A novel technique of peripheral nerve blocks and sedation as primary anesthetic technique for adult emergency hip fracture surgery: A retrospective propensity matched study

Abstract

Background:

No study has evaluated peripheral nerve block as the primary anesthetic technique in adult hip fracture surgery. This retrospective cohort study compares peri-operative outcomes between spinal anesthesia and peripheral nerve block with sedation (block-sedation) in adult emergency hip fracture surgery.

Methods:

Adult patients who underwent hip fracture repair at Fleury Hospital between 2018 and 2025 were screened (n = 503). Of these, patients receiving planned spinal anesthesia (n = 238) or block-sedation (n = 230) were identified. Primary outcome was the success rate of block-sedation in emergency hip fracture surgery, defined as the proportion of patients in whom block-sedation was used without conversion to another anesthetic technique. Secondary outcomes included peri-operative opioid requirement (MME), postoperative pain, intra-operative anesthetic requirements (i.e., ketamine, midazolam, propofol), post-anesthesia care unit (PACU) stay, hospital length of stay, and intra-operative hypotension requiring inotropes.

Results:

Block-sedation was successful without conversion in 98.1% of patients; four patients (1.9%) required conversion to general anesthesia and were excluded from peri-operative outcomes. Median PACU stay was longer in the spinal group (54 min, IQR 42–72) compared with block-sedation (36 min, IQR 27–53; P < 0.001) The incidence of hypotension requiring inotropes was higher in the spinal group (53.0%) compared with the block-sedation group (19.4%; P < 0.001). Postoperative pain scores were comparable between groups (P = 0.126), and postoperative hospital length of stay was also similar (P = 0.416).

Conclusion:

In this propensity-matched cohort study, block-sedation was feasible and safe for MIS hip fracture surgeries, with a high success rate (>98%) and low conversion to general anesthesia.

Introduction

Hip fracture is a major health burden, particularly in older adults, with osteoporosis as a key risk factor.[1,2] The average age presenting with hip fracture is approximately 80 years,[3,4] and with population aging, the global incidence is projected to nearly double between 2018 and 2050.[5] In Canada, about 30,000 hip fractures occur annually, with 90% in patients over 65 and 61% in those over 80.[6]

Emergency surgical repair is usually required to restore mobility and reduce mortality,[7,8,9] as nonoperative management is associated with bone displacement, pain, and loss of function.[10,11] Outcomes remain poor despite surgery, with mortality rates of 7%–14% at 60 days[12,13,14] and 13%–25% at one year.[15,16,17,18] Only 40%–60% of survivors regain pre-fracture mobility,[19,20] and up to 20% require long-term nursing care within a year.[21] Because nearly all patients require surgery, optimizing anesthetic choice is a critical factor in optimizing outcomes for this frail, population.[22,23,24]

Peripheral nerve block is a regional anesthetic technique involving injection of anesthetic around nerves to provide targeted analgesia. They are widely used as adjuncts to general or spinal anesthesia in hip fracture surgery to facilitate positioning and provide postoperative pain control.[25,26] General anesthesia carries risks such as airway compromise, hemodynamic instability, postoperative nausea and vomiting, and delirium.[27] Spinal anesthesia has been shown to provide superior pain control and reduces opioid use compared with general anesthesia.[28,29,30,31,32,33,34,35,36] However, it is associated with hypotension and postoperative urinary retention, and it is contraindicated in anticoagulated patients, which may delay surgery or require general anesthesia instead.[37,38,39,40,41] Peripheral blocks have been shown to be safe in a variety of surgical contexts,[42,43,44,45,46] but evidence is limited regarding their use as the sole anesthetic technique for hip fracture repair.

Prior studies have compared spinal versus general anesthesia in hip fracture surgery, and peripheral blocks have been studied as adjuncts to general anesthesia. However, no studies have evaluated peripheral block as the primary anesthetic technique in adult hip fracture surgery.

This retrospective cohort study compares peri-operative outcomes between spinal anesthesia and peripheral nerve block with sedation (block-sedation) in adult emergency hip fracture surgery. Primary outcome will be conversion rate of block-sedation to general anesthesia. Secondary outcomes included peri-operative opioid requirement, postoperative pain, intra-operative anesthetic requirements, post-anesthesia care unit (PACU) stay, hospital length of stay, and intra-operative hypotension requiring inotropes.

Methods

Study design and patients

This retrospective cohort study was approved by the Nagano Research Ethics Committee (protocol no. 2025–2878), with authorization to access the electronic medical records (EMR) at Fleury Hospital. Adult patients who underwent hip fracture repair at Fleury Hospital between 2018 and 2025 were screened (n = 503). Of these, patients receiving planned spinal anesthesia (n = 238) or block-sedation (n = 230) were identified. Because the study focused exclusively on emergency procedures, elective hip fracture repairs were excluded; none were identified during screening. Thus, 468 patients undergoing emergency hip fracture repair with planned spinal or block-sedation were included.

Data were collected from the EMR over a 2-month period. Patients were identified through a randomized coding system, with all identifiers securely stored on hospital servers. Given the retrospective design and minimal risk to participants, the institutional ethics committee waived the requirement for informed consent in accordance with local regulations. All eligible cases were included to maximize statistical power, and no formal sample size calculation was performed. As with any retrospective study, the possibility of information bias due to incomplete or inconsistent EMR documentation cannot be excluded.

This study followed the STROBE guidelines for observational research, with the completed checklist provided as supplementary material.

Data collection

Demographic data (age, sex, weight, ASA classification) were obtained from preoperative assessment forms. Type of surgery performed were obtained from the operative note. Surgery duration was obtained from the peri-operative nursing notes. Anesthesia technique and intra-operative medications were obtained from the anesthetic record. PACU length of stay, pain scores, and medications were collected from PACU nursing records.

Opioid administration (morphine, hydromorphone, fentanyl, remifentanil, sufentanil, or meperidine) was standardized by converting total opioid doses to morphine milligram equivalents (MME) using established conversion ratios,[47] where 1 mg of intravenous hydromorphone is equivalent to 6 mg of intravenous morphine.

Postoperative pain was assessed using the Numeric Rating Scale (NRS, 0 = no pain, 10 = worst pain imaginable). Pain scores were documented by PACU nursing staff upon PACU admission and at 15-min intervals until PACU discharge. The mean of all recorded pain scores during PACU stay was used in the analysis.

Anesthetic technique

In the spinal group, patients received a single-shot injection of a local anesthetic into the L3–L4 or L4–L5 interspace using aseptic technique, followed by intravenous sedation using propofol, midazolam, ketamine, or a combination as needed. The specific spinal anesthetic and dose range (typically xylocaine 40–50 mg, bupivacaine 5–7.5 mg), and use of adjuncts (e.g., fentanyl) were determined by the attending anesthesiologist based on clinical judgment.

In the block-sedation group, patients received a peripheral nerve block (i.e., combination of femoral and lateral femoral cutaneous nerve, fascia iliaca, and peri-capsular nerve group (PENG) block) using aseptic technique and ultrasound guidance, combined with intravenous sedation using propofol, midazolam, ketamine, or a combination, titrated to patient comfort, and procedural requirements.

The choice of anesthetic technique, drug and dosing were at the discretion of the anesthesiologist. In both groups, inotropes (i.e., ephedrine, phenylephrine, epinephrine) were used for cardiovascular support as needed.

Outcomes

Primary outcome is the success rate of block-sedation in emergency hip fracture surgery, defined as the proportion of patients in whom block-sedation was used without conversion to another anesthetic technique. Secondary outcomes included peri-operative opioid requirement (MME), postoperative pain, intra-operative anesthetic requirements (i.e., ketamine, midazolam, propofol), PACU stay, hospital length of stay, and intra-operative hypotension requiring inotropes.

Statistical analysis

Propensity score matching (PSM) was performed to balance baseline characteristics between the spinal and block-sedation groups. Patients with missing values in covariates were excluded prior to matching. Propensity scores were estimated using logistic regression including age, sex, weight, ASA classification, and surgery duration as covariates. A 1:1 optimal matching algorithm was applied using the MatchIt package in R (version 4.5.1; R Foundation for Statistical Computing, Vienna, Austria). Categorical variables are presented as n (%), and continuous variables as median [interquartile range (IQR)]. Standardized mean differences (SMDs) were calculated using means and SDs to assess covariate balance after matching, with an SMD <0.25 considered acceptable.

Statistical analyses were conducted in SPSS (version 29.0.2.0; IBM Corp., Armonk, NY). Categorical variables are presented as n (%), and continuous variables as median [interquartile range (IQR)]. Categorical variables were compared using Pearson’s Chi-square test, with Fisher’s exact test applied when expected cell counts were <5. Continuous variables were assessed for normality using the Shapiro-Wilk test. Non-normally distributed variables are reported as median [IQR] and compared using the Mann-Whitney U test.

Post-hoc statistical analysis (MIS-only cohort)

Post-hoc analyses were performed for minimally invasive surgeries (MIS), including femoral nail fixation, cannulated screw fixation, and dynamic hip screw fixation, to examine outcomes in a more homogeneous surgical cohort. The same statistical methods as described above were applied.

Results

Matched cohorts

After 1:1 propensity score matching, 215 spinal cases were matched to 215 block-sedation cases. Baseline characteristics before and after matching are summarized in Table 1. Age, sex, weight, and ASA classification were balanced after matching (SMD <0.25); however, surgery duration remained imbalanced (median 47 vs. 27 min for spinal and block-sedation, respectively; SMD 1.187). All variables were retained in analyses to preserve sample size. Most patients were female (70.2% spinal, 74.0% block-sedation), and more than half were classified as ASA I-II (61.4% spinal, 50.7% block-sedation). Most patients were not taking at-home anticoagulant or antiplatelet medications (77.7% spinal, 80.9% block-sedation).

Table 1.

Baseline patient and procedure characteristics after matching (all hip surgeries)

	Spinal, n=215	Block-Sedation, n=215	SMD
Age, years (median [IQR])	86 (79–91)	87 (79–92)	−0.018
Weight, kg (median [IQR])	70 (60–79)	65 (57–78)	0.093
Sex, n (%)
Female	151 (70.2%)	159 (74%)	−0.083
Male	64 (29.8%)	56 (26%)	0.083
ASA, n (%)
I	5 (2.3%)	8 (3.7%)	−0.081
II	127 (59.1%)	101 (47%)	0.244
III	76 (35.3%)	94 (43.7%)	−0.171
IV	7 (3.3%)	12 (5.6%)	−0.113
Surgery duration, min (median [IQR])	47 (36–60.5)	27 (22–35)	1.187
At-home anticoagulant/antiplatelet use, n (%)
None	167 (77.7%)	174 (80.9%)	−0.080
Anticoagulant	21 (9.8%)	17 (7.9%)	0.065
Antiplatelet	27 (12.6%)	24 (11.2%)	0.043
Surgery type, n (%)
Hemiarthroplasty	150 (69.8%)	12 (5.6%)	1.764
Femoral nail fixation	40 (18.6%)	163 (75.8%)	−1.395
Cannulated screw fixation	9 (4.2%)	33 (15.3%)	−0.382
Dynamic hip screw fixation	7 (3.3%)	5 (2.3%)	0.056
Total hip arthroplasty	5 (2.3%)	0	0.218
Hemiarthroplasty + upper limb surgery	0	0
Femoral nail + upper limb surgery	0	1 (0.5%)	−0.096
Perihardware fracture repair	4 (1.9%)	1 (0.5%)	0.130

Peri-operative outcomes

Block-sedation was successful without conversion in 98.1% of patients; four patients (1.9%) required conversion to general anesthesia and were excluded from peri-operative outcomes. Median PACU stay was longer in the spinal group (54 minutes, IQR 42–72) compared with block-sedation (36 min, IQR 27–53; P < 0.001) [Table 2]. Median MME was 0 (IQR 0–3.4) in the spinal group and 0 (IQR 0–5) in the block-sedation group (P = 0.011). Median intra-operative ketamine dose was 0 mg/kg (IQR 0–0.26) in the spinal group and 0.33 mg/kg (IQR 0.01–0.52) in the block-sedation group (P < 0.001). Median intra-operative propofol dose was 2.4 mg/kg/hr (IQR 1.3–3.8) in the spinal group and 4.7 mg/kg/hr (IQR 2.7–6.7) in the block-sedation group (P < 0.001). The incidence of hypotension requiring inotropes was higher in the spinal group (53.0%) compared with the block-sedation group (19.4%; P < 0.001). Postoperative pain scores were comparable between groups (P = 0.126), and postoperative hospital length of stay was also similar (P = 0.416).

Table 2.

Perioperative outcomes after matching (all hip surgeries)

	Spinal, n=215	Block-Sedation, n=211	P
Intraoperative medication needs (median [IQR])
Ketamine dose, mg/kg	0 (0–0.26)	0.33 (0.01–0.52)	<0.001
Midazolam dose, mg/kg	0 (0–0.03)	0.01 (0–0.02)	0.415
Propofol dose, mg/kg/hr	2.40 (1.3–3.83)	4.68 (2.74–6.70)	<0.001
Time from ER to OR, hr (median [IQR])	31.55 (22.17–54.55)	26.33 (20.37–40.95)	<0.001
TXA received intraoperatively, n (%)	32 (14.9%)	11 (5.2%)	<0.001
Estimated blood loss, mL (median [IQR])	150 (100–200)	100 (100–150)	0.003
Hypotensive requiring inotrope intra- or postoperatively, n (%)	114 (53%)	41 (19.4%)	<0.001
Postoperative outcomes (median [IQR])
PACU length of stay, min	54 (41.5–72)	35.5 (27–53)	<0.001
MME	0 (0–3.38)	0 (0–5)	0.011
Postoperative pain score	0 (0–0)	0 (0–0)	0.126
Postoperative hospital length of stay, d	11 (7–15)	11 (7–18)	0.416

Post-hoc peri-operative outcomes (MIS-only cohort)

In the MIS-only matched cohort (57 spinal vs. 57 block-sedation cases), all covariates including surgery duration were balanced (SMD < 0.25) [Table 3].

Table 3.

Baseline patient and procedure characteristics after matching (minimally invasive surgeries only)

	Spinal, n=57	Block-Sedation, n=57	SMD	P
Age, years (median [IQR])	82 (73–87)	84 (72–89)	0.003
Weight, kg (median [IQR])	70 (60–80)	70 (60–80)	0.035
Sex, n (%)
Female	35 (61.4%)	37 (64.9%)	−0.072
Male	22 (38.6%)	20 (35.1%)	0.072
ASA, n (%)
I	3 (5.3%)	4 (7%)	−0.072
II	41 (71.9%)	39 (68.4%)	0.076
III	11 (19.3%)	12 (21.1%)	−0.043
IV	2 (3.5%)	2 (3.5%)	0.000
Surgery duration, min (median [IQR])	34 (23–42)	30 (25–37)	0.096
At-home anticoagulant/antiplatelet use, n (%)			0.425
None	51 (89.5%)	48 (84.2%)	0.155
Anticoagulant	1 (1.8%)	5 (8.8%)	−0.315
Antiplatelet	5 (8.8%)	4 (7%)	0.065
Surgery type, n (%)
Femoral nail fixation	41 (71.9%)	48 (84.2%)	−0.297
Cannulated screw fixation	9 (15.8%)	7 (12.3%)	0.100
Dynamic hip screw fixation	7 (12.3%)	2 (3.5%)	0.327

Results were generally consistent with the main analysis [Table 4]. Block-sedation was successful in 98.2% of cases, with 1 conversion (1.8%) to general anesthesia. PACU stay remained shorter in the block-sedation group (38 vs. 52 min; P < 0.001), as illustrated in Figure 1. Intra-operative propofol, ketamine, and midazolam requirements were higher in the block-sedation group (P < 0.05 for all). The incidence of hypotension requiring inotropes was again lower with block-sedation (19.6% vs. 50.9%; P < 0.001) [Figure 2]. Unlike the main cohort, MME did not differ significantly between groups (P = 0.62). Postoperative pain scores and hospital length of stay remained similar (P = 0.724 and P = 0.285, respectively).

Table 4.

Perioperative outcomes after matching (minimally invasive surgeries only)

	Spinal, n=57	Block-Sedation, n=56	P
Intraoperative medication needs (median [IQR])
Ketamine dose, mg/kg	0 (0–0.286)	0.293 (0.063–0.508)	<0.001
Midazolam dose, mg/kg	0 (0–0.025)	0.014 (0–0.025)	0.027
Propofol dose, mg/kg/hr	2.502 (1.267–4.335)	5.079 (2.991–7.302)	<0.001
Time from ER to OR, hr (median [IQR])	1.12 (0.898–1.712)	1.075 (0.873–1.788)	0.789
TXA received intraoperatively, n (%)	1 (1.8%)	3 (5.4%)	0.3
Estimated blood loss, mL (median [IQR])	100 (100–150)	100 (100–200)	1
Hypotensive requiring inotrope intra- or postoperatively, n (%)	29 (50.9%)	11 (19.6%)	<0.001
Postoperative outcomes (median [IQR])
PACU length of stay, min	52 (42.25–81.25)	38 (28–53)	<0.001
MME	0 (0–5)	0 (0–5)	0.62
Postoperative pain score	0 (0–0)	0 (0–0)	0.724
Postoperative hospital length of stay, d	9 (6–14)	9 (6–18)	0.285

Figure 1.

PACU length of stay by anesthesia technique (minimally invasive surgeries only). PACU = Post-anesthesia care unit

Figure 2.

Incidence of hypotension requiring inotrope by anesthesia technique (minimally invasive surgeries only)

At-home anticoagulant/antiplatelet use was not used in the matching process, but as shown in Table 3, anticoagulant use was somewhat more frequent in the block-sedation group compared to the spinal group (SMD = 0.32). However, the overall distribution of anticoagulation status (none, anticoagulant, antiplatelet) did not differ significantly between groups (P = 0.43).

Discussion

In this propensity-matched cohort study, block-sedation was feasible and safe for MIS hip fracture surgeries, with a high success rate (>98%) and low conversion to general anesthesia.

Compared with spinal anesthesia, block-sedation was associated with shorter PACU stay and lower incidence of hypotension requiring inotropes, while postoperative pain, opioid use, and hospital length of stay were similar. These findings suggest that block-sedation provides effective anesthesia and analgesia, while maintaining hemodynamic stability and recovery efficiency.

The lower hypotension incidence aligns with known effects of spinal anesthesia, particularly in older patients with co-morbidities. Shorter PACU stay may facilitate faster patient flow and more efficient use of hospital resources. Although intra-operative sedative requirements were higher with block-sedation, neither postoperative PACU stay, nor analgesia were compromised.

Post-hoc analyses of MIS were performed to evaluate outcomes in a more homogeneous surgical cohort with similar procedure type and surgery duration. Results were largely consistent with the main analysis. The absence of a difference in postoperative opioid consumption MME in the MIS cohort may reflect smaller sample size and reduced power.

This was not possible in the hemi-arthroplasty cohort; lacking enough data to be analyzed conclusively. However, notably this surgery was accomplished in 12 patients [5.6%] with the block-sedation technique, nonetheless.

Limitations of our study include the retrospective, single center design and potential unmeasured confounding factors. In the main cohort, surgery duration remained somewhat imbalanced despite matching. To address this, we conducted a sensitivity analysis restricted to a more homogeneous minimally invasive surgery subgroup. Findings in this subgroup were consistent with the main analysis, suggesting that the results are not due to the surgery duration imbalance.

Conclusions

Block-sedation is a safe and effective alternative to spinal anesthesia for MIS hip fracture surgeries, associated with faster recovery and lower hypotension without compromising analgesia or hospital stay. Notably this technique was also adequate for hemi-arthroplasty surgery but due to the limitations of this retrospective cohort this data was not conclusive. Prospective multi-center studies are warranted to confirm these findings.

Conflicts of interest

TMH and PLL are shareholders of DivoccoAI.

Supplementary Material

STROBE Statement—checklist of items that should be included in reports of observational studies

	Item No	Recommendation	Page No
Title and abstract	1	(a) Indicate the study’s design with a commonly used term in the title or the abstract	1
		(b) Provide in the abstract an informative and balanced summary of what was done and what was found	1
Introduction
Background/rationale	2	Explain the scientific background and rationale for the investigation being reported	2
Objectives	3	State specific objectives, including any prespecified hypotheses	2
Methods
Study design	4	Present key elements of study design early in the paper	2
Setting	5	Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection	2
Participants	6	(a) Cohort study—Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up Case-control study—Give the eligibility criteria, and the sources and methods of case ascertainment and control selection. Give the rationale for the choice of cases and controls Cross-sectional study—Give the eligibility criteria, and the sources and methods of selection of participants	2
		(b) Cohort study—For matched studies, give matching criteria and number of exposed and unexposed Case-control study—For matched studies, give matching criteria and the number of controls per case	3
Variables	7	Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable	2-3
Data sources/ measurement	8*	For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group	2-3
Bias	9	Describe any efforts to address potential sources of bias	3
Study size	10	Explain how the study size was arrived at	2
Quantitative variables	11	Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why	3
Statistical methods	12	(a) Describe all statistical methods, including those used to control for confounding	3
		(b) Describe any methods used to examine subgroups and interactions	3
		(c) Explain how missing data were addressed	2-3
		(d) Cohort study—If applicable, explain how loss to follow-up was addressed Case-control study—If applicable, explain how matching of cases and controls was addressed Cross-sectional study—If applicable, describe analytical methods taking account of sampling strategy	3
		(e) Describe any sensitivity analyses	3
Results
Participants	13*	(a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed	3
		(b) Give reasons for non-participation at each stage	N/A
		(c) Consider use of a flow diagram	N/A
Descriptive data	14*	(a) Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential confounders	3-4
		(b) Indicate number of participants with missing data for each variable of interest	4-5
		(c) Cohort study—Summarise follow-up time (eg, average and total amount)	N/A
Outcome data	15*	Cohort study—Report numbers of outcome events or summary measures over time	4-5
		Case-control study—Report numbers in each exposure category, or summary measures of exposure	N/A
		Cross-sectional study—Report numbers of outcome events or summary measures	N/A
Main results	16	(a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were included	4-5
		(b) Report category boundaries when continuous variables were categorized	N/A
		(c) If relevant, consider translating estimates of relative risk into absolute risk for a meaningful time period	N/A
Other analyses	17	Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses	4-5
Discussion
Key results	18	Summarise key results with reference to study objectives	6
Limitations	19	Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias	6
Interpretation	20	Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence	6
Generalisability	21	Discuss the generalisability (external validity) of the study results	6
Other information
Funding	22	Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based	6

*Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.

Note: An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/, Annals of Internal Medicine at http://www.annals.org/, and Epidemiology at http://www.epidem.com/). Information on the STROBE Initiative is available at www.strobe-statement.org.

Funding Statement

Nil.