Ultrasound-guided treatment for pediatric phalangeal and metatarsal fractures

Abstract

Objective

This study aimed to compare the effectiveness of ultrasound-guided closed reduction and fixation versus traditional techniques in managing pediatric phalangeal and metatarsal fractures.

Methods

This retrospective study included 112 pediatric patients with phalangeal or metatarsal fractures treated between January 2020 and December 2023. The participants were categorized into two groups: the ultrasound-guided group (US-guided; n = 50, including 37 with phalangeal and 13 with metatarsal fractures) and the conventional fluoroscopy-guided group (C-group; n = 62, including 32 with phalangeal and 30 with metatarsal fractures). The collected data included surgical time, frequency of X-ray examinations, radiation exposure, closed reduction rate, complication rate, and postoperative function. Postoperative functional outcomes were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) scoring system.

Results

Surgical time was significantly shorter in the US-guided group (average 44.36 ± 15.23 min) than in the C-group (average 59.15 ± 18.85 min; p < 0.001). Additionally, the US-guided group required approximately four fewer X-ray examinations (2.98 ± 0.94 vs. 7.31 ± 1.47, p < 0.001). Radiation exposure was significantly lower in the US-guided group (1.73 ± 0.54 mGy) than in the C-group (4.24 ± 0.85 mGy, p < 0.001). In the US-guided group, the surgical time for phalangeal fractures was shorter than that for metatarsal fractures (41.08 ± 14.17 min vs. 53.69 ± 14.74 min, p = 0.009). However, there were no significant differences in the closed reduction rate (US-guided group vs. C-group; 92% vs. 80.6%, p = 0.08), AOFAS score (93.6 ± 7.81 vs. 94.16 ± 5.27, p = 0.65), or complication rate (2% vs. 3.2%, p = 0.69).

Conclusion

Ultrasound-guided closed reduction and fixation significantly shortened surgical time, reduced X-ray frequency and radiation exposure versus fluoroscopy-guided treatment. With additional advantages in efficiency, simplicity and reproducibility, this approach appears to be a safe and effective option for pediatric phalangeal and metatarsal fractures.

Introduction

Foot fractures represent approximately 5–8% of all pediatric fractures, with growth plate involvement in around 7% of cases. Among these injuries, forefoot fractures, which include phalangeal and metatarsal fractures, are the most common acute injuries of the foot [1]. Specifically, acute phalangeal fractures constitute 3% to 4% of all traumatic fractures, predominantly affecting the first and fifth toes [2]. In comparison, metatarsal fractures account for approximately 61% of all foot fractures [1]. Most of these fractures can be effectively treated conservatively with non-weight-bearing immobilization with a cast for 4–6 weeks [2, 3]. However, fractures exhibiting displacements greater than 3–4 mm or angulations exceeding 10° in the sagittal plane require reduction and fixation [4–7].

Fluoroscopy is currently considered the standard technique for guiding closed reduction and fixation for pediatric forefoot fractures. However, it is associated with substantial challenges, mainly related to ionizing radiation exposure, which can increase the risk of radiation-induced tissue damage and long-term complications [8, 9]. In contrast, ultrasound (US) provides real-time imaging without radiation exposure and is widely accessible and cost-effective [10, 11]. Additionally, US has demonstrated sufficient reliability and accuracy in diagnosing pediatric elbow fractures [12–14]. While several studies have reported on the effectiveness and reliability of US-guided reduction in treating various pediatric fractures [15, 16], recent research has also shown that US evaluations achieve diagnostic accuracy comparable to that of radiographs in detecting forefoot fractures [17–19]. Nevertheless, to our knowledge, no studies have specifically investigated the use of US-guided techniques for the treatment of pediatric phalangeal and metatarsal fractures. We hypothesize that US-guided closed reduction and fixation reduces radiation exposure, may shorten surgical time, and achieves procedural efficiency, reproducibility, and ease of implementation comparable to traditional fluoroscopy. To test this hypothesis and address the aforementioned knowledge gap, this study aimed to compare the efficacy of US-guided closed reduction and fixation with that of conventional fluoroscopy-guided techniques in the management of pediatric phalangeal and metatarsal fractures.

Patients and methods

Study design

We conducted a comprehensive, retrospective review of patient records from January 2020 to December 2023 at our hospital. Ethical approval was obtained from the hospital’s ethics committee (2024R134-E01) to ensure that the study was conducted in strict adherence to ethical standards. Written consent for the use of patient data for research purposes was obtained from the legal guardians of all the pediatric participants.

The inclusion criteria were as follows: (1) age under 16 years and (2) fresh fractures with a displacement of more than 3–4 mm or angulation greater than 10° in the sagittal plane. All initial diagnostic imaging was performed using radiographs; ultrasound was employed solely for real-time intraoperative guidance. The exclusion criteria included (1) open fractures, (2) fractures with bony callus formation, (3) pathological fractures, (4) metatarsal fractures associated with Lisfranc injuries, (5) fractures with neurovascular compromise, and (6) incomplete follow-up data. Following application of these criteria, 112 patients were enrolled in the study: 77 with phalangeal fractures and 35 with metatarsal fractures. The participants were categorized into two groups: the ultrasound-guided group (US-guided, n = 50, including 37 with phalangeal and 13 with metatarsal fractures) and the conventional fluoroscopy-guided group (C-group, n = 62, including 32 with phalangeal and 30 with metatarsal fractures).

Surgical procedures

US-guided techniques

All procedures were performed by a single surgical team proficient in musculoskeletal ultrasound for diagnosing fractures. US-guided procedures were conducted by two orthopaedic surgeons, each with over five years of musculoskeletal ultrasound experience and at least two years of focus on US-guided fracture reduction. Additionally, both surgeons had independently completed more than 100 fluoroscopy-guided closed reductions and fixations, ensuring extensive expertise in both imaging modalities. The Procedures were performed using a portable GE LOGIQ e ultrasound system (GE Healthcare, Milwaukee, WI, USA) equipped with an L8-18i-RS high-frequency linear array transducer (bandwidth: 6.7–18.0 MHz; footprint: 34.8 mm × 11.1 mm; GE Healthcare Japan). Throughout the study, the transducer was operated within a frequency range of 7–11 MHz to optimally visualize the superficial phalangeal and metatarsal structures. Key anatomical structures were identified based on their echogenic characteristics throughout the ultrasound examination. Specifically, the dense bone cortex appeared hyperechoic, with a continuous bright cortical line serving as the primary landmark for accurately locating the fracture. Cortical disruption manifested as breaks in this hyperechoic line, and fracture gaps appeared as hypoechoic or anechoic regions. Tendons typically exhibited intermediate echogenicity, whereas tears disrupted echogenic continuity, showing localized areas of hypoechogenicity. Cartilage typically appeared hypoechoic; assessment of its echogenicity, thickness, and surface integrity allowed a preliminary evaluation of injury to this tissue.

Following induction of general anaesthesia, the patients were placed supine on the operating table. Dynamic multiplanar scans of the contralateral uninjured bone were performed from anterior, posterior, and lateral views to obtain detailed anatomical references for the reduction. After routine surgical disinfection and draping, the probe was coated with coupling gel and wrapped in a single sterile laparoscopic sheath. Sterile saline or medical alcohol was then applied to the cover surface to improve acoustic transmission.

During the procedure, the linear array probe was initially placed longitudinally along the axis of the injured bone to ensure close contact between the probe window and cortical surface and achieve optimal imaging. The probe angle and pressure were slowly adjusted to optimize acoustic coupling and reduce artefacts. Longitudinal, transverse, and oblique scans were obtained to comprehensively evaluate the fracture morphology and identify the cortex, adjacent tendons, and cartilage. The probe was slightly tilted and slid to avoid the influence of acoustic shadows from adjacent bones, while timely adjustments of the probe pressure, angle, and limb position helped improve image quality and fracture visualization. One surgeon maintained the probe position, while the other performed closed reduction under real-time ultrasound guidance, continuously monitoring the alignment of the proximal and distal cortices to achieve the most accurate anatomical reduction.

Common intraoperative imaging challenges included shadows from adjacent bone surfaces, reflection artefacts caused by air bubbles within the coupling gel or probe covers, and image degradation due to poor probe contact or suboptimal patient positioning. These issues were addressed by compressing sterile coupling gel within the probe cover to remove bubbles, adjusting the probe angle and pressure, and repositioning the limb to better expose the fracture site.

Following fracture reduction, multiplanar ultrasound scans were repeated to assess the fracture site and compare it with the contralateral normal bone to comprehensively evaluate reduction quality and fracture stability. Stable fractures were immobilized with casts, whereas unstable fractures were percutaneously fixed with Kirschner wires (K-wires), which appeared as hyperechoic signals, followed by casts. The insertion paths and angles for the K-wires were designed under ultrasound to ensure the safest and most effective fixation strategy (Fig. 1). Under continuous real-time ultrasound guidance, the K-wire tip was precisely advanced to the bone cortex. Controlled cortical penetration was then achieved using a high-speed power drill, with the operator integrating both ultrasound visual cues—such as transient hyperechoic “bump-like” signals at the penetration site—and tactile feedback, notably a sudden loss of resistance or a “giving way” sensation, to accurately confirm cortical breach and immediately halt advancement. Throughout the reduction and fixation processes, fluoroscopy was not needed; final confirmation of fracture reduction and K-wire positioning was achieved with fluoroscopic X-ray only after fixation was completed. In cases where US-guided closed reduction failed, open reduction and internal fixation were performed. Typical cases included a 15-year-old female with a displaced fracture at the neck of the second phalanx, characterized by complete fracture separation and a 2 mm overlap between the proximal and distal fragments (Fig. 2), and a 4-year-old boy with a Salter–Harris type II fracture at the base of the first metatarsal, exhibiting 35° sagittal angulation and 4 mm displacement (Fig. 3).

Fig. 1.

Surgical procedure illustrated in detail. A Fracture examined from the anterior view using ultrasound imaging. B Fracture examined from the lateral view using ultrasound imaging. C One surgeon performs ultrasound imaging of the fracture site, while the other reduces the fracture under real-time ultrasound guidance. D The fracture reduction position is maintained by one surgeon, while the other inserts a K-wire under real-time ultrasound guidance

Fig. 2.

Ultrasound images of a 15-year-old female with a displaced fracture at the neck of the second phalanx, characterized by complete fracture separation and a 2 mm overlap between the proximal and distal fragments. (1–2 A): Anteroposterior and oblique X-ray images showing the fracture site, indicated by a green arrow. (1B–2B): Lateral ultrasound images of the fracture. (1B) Discontinuity of the cortical bone with high signal interruption at the fracture site, presenting as a hypoechoic area. (2B) Restoration of cortical bone continuity and a high signal after fracture reduction. (1–2 C): (1 C) Plantar view ultrasound images displaying intact and continuous flexor tendons (▽) alongside a hypoechoic fracture site. (2 C) Restoration of cortical bone continuity following reduction. (1D–2D): (1D) Ultrasound-guided insertion of a K-wire (red arrow). (2D) Postoperative X-ray image confirms successful fracture fixation and reduction quality

Fig. 3.

Ultrasound images of a 4-year-old boy with a Salter–Harris type II fracture at the base of the first metatarsal, characterized by 35° sagittal angulation and 4 mm displacement. (1–2 A): Anteroposterior and oblique X-ray views of the fracture, with the green arrow indicating the fracture site. (1B–2B): (1B) Lateral ultrasound images of the fracture, showing the epiphyses as a hypoechogenic band with a central, high-signal ossification zone indicated by yellow arrows. (2B) Postreduction ultrasound image demonstrating restored continuity of cortical bone, intact adjacent articular cartilage, and uniform cartilage (▽). (1 C–C): (1 C) Posterior ultrasound images of the fracture; the △ symbol indicates the displacement, which appears hypoechoic. (2 C) Postreduction image showing complete disappearance of the displacement and restored cortical bone continuity. (1D–2D): (1D) Ultrasound-guided insertion of a K-wire, indicated by the red arrow. (2D) Postfixation X-ray confirms satisfactory fixation and alignment

Fluoroscopy-guided techniques

In the conventional group, all participants (patients, surgeons, and nurses) adhered strictly to radiation safety protocols to minimize radiation exposure. The C-arm X-ray device was precisely positioned, and fluoroscopy was used to identify the fracture details. Under X-ray guidance, manual traction, rotation, and manipulation were performed to accurately realign the fracture fragments. After successful reduction, the most suitable fixation method was selected on the basis of the fracture type and location. Follow-up X-ray was performed to assess the accuracy of the reduction and fixation.

Follow-up and evaluation

The radiation dose was quantified with the dose area product (DAP; mGy/cm²), which was measured with an ionization chamber integrated into the portable image intensifier. Postoperatively, a functional position cast was applied for 6–8 weeks to support initial bone healing and prevent further displacement. After cast removal and following training in appropriate rehabilitation techniques, the patients performed functional exercises under the supervision of their families.

During the follow-up period, each patient underwent both functional and radiographic evaluations. Assessments included delayed union, nonunion, and refracture. Additional data were collected on pin-site infections, nerve injuries, and acute compartment syndrome. All patients underwent standard postoperative monitoring for 11–18 months, with complete follow-up and no missing data, and were assigned rehabilitation exercises to facilitate functional recovery. The functional outcomes were assessed using the AOFAS score at the final follow-up, according to which the results were categorized as excellent (> 90 points), good (81–90 points), fair (61–80 points), or poor (< 60 points).

Statistical analysis

Statistical analysis was conducted using IBM SPSS Statistics version 26.0. Continuous variables are expressed as the means ± standard deviations and were compared between groups using the t-test. Categorical variables were compared between groups using the χ²-test. A p-value < 0.05 was considered statistically significant.

Results

Characteristics of the study patients

The demographic information and fracture characteristics of the patients are summarized in Table 1. There were no significant differences between the two groups in terms of age, gender distribution, fracture side, or fracture site (p > 0.05). A more detailed analysis of fracture characteristics further confirmed the comparability of the two cohorts, with no significant differences found in anatomic subtypes (such as phalanges: distal, middle, proximal; metatarsals: head/neck, shaft, base), pathologic fracture types (including diaphyseal, metaphyseal, and Salter-Harris fractures), or Salter-Harris classification distribution (all p > 0.05).

Table 1.

Patient demographics and fracture characteristics

	US-guided (n = 50)	C-group (n = 62)	p-value
Mean age (years)	8.63 ± 3.11	8.31 ± 2.99	0.58
Sex, n			0.5
Male	29	32
Female	21	30
Side, n			1
Left	29	36
Right	21	26
Fracture Site, n (%)			0.76
Isolated phalangeal fracture	27 (54.0%)	29 (46.8%)
Multiple phalangeal fractures	10 (20.0%)	11 (17.7%)
Isolated metatarsal fracture	10 (20.0%)	17 (27.4%)
Multiple metatarsal fractures	3 (6.0%)	5 (8.1%)
Anatomic Subtype, n (%)	(n = 65)	(n = 84)	0.29
Phalangeal fractures	48 (73.8%)	53 (63.1%)
Distal phalanx	1 (1.5%)	6 (7.1%)
Middle phalanx	5 (7.7%)	4 (4.8%)
Proximal phalanx	42 (64.6%)	43 (51.2%)
Metatarsal fractures	17 (26.2%)	31 (36.9%)
Head/Neck	7 (10.8%)	10 (11.9%)
Shaft	6 (9.2%)	13 (15.5%)
Base	4 (6.2%)	8 (9.5%)
Pathological Subtype, n (%)	(n = 65)	(n = 84)	0.88
Diaphyseal fracture	16 (24.6%)	22 (26.2%)
Metaphyseal fracture	32 (49.2%)	43 (51.2%)
Salter-Harris fracture	17 (26.2%)	19 (22.6%)	0.19
Type I	0	0
Type II	16	14
Type III	0	1
Type IV	1	4
Type V	0	0

1. The Fracture site analysis was performed on a per-patient basis. Analyses for Anatomic Subtype and Pathological Fracture Type were conducted at the level of individual fracture foci (hence, total n exceeds patient number)

2. Group abbreviations: US-guided, Ultrasound-guided group; C-group, conventional fluoroscopy-guided control group

The surgical and clinical outcome comparisons between the two groups are summarized in Table 2. In terms of surgical outcomes, the US-guided group had a significantly shorter average surgical time (44.36 ± 15.23 min) compared to the C-group (59.15 ± 18.85 min; p < 0.001). Additionally, the US-guided group required significantly fewer X-ray examinations (2.98 ± 0.94 vs. 7.31 ± 1.47; p < 0.001), corresponding to an average reduction of approximately four scans. Radiation exposure was also substantially lower in the US-guided group (1.73 ± 0.54 mGy) than in the C-group (4.24 ± 0.85 mGy; p < 0.001). As confirmed by post-hoc power analysis, excellent statistical power (> 98%) was achieved for all primary outcome measures at the α = 0.05 level, including surgical time (Cohen’s d = −0.85), number of X-ray examinations (Cohen’s d = −3.43), and radiation dose (Cohen’s d = −3.45). No statistically significant differences were identified between the groups in terms of the total closed reduction rate (92% vs. 80.6%; p = 0.08), length of hospital stay, average time to surgery, or cast removal time. Among patients in the US-guided group (Table 3), the surgical duration for phalangeal fractures was significantly shorter than that for metatarsal fractures (41.08 ± 14.17 min vs. 53.69 ± 14.74 min; p = 0.009). However, subgroup analysis of post-hoc power within the US-guided group revealed moderate statistical power (68%) for detecting the reduction in surgical time (Cohen’s d = −0.88). Furthermore, in the US-guided group, no significant differences were observed in the closed reduction rate (91.9% vs. 92.3%; p = 1.00), frequency of X-ray examinations, or radiation exposure between patients with phalangeal fractures and those with metatarsal fractures.

Table 2.

Surgical and clinical outcome comparison between the two groups

	US-guided (n = 50)	C-group (n = 62)	Cohen’s d	p-value
Total closed reduction rate, n (%)	46 (92%)	50 (80.6%)		0.08
K-wire fixation, n (%)	32 (64.0%)	43 (69.4%)		0.55
Surgical time (mins)	44.36 ± 15.23	59.15 ± 18.85	−0.85	< 0.001 *
Frequency of X-ray examinations (number)	2.98 ± 0.94	7.31 ± 1.47	−3.43	< 0.001 *
Radiation exposure (mGy)	1.73 ± 0.54	4.24 ± 0.85	−3.45	< 0.001 *
Average time to surgery (days)	2.32 ± 1.80	2.48 ± 2.09	−0.08	0.66
Hospital stay (days)	5.66 ± 3.97	6.42 ± 3.86	−0.19	0.31
Cast removal time(weeks)	6.34 ± 0.63	6.23 ± 0.6	0.18	0.48
Follow-up duration (months)	13.89 ± 1.75	14.32 ± 1.49	−0.27	0.16
AOFAS score	93.6 ± 7.81	94.16 ± 5.27	−0.09	0.65
AOFAS, n				0.42
Excellent (> 90)	47	58
Good (81–90)	2	3
Fair (61–80)	0	1
Poor (< 60)	1	0
Complication rate, n (%)	1 (2%)	2 (3.2%)		0.69
Complications, n				0.42
Pin-site infection	0	0
Nerve injury	0	1
Nonunion	0	0
Delayed union	0	1
Acute compartment syndrome	0	0
Refracture	1	0

K-wire Kirschner wire, AOFAS American Foot & Orthopaedic Ankle Society

^*Significant at p < 0.05

Table 3.

Postoperative data comparison: phalangeal (n = 37) vs. metatarsal (n = 13) fractures in the ultrasound group

	Phalanges (n = 37)	Metatarsals (n = 13)	Cohen’s d	p-value
Closed reduction rate, n (%)	34 (91.9%)	12 (92.3%)		1
K-wire fixation, n (%)	23 (62.2%)	9 (69.2%)		0.9
Surgical time (mins)	41.08 ± 14.17	53.69 ± 14.74	−0.88	0.009 *
Frequency of X-ray examinations (number)	2.89 ± 0.88	3.23 ± 1.09	−0.67	0.27
Radiation exposure (mGy)	1.68 ± 0.51	1.87 ± 0.63	−0.36	0.27
Follow-up duration (months)	13.67 ± 1.64	14.54 ± 1.94	−0.52	0.12
AOFAS score	94.38 ± 3.87	91.38 ± 14.04	0.39	0.46
AOFAS, n				0.18
Excellent (> 90)	36	11
Good (81–90)	1	1
Fair (61–80)	0	0
Poor (< 60)	0	1
Complication rate, n (%)	0 (0%)	1 (7.7%)		0.26
Complications, n				1
Pin-site infection	0	0
Nerve injury	0	0
Nonunion	0	0
Delayed union	0	0
Acute compartment syndrome	0	0
Refracture	0	1

^*Significant at p < 0.05

Clinical outcomes

Foot function, as evaluated by the AOFAS score at the final follow-up, was not significantly different between the US-guided group (93.6 ± 7.81) and the C-group (94.16 ± 5.27; p = 0.65). Similarly, there was no significant difference in complication rate between the two groups (2% vs. 3.2%; p = 0.69). In the US-guided group, no significant differences were observed between patients with phalangeal fractures and those with metatarsal fractures in terms of the AOFAS score (94.38 ± 3.87 vs. 91.38 ± 14.04; p = 0.46) or complication rate (0% vs. 7.7%; p = 0.26). Neither group reported cases of pin-site infections, nonunion, or acute compartment syndrome during the follow-up period.

Among the complications in the C-group, one patient with a first metatarsal fracture experienced delayed union, and another patient with multiple fractures involving the second through fourth metatarsals was diagnosed with nerve injury and presented with paraesthesia. Although the nerve symptoms significantly improved, they had not completely resolved by the end of the follow-up period. In the US-guided group, one patient with a fifth phalangeal fracture experienced refracture. The complication types and follow-up durations are summarized in Table 4. No statistically significant differences were observed between the groups regarding the rates of nerve injury, delayed union, or refracture events. Furthermore, no patients in this study required secondary interventions or unplanned follow-up imaging.

Table 4.

Complications and follow-up duration

Patient	Complication	Age (years)	Sex	PH/MT involvement	Follow-up (months)	Additional surgery	AOFAS score (last)
1	Refracture	10.4	male	5th PH	15	NO	95
2	Delayed Union	14.2	male	1th MT	15	NO	92
3	Nerve injury	16.3	male	2-4th MT	13	NO	90

PH phalanx, MT metatarsal

Discussion

Ultrasound technology has been extensively employed in the diagnosis and management of fractures, offering advantages in real-time visualization and procedural guidance. Regarding surgical time, prior investigations have established that US guidance for upper extremity fractures is associated with a marked reduction in surgical duration relative to conventional fluoroscopy guidance [20, 21]. Consistent with these findings, our results indicated a significantly shorter mean surgical time in the US group (44.3 min) than in the fluoroscopy group (59.1 min, p < 0.001), corresponding to an approximate reduction of 15 min. Although comparable data for pediatric foot and ankle fractures are lacking, our surgical time is similar to that reported for the US-guided management of pediatric upper limb fractures (38.4 min) [22].The greater surgical time under traditional radiographic guidance primarily results from repeated adjustments during fracture reduction, whereas US facilitates real-time monitoring and prompt fixation, likely accounting for the observed time reduction [20, 22]. In our opinion, the substantial reduction in operative time observed in this study can be attributed to three primary factors. First, real-time multi-planar imaging decreases the dependence on repeated manipulation and fluoroscopic positioning. Second, ultrasound guidance facilitates the precise planning of fixation trajectories and accurate stabilization, thereby reducing the need for repetitive adjustments. Third, the dual-operator (four-handed) technique enables a coordinated workflow that optimizes procedural efficiency.

It should be noted, however, that the US-guided procedures in this study were performed using a dual-operator (four-handed) technique, which may have contributed to the efficiency of the process by allowing continuous probe manipulation and simultaneous reduction/fixation. Notably, this dual-operator approach may not be feasible in all clinical settings, as resource availability and personnel training can vary significantly. Consequently, outcomes and procedural efficiency might differ when a single surgeon performs the procedure, potentially necessitating longer operative times or additional training. Nonetheless, this collaborative model is intrinsically well-aligned with US-guided techniques and represents the routine clinical practice at our center. Moreover, our data revealed a significantly shorter surgical time for phalangeal fractures (41 min) than for metatarsal fractures (53.6 min, p = 0.009), possibly because of the distal anatomical location, increased mobility of the phalanges, and relative ease of ultrasonographic visualization and positioning. Notably, some studies have reported marginally prolonged surgical times with US guidance [23], possibly due to differences in surgeon proficiency and procedural protocols.

Closed reduction and internal fixation under fluoroscopic guidance remains the standard intraoperative approach; however, this approach involves considerable radiation exposure to both the patient and the clinical staff [24]. Pediatric tissues are relatively highly radiosensitive due to elevated water content and proliferative cellular activity [25]. Although the radiation delivered during a single session commonly remains within safety thresholds, cumulative exposure may increase long-term carcinogenic risks [26, 27]. It should be acknowledged, however, that the extremities are relatively less radiosensitive than central body parts, even in pediatric patients. Multiple investigations have corroborated that US guidance markedly reduces both the frequency of fluoroscopy and the radiation dose [28–30]; our results substantiated this finding, showing that US-guided procedures required significantly fewer exposure to fluoroscopic procedures (2.98 vs. 7.31; p < 0.001), resulting in an average reduction of approximately four exposures and reduced radiation doses (1.73 vs. 4.24 mGy; p < 0.001) compared with fluoroscopy guidance. This finding aligns with the ALARP (As Low As Reasonably Practicable) principle in pediatric patients, emphasizing the importance of minimizing radiation exposure. While radiation reduction is an important benefit, the value of US guidance is further enhanced by its ability to improve procedural efficiency, reproducibility, and ease of implementation. These advantages constitute the core practical benefits of the technique. Notably, fluoroscopy in the US group was utilized solely to verify implant positioning and reduction adequacy postfixation, eliminating the need for continuous radiographic dependency, which is consistent with the literature [21, 22].

In terms of clinical outcomes, the complication rates were comparable between the groups (2.0% vs. 3.2%, p = 0.69), as was the final AOFAS score (93.6 vs. 94.1, p = 0.65), indicating a low incidence of complications and satisfactory functional recovery following timely reduction and fixation in pediatric phalangeal and metatarsal fractures regardless of the procedure, in accordance with prior studies [31, 32]. Within the US group, no significant differences in the complication rate (0% vs. 7.7%, p = 0.26) or AOFAS score (94.4 vs. 91.4, p = 0.46) were observed between the phalangeal and metatarsal fracture subgroups. Although postoperative ultrasonographic evaluation was not performed, previous studies have touted the noninvasive, repeatable nature of ultrasound for the dynamic assessment of callus formation and soft tissue repair, allowing the early detection of complications [33, 34]. In the present study, one case each of pin site infection and refracture resolved completely; however, a patient with multiple metatarsal fractures complicated by nerve injury exhibited normal foot motor function at the 13-month postoperative follow-up but continued to experience mild sensory deficits, which is consistent with reports linking severe fracture displacement or multiple metatarsal fractures to secondary nerve injury [32].

Radiographic assessment of the growth plates and joint congruity is substantially limited in skeletally immature patients because of incomplete ossification [22, 35]. US is superior to radiography in delineating fracture lines, displacement, and physeal involvement, thereby facilitating precise reduction and mitigating growth plate injury risk [29, 36]. Our results align with prior evidence demonstrating superior soft tissue contrast resolution of ultrasound, which allows visualization of unossified growth plates and joint congruity and offering critical insights for the reduction of physeal avulsion fractures and tarsometatarsal joint injuries.

Although some reports have indicated challenges in delineating K-wire penetration depth via ultrasound [22], our findings revealed that ultrasound allowed real-time K-wire tip localization and trajectory optimization. The small size of the pediatric forefoot bones allowed clear visualization of the K-wire when the probe was aligned parallel to the needle path, thus minimizing iatrogenic soft tissue injury. It should be acknowledged, however, that once the K-wire tip penetrates the bone cortex, it becomes no longer visible under ultrasound, which may entail a risk of deviation during advancement. In our cohort, this risk was effectively mitigated by comprehensive preoperative ultrasound planning, continuous real-time monitoring of the K-wire shaft, and the operator’s reliance on tactile feedback to detect cortical breach. For less-experienced clinicians, we recommend supplemental fluoroscopy as an adjunct to ensure accurate wire placement and enhance procedural safety. While ultrasound can be used to perform multidimensional evaluations of reduction and fixation quality, previous studies have shown no statistically significant difference in closed reduction success rates compared with fluoroscopy [37]. In our study, there was also no significant difference in the success rates between the ultrasound and fluoroscopy groups (92.0% vs. 80.6%, p = 0.08).

Despite the clear advantages of US-guided fracture management, several challenges remain. The limited incorporation of musculoskeletal ultrasound training within standard pediatric and general orthopedic curricula continues to impede its widespread implementation. At our institution, the US-guided technique was first introduced in 2013, initially focusing on minimally displaced, technically simpler upper limb fractures. All operators underwent a structured training program that included expert-led instruction, supervised simulation exercises, and mentored hands-on practice. With increasing experience, the indications were progressively expanded to include pediatric forefoot fractures. A standardized two-operator collaborative workflow was consistently employed, as detailed in the “US-guided techniques” section. It is important to note that by the study’s commencement, operators had already achieved a high level of proficiency, so the learning curve for pediatric phalangeal and metatarsal fracture treatment could not be evaluated within this retrospective study design. Nevertheless, for less experienced surgeons or centers newly adopting US-guided techniques, we strongly recommend the use of fluoroscopy as an adjunctive tool to confirm K-wire positioning and ensure procedural safety. Fluoroscopy can provide complementary visualization during critical steps, thereby mitigating risks associated with limited ultrasound visibility and operator inexperience. Existing evidence supports that foundational competence in musculoskeletal ultrasound can be attained through brief, focused training sessions: orthopedic surgeons accurately diagnosed long bone fractures following just one hour of training [38]; emergency physicians achieved radiograph-level diagnostic accuracy for pediatric wrist fractures after 1.5 h of instruction [39]; and a systematic review confirmed proficiency can be reached within 1 to 4 h of combined theoretical and practical training [16]. Furthermore, recent clinical guidelines further endorse its adoption: the 2023 guideline jointly issued by the German Association of Scientific Medical Societies (AWMF) and the German Commission on Radiological Protection (SSK) recommends ultrasound for pediatric fracture diagnosis [40]. Additionally, the 2024 S2e guideline from Ruhr University outlines 21 specific indications for fracture ultrasound use [41], thereby helping to alleviate concerns regarding training requirements.

Our study has several limitations, including its retrospective, single-center design and the absence of randomization, which may introduce selection bias and confounding variables. Additionally, the limited sample size and follow-up duration limit the generalizability of the findings. Postoperative assessments relied solely on AOFAS scores, neglecting pain and activity metrics, thereby restricting comprehensive evaluation of long-term functional recovery. Notably, although no formal cost-effectiveness analysis was conducted, the observed reductions in operative time suggest potential savings in anesthesia and operating room costs, consistent with previous reports that ultrasound-guided minimally invasive techniques reduce healthcare expenditures [28].

Despite these limitations, our results validate the clinical potential of ultrasound guidance. We recommend establishing demonstration centers in well-resourced hospitals to develop standardized intraoperative protocols and core training modules, followed by replication through a “training – practice – feedback – optimization” cycle. For broader implementation in modern orthopedic centers, it is essential to create structured ultrasound training courses and standardized educational programs to ensure operator proficiency and patient safety. Additionally, increasing multicenter prospective studies is crucial to validate these approaches in diverse clinical settings. Future research should focus on large-scale cohorts to simplify workflows, quantify learning curves, establish efficient training systems, and extend follow-up periods to confirm long-term efficacy, thereby clarifying the role of ultrasound in intraoperative management and postoperative monitoring.

Conclusion

US-guided closed reduction and fixation significantly shortened surgical time and reduced both the X-ray frequency and radiation dose compared to conventional fluoroscopy-guided treatment. Furthermore, US guidance demonstrated clear advantages in procedural efficiency, reproducibility, and ease of implementation. These benefits indicate that US guidance appears to be a safe, effective, and promising alternative for the management of pediatric phalangeal and metatarsal fractures.

Authors’ contributions

G.L., X.W., J.L., X.L., J.X., X.C., and T.W. were involved in data collection and follow-up assessments. X.W., X.S., and G.L. were responsible for literature search and study design. G.L. drafted the manuscript, which was finalized by G.L. and X.W. All authors have read and approved the submitted manuscript.

Funding

This study was supported by the Hubei Provincial Natural Science Foundation of China (Grant No. 2022CFB460).

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The Ethics Committee of Wuhan Children’s Hospital (2024R134-E01) granted final approval for this study. Written informed consent was obtained from all guardians of the patients prior to their participation.

Consent for publication

All guardians of the patients provided written consent for the publication of the study results.

Competing interests

The authors declare no competing interests.