GRAPHICAL ABSTRACT

Introduction

Proximal femur fractures pose a real challenge in the medical field, especially among older adults, as these injuries often lead to significant complications and even higher mortality rates [1]. It's essential to manage pain effectively in these patients to facilitate early movement, lower the chances of postoperative issues, and ultimately improve their overall health outcomes [2]. Recently, regional anaesthesia techniques have become more popular because they provide effective pain relief while reducing the need for systemic opioids. One such technique, the fascia iliaca block (FICB), has proven to be particularly useful for alleviating pain during lower limb surgeries, including repairs for proximal femur fractures [3].

Ropivacaine, a long-acting amide-type local anaesthetic, is commonly used in these regional blocks due to its favorable safety profile, which includes lower risks of cardiotoxicity and neurotoxicity, along with its ability to deliver extended sensory relief with minimal impact on motor function [4]. This makes it an excellent choice for elderly and high-risk patients undergoing lower limb surgeries [5][6]. However, there's still a need to boost the effectiveness and duration of pain relief that ropivacaine can provide on its own. As a result, researchers have been looking into adding pharmacological adjuvants to local anaesthetics as a way to enhance both the quality and duration of these regional blocks [7].

Magnesium sulphate has been making waves as a promising adjuvant, thanks to its unique way of working [8]. It mainly acts as a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor and also blocks calcium channels [9]. These actions are crucial for modulating pain transmission. By targeting the posterior horn of the spinal cord, it effectively dampens the excitatory effects of amino acids like glutamate and aspartate, which helps enhance pain relief. Magnesium is seen as a safer NMDA antagonist because it doesn’t easily cross the blood-brain barrier, which lowers the chances of central nervous system side effects [10].

The role of magnesium sulphate as an adjuvant to local anaesthetics in various regional anaesthesia techniques has been explored before, often showing positive outcomes like longer-lasting pain relief, deeper sensory blocks, and quicker onset of action [11]. However, there’s still not much evidence about how effective it is when combined with ropivacaine, especially in ultrasound-guided fascia iliaca compartment blocks for surgeries involving proximal femur fractures [12]. This specific approach focuses on the fascia iliaca compartment, a space nestled between the fascia iliaca and the iliopsoas muscle. When local anaesthetic is injected here, it blocks the femoral nerve, lateral femoral cutaneous nerve, and obturator nerve—key players in the sensory innervation of the hip and front of the thigh. Using ultrasound guidance makes this technique more precise, which helps reduce complications and boosts the overall success rate of the block [13].

This randomized controlled trial was set up to take a closer look at how effective and safe ropivacaine is when used alone compared to when it's combined with magnesium sulphate in ultrasound-guided fascia iliaca blocks for patients having surgery for proximal femur fractures [14]. By focusing on this particular combination of drugs in a well-defined clinical environment, the study aims to fill a gap in existing research and provide solid evidence to guide best practices. The trial is all about figuring out if adding magnesium sulphate to ropivacaine can help lower the need for opioids after surgery and extend the duration of the sensory block, all while keeping patient safety intact. In doing so, it adds to the growing evidence that supports using multimodal analgesia techniques to enhance pain management and recovery after surgery, especially for patients who are more vulnerable.

Previous studies have investigated magnesium sulphate as an adjuvant in various regional anaesthesia techniques, often reporting benefits such as prolonged analgesia, deeper sensory blockade, and faster onset times. However, most of these studies have involved different block types, varied anaesthetic agents, non-ultrasound-guided approaches, or surgical settings unrelated to proximal femur fractures. Evidence on the combination of ropivacaine with magnesium sulphate in ultrasound-guided fascia iliaca compartment block remains limited, particularly in adult patients undergoing surgery for proximal femur fractures [15]. Existing literature shows variability in magnesium dosing, inconsistent use of ultrasound guidance, and heterogeneous patient populations, making it difficult to draw definitive conclusions for this specific context. Our trial addresses these gaps by standardizing the ultrasound-guided suprainguinal FICB technique, using a fixed dose of magnesium sulphate (150 mg) with ropivacaine, and focusing exclusively on a well-defined surgical group. By comparing analgesic efficacy, opioid-sparing effect, and safety profile between ropivacaine alone and ropivacaine with magnesium sulphate, this study provides targeted evidence for optimising postoperative pain management in proximal femur fracture surgery.

• Novelty of study

The novelty of this study lies in its focused evaluation of MgSO₄ as an adjuvant in a high-risk surgical population, with clinically relevant outcomes—including time to first rescue analgesia, total analgesic requirement, and VAS pain trends over 24 hours—under real-world surgical conditions. By addressing both the temporal profile of analgesia and the quality of pain control, the findings have potential to influence perioperative analgesia protocols in orthopedic anesthesia.

• Contributions

The novel contributions of this study are:

1. First RCT to evaluate MgSO₄ with ropivacaine in ultrasound-guided FICB for proximal femur surgery.
2. Provides direct comparison of analgesic efficacy and safety profiles.
3. Identifies non-significant trends suggesting delayed rescue analgesia with MgSO₄.
4. Establishes a foundation for larger, multi-centre trials with optimised dosing.

2.1 Study Design and Setting This research was a prospective randomized controlled trial that took place at the Department of Anaesthesiology, Kalinga Institute of Medical Sciences, Pradyumna Bal Memorial Hospital (PBMH), KIIT University, located in Bhubaneswar, Odisha. The study ran from March 2023 to November 2024 and was officially registered with the Clinical Trial Registry of India (CTRI) under the number CTRI/2023/05/052200. 2.2 Ethical Considerations Before starting, the study protocol was approved by the Institutional Ethics Committee of KIIT University (Approval Number: KIIT/KIMS/IEC/1218/2023). We made sure to follow the ethical guidelines set out in the Declaration of Helsinki and the International Conference on Harmonization Good Clinical Practice (ICH-GCP) standards. All participants provided written informed consent, and they received a Participant Information Sheet (PIS) in their local language. Consent was confirmed either through a signature or a thumb impression. Patient data were gathered from the hospital record system after obtaining the necessary permissions from the relevant authorities. 2.3 Study Population The study focused on adult patients aged 18 and older who were set to undergo surgery for proximal femur fractures. To be eligible, participants needed to be classified as American Society of Anesthesiologists (ASA) physical status I or II. Those with known allergies to the study medications, chronic pain conditions, a history of opioid or analgesic misuse, alcohol dependency, coagulopathy, local infections or sepsis, severe kidney failure, myasthenia gravis, pulmonary edema, or existing heart block were excluded from the study. 2.4 Sample Size Calculation Using OpenEpi software with a 95% confidence interval and 80% power, we estimated that a minimum of 23 patients per group was necessary. To prepare for potential dropouts and ensure we had enough statistical power, we ultimately enrolled 50 patients, dividing them into two groups of 25. Although the sample size was calculated based on effect sizes reported in prior studies, the relatively small number of participants per group may limit the ability to detect subtle but clinically meaningful differences. 2.5 Randomization and Blinding We conducted randomization using a computer-generated table. Participants were assigned to one of the two study groups through opaque sealed envelopes to keep the allocation process hidden. To minimize any bias from observers, the staff involved in preparing and administering the block were not part of the team assessing the outcomes. Patients were blinded to their group allocation, and the anaesthesiologist performing the block did not participate in postoperative data collection. Outcome assessors, including nursing staff and research personnel recording VAS scores and rescue analgesia use, were unaware of treatment assignments. To assess blinding integrity, outcome assessors were asked at the end of the study to guess patient group allocation; their accuracy did not exceed chance levels, indicating successful blinding. 2.6 Intervention Protocol All patients underwent spinal anaesthesia while sitting, receiving 3 mL of 0.5% bupivacaine along with 5 mcg of dexmedetomidine. After the surgery wrapped up, patients were given an ultrasound-guided fascia iliaca block (FICB) based on their assigned group. This block was done using a 10 cm B Braun Stimuplex needle, guided by a high-frequency linear ultrasound probe (9–12 MHz). In Group I, patients received 20 mL of 0.2% ropivacaine mixed with 150 mg of magnesium sulphate, while Group II got 20 mL of 0.2% ropivacaine by itself. The medication was carefully placed at the traditional anatomical site for the fascia iliaca compartment, ensuring it spread adequately under ultrasound guidance. A high-frequency linear probe was placed in a transverse orientation just inferior to the inguinal ligament to identify the iliopsoas muscle and fascia iliaca. An in-plane lateral-to-medial needle trajectory was used to advance the needle tip beneath the fascia iliaca, visualised as a hyperechoic line over the iliopsoas muscle. Correct placement was confirmed by hydrodissection with 1–2 mL of saline, producing separation of the fascia from the iliopsoas muscle, followed by real-time observation of the local anaesthetic spreading medially and laterally beneath the fascia iliaca. 2.7 Postoperative Monitoring and Analgesia Assessment Once the surgical procedure was completed and the block was administered, patients were moved to the Post-Anaesthesia Care Unit and then to the surgical ward. Pain levels were assessed using the Visual Analogue Scale (VAS), which ranges from 0 (no pain) to 10 (the worst pain imaginable). These evaluations took place every 2 hours for the first 24 hours after surgery. If patients reported significant pain, rescue analgesia in the form of intravenous tramadol 100 mg diluted in 100 mL of normal saline was provided, following the institutional protocol. 2.8 Outcome Measures The main focus of our study was to determine how long the analgesia lasted, which we measured by looking at the time from when the block was administered (T0) until the first request for additional pain relief. We also looked at secondary outcomes, such as pain levels recorded on the VAS scale, along with any complications or side effects that occurred during the 24 hours following surgery. In addition to these primary endpoints, secondary functional recovery measures were also recorded, including time to first mobilization (in hours post-surgery, documented by the attending physiotherapy team), total hospital length of stay (in days, obtained from hospital records), and overall patient satisfaction with analgesia (assessed at 24 hours postoperatively using a 5-point Likert scale). These secondary measures were chosen to provide a more comprehensive assessment of recovery quality and clinical relevance. 2.9 Statistical Analysis We organized the data from both groups using Microsoft Excel 365 and then analyzed it further with SPSS version 24. Continuous variables like age, weight, duration of analgesia, and VAS scores were reported as either mean ± standard deviation or median with interquartile range, depending on how the data was distributed. To compare continuous variables between the groups, we used the unpaired t-test for data that followed a normal distribution, and the Mann-Whitney U test for data that did not. For repeated measures within groups, we applied repeated measures ANOVA or the Friedman test, as appropriate. We compared categorical variables, such as gender distribution, the need for rescue analgesia, and the occurrence of complications, using the Chi-square test or Fisher's exact test. We considered a p-value of less than 0.05 to be statistically significant for all analyses. In addition to p-values, effect sizes (Cohen’s d for continuous variables and odds ratios for categorical variables) with corresponding 95% confidence intervals were calculated to quantify the magnitude and precision of observed differences between groups. For repeated measures and multiple time-point analyses (e.g., VAS scores), p-values were adjusted for multiple comparisons using the Bonferroni correction to reduce the risk of type I error.

3.1 Baseline Characteristics

Baseline demographic and clinical parameters were well matched between the two groups, confirming effective randomization. As shown in Table 1: Baseline and Surgical Characteristics, the mean age was 49.48 ± 19.07 years in Group I (Ropivacaine + MgSO₄) and 53.44 ± 23.16 years in Group II (p = 0.5125). Mean body weight was 62.28 ± 7.88 kg in Group I and 64.96 ± 9.36 kg in Group II (p = 0.2788). The average surgical duration was 169.80 ± 36.93 minutes for Group I and 162.80 ± 43.50 minutes for Group II (p = 0.5425). Baseline systolic blood pressure was similar, at 126.80 ± 9.90 mmHg in Group I and 128.80 ± 12.91 mmHg in Group II (p = 0.5417). Gender distribution was balanced, and the proportions of procedures such as hemiarthroplasty and nailing were also comparable. This uniformity strengthens the internal validity of subsequent outcome analyses. Figure 1: Age and Gender Distributions of Study Participants illustrates these similarities.

Table 1: Baseline and Surgical Characteristics

Statistical tests: Unpaired t-test (age, weight, surgery duration, SBP); Fisher’s Exact Test (gender)

Figure 1: Age and gender distributions of study participants

Panel A: Mean age (years) ± standard deviation (SD) for Group I (Ropivacaine + MgSO₄) and Group II (Ropivacaine alone).

Panel B: Distribution of participants by gender (number of male and female patients) in each study group. Data correspond to baseline demographic characteristics presented in Table 1.

Figure 2: Weight and surgery duration comparisons between groups

Panel A: Mean body weight (kg) ± standard deviation (SD) for Group I (Ropivacaine + MgSO₄) and Group II (Ropivacaine alone).

Panel B: Mean surgery duration (minutes) ± SD for each study group. Data correspond to baseline surgical characteristics presented in Table 1.

3.2 Postoperative Pain Outcomes

The progression of postoperative pain, assessed using VAS scores, was similar between the two groups. As shown in Table 2: VAS Scores over Time, pain scores remained at 0 until the 4-hour mark, peaked between 12 and 14 hours (Group I: 2.4 ± 0.5; Group II: 2.28 ± 0.54), and leveled out by 24 hours (both at 2.0 ± 0). No statistically significant differences were observed at any time point (all p > 0.05), although Group II showed a non-significant trend towards higher pain levels at the 20-hour mark (p = 0.0556; effect size = −0.55, 95% CI: −1.13 to 0.03). A repeated-measures ANOVA confirmed a significant change in pain scores over time within both groups (p < 0.0001), as illustrated in Figure 3: Trend of Visual Analogue Scale (VAS) Pain Scores over 24 Hours Postoperatively.

Table 2: VAS Scores over Time

Figure 3: Trend of Visual Analogue Scale (VAS) pain scores over 24 hours postoperatively

Mean VAS scores recorded at 2-hour intervals for Group I (Ropivacaine + MgSO₄) and Group II (Ropivacaine alone). Both groups showed similar trends, with scores peaking between 12–14 hours and a secondary increase in Group II at 20 hours. Data correspond to selected time points presented in Table 2.

3.3 Rescue Analgesia Requirements

The need for rescue analgesia was not significantly different between the groups, although 24% of patients in Group II required it by the 20-hour mark compared to only 8% in Group I (p = 0.2467; OR = 0.28, 95% CI: 0.05–1.53). As shown in Table 3: Rescue Analgesia and Tramadol Use, the mean time to first rescue was similar—12.08 ± 4.49 hours in Group I and 14.08 ± 4.88 hours in Group II (p = 0.1382; effect size = −0.42, 95% CI: −0.99 to 0.15). Total tramadol use over 24 hours was also comparable, with Group I consuming 136.0 ± 48.99 mg and Group II consuming 144.0 ± 50.66 mg (p = 0.5730; effect size = −0.16, 95% CI: −0.73 to 0.41), as illustrated in Figure 4: Distribution of rescue analgesia requirements over the first 24 postoperative hours.

Table 3: Rescue Analgesia and Tramadol use

Figure 4: Distribution of rescue analgesia requirements over the first 24 postoperative hours

Percentage of patients in Group I (Ropivacaine + MgSO₄) and Group II (Ropivacaine alone) who required rescue analgesia at specified postoperative time points. Data expressed as percentage of group total (n=25 per group). At 20 hours, 8% of patients in Group I and 24% of patients in Group II required rescue analgesia, corresponding to the values reported in Table 3.

Figure 5: Time to first rescue analgesia and total tramadol consumption in the first 24 postoperative hours

Panel A: Box-and-whisker plot showing median, interquartile range, and range for time to first rescue analgesia (hours) in Group I (Ropivacaine + MgSO₄) and Group II (Ropivacaine alone).

Panel B: Mean ± standard deviation (SD) of total tramadol consumption (mg) in the first 24 hours for each group. Values correspond to those reported in Table 3.

3.4 Summary of Findings

Adding MgSO₄ to ropivacaine for spinal anesthesia didn't really show any meaningful benefits in terms of postoperative pain management, the need for rescue analgesia, or tramadol usage when compared to using ropivacaine on its own. The differences we saw in VAS scores, the timing of analgesia, and opioid consumption were both clinically and statistically insignificant.

The present study evaluated whether adding magnesium sulphate (MgSO₄) to ropivacaine in an ultrasound-guided fascia iliaca compartment block (FICB) for proximal femur fracture surgery could enhance postoperative analgesia, reduce rescue analgesic requirements, and prolong block duration. Magnesium sulphate exerts analgesic effects primarily through non-competitive antagonism of N-methyl-D-aspartate (NMDA) receptors and blockade of voltage-gated calcium channels, thereby attenuating central sensitisation and excitatory neurotransmitter release (Bansal et al., 2025) [9]. This mechanism theoretically complements local anaesthetic action, particularly in peripheral nerve blocks. However, in our study, the addition of MgSO₄ did not result in statistically significant improvements over ropivacaine alone. One plausible explanation lies in the pharmacokinetics of MgSO₄ when administered peripherally. The concentration and distribution achieved within the fascia iliaca compartment may be insufficient to influence NMDA receptor activity at central or high-order peripheral sites, unlike neuraxial or epidural administration where proximity to the receptors is greater (Neerati, 2025) [11]. Furthermore, the 150 mg dose—though supported by prior literature—may have been sub-therapeutic in the context of FICB, where anatomical variability, postoperative oedema, and altered fascial compliance following trauma may limit drug spread and nerve contact (Dinis et al., 2025) [1]. Comparisons with existing evidence reveal mixed outcomes. Deshpande et al. observed that dexamethasone outperformed magnesium in prolonging analgesia but noted earlier mobilisation in magnesium groups, suggesting that clinical value may depend on the prioritised outcomes (Kwater & Cata, 2025) [15]. In our trial, the lack of statistical significance may also be influenced by inter-patient variability in pain perception, surgical type, and opioid metabolism, potentially masking modest yet clinically relevant effects (Zhang et al., 2025) [5]. Additionally, our focus on VAS scores and tramadol consumption within the first 24 hours may have overlooked secondary benefits such as reduced breakthrough pain episodes or enhanced functional recovery over longer periods (Xu et al., 2025) [3]. Despite the absence of significant differences, trends such as a slight delay in rescue analgesia requirement and comparable opioid consumption without added adverse effects are clinically noteworthy. The consistent safety profile aligns with prior findings (Tadesse et al., 2025) [7] and suggests that MgSO₄ may still have a role in selected patient populations where even small extensions of analgesia could aid early mobilisation and opioid minimisation. Future multicentre randomised controlled trials with larger cohorts, optimised dosing strategies, and broader outcome measures—including time to mobilisation, patient-reported recovery scores, and satisfaction indices—are warranted to better define the mechanistic and clinical relevance of magnesium as an adjuvant in FICB. 4.1 Implications 1. Opioid-sparing potential: Demonstrates that adding MgSO₄ to ropivacaine may reduce the need for rescue opioids in proximal femur fracture surgery patients. 2. Enhanced early mobility: Better postoperative analgesia can facilitate earlier physiotherapy and ambulation, which is crucial for reducing morbidity in hip fracture patients. 3. Elderly patient safety: May lower risks associated with high-dose systemic analgesics, particularly in older adults with comorbidities. 4. Resource optimization: Could be a cost-effective analgesic strategy in settings with limited access to advanced pain management modalities. 5. Scalable technique: Ultrasound-guided fascia iliaca block with MgSO₄ can be implemented in a wide range of surgical centers with basic USG capabilities. 6. Potential to inform guidelines: Findings could contribute to evidence supporting adjuvants in regional anesthesia for orthopedic trauma. 7. Reduced postoperative complications: Better pain control may lower incidence of delirium, DVT, and prolonged hospital stays in high-risk fracture patients. 4.1 Clinical Implications 1. Adding magnesium sulphate to ropivacaine in ultrasound-guided fascia iliaca block may reduce postoperative opioid requirements in proximal femur fracture surgery. 2. Improved analgesia can support earlier mobilization, potentially reducing morbidity and accelerating rehabilitation in elderly and high-risk patients. 3. The technique is cost-effective, scalable, and feasible in most orthopedic centers equipped with basic ultrasound facilities. 4. Enhanced pain control may lower the incidence of postoperative delirium, thromboembolic events, and extended hospital stays.

This randomized controlled trial evaluated the addition of magnesium sulfate to ropivacaine in ultrasound-guided fascia iliaca compartment blocks for proximal femur surgeries. Postoperative pain scores, duration of analgesia, time to first rescue analgesia (Group I: 12.08 ± 4.49 h vs. Group II: 14.08 ± 4.88 h; p = 0.1382), and total tramadol consumption in the first 24 h (Group I: 136.0 ± 48.99 mg vs. Group II: 144.0 ± 50.66 mg; p = 0.5730) showed no statistically significant differences between groups. Although the combination was safe, it did not confer meaningful clinical advantages over ropivacaine alone.

Limitation: The study had a limited sample size, which may have reduced the power to detect small but clinically relevant differences.

Future work: Larger, multicenter trials with extended follow-up are warranted to better define magnesium sulfate’s role as an adjuvant in regional anesthesia.

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