Perioperative analgesia with combined Pericapsular Nerve Group (PENG) and lateral femoral cutaneous nerve blocks in pediatric femoral neck surgery: a two-case report

Abstract

Background

The importance of regional anesthesia techniques is increasing as part of multimodal analgesia strategies for managing postoperative pain in pediatric hip and femur surgeries.

Case presentation

We aim to present two cases, aged 10 years and 18 months, scheduled for surgery due to femoral neck fractures. As part of multimodal pain management, ultrasound-guided PENG + LFCN blocks were performed in both cases. Postoperative pain was assessed using VAS and FLACC scales.

Conclusions

Our observations in these two cases suggest that the combined administration of PENG and LFCN blocks may serve as a valuable adjunctive strategy in the multimodal analgesia management of pediatric femoral neck fractures. Nevertheless, further large-scale clinical studies are warranted to more clearly delineate the efficacy and safety profile of this combination in routine clinical practice.

Background

Postoperative pain is significant in pediatric hip and femur surgeries, as it is frequently of moderate to severe intensity [1, 2]. Because opioids are commonly preferred for the management of this pain, side effects such as nausea, vomiting, sedation, and respiratory depression may occur, potentially adversely affecting the recovery process [1–3]. Therefore, the importance of multimodal analgesia—and consequently regional anesthesia techniques—has increased in pediatric anesthesia to reduce opioid use.

The Pericapsular Nerve Group (PENG) block is an ultrasound-guided regional anesthesia technique that targets the articular branches of the femoral nerve (FN), obturator nerve (ON), and accessory obturator nerve (AON), which innervate the anterior capsule of the hip joint. It was first described by Rafael Girón-Arango and colleagues in 2018 to provide analgesia in patients with hip fractures [1, 4, 5]. While selectively blocking the nerves responsible for the sensory innervation of the hip, it preserves motor function because it does not affect the main trunks of the femoral and obturator nerves. Compared with femoral nerve blocks, its major advantages include enabling early postoperative mobilization and allowing earlier and easier neurological assessment. These benefits positively influence the rehabilitation process, particularly in pediatric patients in whom early mobilization is important [2, 3].

Although the PENG block provides effective analgesia for the hip capsule, it does not cover the anterolateral aspect of the thigh where surgical incisions are commonly located. Therefore, it can be combined with a lateral femoral cutaneous nerve (LFCN) block, which provides analgesia to this region, resulting in more comprehensive analgesia for the hip area [1–4, 6].

In this report, we aimed to present two pediatric cases who underwent surgery for femoral neck fractures.

As per institutional regulations, formal ethical approval was not mandatory for this case report. Written informed consent for publication was obtained from the patients’ parents. The work adhered to the ethical standards of the Declaration of Helsinki.

Case 1

A 10-year-old, 25-kg male patient scheduled for femoral nailing due to a femoral neck fracture was included. After ensuring sterile conditions, the iliopsoas tendon and the lateral femoral cutaneous nerve (LFCN) were identified using a 12–15 MHz high-frequency linear ultrasound (US) probe. Preoperatively, PENG and LFCN blocks were administered to the patient in the supine position. Under ultrasound guidance, the needle was advanced beneath the iliopsoas tendon using an in-plane technique with a 22G 50-mm echogenic block needle, and 0.5 mL/kg of 0.25% bupivacaine was administered. In the same plane, the needle was retracted, and 0.3 mL/kg of 0.25% bupivacaine was injected into the adipose tissue surrounding the lateral femoral cutaneous nerve (Table 1).The patient’s surgery lasted 2 h and 50 min. During the operation, anesthesia was maintained with 1 MAC sevoflurane and remifentanil infusion at 0.05–0.25 µg/kg/min, titrated according to hemodynamic response, with a total remifentanil consumption of 500 µg. At the end of the procedure, 600 mg of acetaminophen was administered for multimodal analgesia. An intravenous fentanyl patient-controlled analgesia (PCA) device was prepared according to the patient’s body weight (PCA settings: 10 µg loading dose, 5 µg bolus, 8–10 min lockout). In the early postoperative period, the quality of the block was verified using cold-heat and pinprick tests over the anterolateral aspect of the thigh, corresponding to the surgical incision site and the LFCN dermatome (L2-L3). The patient was monitored for 42 h. Hemodynamic parameters remained stable. The Visual Analog Scale (VAS) scores were 0 at postoperative hours 1, 2, 6, and 12, increasing to 5 at 24 h (Table 2). Apart from acetaminophen administered three times daily, the patient received a total of three PCA boluses (two within the first 24 h), consuming 25 µg of fentanyl. At 42 h postoperatively, the patient was pain-free and, with surgical clearance, was discharged with appropriate recommendations.

Table 1.

Clinical and Perioperative Characteristics of the Cases

Parameter	Case 1	Case 2
Sex	Male	Male
Age	10 years	18 months
Weight	25 kg	10 kg
ASA Physical Status	I	I
Comorbidity	None	None
Type of Surgery	Femoral fracture / Intramedullary nailing	Femoral fracture / Implant removal
Duration of Surgery	2 h 50 min	30 min
Type of Anesthesia	General anesthesia + PENG + LFCN block	Sedoanalgesia + PENG + LFCN block
Local Anesthetic Type and Dose	PENG: 0.5 mL/kg of 0.25% bupivacaine LFCN: 0.3 mL/kg of 0.25% bupivacaine	PENG: 0.5 mL/kg of 0.25% bupivacaine LFCN: 0.3 mL/kg of 0.25% bupivacaine

Table 2.

Case 1 VAS Scale

Hour	1st	2nd	3rd	4th	5th	6th	12th	24th	48th
VAS	0	0	0	0	0	0	0	5	discharged

Case 2

An 18-month-old male patient weighing 10 kg had previously undergone closed reduction and internal fixation for a traumatic femoral neck fracture and was scheduled for removal of the fixation devices. After obtaining written informed consent from the family, standard hemodynamic monitoring was applied. Nasal oxygen supplementation was provided at 2 L/min. Sedoanalgesia was administered with 0.1 mg/kg midazolam and 1 mg/kg ketamine, appropriate for the surgical procedure. After ensuring aseptic conditions under ultrasound guidance, the inguinal region was scanned. The inguinal region was scanned under ultrasound guidance with the patient in the supine position. After identifying the anterior inferior iliac spine, the linear US probe was rotated in a cranio-caudal direction to visualize the femoral artery, vein, nerve, iliopsoas tendon, and lateral femoral cutaneous nerve (LFCN) in the same plane. To avoid multiple needle insertions and minimize the risk of vascular injury, PENG and LFCN blocks were performed through a single entry point using an in-plane technique with a 22G 50-mm echogenic needle. First, 0.5 mL/kg of 0.25% bupivacaine was injected beneath the iliopsoas tendon over the iliopubic eminence. Subsequently, without withdrawing the needle from the skin, it was retracted and 0.3 mL/kg of 0.25% bupivacaine was administered around the LFCN, which was visualized near the rectus muscle (Table 1). The surgical procedure lasted 30 min, and no additional perioperative analgesic was required. Intraoperative and postoperative hemodynamic parameters were stable and remained within the age-appropriate normal range. In the postoperative period, the patient remained comfortable, with pain assessed using the Face, Legs, Activity, Cry, Consolability (FLACC) scale, showing scores ranging from 0 to 2 during the first 12 h, and only scheduled paracetamol was administered for analgesia. (Table 3). No block-related complications or motor weakness were observed, and the patient was discharged with recommendations at postoperative hour 12 on the following day (Figs. 1 and 2).

Table 3.

Case 2 FLACC Scale

Hour	1st	2nd	3rd	4th	5th	6th	12th	24th	48th
FLACC	0	0	0	0	0	0	2	discharged

Fig. 1.

Pericapsular nerve group (PENG) block

Fig. 2.

Lateral Femoral Cutaneous Nerve (LFCN) block

Discussion and conclusion

Although the PENG block is well established in the adult literature, evidence supporting its use in the pediatric population remains limited. Most existing reports have focused on school-aged children [1, 2, 4]. Data on the combined use of PENG and LFCN blocks in children under five years of age—as exemplified by Case 2 (18 months old)—are particularly scarce [3].

Sonoanatomic studies in young children have demonstrated that the femoral nerve lies in close proximity to the target site (iliopsoas notch), indicating that local anesthetic dosing (mg/kg) must be carefully titrated [2]. Aksu et al. have described performing both blocks through a single needle insertion [7]. Our cases extend this approach to the pediatric population. No complications or signs of local anesthetic toxicity were observed with the doses used in our patients.

Beltramini et al. reported that VAS can be used for pain assessment in pediatric patients aged six years and older [8]. Reports also recommend the FLACC scale for evaluating postoperative pain in children between two months and seven years of age [9]. In our study, VAS was used to assess pain in the first case, whereas FLACC was employed for the second case, who was 18 months old.

Roy et al., in their published case series, reported that the combined use of PENG and LFCN blocks may provide more effective analgesia in hip surgery [10]. The combination of PENG and LFCN blocks may contribute to a reduction in opioid consumption in pediatric cases undergoing surgery for femoral fractures. For example, Orozko et al. reported an 8-year-old case in which the PENG + LFCN combination provided adequate analgesia, with no need for any analgesics or opioids during the first 72 h postoperatively [11]. Similarly, Domagalska et al. emphasized that the PENG block enabled opioid-free pain management in children aged 2 and 4 years [12]. Other reports in the literature also indicate that the PENG block significantly reduces opioid consumption. Bunnell et al. reported in a case series that one of three pediatric patients required no opioids, whereas in the other two patients, the first opioid requirement was relatively delayed, occurring 12–17 h postoperatively [4]. Similarly, in our series, Case 1 required only a low dose of supplemental opioid, indicating that while this technique may not ensure opioid-free recovery in all patients, it may contribute to a clinically meaningful reduction in overall opioid consumption.

The combination of PENG and LFCN blocks through a single needle insertion may be considered a noteworthy technical option in pediatric regional anesthesia, as it potentially minimizes procedural invasiveness. The successful implementation of this ‘single-needle’ approach in an 18-month-old patient (Case 2) provides an indication of its practical feasibility in young children. Furthermore, this method may hold clinical value by limiting the number of needle passes, thereby carrying the potential to reduce tissue trauma and the risk of possible procedural complications [7].

Despite the clinical significance of our findings, this study has several limitations that should be acknowledged. First, the extremely small sample size (n = 2) inherently limits the statistical power and the ability to draw definitive conclusions. Second, the absence of a control or comparison group makes it difficult to ascertain whether the observed outcomes were solely attributable to the intervention or other confounding factors. Finally, the short follow-up duration (≤ 48 h) restricts our understanding of the long-term efficacy and potential delayed adverse effects of the treatment. Consequently, these findings may not be fully generalizable to the broader pediatric population. Further large-scale, controlled studies with extended follow-up periods are warranted to validate these preliminary observations and establish more robust clinical guidelines.

In summary, the combined use of PENG and LFCN blocks may represent a potentially safe and effective strategy for perioperative analgesia in pediatric femoral neck surgery. These cases suggest that this technique may have the potential to reduce opioid requirements. Although the observed outcomes are promising, large-scale randomized controlled trials are needed to determine whether this approach could establish a new standard in pediatric anesthesia practice.

Authors’ contributions

OPK wrote the main manuscript text, prepared figures, tableHK wrote the main manuscript text, prepared figuresAll authors reviewed the manuscript.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Data availability

All relevant data are included within the article.

Declarations

Ethics approval and consent to participate

Ethical approval was not required due to the nature of this case report.

Consent for publication

Written informed consent was obtained from the patients’ parents for publication of clinical details and images.

Competing interests

The authors declare no competing interests.