefit reached statistical significance in colon surgery (P = 0.027) but not in rectal surgery (P = 0.104). Mechanistically, this discrepancy may be attributed to anatomical variations in sensory innervation. Laparoscopic colon surgery primarily involves somatic abdominal trauma within the T7–L1 dermatomes, which are well-covered by a QLB. In contrast, rectal surgery entails extensive dissection deep within the pelvis, stimulating pelvic autonomic plexuses and pudendal nerves (S2–S4) that are theoretically beyond the block’s reach. However, as this was a post-hoc exploratory analysis, these findings should be viewed as hypothesis-generating rather than definitive. This divergence underscores the inherent uncertainty regarding LB’s efficacy across different abdominal fascial planes.^6,7,28–30 These exploratory subgroup findings are hypothesis-generating, as the study was not powered for such comparisons. The non-significant results in the rectal group may reflect a limited sample size rather than a lack of efficacy in managing deep pelvic pain. Consequently, observed differences are subject to type I or type II errors and require validation in adequately powered trials.

From a clinical perspective, a single-shot QLB with LB presents a viable, catheter-free alternative to epidural analgesia, facilitating early mobilization. Nevertheless, several limitations and clinical nuances warrant cautious interpretation. First, while liposomal bupivacaine demonstrated a statistically significant improvement in QoR-15 scores at POD 2 (mean difference of 4.38), this margin falls below the predefined global MCID of 6.0 points typically cited for major abdominal surgeries. We attribute this phenomenon to a pronounced ceiling effect inherent to our highly optimized ERAS pathway. The baseline recovery trajectories in our control group were already exceptionally high due to minimally invasive laparoscopic techniques and standardized multimodal analgesia; consequently, the absolute margin for further improvement is inevitably compressed. Furthermore, a rigid MCID threshold may not fully capture the clinical relevance of marginal gains within a highly optimized clinical context. Achieving an enhancement of over 4 points in multidimensional recovery during the vulnerable 48-hour transition phase still represents a meaningful optimization of patient comfort and reflects the clinical value of providing continuous analgesia during the period when conventional local anesthetics typically lose their effectiveness. Second, the distinct physical appearance and ultrasound echogenicity of liposomal bupivacaine compared to standard ropivacaine may have introduced a risk of unblinding for the clinician performing the block, which could lead to performance bias. Third, we intentionally excluded local anesthetic adjuvants such as dexamethasone in our control group to avoid potential confounding effects on recovery quality, although these agents are frequently utilized in clinical practice to extend block duration. Finally, we did not compare our single-shot technique against continuous catheter systems, which represent a well-established clinical alternative for providing extended analgesia beyond 48 hours.

Conclusion

Liposomal bupivacaine in ultrasound guided quadratus lumborum blocks significantly increased QoR 15 scores at 48 hours compared to ropivacaine. However, the 4.38 point difference fell short of the 6 point minimal clinically important difference. This modest statistical benefit requires cautious interpretation within established recovery protocols. Routine clinical adoption must be weighed against cost effectiveness and overall utility. Further large scale multicenter trials are warranted to confirm the clinical significance of these findings.