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Clin Exp Emerg Med > Volume 11(2); 2024 > Article
Geizhals, Shou, Rudnin, Tama, Greenstein, Hahn, Chacko, Basile, and Marino: Femoral nerve blocks versus standard pain control for hip fractures: a retrospective comparative analysis

Abstract

Objective

Pain control for hip fractures is often achieved via intravenous opioids. However, opioids can have dangerous adverse effects, including respiratory depression and delirium. Peripheral nerve blockade is an alternative option for pain control that reduces the need for opioid analgesia. The purpose of this study was to compare the use of femoral nerve blocks versus standard pain control for patients with hip fractures.

Methods

This retrospective study included adult patients presenting to the emergency department with isolated hip fractures between April 2021 and September 2022. The intervention group included all patients who received a femoral nerve block during this time. An equivalent number of patients who received standard pain control during that period was randomly selected to represent the control group. The primary outcome was preoperative opioid requirement, assessed by morphine milligram equivalents (MMEs).

Results

During the study period, 90 patients were included in each group. Mean preoperative MME was 10.3 (95% confidence interval [CI], 7.4–13.2 MME) for the intervention group and 14.0 (95% CI, 10.2–17.8 MME) for the control group (P=0.13). Patients who received a femoral nerve block also had shorter time from emergency department triage to hospital discharge (7.2 days; 95% CI, 6.2–8.0 days) than patients who received standard care (8.6 days; 95% CI, 7.2–10.0 days). However, this difference was not statistically significant (P=0.09).

Conclusion

Femoral nerve blockade is a safe and effective alternative to opioids for pain control in patients with hip fractures.

INTRODUCTION

Hip fractures are a significant health risk, particularly among elderly individuals [1]. Hip fractures often precipitate rapid declines in health, with some studies observing an eightfold increase in mortality risk within the 3 months following a hip fracture [2,3]. In 1992, the International Osteoporosis Foundation estimated that 18% of women and 6% of men suffer hip fractures [4]. Due to the increasing elderly population, the yearly incidence of hip fractures worldwide is projected to reach 6.3 million by 2050 [5,6].
Patients with hip fractures typically present to the emergency department (ED) with a chief complaint of pain. Optimized pain control is critical for patients with hip fractures in the ED, particularly in elderly patients for whom pain management can be challenging [7]. In the ED, pain control for hip fractures is often achieved with intravenous opioids. Still, opioid use is associated with many adverse effects ranging from nausea and vomiting to respiratory depression and delirium [810]. Prolonged use of opioids can also lead to opioid dependence, contributing to the ongoing opioid epidemic in the United States [11]. Finally, opioid dosing can be challenging in elderly patients due to impaired renal elimination and a high prevalence of outpatient opioid prescriptions [12]. Despite these drawbacks, opioids remain the analgesic of choice for patients presenting with hip fractures.
One promising alternative to opioids is regional analgesia, which involves the injection of local anesthetic adjacent to nerves that supply the area of pain. In the case of hip fractures, femoral nerve blockade has been shown to reduce the need for opioids. In a recent Cochrane review and meta-analysis of 49 studies with 3,061 participants, femoral nerve blocks were found to reduce pain with movement by 2.5-fold (0–10 scale) within 30 minutes of administration and to reduce the risk of an acute confused state. Femoral nerve blocks may also reduce the risk of pneumonia and time to mobilization after surgery [13,14].
The Cochrane review has been critiqued for combining studies with a wide range of patient populations, techniques for administration, and types of anesthetics (with and without adjunct treatments) [15]. Furthermore, in most of the studies analyzed, the nerve blockade was performed by an anesthesiologist in the perioperative setting, which is not always feasible and does not address pain on initial ED presentation. Nevertheless, femoral nerve blockade represents a promising alternative to opioids, and guidelines from the American Academy of Orthopaedic Surgeons support the use of regional analgesia to improve preoperative pain control in patients with hip fractures [16]. Although the advantages of nerve blockade have been previously studied, limited studies have been conducted in the ED. The primary goal of this study was to examine the effectiveness of femoral nerve blocks versus opioid use by emergency medicine providers for pain management in patients with hip fractures.

METHODS

Ethics statement

The study was approved by the Institutional Review Board of Northwell Health (No. 23-0794). Informed consent was waived due to the retrospective nature of the study.

Study design and setting

This was a retrospective study of patients with hip fractures presenting to the ED of Staten Island University Hospital (Staten Island, NY, USA). The study population included all adult patients with isolated hip fractures, including fractures of the femoral head, femoral neck, intertrochanteric femur, and trochanteric femur, who presented to the ED between April 4, 2021, and September 12, 2022, and subsequently underwent surgical repair.
Patients who underwent a femoral nerve block were identified through an ultrasound database. An equal number of patients who received standard pain control (without femoral nerve or regional block) was randomly selected to represent the control group. Eligible control subjects were identified using an institutional database query, Allscripts Sunrise Clinical Manager (Allscripts Sunrise ver. 16.3, Veradigm). This method was intended to balance characteristics between the two groups.
All femoral nerve blocks were performed by an ED provider (attending physician, resident, or physician assistant) under the supervision of a physician trained and credentialed in femoral nerve block administration. Patients were positioned supine with the affected extremity abducted and slightly externally rotated. A high-frequency linear ultrasound probe (8–18 MHz) was placed transversely on the femoral crease to locate the femoral nerve. Once identified, the area was anesthetized with a 2 mg/kg dose of 0.5% bupivacaine solution. Then, a 20- or 22-gauge nerve block needle catheter was guided in-plane using the transducer to place the needle tip adjacent to the lateral aspect of the femoral nerve below the fascia iliaca. Correct needle placement was confirmed by injecting normal saline and observing displacement of the femoral nerve by the injectate on ultrasound.
All opioids were administered based on the treating physician's discretion. The specific type and dosage of medication varied based on individual patient needs, which were assessed using clinical judgment and standardized pain scales. Medication dosage was titrated based on the patient's response to the medication and the pain relief achieved.
Patient demographics, clinical characteristics, and medications were collected from medical records and stored in REDCap (Vanderbilt University), a secure web-based data capture application [17,18]. Patient demographics included age, sex, weight, and height. Body mass index was calculated as weight (kg) divided by height (m) squared. Clinical characteristics included type of hip fracture, hospital course (time of ED triage, operation, and hospital discharge), and discharge disposition (home, inpatient rehabilitation, hospice, hospital, or death). Medications were divided into preoperative and postoperative and categorized as analgesics (morphine, hydromorphone, oxycodone, fentanyl, tramadol, meperidine, ibuprofen, ketorolac, celecoxib, and acetaminophen) or antiemetics (ondansetron, metoclopramide, and prochlorperazine).
The primary outcome was the mean morphine milligram equivalent (MME), which was calculated based on the total combined analgesic requirement [19]. Secondary outcomes were total antiemetic requirements, time from ED triage to hospital discharge, and discharge dispositions for each treatment group. While the primary outcome centered on comparing femoral nerve blocks to opioids, the secondary outcomes provide a more comprehensive understanding of the impacts of different pain management approaches on the patient experience and ED efficiency. Examining these outcomes provides insights into the multifaceted aspects of patient care beyond immediate pain relief.

Statistical analysis

Patient characteristics are presented with simple statistics (mean with standard deviation or number with percentage of patients). Differences in patient characteristics between groups were evaluated by two-sided Welch t-test (for continuous variables) or chi-square test (for categorical variables). Differences in mean MME between treatment groups were assessed preoperatively and postoperatively by two-sided Welch t-test. Data analysis was conducted using Jamovi Project ver. 2.3 (https://www.jamovi.org), and P-values of <0.05 were considered statistically significant.

RESULTS

During the study period, 90 hip fracture patients received a femoral nerve block, and 90 hip fracture patients who received standard care were randomly selected as controls. No adverse events related to the procedure were reported for the study population. Patient characteristics for each treatment group are presented in Table 1. There were no significant differences in patient age and body mass index between groups.
Patients who received a femoral nerve block had a lower mean preoperative analgesic requirement (10.3 MME; 95% confidence interval [CI], 7.4–13.2 MME) compared to patients who received standard care (14.0 MME; 95% CI, 10.2–17.8 MME) (Fig. 1). However, this difference was not significant (P=0.13). Patients who received a femoral nerve block also received more preoperative antiemetics (21%) than those who received standard care (13%). Treatment groups had similar postoperative analgesic and antiemetic requirements (P>0.05).
Patients who received a femoral nerve block had a shorter mean time from ED triage to hospital discharge (7.2 days; 95% CI, 6.2–8.0 days) compared to patients who received standard care (8.6 days; 95% CI, 7.2–10.0 days) (Fig. 2), but this difference was not significant (P=0.09).
The two treatment groups had similar mortality rates (three patients in each group). However, 74 patients (82.2%) in the intervention group were discharged to rehabilitation, compared to only 64 (71.1%) in the control group. Conversely, 12 patients (13.0%) in the intervention group were discharged home, compared to 19 patients (21.1%) in the control group. Overall, discharge disposition was similar between treatment groups (P=0.326).
Subjects in both cohorts appeared to have received their first dose of pain medication at around the same time before operative repair. Subjects in the intervention group received the first dose of pain medication at 298 minutes, while subjects in the control group received their first dose at 200 minutes. Of those requiring a second dose of analgesics, subjects in the intervention group received their second dose of pain medication at 495 minutes, while those in the control group received their first dose of pain medication at 507 minutes.

DISCUSSION

In this retrospective analysis, we compared the effectiveness of femoral nerve blocks versus opioid use by emergency medicine providers for pain management in subjects with hip fractures. We found that preoperative MME was lower for the intervention group than the control group, whereas postoperative MME requirements were similar between groups. This suggests that femoral nerve blocks may have been more effective at controlling preoperative pain. It also implies that femoral nerve blocks may be as effective as the current standard of care in managing pain after surgery. Furthermore, no adverse events related to the procedure were reported during the study, suggesting that femoral nerve blocks are a safe and effective alternative to opioids in managing pain from hip fractures.
Compared to patients in the control group, patients receiving femoral nerve blocks also had a shorter mean time from ED triage to operation and hospital discharge. Although these differences were not statistically significant, the trend toward shorter hospitalization suggests a potential benefit of femoral nerve blocks in expediting recovery and discharge. This finding is consistent with previous studies demonstrating the effectiveness of femoral nerve blocks in reducing hospital length of stay [20,21]. Several factors could contribute to the extended hospital stays for patients without femoral nerve blocks. One reason could be that patients receiving only opioids may have been experiencing prolonged pain, potentially leading to complications or delays in their recovery process. Additionally, the sedating effects of opioids could impact patient mobility and participation in physical therapy, which might hinder discharge. Another aspect to consider is that patients experiencing complications require closer monitoring and evaluation before they can be safely discharged. This cautious approach, while essential for patient safety, could contribute to the overall length of hospitalization. Future studies should explore this finding further and investigate underlying contributory factors. Understanding the impact of femoral nerve blocks on hospital length of stay could provide valuable insights for optimizing pain management strategies and enhancing patient care in this population.
In this study, the average time from ED arrival to surgery was 49.6 hours. Patients who received femoral nerve blocks showed a slight decrease in preoperative analgesic requirements, although this difference was not significant. Similarly, there was a reduction in the time from ED triage to hospital discharge for patients with femoral nerve blocks, which also did not reach statistical significance. These findings suggest that timely surgical intervention and multimodal pain management strategies, such as combining nerve blocks with opioids, enhance patient comfort and improve overall outcomes.
Our results demonstrated an interesting trend regarding the administration of preoperative antiemetics: 21% of patients in the intervention group received an antiemetic, compared to only 13% of patients in the control group. This finding suggests that femoral nerve blocks are associated with an increased need for preoperative antiemetics in hip fracture patients, which is surprising given that these patients received fewer opioids. However, this result should be interpreted in the context of the study design and potential factors that may contribute to this outcome. For example, it is possible that the two groups had underlying differences in patient characteristics or other factors that influenced the need for antiemetic medications.
Treating acute pain in the ED can be complex and is often suboptimal [22]. Standard treatment of acute pain due to hip fractures has historically been limited to opioids and anti-inflammatory medications, which can have systemic side effects––particularly in the geriatric population––including respiratory depression, nausea, and delirium. Local anesthesia administration, such as femoral nerve blocks, has been shown by multiple studies to improve pain control and decrease opioid requirements [23]. Although femoral nerve blocks can be administered via anatomic landmarks with nerve stimulators, ultrasound guidance has led to greater than 95% success rates [24].
Historically, similar studies have examined nerve blocks performed by anesthesiologists. However, recent studies have shown that ED providers can be trained relatively quickly to perform this procedure [25]. As the procedure has become more common, more EDs have included femoral nerve blocks in their consensus list of ultrasound‐guided regional anesthesia techniques most likely valuable for emergency medicine practice [26]. All femoral nerve blocks in this study were performed by ED providers, which reflects real-world applicability and highlights the feasibility of this procedure in the ED. On the other hand, including ED providers with a wide range of experience and expertise may have introduced variability in the quality and consistency of the nerve blocks performed. Therefore, the results of this study should be interpreted with caution.
This study has several other limitations. First, the study was conducted at a single institution, which may limit the generalizability of our findings to other settings. Second, the study was retrospective, possibly introducing sampling bias. Although patients were selected for the groups using an institutional database query that randomly identified eligible subjects based on the study criteria, there may still be underlying differences in the patient populations that could affect the results. Third, the study had a sample size of 90 patients in each treatment group, which may have been underpowered to detect significant differences. In a post hoc power analysis of the primary outcome, the study had a power of only 33% to detect differences in MME requirements. While a sample size of 90 patients might seem adequate, it is crucial to consider the complexity and variability of the hip fracture population and the multifactorial nature of pain management outcomes.
Additionally, the possibility exists that femoral nerve blocks were administered primarily to patients who were more cooperative or better suited for the procedure. This potential selection bias could have impacted the outcomes observed in our study. Cooperative patients might have had different pain profiles or responses to the femoral nerve block. This could affect the overall efficacy and generalizability of the findings. While efforts were made to standardize the administration of nerve blocks and minimize biases, this inherent limitation in our sample selection process could also have influenced the results.
The lack of blinding in administration of femoral blocks versus opioids is also a limitation of this study. Implementing blinding in the ED, particularly for procedures like femoral nerve blocks, is challenging due to practical constraints. Despite this limitation, the study provides insights into the effectiveness of femoral nerve blocks within the real-world context of clinical practice in the ED.
Finally, we focused only on pain management and did not evaluate other outcomes, such as patient satisfaction, quality of life, or healthcare costs. Therefore, the results may not comprehensively assess the effectiveness of femoral nerve blocks versus opioid use for hip fracture pain management.
Future studies should compare types of hip fractures between groups to interpret the observed effects. Since femoral nerve blocks may not fully cover the articular aspect of the hip, which receives innervation from the obturator nerve, it would be interesting to examine the MME of nerve block patients with different types of hip fractures, such as articular, subcapital, and intertrochanteric fractures. This additional analysis could provide insights into the potential variations in the effectiveness of femoral nerve blocks based on the specific location and type of hip fracture.
In conclusion, this study provides valuable insights into the effectiveness of femoral nerve blocks versus opioid use for pain management in subjects with hip fractures. Future studies that address this study’s limitations and evaluate a broader range of outcomes could provide a more comprehensive understanding of optimal pain management strategies in patients with hip fractures. Our findings suggest that femoral nerve blocks are a safe and effective alternative to opioid use for pain management in patients with hip fractures.

NOTES

Author contributions
Conceptualization: JM, JB, YS, JG; Data curation: all authors; Formal analysis: all authors; Investigation: all authors; Methodology: all authors; Resources: all authors; Writing–original draft: all authors; Writ­ing–review & editing: all authors. All authors read and approved the final manuscript.
Conflicts of interest
The authors have no conflicts of interest to declare.
Funding
The authors received no financial support for this study.
Acknowledgments
The authors acknowledge Dr. Esben Iversen for his contribution in review and writing the manuscript.
Data availability
Data analyzed in this study are available from the corresponding author upon reasonable request.

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Fig. 1.
Morphine milligram equivalent (MME) requirements. (A) Presurgery. (B) Postsurgery. CI, confidence interval.
ceem-23-112f1.jpg
Fig. 2.
Hospital length of stay. CI, confidence interval.
ceem-23-112f2.jpg
Table 1.
Demographics and clinical characteristics of subjects (n=180)
Characteristic Femoral nerve block group (n=90) Control group (n=90) P-value
Age (yr) 58 (41–73) 60 (42–74) 0.240
Sex 0.009
 Male 19 (21.1) 35 (38.9)
 Female 71 (78.9) 55 (61.1)
Height (cm) 162.5±9.75 166.3±10.2 0.019
Weight (kg) 68.2±17.55 69.1±17.58 0.210
Body mass index 0.340
 No. of patients 81 79
 Mean (kg/m2) 25.1 25.1
Treatment time
 Triage to nerve block (min) 274.0±487.0 NA 0.675
 Triage to outpatient repair (hr) 49.6±23.0 42.4±51.3 0.230
 Triage to hospital discharge (day) 7.2±4.3 8.6±6.8 0.093
MME requirement
 Preoperative 10.3±14.1 14±18.3 0.132
 Postoperative 6.0±8.1 6.2±8.5 0.877
Antiemetic requirement
 Preoperative 19 (21.1) 12 (13.0) 0.167
 Postoperative 10 (11.1) 9 (10.0) 0.808
Disposition 0.326
 Home 12 (13.3) 19 (21.1)
 Rehabilitation 74 (82.2) 64 (71.1)
 Hospital 1 (1.1) 2 (2.2)
 Hospice 0 (0) 2 (2.2)
 Expired 3 (3.3) 3 (3.3)

Values are presented as median (interquartile range), number (%), or mean±standard deviation, unless otherwise indicated. Percentages may not total 100 due to rounding.

NA, not available; MME, morphine milligram equivalent.

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