Reappraising the fascia iliaca compartment block and pericapsular nerve group block for geriatric hip fractures: a narrative review

Abstract

Regional analgesia is a cornerstone of multimodal pain management for hip fractures, yet the optimal choice between the pericapsular nerve group (PENG) block and the fascia iliaca compartment block (FICB) remains a subject of ongoing debate. Current literature often presents conflicting outcomes due to the heterogeneous pathophysiology of hip fractures which complicates a universal approach. This narrative review synthesizes current anatomical and clinical evidence to reconcile these discrepancies. By evaluating the relative strengths and limitations of each technique, we identify three critical dimensions including pathology, patient factors, and performance. Our synthesis indicates that pathology dictates the target. Based on anatomical considerations, intracapsular fractures may benefit from the targeted coverage of the PENG block, whereas extracapsular injuries involve somatic pathways that appear more effectively addressed by the FICB. Patient-centered priorities like delirium prevention in the frail elderly must be balanced against the theoretical benefits of motor sparing. Furthermore, the clinical utility of motor preservation is only realized when coupled with early active rehabilitation. Consequently, the PENG block and FICB should be viewed as complementary rather than competitive strategies. This review offers the 3P framework as an evidence-based synthesis tool to assist clinicians in personalized technique selection. Future research should prioritize defining which technique best suits specific patient phenotypes and functional goals instead of pursuing a universal gold standard.

Introduction

Hip fracture managementremains a major challenge in geriatric anesthesia. With an aging global population, the incidence of proximal femoral fractures is rising, imposing a significant burden on healthcare systems and threatening the functional independence of older adults [1–3]. Beyond skeletal injury, a hip fracture acts as a severe systemic stressor, triggering sympathetic activation, catabolism, and cognitive decompensation [4, 5]. Optimal perioperative pain control is foundational to mitigating adverse outcomes in this vulnerable cohort. While opioid-based regimens have historically been the mainstay of analgesia, their dose-dependent adverse effects (such as respiratory depression, sedation, and delirium) exacerbate frailty and functional decline [6–8]. Consequently, ultrasound-guided fascial plane blocks have evolved from supportive adjuncts to essential components of modern multimodal analgesic and Enhanced Recovery After Surgery (ERAS) pathways [9–11].

Over the past decade, the fascia iliaca compartment block (FICB) has been extensively integrated into clinical pathways. The supra-inguinal approach (S-FICB) is increasingly favored for its superior cranial spread [12, 13]. By delivering a high volume of local anesthetic beneath the fascia iliaca, S-FICB facilitates proximal spread to the lumbar plexus to consistently block the femoral and lateral femoral cutaneous nerves [14]. However, this extensive neural blockade lacks selectivity. The resulting quadriceps weakness is acceptable in bedbound patients but directly conflicts with the early mobilization goals of ERAS protocols [15, 16]. To address this limitation, the introduction of the pericapsular nerve group (PENG) block in 2018 offered a compelling motor-sparing alternative [17]. By specifically targeting the articular branches of the femoral, obturator, and accessory obturator nerves, the PENG block demonstrates clear clinical utility. It provides rapid analgesia, facilitates patient positioning for neuraxial anesthesia, and preserves quadriceps strength [17–19].

While the anatomical advantages of the PENG block are evident, translating them into consistent clinical practice remains complex. Current literature comparing the PENG block to volume-dependent techniques is frequently confounded by heterogeneous fracture subtypes, varying patient baseline functional status, and disparate institutional resources. Viewing these techniques as purely competitive alternatives may not fully capture the clinical reality or the heterogeneous pathophysiology of hip fractures. These complexities demand a tailored approach rather than a universal strategy. Therefore, the choice between these modalities should be a deliberate clinical judgment based on the unique requirements of each case [20–23].

This narrative review provides a comprehensive synthesis of current evidence regarding the comparative roles of ultrasound-guided FICB and PENG blocks. By evaluating existing literature, we identify that the optimal selection of a regional technique depends on a systematic evaluation of multiple clinical dimensions. These findings are organized into a 3P framework representing pathology, patient factors, and performance. Rather than a primary driver of selection, this framework serves as a tool to synthesize evidence informed findings and guide clinicians in navigating the complexities of individualized care.

Methods

We conducted a comprehensive literature search of PubMed, Embase, and the Cochrane Library for articles published between January 2010 and December 2025. The search utilized combinations of MeSH terms and free-text keywords, including “Pericapsular Nerve Group block,” “Fascia Iliaca Compartment Block,” “hip fracture,” and “regional anesthesia.” To ensure a complete evidence base, we manually screened the reference lists of key anatomical and clinical studies to identify additional foundational sources.

Consistent with the standards of a narrative review, our selection process prioritized studies that provided the highest degree of anatomical and procedural clarity. We specifically included randomized controlled trials, prospective observational studies, and cadaveric investigations that examined hip joint innervation or the efficacy of the PENG and FICB techniques. We excluded case reports, conference abstracts, and studies focusing exclusively on elective hip arthroplasty because the nociceptive profiles of elective surgery differ significantly from those of acute hip fractures. The final selection of studies was based on their ability to provide detailed descriptions of needle placement and injectate volumes. This detail was essential for our comparative analysis of clinical outcomes.

A significant limitation in current literature is the frequent lack of differentiation between infra-inguinal and supra-inguinal approaches to the FICB. Because these techniques are anatomically distinct, especially regarding their volume-dependent spread to the lateral femoral cutaneous nerve, electronic indexing often fails to distinguish between them. To address this, we implemented a structured reclassification protocol for all retrieved FICB studies. We scrutinized the procedural methodology of each study and categorized it based on the specific injection site relative to the inguinal ligament. Concurrently, we extracted data on local anesthetic volume and concentration to assess whether the dosing regimens aligned with the intended mechanism of spread. Our synthesis then integrated these categorized clinical findings with cadaveric data to reconcile anatomical rationale with clinical performance. This approach allowed for a robust evaluation of the evidence that ultimately informs the 3P synthesis tool.

Overview of the current evidence landscape

The evolution of regional anesthesia for hip fractures has been shaped by the competing priorities of effective analgesia and motor preservation. For decades, the femoral nerve block (FNB) served as the gold standard. However, its utility was limited by dense quadriceps weakness, which increases the risk of inpatient falls, and by unreliable blockade of the obturator nerve. This left a significant analgesic gap for intracapsular fractures [10, 24–27].

Efforts to address these limitations led to the “3-in-1” block and, subsequently, the FICB [28–31]. While the infra-inguinal FICB reduced the risk of direct neural injury compared to the FNB, it failed to consistently block the proximal obturator branches due to the anatomical barrier of the iliacus muscle [29, 30]. This prompted a shift toward the S-FICB, which employs a proximal injection to facilitate cephalad spread to the lumbar plexus [32]. Although the S-FICB improved coverage of the lateral femoral cutaneous nerve, it remains a non-selective compartment technique. As a result, it frequently causes femoral motor weakness, mirroring the rehabilitation challenges originally observed with the FNB [14, 16, 33].

The introduction of the PENG block marked a fundamental transition from volume-dependent compartment blocks to targeted nerve blockade [17]. Instead of flooding the lumbar plexus, the PENG block targets the terminal articular branches of the femoral, obturator, and accessory obturator nerves within the iliopsoas plane [34]. Theoretically, this dissociates analgesia from motor impairment and offers a direct solution to the limitations of prior techniques. However, as summarized in Table 1, clinical evidence regarding its comparative efficacy remains heterogeneous. Studies frequently employ disparate comparators, varied fracture definitions, and diverse local anesthetic concentrations.

Table 1.

Clinical heterogeneity among studies comparing the PENG block and FICB in hip surgery

Study (author, year)	Study design	Population	Intervention (drug/volume)	Comparator (drug/volume)	Primary outcomes	Key findings
Liao et al. (2025) [35]	RCT (N = 64)	Hip fractures (excl. subtrochanteric, cognitive impairment)	PENG (0.33% ropivacaine, 30 mL)	S-FICB (0.33% ropivacaine, 30 mL)	Block success rate (NRS decrease > 2)	PENG superior to FICB
Li et al. (2025) [36]	Retrospective (N = 216)	THA (fracture + non-fracture; excl. cognitive impairment)	PENG (0.3% ropivacaine, volume NR)	S-FICB (0.3% ropivacaine, volume NR)	Pain scores, quadriceps weakness	PENG superior to FICB
Huang et al. (2025) [37]	RCT (N = 78)	THA (fracture + non-fracture)	PENG (0.5% ropivacaine 10 mL) + LIA (0.25% ropivacaine 20 mL)	S-FICB (0.25% ropivacaine 40 mL) + LIA (saline 20 mL)	Pain scores, quadriceps motor block	PENG + LIA superior to FICB
Esteller et al. (2025) [38]	RCT (N = 68)	Intracapsular hip fractures (excl. cognitive impairment)	PENG (0.2% ropivacaine, 15 mL)	S-FICB (0.2% ropivacaine,15 mL)	Pain scores	PENG superior to FICB
Gedikbaş et al. (2025) [39]	Retrospective (N = 115)	Intertrochanteric fractures	PENG (drug/vol: NR)	S-FICB (drug/vol: NR)	Pain scores, motor block duration	PENG superior to FICB
Vetrone et al. (2025) [40]	Retrospective (N = 80)	THA (non-fracture)	PENG (0.5% ropivacaine, 20 mL) + LFCN (0.5% ropivacaine, 10 mL)	I-FICB (0.5% ropivacaine, 20 mL)	Quadriceps motor block, pain scores	PENG + LFCN superior to FICB
Brueggeman et al. (2025) [41]	Retrospective (N = 2137)	Mixed fractures (excl. dementia)	PENG (catheter, drug/volume: NR)	FICB (unspecified; Catheter, Drug/Volume: NR)	Opioid consumption, Pain scores	PENG superior to FICB
Pavithra et al. (2024) [42]	RCT (N = 80)	Intertrochanteric fractures	PENG (landmark, 0.5% ropivacaine, 30 mL)	I-FICB (landmark, 0.5% ropivacaine, 30 mL)	Positioning comfort, duration of analgesia	PENG superior (positioning); FICB superior (duration)
Baheti et al. (2024) [43]	RCT (N = 60)	Neck of femur fracture	PENG (0.25% levobupivacaine, 20 mL)	I-FICB (0.25% levobupivacaine, 20 mL)	Pain scores during positioning, hemodynamics	PENG superior to FICB
Girombelli et al. (2024) [44]	Retrospective (N = 52)	THA (non-fracture)	PENG (0.5% ropivacaine, 20 mL) + LFCN (0.5% ropivacaine, 10 mL)	FICB (unspecified, 0.5% ropivacaine, 20 mL)	Pain scores, opioid consumption	PENG + LFCN superior to FICB
Keskes et al. (2023) [45]	RCT (N = 89)	Mixed hip fractures (excl. unable to understand VAS)	PENG (0.25% bupivacaine, 10 mL + 2% lidocaine, 10 mL)	S-FICB (0.25% bupivacaine, 10 mL + 2% lidocaine, 10 mL)	Pain scores	PENG superior to FICB
Nuthep et al. (2023) [46]	RCT (N = 59)	Mixed hip fractures (excl. unable to communicate)	PENG (0.25% bupivacaine, 20 mL) + S-FICB (0.25% bupivacaine, 20 mL)	S-FICB (0.3% ropivacaine, 30 mL)	Pain scores, time to sit up	Comparable outcome (PENG added no benefit)
Duan et al. (2023) [47]	RCT (N = 57)	Femoral neck fracture	Continuous PENG (0.25% ropivacaine, bolus 20 mL + catheter) + LIA (0.25% ropivacaine 10 mL)	FICB (0.25% ropivacaine, bolus 30 mL + catheter) + LIA (0.25% ropivacaine 10 mL)	Pain scores, quadriceps strength	PENG superior to FICB
Liang et al. (2023) [48]	RCT (N = 92)	THA (fracture + non-fracture)	PENG (0.33% ropivacaine, 20 mL) + LFCN (0.33% ropivacaine, 10 mL)	S-FICB (0.33% ropivacaine, 30 mL)	Time to first walk, hip flexion/muscle strength, pain scores	PENG + LFCN superior to FICB
Kong et al. (2022) [49]	RCT (N = 50)	PFNA, intertrochanteric fractures (excl. cognitive impairment)	PENG (0.375% ropivacaine, 30 mL)	I-FICB (0.375% ropivacaine, 30 mL)	Pain scores, quadriceps weakness, opioids	PENG superior to FICB
Kalashetty et al. (2022) [50]	RCT (N = 90)	Hip surgeries	PENG (0.25% bupivacaine, 20 mL)	I-FICB (0.25% bupivacaine, 30 mL)	Pain scores	PENG superior to FICB
Mosaffa et al. (2022) [51]	RCT (N = 52)	Mixed hip fractures	PENG (0.5% ropivacaine, 3 mL/kg)	I-FICB (0.5% ropivacaine, 3 mL/kg)	Pain scores	PENG superior to FICB
Senthil et al. (2021) [52]	RCT (N = 40)	Mixed hip fractures (excl. unable to comprehend)	PENG (0.25% levobupivacaine, 30 mL + dexamethasone 4 mg)	I-FICB (0.25% levobupivacaine, 30 mL + dexamethasone 4 mg)	Total fentanyl, pain scores, quadriceps strength	PENG superior to FICB
Jadon et al. (2021) [53]	RCT (N = 66)	Mixed hip fractures (excl. cognitive impairment)	PENG (0.25% bupivacaine, 25 mL + dexamethasone 8 mg)	S-FICB (0.25% bupivacaine, 25 mL + dexamethasone 8 mg)	Pain scores, ease of spinal positioning	PENG superior to FICB

Substantial clinical heterogeneity is evident in both block methodology and pharmacological reporting. FICB techniques are classified as supra-inguinal (S-FICB), infra-inguinal (I-FICB), or not specified. Local anesthetic regimens are reported within parentheses as (drug/volume) to maintain uniformity and facilitate cross-study comparisons. Abbreviations: excl. excluded, FICB fascia iliaca compartment block, I-FICB infra-inguinal FICB, LFCN lateral femoral cutaneous nerve block, LIA local infiltration analgesia, NR not reported, PENG pericapsular nerve group, RCT randomized controlled trial, S-FICB supra-inguinal FICB, THA total hip arthroplasty

A critical confounder contributing to the substantial heterogeneity observed in Table 1 is a procedural mismatch regarding injectate volume. Many randomized controlled trials standardize volumes (typically 20 to 30 ml) across all study arms to maintain blinding [35, 37, 49, 52]. This approach ignores a fundamental mechanistic divergence. The PENG block targets a confined myofascial plane where 15 to 20 ml is anatomically sufficient [18, 54, 55]. Conversely, the S-FICB relies on a “bulk flow” mechanism. Effective cephalad spread to the lumbar plexus roots often necessitates volumes exceeding 40 ml in an S-FICB [14]. Consequently, comparative outcomes in such trials may reflect the under-dosing of the FICB arm rather than the inherent technical advantage of the PENG block. This anatomical mismatch complicates direct comparison. A 20 ml PENG block is an optimized technique, whereas a 20 ml S-FICB is a sub-therapeutic intervention. This discrepancy strongly highlights the need for a structured framework to accurately interpret clinical results.

The “3P Framework”: synthesizing the evidence

The heterogeneity observed in contemporary randomized controlled trials extends beyond volume discrepancies and is further amplified by significant clinical variations, indicating that the optimal utility of the PENG block is governed by specific clinical variables rather than universal superiority. As illustrated in Table 1, current literature frequently combines distinct pathological states and diverse patient selection criteria. The resulting data present conflicting outcomes precisely because clinical efficacy relies heavily on multidimensional variables such as underlying pathology, patient characteristics, and block execution. Consequently, a simplistic ranking of these regional anesthesia techniques is clinically inadequate. To systematically navigate this heterogeneous evidence and translate it into actionable clinical guidelines, we have synthesized these multidimensional factors into a structured paradigm: the pathology-driven, patient-tailored, and performance-oriented (“3P”) framework.

Pathology-driven analysis: aligning block precision with fracture phenotypes

A primary source of clinical heterogeneity in the literature is the aggregation of intracapsular and extracapsular fractures into a single cohort. From a pathophysiological perspective, these entities represent distinct nociceptive phenotypes with fundamentally different analgesic requirements [34, 56, 57].

Intracapsular fractures: targeted denervation and motor preservation

For intracapsular fractures, the primary nociceptive burden originates mainly from the anterior hip capsule. In a recent review regarding the evolution of the technique, Girón consolidated the conceptual basis of the block: targeting the articular branches of the femoral, obturator, and accessory obturator nerves [18]. Furthermore, anatomical validation studies using CT contrast indicate that an injectate volume of approximately 20 ml achieves effective spread to these neural targets in 80–100% of specimens [54, 55, 58]. This pathological congruence, which provides potent analgesia while maintaining the integrity of the functional motor unit, is essential for facilitating early mobilization and reducing the systemic stress response in the elderly population [22, 38, 59, 60].

Extracapsular fractures: the LFCN and the incisional gap

The anatomical selectivity of the PENG block becomes a potential limitation in extracapsular trauma. Intertrochanteric and subtrochanteric fractures involve a more expansive injury pattern where nociceptive signaling originates not only from the capsule but also from the lateral muscular compartments [56, 61].

Furthermore, it is essential to explicitly define the anatomical and clinical role of the LFCN within the context of comprehensive perioperative care. Because this nerve provides purely cutaneous innervation, its blockade does not alleviate deep bone nociception or primary fracture pain. However, regardless of the fracture type or the specific surgical approach utilized, the surgical incisions invariably traverse its sensory territory. Given that a substantial proportion of overall postoperative pain originates directly from these superficial skin incisions and surrounding soft tissue trauma, targeting the lateral femoral cutaneous nerve serves a highly critical and independent role in mitigating surgical incisional pain and optimizing early postoperative comfort. The consistent sparing of the LFCN by the PENG block thus creates a clinically relevant “incisional gap” in procedures requiring extensive lateral dissection [21, 56].

Reconciling clinical discrepancies through phenotypic alignment

This anatomical dichotomy, summarized in Table 2, helps explain the divergent findings in trials comparing the PENG block with the S-FICB. The S-FICB functions as a volume-dependent field block that frequently encompasses the LFCN, providing broader sensory coverage at the expense of potential motor blockade [14, 28]. In study populations dominated by extracapsular injuries, this broader coverage often results in non-inferior dynamic pain scores compared with the PENG block used in isolation [21].

Table 2.

Anatomical and clinical distinctions for guiding regional block selection

Feature	Intracapsular fractures	Extracapsular fractures
Clinical diagnoses	Primarily femoral neck fractures	Intertrochanteric and subtrochanteric fractures
Nociceptive source	Pain originates from the anterior capsule, synovium, and intra-articular ligaments	Pain involves the greater trochanter, lateral femoral wall, and periosteum
Surgical dissection	Trauma is confined to the deep joint space with minimal lateral soft tissue disruption	Extensive incision involves the fascia lata, tensor fasciae latae, and vastus lateralis
Target innervation	Restricted to high articular branches of the FN, ON, and AON	Includes articular branches plus the LFCN and lateral afferents
PENG block	Provides site-specific capsular analgesia while preserving motor function	Leaves an “incisional gap” due to failure to block the LFCN and lateral skin
S-FICB	Offers inconsistent obturator nerve coverage with unnecessary motor block	Relies on volume-dependent spread to effectively cover the LFCN and surgical site

Abbreviations: AON accessory obturator nerve, FN femoral nerve, LFCN lateral femoral cutaneous nerve, ON obturator nerve, PENG pericapsular nerve group, S-FICB supra-inguinal fascia iliaca compartment block

These observations suggest that regional anesthesia selection should be guided by phenotype-specific alignment. The PENG block appears optimal when the nociceptive burden is predominantly capsular and motor preservation is a priority. Conversely, extracapsular injuries may require a more integrated strategy, such as a combined approach that supplements the PENG block with targeted LFCN blockade, to ensure comprehensive modulation of both deep and superficial surgical insults [48, 62].

Patient-tailored synthesis: physiological reserve and frailty

While fracture pathology defines the anatomical requirements for analgesia, patient-specific physiological reserve determines the clinical value of the intervention. A critical examination of the literature reveals a gap between reported efficacy and real-world effectiveness. This discrepancy is driven largely by the systematic underrepresentation of the demographic most frequently encountered in hip fracture care: older adults with cognitive impairment and advanced frailty [63, 64].

Frailty and cognitive impairment: the evidence gap

Epidemiological studies indicate that up to 40% of patients presenting with proximal femoral fractures have preexisting dementia or significant cognitive impairment [63–65]. Despite this, systematic reviews demonstrate that many randomized trials in regional anesthesia exclude these patients. The rationale for exclusion frequently cites the inability to provide informed consent or the failure to comprehend and cooperate with pain assessment scales [10, 63]. Detailed analyses of trial eligibility criteria further identify the “inability to follow instructions” as a recurrent reason for exclusion [35, 36, 38, 45, 46, 63].

This methodological filtering creates a cohort whose physiological vulnerability and care priorities are not adequately reflected in trial-derived outcomes. For these high-risk patients, geriatric consensus guidelines emphasize that the primary objectives of analgesia extend well beyond numerical pain scores. Key goals include the prevention of delirium, functional decline, and the loss of independent living [9, 11].

However, exceptions to this trend offer critical insights [66–68]. Unneby and colleagues specifically recruited patients with dementia to investigate whether the FNB could mitigate postoperative delirium [67]. Notably, they found no significant difference in delirium incidence between the block group and conventional analgesia. This finding is pivotal: it suggests that while regional anesthesia is essential for nociceptive control, it is not a panacea for cognitive dysfunction in patients with established neurodegeneration. In this vulnerable demographic, the pathophysiology of delirium is likely driven by multifactorial insults, including hospitalization stress and polypharmacy, that extend beyond pain alone. This underscores that for patients with limited cognitive reserve, the value of a nerve block should be evaluated within a broader, geriatric-focused multimodal strategy rather than as a standalone preventive measure for delirium [69]. Consequently, the choice between the PENG block and the FICB assumes significance not merely as a question of sensory coverage, but as a determinant of whether limited physiological and functional reserves are preserved.

Physiological reserve and motor preservation

In physiologically robust individuals, quadriceps weakness following an FICB may represent a minor inconvenience. In contrast, for frail older adults operating close to the threshold of immobility, even modest iatrogenic reductions in quadriceps strength can have disproportionate consequences [69]. The concept of physiological reserve provides a useful explanatory framework here: frail individuals lack the physiological redundancy required to accommodate additional functional insults [70, 71].

By preferentially sparing motor branches, the PENG block directly aligns with this constraint. Kinematic and functional studies suggest that relatively small differences in quadriceps strength can determine whether a patient is able to perform essential early mobility tasks, such as a stand-pivot transfer, on the first postoperative day [72]. Although the relative analgesic efficacy of the PENG block versus the S-FICB remains debated in younger or more robust cohorts, its motor-sparing profile may confer a highly meaningful safety advantage in patients with sarcopenia, preexisting neurological deficits, or limited baseline mobility [22, 23]. Given the established association between early mobilization and reduced length of stay, fewer pulmonary complications, and decreased rates of institutionalization, motor preservation emerges as a clinically critical outcome in its own right [73, 74].

Delirium and neurocognitive outcomes

Beyond motor function, the choice of regional analgesic strategy may influence neurocognitive recovery. Postoperative delirium remains the most common complication following hip fracture surgery and is independently associated with increased mortality, prolonged hospitalization, and long-term cognitive decline [75]. Its pathophysiology is closely linked to poorly controlled pain, opioid exposure, and the resulting neuroinflammatory cascade [6, 76].

While Unneby’s study highlights the inherent difficulty of preventing delirium in patients with pre-existing dementia, the broader clinical objective of mitigating perioperative neurocognitive decline remains highly relevant [67]. Recent data suggest that the PENG block may contribute to this goal by preserving early postoperative cognitive function. A recent randomized controlled trial involving elderly hip surgery patients demonstrated significantly higher MMSE scores and a lower incidence of perioperative neurocognitive disorder (PND) in those receiving PENG blocks compared with control groups [77]. These improvements were associated with attenuated levels of proinflammatory mediators, such as high-mobility group box 1 (HMGB1), suggesting that effective regional analgesia helps modulate the systemic inflammatory response. By shielding the aging brain from surgical stress, the PENG block represents a promising strategy to improve neurocognitive outcomes and enhance postoperative recovery in this vulnerable population [77–79].

Collectively, these divergent findings suggest a nuanced reality: while targeted regional blocks can attenuate the neuroinflammatory drivers of delirium, their protective effect is heavily modulated by the patient's baseline cognitive reserve. This reinforces the need for precision in technique selection, prioritizing strategies that minimize opioid requirements and facilitate early mobilization, while acknowledging that in high-risk groups, anesthetic interventions are but one component of comprehensive delirium prevention.

Complementary studies assessing patient-centered outcomes, such as the Quality of Recovery-15 (QoR-15) score, further indicate that opioid-sparing strategies are associated with improved early recovery profiles [80]. These observations align with longitudinal data emphasizing the importance of comprehensive pain management in reducing the risk of persistent postsurgical pain and cognitive deterioration in vulnerable older adults [81].

Performance-oriented outcomes: a matrix of clinical trade-offs

Evaluating regional analgesia must extend beyond static pain scores to functional performance. No single block simultaneously optimizes all clinically relevant outcomes. Instead, the existing evidence describes a matrix of trade-offs across multiple domains, where analgesic completeness, motor preservation, procedural facilitation, and rehabilitation feasibility must be balanced. In this framework, the ultimate determinant of clinical success is not analgesia in isolation but its alignment with perioperative and rehabilitative workflows [18, 82].

Procedural facilitation: positioning for neuraxial anaesthesia

The ability to position a patient comfortably for spinal anesthesia often represents the earliest functional test of analgesic performance. This maneuver generates intense dynamic nociceptive input that substantially exceeds pain at rest. Across randomized comparative studies, the PENG block has consistently been associated with superior analgesic conditions for sitting positioning when compared with the FICB [45, 83].

Importantly, this advantage appears to be biomechanical rather than purely sensory. Unlike the FICB, which frequently induces quadriceps weakness, the PENG block preserves sufficient motor tone to allow patients to actively assist with maintaining a seated posture [53]. This active participation reduces the physical burden on nursing staff, facilitates safer positioning, and reduces reliance on intravenous analgesics, thereby contributing to improved hemodynamic stability during neuraxial block placement [84]. In this critical procedural window, the PENG block demonstrates a notable performance advantage.

Translating motor sparing into functional recovery

Although motor-sparing techniques are promoted for facilitating early mobilization, their theoretical advantages do not always translate into real-world rehabilitation gains [22, 27]. The benefit conferred by quadriceps sparing represents a finite window of opportunity, especially as the motor blockade associated with a single-shot S-FICB typically resolves within 6 h. In the context of geriatric frailty, this brief period of motor impairment may be clinically negligible, as these patients are rarely candidates for immediate postoperative ambulation. Evidence suggests that this potential benefit is frequently lost when institutional protocols do not mandate immediate physiotherapy or when staffing constraints delay mobilization [73, 84]. This is particularly salient in resource constrained settings where the implementation of best clinical practices for hip fracture management is often hindered by systemic barriers and organizational factors rather than the specific choice of regional technique [85].

In such passive recovery environments, where trauma pathways have not yet integrated formal accelerated recovery protocols, the selective sensory profile of the PENG block becomes less favorable. Its consistent sparing of the LFCN leaves lateral wound and soft-tissue pain insufficiently covered, a phenomenon clinically reflected as residual “incisional escape” pain [56]. Without early mobilization to counterbalance this somatic pain through movement-related analgesia, the trade-off shifts. Under these conditions, the broader sensory coverage of the S-FICB may provide superior overall comfort despite its associated motor impairment [21].

These observations highlight a critical principle: the performance value of a motor-sparing block is inseparable from the velocity and reliability of the rehabilitation pathway. Motor preservation confers benefit only when it is actively exploited.

Context-dependent technique selection

Analgesic techniques do not exist in isolation; their clinical value is determined by how well their pharmacological and functional profiles align with the demands of care pathways. The PENG block performs optimally in environments characterized by early mobilization, adequate physiotherapy resources, and a focus on maintaining patient autonomy [15]. In contrast, when early rehabilitation is unlikely or delayed, a strategy prioritizing the comprehensive sensory coverage of the FICB may better align with performance goals.

Thus, performance outcomes should not be viewed merely as an extension of pain scoring, but as an integrative endpoint reflecting how analgesia interacts with procedural demands and institutional capacity. Within this trade-off framework, neither the PENG block nor the S-FICB emerges as universally superior. Rather, each demonstrates context-dependent advantages that must be interpreted within the broader clinical setting.

Discussion

The expanding literature on regional analgesia for hip fractures reflects a field grappling with how data should be interpreted, rather than a lack of evidence. The ongoing debate surrounding the PENG block exemplifies this challenge. Despite increasing anatomical validation and supportive clinical trial evidence, its role relative to FICB-based techniques remains variable. This variability appears to arise less from intrinsic inconsistency within the evidence, and more from the use of evaluative frameworks insufficiently aligned with clinical complexity. To facilitate interpretation, the pathology-driven, patient-tailored, and performance-oriented (3P) framework offers a structured approach (Fig. 1).

Fig. 1.

The “3P” framework for hip fracture analgesia decision-making. This conceptual model guides analgesic selection by integrating three interdependent domains: pathology-driven considerations (fracture phenotype and nociceptive architecture), patient-tailored factors (physiological reserve and frailty), and performance-oriented goals (rehabilitation logistics). By synthesizing these elements, the diagram demonstrates how the choice between the pericapsular nerve group (PENG) block, supra-inguinal fascia iliaca compartment block (S-FICB), and hybrid strategies (e.g., PENG + lateral femoral cutaneous nerve [LFCN] block) is determined by clinical synthesis and contextual alignment, rather than anatomical assumptions alone. Abbreviations: LFCN, lateral femoral cutaneous nerve block; PENG, pericapsular nerve group; S-FICB, supra-inguinal fascia iliaca compartment block

Synthesising the evidence

When the available evidence is examined through this framework, several insights emerge. From a pathological perspective, a hip fracture does not represent a single analgesic entity. Intracapsular and extracapsular fractures differ fundamentally in their nociceptive architecture, yet they are frequently analyzed as a homogeneous group. In settings constrained by pathology, particularly isolated intracapsular fractures, the selective sensory profile of the PENG block aligns closely with the dominant pain generators [18]. This offers a coherent explanation for its favorable analgesic profile and relative preservation of motor function.

Patient-level factors further modulate clinical relevance. Much of the current evidence is derived from cognitively intact and physiologically robust individuals. In contrast, real-world hip fracture care is largely delivered to patients with frailty and limited physiological reserve. Within this population, outcomes such as early mobilization and delirium prevention assume greater importance than pain intensity alone [69, 74]. Consequently, the preservation of motor function represents a critical mechanism for protecting physiological reserve, rather than a mere marginal technical advantage.

Furthermore, analgesic value is realized only when it aligns with procedural demands and rehabilitation pathways. The functional benefits of motor sparing are inherently time-dependent and contingent on the feasibility of early mobilization. When mobilization is delayed or impractical, broader sensory coverage may better support patient comfort, regardless of motor consequences. This reinforces the premise that block performance is not a fixed property of the technique itself, but an emergent characteristic shaped by anatomy, patient reserve, and systems of care.

Clinical implementation and safety

Several practical factors arise at the interface between these dimensions and real-world implementation. Issues such as early application in the emergency department, vascular safety in anticoagulated patients, and the trade-offs between single-shot and continuous catheter techniques all influence delivery [11, 86]. While these considerations do not redefine the fundamental merits of individual blocks, they heavily shape how theoretical advantages translate into clinical workflows. Their role is best understood as modifying feasibility, safety, and implementation fidelity, rather than determining block selection in isolation.

Collectively, the evidence suggests that many apparent discrepancies within the literature reflect differences in clinical context that are not adequately captured by conventional outcome measures. By situating analgesic performance within its anatomical, patient, and system-dependent context, the 3P framework explains why regional blocks may appear to perform inconsistently across studies without requiring resolution through forced assertions of technical superiority.

Navigating guideline discrepancies and evolving evidence

While our conceptual framework highlights the precise anatomical advantages of the pericapsular nerve group block for intracapsular fractures, we must acknowledge the conservative stance of the 2021 PROSPECT guidelines regarding its routine application. This discrepancy largely stems from a chronological gap in the literature. The PROSPECT recommendations were formulated based on literature available prior to 2021, a phase primarily focused on anatomical validation and preliminary feasibility. However, the subsequent years have witnessed a paradigm shift with a surge in high-quality randomized controlled trials and network meta-analyses. These recent studies explicitly demonstrate the clinical advantages of the pericapsular nerve group block in head-to-head comparisons, particularly concerning motor function preservation and the optimization of Enhanced Recovery After Surgery protocols. Therefore, to bridge the gap between established population-based guidelines and recent clinical advancements, our framework incorporates this newly evolved evidence to guide modernized and individualized clinical decision-making.

The emergence of the PENG block represents a sophisticated evolution in the analgesic management of hip fractures, offering a targeted approach to the sensory innervation of the hip capsule. This technique is increasingly supported by high quality clinical trials that demonstrate its efficacy in providing effective pain relief. However, the interpretation of its overall impact must account for the diverse methodologies employed across different clinical settings. The current evidence base, while promising, is characterized by variations in injectate volumes and patient demographics, which can lead to divergent results in secondary outcomes. Rather than establishing a singular gold standard, the PENG block is best understood as a highly effective and anatomically precise tool that expands the clinician’s repertoire alongside traditional techniques like the fascia iliaca compartment block. A critical appraisal suggests that while the anatomical rationale and growing evidence for PENG are compelling, the integration of these findings requires a careful consideration of the study limitations and heterogeneity.

Limitations and future directions

The synthesis of evidence in this review is constrained by the methodological heterogeneity and varying sample sizes inherent to current regional anesthesia literature. While the inclusion of both randomized trials and retrospective data provides a broad clinical overview, these diverse study designs and occasionally underpowered cohorts limit the feasibility of a formal quantitative meta-analysis. This review instead adopts a qualitative framework that prioritizes mechanistic plausibility, using anatomical insights to reconcile divergent clinical findings. Such an approach acknowledges the fragmented nature of the current evidence while identifying the specific knowledge gaps that future research must address through more standardized protocols and larger patient populations. Additionally, a notable limitation of this review is its primary focus on conventional anterior fascial plane blocks typically initiated by anesthesia providers. Consequently, the expanding and critical role of perioperative, ultrasound-guided local infiltration analgesia was not fully synthesized within this scope [87, 88]. Omitting a comprehensive appraisal of these joint-targeted and pericapsular infiltration techniques inherently constrains the holistic view of multimodal pathways available for frail older adults.

A primary area for future investigation is the transition from surrogate markers to patient-centered endpoints. Most current studies rely on static pain scores and opioid consumption, which do not fully reflect the quality of recovery for hip fracture patients. Future large-scale trials should prioritize outcomes with greater functional relevance, such as the incidence of chronic postsurgical pain, cognitive trajectories, and the return to prefracture living status during long term follow up [89–93]. Furthermore, the phenomenon of rebound pain after block resolution requires focused study to determine whether it stems from neurophysiological hyperalgesia or gaps in transitional care [90, 94–97]. Addressing this transition is critical, as extending sensory blockade alone via liposomal formulations may merely delay rather than prevent pain escalation [98, 99].

Accordingly, the next frontier in regional anesthesia research involves refining exit strategies through the integration of perineural adjuvants, extended-release formulations, and continuous catheter techniques [100, 101]. While continuous blocks offer a more gradual offset that may mitigate rebound pain, they introduce trade-offs related to mobility and management burden. The ultimate goal is to move beyond simple block initiation and develop structured transitional protocols tailored to specific patient phenotypes. Investigating the clinical synergy between anesthesiologist-performed fascial blocks and surgeon-directed local infiltration analgesia pathways remains a vital frontier for geriatric hip fracture trial design. By focusing on the quality of the analgesic transition and the long-term functional trajectory, future research can ensure that regional techniques provide a meaningful and sustained impact on the recovery of the geriatric population.

Conclusion

Current evidence suggests that no single technique serves as a universal “gold standard” for hip fracture analgesia. Instead, clinical success depends on the complex interaction between fracture pathology, patient physiology, and specific performance goals. The 3P framework integrates these factors into a practical tool to guide individualized block selection, moving the clinical focus away from a one-size-fits-all approach. While this evidence informed synthesis provides a structured foundation for decision making, it currently functions as a hypothesis generating model. Future research is now required to prospectively validate these 3P variables and determine their definitive impact on long term functional outcomes in the geriatric population.

Abbreviations

3P

Pathology-driven, patient-tailored, and performance-oriented

ERAS

Enhanced Recovery After Surgery

FICB

Fascia iliaca compartment block

FNB

Femoral nerve block

I-FICB

Infra-inguinal fascia iliaca compartment block

LFCN

Lateral femoral cutaneous nerve

PENG

Pericapsular nerve group

QoR-15

Quality of Recovery-15

S-FICB

Supra-inguinal fascia iliaca compartment block

Authors' contributions

J.L. and J.J. contributed to the conceptualization, methodology, and investigation, and wrote the main manuscript text. J.B. and L.B. contributed to the conceptualization, provided supervision, and critically reviewed and edited the manuscript. J.L. and J.J. contributed equally to this work. J.B. and L.B. contributed equally as corresponding authors. All authors reviewed the manuscript.

Funding

Not applicable.

Data availability

No datasets were generated or analyzed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.