K-wire shows striking advantages to plateosteosynthesis for distal metaphyseal radius fracture in children: a retrospective, two-center study

Abstract

Background

Metaphyseal distal radius fractures are very common in children. Even though there is a return toward successful conservative treatment, there are still distal radius fractures that require surgical treatment. K-wire osteosynthesis has become the most common surgical procedure. But no gold standard has been defined yet and evidence directly comparing pin and plate fixation in pediatric patients remains limited. Some hospitals prefer plate osteosynthesis for metaphyseal fractures in especially older children. Aim of the study was to compare complications, operative time, radiation exposure, reduction quality, and functional outcomes of K-wire versus plate osteosynthesis in pediatric metaphyseal distal radius fractures.

Methods

We retrospectively analyzed children aged 2–15 years treated for metaphyseal distal radius fractures between 2010 and 2022 at two Level I trauma centers. Demographic, radiographic, and surgical data were extracted from hospital records. Postoperative alignment was measured on early radiographs, and complications were graded using the modified Clavien-Dindo-Sink classification. Secondary outcomes included reduction quality, operative and fluoroscopy times, hospital stay, immobilization, and range of motion.

Results

Among 554 fractures, 352 (64%) were fixed with K-wires and 202 (36%) with plates. Complications occurred in 11% of K-wire and 20% of plate cases (p = 0.0034); severe events were rare (3% vs. 2.5%, p = 0.09). K-wire fixation was faster (25 (23) vs. 57 (24) min, p < 0.001), dose-area product (107 (294) vs. 172 (220) Gy·cm², p < 0.0001), and hospitalization (1.8 (1.5) vs. 2.4 (1.6) days; p < 0.0001) shorter, but longer immobilization (4 (0.7) vs. 1.9 (1.7) weeks; p < 0.0001). Plate fixation achieved superior reduction (92% vs. 67%, p < 0.0001). Secondary displacement occurred in 3% of K-wire cases, all single-wire constructs; 27% of those with secondary dislocation required revision. No pseudarthroses were observed in both groups.

Conclusions

K-wire osteosynthesis offers a safe, efficient, and minimally invasive option with fewer complications, shorter recovery and shorter radiation exposure time. Plate fixation provides better reduction but higher morbidity and longer surgery, and should be reserved for irreducible fractures or older children with little remodeling potential. However, both methods achieved reliable healing and full functional recovery.

Introduction

Forearm fractures are among the most common fractures in children, with the distal third most frequently affected [8, 14, 19]. Fractures closer to the distal growth plate in younger patients have greater remodeling potential, allowing correction of posttraumatic malalignment. After a phase of excessive osteosynthesis, the current trend in the treatment of distal radius fractures in children seems to be moving toward a more conservative approach [4, 7]. Recent pediatric trauma practice increasingly accepts greater displacement in metaphyseal fractures [1, 21]. Nevertheless, conservative management likewise has its limitations. If the remodeling capacity of the malalignment after fracture is insufficient to correct it to a physiological axis, this disorder will remain lifelong. Cadaver studies have shown that malalignment of the distal radius disrupts pronation and supination [2, 15, 17]. Greig et al. conducted a targeted literature review to examine the management of distal radius fractures in adolescents. In addition to recommending a threshold that suggests surgical treatment for distal radius fractures in adolescents, their study criticized the lack of comparison between plate and pin fixation in the pediatric population [12]. Fixation with percutaneous Kirschner wire (K-wire) is recommended in patients who carry high risk of reduction loss after closed treatment in order to prevent lifelong limitation of pronation and supination [18]. Surgical methods used in the metaphysis of the distal forearm include K-wire osteosynthesis and plate osteosynthesis. K-wire osteosynthesis is a minimally invasive technique in which the fracture is typically reduced in a closed manner and the K-wire is inserted percutaneously. The end of the wire can be left percutaneous to avoid a second surgery for implant removal. In most cases, due to the increase in bone diameter distally and the resulting unfavorable angle of wire insertion, it is necessary to cross the distal growth plate to achieve sufficient stabilization of the metaphyseal fracture. Plate osteosynthesis, by contrast, is an invasive procedure involving a large skin incision and open reduction of the fracture. Fixation is achieved with two to three screws placed distal and proximal to the fracture, avoiding the growth plate.

From a pediatric surgery perspective, plate osteosynthesis is playing an increasingly minor role in the surgical treatment of fractures in children. Volar plating is the standard fixation method for distal radius fractures in adults. However, its high invasiveness and the need for a second surgery under general anesthesia for implant removal conflict with the principles of minimally invasive, child-appropriate care [25].

This study directly compared K-wire fixation and volar plate osteosynthesis regarding complications, operative duration, radiation exposure, length of hospitalization, reduction quality, and postoperative function in children with metaphyseal distal radius fractures treated at two Level I trauma centers. The analysis was conducted as a retrospective cohort study based on routinely collected clinical and radiographic data.

Materials and methods

Data collection

This retrospective study included children aged 2–15 years with metaphyseal distal radius fractures treated surgically between January 2010 and December 2022 in two level-1 trauma centers. This retrospective comparative study represents Level III evidence. Only patients classified as having an AO pediatrics M/2 or M/3 fracture were included. Center 1 used both plate and K-wire osteosynthesis, while the Center 2 primarily used K-wires. Procedures were performed by multiple fellows in supervision or specialists itself. The study was conducted in accordance with the Declaration of Helsinki and approved by the relevant Ethics Committees.

The metaphysis was defined as the square beneath the distal radial articular surface (Fig. 1).

Fig. 1.

Definition of the metaphysis as a square under the growth plate of the radius

Clinical examination and functional outcome

Center 2 provided structured in-house follow-up including implant removal. The follow-up ended with the patient being cleared for sports approximately 8 weeks after surgery. If mobility was still restricted at that point, a further examination was carried out 12 weeks after surgery. If there were any abnormalities in the further healing process, the follow-up continued for up to 1 year after surgery. Center 1 used predominantly outpatient follow-up with complication reporting. However, implant removal was also mainly performed at this center. Both centers assessed range of motion and wound/scar status; radiographs were obtained when indicated. Examinations were performed by different physicians, and complications were identified during follow-up.

Complications

Complications were classified using a modified Clavien-Dindo-Sink system [11], distinguishing mild (types 1–2) from severe (types 3–4) complications. Movement restriction was categorized by duration (mild < 3 months, moderate 3–6 months, severe > 6 months). Secondary endpoints included procedure-related complications in relation to patient characteristics and intraoperative parameters.

Radiological measurement of reduction quality

Reduction quality was analyzed based on angular deformity in the sagittal and frontal plane on intra- or early postoperative radiographs. According to Stark et al., deformity in sagittal and frontal plane ≤ 5° was defined as good, 6°–10° moderate, and > 10° poor [23]. Measurements were performed by a supervised resident. Inter-rater reliability was not assessed. Angular deformity was measured using shaft axis lines. Figure 2 shows an example of how the measurement was done.

Fig. 2.

Measurement of the angular deformity of the fracture in the sagittal plane. The angle alpha describes the size of the angular deformity in the sagittal plane

Statistical analysis

Patient and radiographic data were obtained from clinical documentation and PACS systems. Statistical analysis was performed using SAS 9.4 and SPSS v24. Continuous variables were summarized as means and standard deviations. Group comparisons used the Kruskal–Wallis test for non-parametric data, the Student’s t-test when normally distributed, and the chi-square or Fisher’s exact test for categorical variables. The association between age and length of hospital stay was assessed using Spearman’s rank correlation coefficient due to the non-normal distribution of hospital stay. As the time interval between primary surgery and implant removal was not normally distributed, differences between groups were analyzed using the Mann–Whitney U test. The Cochran–Armitage trend test assessed the relationship between reduction quality and movement restriction. Significant variables in univariable analysis were entered into a multivariable logistic regression model.

To evaluate the effects of treating center (center 1 vs. center 2) and age group (≤ 10 years vs. ≥ 11 years) on preoperative dislocation in the frontal and sagittal axes, separate two-way analyses of variance (ANOVA) were conducted. Both factors were entered as fixed effects, and the interaction term (center × age group) was included in each model. Estimated marginal means (EMMs) with 95% confidence interval (CI) were calculated to provide model-adjusted group comparisons. For two-level main effects, Cohen’s d was additionally calculated using pooled standard deviations and interpreted as small (0.2), medium (0.5), or large (0.8). Homogeneity of variances was assessed using Levene’s test. A significance level of α = 0.05 was applied.

Aim of the study

Aim of the study was to compare complications, operative time, radiation exposure, reduction quality, and functional outcomes of K-wire versus plate osteosynthesis in pediatric metaphyseal distal radius fractures.

Results

Data collection

In total 545 patients with 554 fractures were identified of whom 214 patients with 217 fractures (39%) underwent surgery at center 2 and 332 patients with 337 fractures (61%) at center 1. 199 patients with 202 fractures (36%) underwent surgical treatment with plate osteosynthesis and 347 patients with 352 fractures (64%) underwent surgical treatment with K-wire osteosynthesis. Plate osteosynthesis was performed in all cases using a volar approach according to Henry [6]. The time interval between primary surgery and implant removal differed significantly between groups. Patients treated with K-wire fixation underwent implant removal after a median of 4 weeks, whereas implant removal in the plate group occurred after a median of 16 weeks (p < 0.001, Mann–Whitney U). When analyzing both trauma centers separately, K-wire osteosynthesis was the predominant method of fixation in center 2, accounting for 97% of all cases. Just 3% of all osteosynthesis in center 2 were plate osteosynthesis. In trauma center 1, 42% of procedures involved K-wire osteosynthesis and 58% involved plate osteosynthesis.

In the plate osteosynthesis group, there was a significantly higher proportion of males (158 males, 44 females, p = 0.04, pooled t-test), older patients (10.8 (3.1) versus (vs.) 9.1 (3.2) years (y), p < 0.0001, pooled t-test), and heavier patients (46.4 (18.4) vs. 37.7 (17.4) kilogram (kg), p < 0.0001, pooled t-test). Body height, on the other hand, did not differ between the two groups (1.51 (0.21) vs. 1.46 (0.21) meter (m), p = 0.1, pooled t-test). The significance remained even when considering the selected osteosynthesis method within a single center only.

Of all metaphyseal fractures treated by K-wire osteosynthesis, in 78% of cases (276/352) the wire was inserted via the radial styloid process, while in 21% (72/352) it was inserted via the radial metaphysis without crossing the growth plate. In 74% (260/352) of all K-wire fixations only a single K-wire was inserted, in 26% (92/352) fractures two K-wires were inserted. In 7 patients, K-wire osteosynthesis was performed monocortically and the wire was advanced proximal into the medullary canal. All K-wire osteosyntheses were performed in a retrograde manner.

Complications and influencing factors

Complications occurred in 20% (40/202) of patients after plate osteosynthesis and in 11% (38/352) after K-wire fixation, with a significantly higher overall complication rate in the plate group (p = 0.0034, chi-square test). However, there was no significant difference in complication severity between groups (p = 0.09, Fisher’s exact test).

The postoperative complications are listed in detail in Table 1.

Table 1.

Complications depending on the type of osteosynthesis

	K-wire	Plate
Clavien 1
Movement restriction for 3 months	1	1
Pressure ulcer	2	0
Hypertrophic scar	3	32
Periosteosynthetic infection (without intervention)	16	0
Clavien 2
Acute osteomyelitis	1	0
Movement restriction for 3–6 months	0	1
Material retention	1	0
Neurology after surgery	2	0
Peri-implant fracture (treated conservative)	0	1
Periosteosynthetic infection (antibiotics)	1	0
Clavien 3
Movement restriction over 6 months	1	1
Angular deformity radius with revision	5	1
Neurology after surgery	0	1
Peri-implant fracture (revision surgery needed)	0	1
Periosteosynthetic infection (revision surgery)	1	0
Migration of the osteosynthesis material	4	0
Clavien 4a
Secondary compartment syndrome	0	1

In the case of neurological dysfunction after surgery, healing in one case only regressed after a long period of time, so this complication was classified as type 3.

Table 2 summarizes complication frequencies by osteosynthesis type and severity.

Table 2.

There was no significant difference in complication severity between groups (p = 0.09, Fisher's exact test)

	K-wire	Plate
Mild complication = Clavien 1 and 2	27/38 (71%)	35/40 (87.5%)
Serious complication = Clavien 3 and 4	11/38 (29%)	5/40 (12.5%)

The occurrence of complications was independent of gender (p = 0.29, chi-square test), mechanism of trauma (extension vs. flexion fracture; p = 0.48, chi-square test), and fracture type (incomplete (M/2) vs. complete (M/3) fracture; p = 0.34, chi-square test). Neither the number of K-wires (p = 0.28, Cochran–Armitage trend test), the entry point (p = 0.8, Fisher's exact test), nor the wire course (intramedullary or bicortical; p = 0.06, Fisher's exact test) had a significant influence on the occurrence of complications.

Soft-tissue damage associated with the fracture had no effect on the occurrence of complications (p = 1.0, Fisher’s exact test). The fracture mechanism (extension vs. flexion; p = 0.48, chi-square test) and fracture type (M/2 vs. M/3; p = 0.34, Fisher’s exact test) also showed no influence on complication severity. Patient age (p = 0.30), weight (p = 0.09), and BMI (p = 0.05) had no influence on complication rates (pooled t-test). Furthermore, neither age (p = 0.43, pooled t-test), nor weight (p = 0.45, Satterthwaite t-test) affected the severity of complications. Patients without complications were significantly taller than those with complications (p = 0.009; mean difference = 0.12 m (95% CI [0.03–0.21], pooled T-test). But the patient`s stature had no influence on the severity of complications (p = 0.6, pooled t-test). In the multivariable logistic regression including age, neither patient’s height nor age emerged as independent predictors (height p = 0.68, age p = 0.5 (Omnibus tests p = 0.029, Hosmer and Lemeshow test p = 0.219)). In all cases, bone healing occurred regardless of the osteosynthesis technique used. None of the cases resulted in pseudarthrosis. And no growth disorders were observed.

Secondary displacement occurred in 15 of 554 patients (3%), all following K-wire fixation with a single wire. Revision surgery was required in four cases; in eleven, the displaced position was accepted. One non-revised patient developed persistent restriction of forearm rotation. All patients were immobilized postoperatively (3 upper-arm, 12 forearm casts). An associated ulnar fracture was present in 14 cases. One patient with an isolated radial fracture developed a pin site infection requiring early wire removal. The secondary dislocation had occurred, while the wire was in place. Patient age (p = 0.37), weight (p = 0.68), and height (p = 0.77) showed no significant association with secondary displacement (pooled t-test).

Impact of treating center on postoperative complications

Two subgroup analyses were performed to examine the relationship between osteosynthesis technique or treating center and the occurrence of complications. In the first analysis, only the complications following K-wire osteosynthesis in the two centers were compared. No significant difference in overall complication rates was observed between the two centers (p = 0.436, chi-square test). Complications occurred in 9.2% of cases at center 1 and 11.8% at center 2. Likewise, the distribution of mild versus severe complications did not differ significantly between institutions (p = 0.478, Fisher’s exact test).

In the second subgroup analysis, the incidence of complications following K-wire osteosynthesis and plate osteosynthesis was compared only in the center where approximately the same number of K-wire osteosynthesis and plate osteosynthesis procedures were performed. Among patients treated with K-wire fixation, complications occurred in 9.2%. In contrast, 19.9% treated with plate osteosynthesis experienced a complication. Comparative analysis using Pearson’s chi-square test demonstrated a statistically significant association between fixation method and complication occurrence (p = 0.007).

A multivariable logistic regression model including age and sex was performed to adjust for potential confounding factors (Omnibus test p = 0.006, Hosmer–Lemeshow test p = 0.400). After adjustment, K-wire fixation was associated with significantly lower odds of postoperative complications compared with plate osteosynthesis (adjusted (a)OR 0.36; 95% CI 0.18–0.71; p = 0.003). Accordingly, plate fixation was associated with approximately 2.8-fold increased odds of complication compared to K-wire fixation. Age showed a non-significant trend toward reduced complication risk (aOR 0.92 per year; 95% CI 0.83–1.01; p = 0.093), while sex was not independently associated with complication occurrence (p = 0.236).

Hospital stay, radiation exposure, operation duration and postoperative immobilization

A longer operation duration was significantly more frequently associated with the occurrence of a complication (36.0 (29.1) vs. 41.4 (23.2) minutes (min), p = 0.006, Kruskal–Wallis test). But in the multivariable logistic regression, there was a significant interaction between the osteosynthesis technique and the duration of surgery (p = 0.020). In addition, with an average duration of surgery, plate osteosynthesis was associated with a 2.5-fold increase in the odds of a complication occurring (OR 2.46; 95% CI 1.41–4.29; p = 0.002).

The length of hospital stay was significantly longer after plate osteosynthesis than after K-wire osteosynthesis (2.4 (1.6) vs. 1.8 (1.5) days (d), p < 0.0001, Kruskal–Wallis test). Spearman rank correlation analysis demonstrated a weak positive association between age and length of hospital stay with older children tending to have a longer stay (ρ = 0.224, p < 0.001).

The postoperative immobilization period in a cast was significantly longer after K-wire osteosynthesis than after plate osteosynthesis (4.0 (0.7) vs. 1.9 (1.7) weeks (w), p < 0.0001, Kruskal–Wallis test). Plate osteosynthesis had a mean operative time of 57 min, whereas K-wire osteosynthesis averaged 25 min and was therefore performed significantly faster (57 (25) vs. 25 (24) min, p < 0.0001, Kruskal–Wallis test).

When performing K-wire osteosynthesis, the radiation exposure time was significantly shorter than with plate osteosynthesis (70 (86) vs. 89 (79) seconds (sec), p < 0.0001, Kruskal–Wallis test). Consequently, the dose area product was significantly higher for plate osteosynthesis than for K-wire osteosynthesis (172 (220) vs. 107 (294) Gy cm², p < 0.0001, Kruskal–Wallis test).

Quality of reduction

The quality of reduction was measured by the postoperative axial deviation in the sagittal and frontal planes. The quality of reduction was significantly better after plate osteosynthesis than after K-wire osteosynthesis (p < 0.0001, chi-square test). Table 3 shows the differences in the quality of reduction.

Table 3.

Reduction quality depending on the used osteosynthesis

Reduction quality	Good	Moderate	Poor
K-wire	237 (67%)	91 (26%)	24 (7%)
Plate	187 (93%)	14 (7%)	1 (0.5%)

The postoperative residual axial deviation had no significant influence on the occurrence of complications (p = 0.1, Kruskal–Wallis test). However, a significant influence on the severity of complications (p = 0.047, Kruskal–Wallis test) was demonstrated, with severe complications more frequently associated with a higher postoperative axial deviation.

Age and center effects on surgical indication thresholds

A subgroup analysis was performed to evaluate potential center- and age-related differences in surgical indication according to the degree of angular deformity in the frontal and sagittal planes. A total of 536 fractures were included in this subgroup-analysis. In 18 fractures, the preoperative X-rays were missing, so no angular deformity could be measured here. Of these 536, 321 were treated at center 1 and 215 at center 2. Overall, 298 patients were aged ≤ 10 years and 238 were aged ≥ 11 years. Table 4 shows the estimated marginal means of preoperative frontal and sagittal malalignment depending on the operating center and age group.

Table 4.

Model-adjusted EMMs and 95% CI for preoperative frontal and sagittal malalignment derived from two-way ANOVA including center and age group as fixed factors

Group	n	Frontal malalignment		Sagittal malalignment
		EMM (°)	95% CI	EMM (°)	95% CI
Center 1	321	7.20	6.35–8.05	21.2	19.9–22.5
Center 2	215	9.40	8.31–10.49	21.3	19.6–23.0
≤ 10 years	298	9.20	8.32–10.09	21.7	20.2–23.2
≥ 11 years	238	7.39	6.33–8.46	20.3	18.6–22.0

Regarding malalignment in the frontal plane, a significant main effect of center was observed in the two-way ANOVA (p = 0.002), corresponding to a small effect size (Cohen’s d = 0.31). A significant main effect of age group was also found (p = 0.010), again indicating a small effect (Cohen’s d = 0.22). The interaction between center and age group was not statistically significant (p = 0.398).

Regarding malalignment in the sagittal plane, two-way ANOVA revealed no significant main effect of center (p > 0.05) and no significant main effect of age group (p > 0.05). No significant interaction between center and age group was observed for sagittal dislocation (p > 0.05).

Influence of fracture morphology on the choice of osteosynthesis procedure

Another analysis examines the relationship between fracture morphology and the choice of osteosynthesis procedure. 541 cases (97.7%) were available for this subgroup-analysis, while 13 cases (2.3%) had missing data and were excluded from this comparison.

Among the analyzed fractures, 22% (119/541) were classified as AO-pediatric subtype M/2 and 78% (422/541) as M/3. In the K-wire group, 23% (81/346) were M/2 and 77% (265/346) were M/3. In the plate fixation group, 19% (38/195) were M/2 and 81% (157/195) were M/3. Chi-square analysis demonstrated no significant association between AO-pediatric fracture subtype (M/2 vs. M/3) and osteosynthesis technique (p = 0.290).

Discussion

No consensus “gold standard” has been established for the surgical treatment of metaphyseal distal radius fractures in children [13, 18]. Percutaneous K-wire fixation remains the most widely used and evidence-supported approach, while volar plating, although standard in adults, is reserved for selected pediatric cases. Recent reports show good short-term results with both methods, but high-level comparative data and long-term outcomes are lacking.

In this retrospective two-center study, we evaluated the outcome of the two methods and assessed complications, surgery duration, hospital stay, radiation exposure with dose area product, immobilization duration, and postoperative alignment. We also examined differences in treatment indication between the two centers and evaluated the influence of age on the choice of osteosynthesis. The current study shows that K-wire osteosynthesis offers a minimally invasive option with fewer complications and shorter recovery, likely due to reduced soft-tissue trauma and less need for postoperative monitoring, whereas plate fixation offers better reduction and a shorter immobilization time. Additionally, K-wire are associated with significantly less radiation. This may reflect the minimally invasive technique, but also the emphasis of pediatric surgeons—who performed most K-wire fixations—on minimizing radiation. In previous, it has been reported that radiation duration correlates with the surgeon’s efforts to reduce it [9]. The difference in radiation exposure could therefore be since the center, where almost no plate osteosynthesis was performed and predominantly wire osteosynthesis was used, follows a philosophy of keeping radiation exposure as low as possible. Nevertheless, it can be assumed that the automatic adjustment by the C-arm is highly regulated even with metal (plates and screws) in place, which may also lead to higher radiation dose exposure.

Postoperative complications occurred in 14% of patients with most being minor which is consistent with recent published data [26]. Although plate fixation was associated with a higher overall complication rate than K-wire fixation, the distribution of complication severity did not differ significantly between the two techniques. The significantly higher incidence of complications following plate osteosynthesis remained even after the osteosynthesis procedures were examined in a single center alone. Furthermore, no difference in the occurrence of complications following wire osteosynthesis could be observed between the two centers. The predominant complication after plate fixation was hypertrophic scarring, a condition that may result in restricted mobility and psychological discomfort [24]. In our series, functional outcomes remained unaffected, yet patients and parents frequently voiced concern about the visible scar. In contrast, pin site infections were most common after K-wire fixation, usually resolving with local care. The occurrence of pin infections is consistent with recent reports [26]. Besides the second anesthesia required for implant removal, the significantly longer duration of plate osteosynthesis procedures was a major negative factor. It is well established that longer operative duration is associated with a higher risk of complications [5]. However, the subsequent multivariable regression analysis showed that the effect on the incidence of complications was less due to the duration of the operation than to the osteosynthesis procedure itself (plate osteosynthesis). Nevertheless, it should be noted that a shorter duration of the operation is also preferable from an economic point of view. The more invasive procedure also resulted in a longer hospital stay. In addition, age was weakly associated with length of hospital stay, with older children experiencing slightly longer hospitalizations. Given that plate osteosynthesis was performed more frequently in older patients and was associated with longer hospital stay, a confounding effect between age and type of osteosynthesis is likely. Even though the difference in hospitalization time between the osteosynthesis groups is not very large, it is still noteworthy. It is possible that children who underwent plate osteosynthesis required intravenous pain therapy for a longer period of time—after all, the surgical approach is significantly more invasive and therefore more painful—resulting in a hospitalization period that was extended by approximately 1 day.

Transient nerve irritations observed in both groups resolved spontaneously. No patient suffered tendon or artery injury in this study. One severe complication—a compartment syndrome—occurred following volar plating. No long-term damage occurred, as it was relieved at an early stage in an emergency procedure. Compartment syndrome in this context is an extremely rare occurrence and may be attributable to the upper arm tourniquet used during the operation [20].

Surprisingly, the univariate analysis showed that shorter stature was significantly more frequently associated with the occurrence of complications, although one might think that taller children require greater stability of osteosynthesis and that plate osteosynthesis is therefore more favorable. However, in the multivariable logistic regression including age, neither stature nor age proved to be independent predictors. This suggests that the association observed in the univariate analysis may be confounded by other factors or that body size has no independent influence on the risk of complications.

Revision due to inadequate fracture alignment was more common after K-wire fixation than after plate osteosynthesis. Secondary dislocation has been reported in up to 10% after K-wire osteosynthesis in children [18]. In the current study, secondary dislocation occurred exclusively in the K-wire group. In cases that warranted revisionary surgery, the fracture was fully displaced and fixed with a single bicortical wire, often with short proximal anchorage. Biomechanical studies suggests that longer anchoring in the proximal fragment in accordance with interfragmentary osteosynthesis leads to a significantly more stable result compared to the intra-focal technique, which is equivalent to very short proximal anchoring [10]. Another possibility is to use a second K-wire as it may improve stability without increasing complications as shown in this study. The incidence of complications due to a second K-wire was not increased in the present patient cohort.

After plate osteosynthesis a cast was applied until the sutures were removed to protect the wound and, above all, for analgesia to reduce the need for pain medication. The wire fixation did not provide sufficient stability, so postoperative immobilization with a cast was necessary until sufficient bone consolidation had occurred. Postoperative immobilization was significantly longer after K-wire fixation, as only volar plating allows earlier functional mobilization. Van Egmond et al. similarly reported excellent early functional outcomes following plate osteosynthesis [25]. Movement restrictions were rare and largely reversible. One case after K-wire (supination and pronation were reduced by one third) and one case after plate osteosynthesis (extension capacity of the wrist was reduced to 20°) showed restricted movement beyond 6 months.

Malalignment of distal radius fractures can impair pronation and supination [15]. Owing to the high remodeling potential of the distal metaphysis, greater displacement is often managed conservatively [1, 21]. In contrast, malalignment in dia- and diametaphyseal fractures can cause lasting motion deficits [27]. In this study, postoperative malalignment did not increase complication rates, though more severe deformities were associated with higher complication severity, likely due to the need for revision. Likewise, the quality of reduction did not influence whether prolonged postoperative movement disorders occurred. Plate fixation achieved superior reduction quality to K-wire fixation due to its greater precision and stability [16]. It is important to emphasize that complete bone healing occurred in all cases without pseudarthrosis, confirming K-wire fixation as a reliable method despite occasional secondary displacement. Although one might think that the more unstable M/3 fracture could have led to the choice of plate osteosynthesis, the fracture morphology according to the AO subtype for children (M/2 vs. M/3) was not related to the choice of osteosynthesis technique. In contrast, age proved to be a strong and independent determinant of implant selection. Younger children were significantly less likely to receive plate osteosynthesis, with the use of plates increasing significantly with age. This pattern reflects a clinically intuitive treatment strategy: higher remodeling potential in younger children favors less invasive stabilization, while adolescents are treated more like adults, with less tolerance for residual deformities and a greater tendency toward plate osteosynthesis.

An examination of which center indicated surgery based on which angular deformity shows that, firstly, center 1 had stricter criteria for indicating surgery in cases of frontal angular deformity and, secondly, that in both centers, a lower angular deformity led to an indication for surgery as the patient's age increased—meaning that age, in line with reduced remodeling capacity, was a decisive factor in indicating surgery even for smaller angular deformities. While the initial deformity differed slightly between the centers, the therapeutic approach appears to be structurally comparable overall. Even though no threshold value leading to surgical indication could be identified due to the lack of a non-surgical group, this retrospective study shows a pattern similar to that found in current studies, indicating the degree of angular deformity at which surgery was performed, always taking the patient's age into account [21].

Overall, these findings underline that implant choice in operatively treated distal forearm fractures in children is driven primarily by patient age and age-related treatment philosophy rather than by basic AO-Pediatric fracture subtype. Nevertheless, literature clearly favors K-wires as the “method of choice”—also in older, already juvenile patients [3, 12, 22]—and only uses plates for specific indications.

Strengths and limitations

While these results are highly relevant for pediatric trauma surgeons, this study has limitations that warrant discussion. Strengths include the largest comparative cohort to date, treatment at two high-volume Level I trauma centers with technique-specific expertise, and systematic classification of complications using the modified Clavien-Dindo-Sink system.

Limitations inherent to the retrospective design include selection bias (surgeons selected the implant), variable follow-up and documentation, incomplete recording of minor complications treated outside the hospital, and lack of patient-reported outcomes. Methodological limitations include follow-up ending without taking into account the end of growth, single-person axial deviation measurements, variable assessment of range of motion, a wide patient age range (2–15 years), and involvement of multiple surgeons and disciplines, introducing potential expertise and center biases that may have affected outcomes and complication rates. Furthermore, another limitation of this study is that the classification of postoperative residual malalignment according to Stark et al. into different degrees of severity does not sufficiently take into account the fact that frontal angular deformities are less tolerable than sagittal ones.

It can be assumed that the follow-up examinations and documentation were carried out differently. This leads to a strong confounding variable. This expertise bias probably had an impact on complication rates and outcomes.

Conclusion

K-wire osteosynthesis should be considered the gold standard for children with sufficient growth potential, offering shorter surgery and hospital stays, and fewer postoperative complications. Its minimally invasive nature and ease of implant removal without anesthesia make it particularly suitable for younger children, where malalignment can be accepted. Plate fixation should be reserved as a secondary strategy for cases in which closed reduction fails to achieve age-appropriate alignment.

Abbreviations

K-wire

Kirschner wire

ACS

Picture archiving and communication system

SPSS

Statistical package for the social sciences

SAS

Statistical analysis system

SD

Standard deviation

CI

Confidence interval

min

Minutes

sec

Seconds

Gy·cm²

Dose area product unit (Gray × square centimeters)

kg

Kilogram

m

Meter

y

Years

d

Days

w

Weeks

vs.

Versus

OCEBM

Oxford Centre for Evidence-Based Medicine

BMI

Body mass index

EMM

Estimated marginal mean

Author contributions

F.W. contributed to the conceptualization and design of the study, developed the methodology, performed data acquisition, and conducted the analysis and interpretation of the data. F.W. also prepared the original manuscript draft and contributed to visualization. L.F. contributed to data acquisition and participated in the analysis and interpretation of the data. P.G. contributed to project administration and participated in the analysis and interpretation of the data. M.B. contributed to project administration and participated in the analysis and interpretation of the data. S.SF. contributed to project administration and participated in the analysis and interpretation of the data. L.W. provided supervision, contributed to the analysis and interpretation of the data, and was responsible for writing, including critical review and editing of the manuscript. All authors read and approved the final manuscript.

Funding

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

Data availability

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

Declarations

Ethics approval and consent to participate

We confirm that no individual patient consent was obtained for this study because all data were collected and analyzed retrospectively and fully anonymized prior to analysis. No identifiable personal information, images, or videos are included in the manuscript. According to institutional and national ethical standards, specific patient consent was therefore not required. Ethical approval for the study was granted by the responsible ethics committees (“Ethikkommission II der Universität Heidelberg” (project ID 2023-813-AF 11—date of approval 22 February 2023) and “Landesärztekammer Rheinland-Pfalz” (project ID 2023-17035-retrospective—date of approval 19 May 2023).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.