Introduction

Supracondylar fracture is currently the most prevalent distal humerus fracture in children. It constitutes 60% of all elbow fractures and 16% of all paediatric fractures and mostly occurs between ages 5 and 7 [1].

According to the literature, the majority of cases occur on the left side, with equal distribution among males and females [2,3].
Fractures can be divided according to the mechanism of injury into two types, flexion and extension. Extension type constitutes up to 97% of all cases and mainly results from a fall on an outstretched hand with the elbow in full extension [2,4].

Suspicion of supracondylar fracture should be followed with an x-ray obtained in AP (anterior-posterior) and lateral views. This imaging modality is considered the „gold standard” as it defines the type of fracture [5].

In terms of management, either operative or non-operative treatment is used. The choice depends on Gartland’s classification. In broad terms, undisplaced fractures are usually managed conservatively (with a cast). When dealing with displacement, closed reduction and percutaneous pinning are performed; eventually, an open reduction might be indicated. Some indications for open reduction are failure of closed reduction, vascular compromise in the limb, an open fracture, and suspicion of neurologic injury [5-8].

Neurovascular complications are reported in 5-19% of displaced fractures. The most commonly reported complication involves the anterior interosseous nerve, a branch of the median nerve [8].
The vascular injury most commonly affects the brachial artery and can be diagnosed both clinically through a physical examination and with the use of methods such as ultrasonography with Doppler mode or angiography [9].

A compartment syndrome leading to Volkmann’s ischemic contracture is one of the rarest yet most tragic complications. This contracture results in a complete deficit of limb function [6].
The proper bone union occurs with the restoration of bone cortex continuity, which can eventually lead to the regaining of physiologic limb function [10].

Nevertheless, there is still room for discussion on which pin configuration should be chosen. Nowadays, two major techniques are used, crossed pinning with 2 pins and lateral pinning using 2 or 3 pins. The first one is said to provide more mechanical stability but simultaneously has a higher risk of ulnar nerve injury with the introduction of a medial pin. The second one is considered safer in terms of nerve injury incidence; nonetheless, it is considered less stable [11-14].

Several studies have compared these 2 techniques in terms of surgical outcomes, with no definite consensus on the gold standard [15-18].

Aim

The study aimed to introduce the results of surgical management of supracondylar fractures of the humerus in children, depending on which method of percutaneous K-wires pinning was used. In addition, certain relations between the results and clinical and sociodemographic data were sought.

Materials and methods

Our study included 75 patients (65% boys) who underwent surgery between September 2010 and June 2021 for a supracondylar humerus fracture in the paediatric population (Fig. 1A-B). Patients were searched in a hospital patient database and were consecutively invited by telephone to an appointment during which the examination took place, and caregivers completed a self-administered questionnaire.

Inclusion criteria were a history of supracondylar humerus fracture, patient age at injury <18 years, patient surgery under general anaesthesia with closed repositioning and fracture stabilisation by percutaneous insertion of Kirschner wires, and no previous elbow trauma. Exclusion criteria were other diagnoses, older age of the patient at the time of injury, another method of fracture stabilisation (including open repositioning), and previous trauma to the elbow region in the patient.

The mean age at the time of the study was 9.3 years (range: 4-16 years). On the day of the study, the parents of the patients completed a self-administered questionnaire regarding clinical data, circumstances of the fracture, perioperatively reported complaints, recovery time, and assessment of satisfaction with current limb function. The questionnaire also included current pain on the Visual Analogue Scale (VAS).

On the day of the examination, the physician evaluated the limb’s mobility (limb axis, elbow joint extension, flexion, forearm supination, and pronation) using a goniometer and assessed the neurological status of the operated limb.

Patients were evaluated according to the Mayo Elbow Score, which considers the pain component, range of motion at the elbow joint, elbow joint stability, and ability to perform basic activities of daily living. Patients were also evaluated according to the Flynn evaluation criteria, taking into account the change in limb axis and mobility limitation. The Baumann angle was assessed using available postoperative radiographs.

Statistical analysis was performed to look for correlations between individual factors, clinical data, and the way the wires were inserted (crosswise, from the side).
The statistical analysis was performed in STATISTICA 13.3 (StafSoft Inc., Tulsa, OK, USA) software. In the analysis, p < 0.05 was considered statistically significant. The normal distribution of data was assessed with the Shapiro-Wilk test. For analysis, the Mann-Whitney U test or Student’s t-test and Kruskal-Wallis ANOVA or One-way ANOVA tests were used when applicable. Correlation analysis was conducted using the Spearman correlation method.

Results

Seventy-five patients with a history of supracondylar humerus fracture were included in the study. The mean age of the patients at the time of injury was 6.83 (range: 2-14 years). The right limb was fractured in 42.7% of cases. In 44.0% of the operated patients, the broken limb was the dominant limb. A fall from above own height was indicated by 60.0% of the respondents. In the remaining cases, the fracture mechanism was a fall from their own height. Fractures occurred most frequently in the spring (44% of patients) and least frequently in autumn (12% of patients). Crossed K-wires were inserted in 82.7% of patients, while from the side in 17.3% (Fig. 2A-B, 3A-B). In the question regarding return to function, the most frequently picked answer was < 2 months (30.7%). Complete loss of function was indicated by 8.0% of the patients surveyed (Tab.1).

The mean VAS pain score at the time of the study was 0.2 (range: 0-10). The most frequently chosen response was 0 (84.0%).

In the assessment of satisfaction with the current limb function, 81.3% of subjects indicated satisfaction, 16.0% moderate satisfaction, and 2.7% reported dissatisfaction.
As a result of the injury and surgical intervention, 20.0% of the subjects reported transient nerve dysfunction, most commonly in the median nerve (11% of patients). Two patients indicated a loss of function from several nerves (Tab. 2).

In all subjects with a selective innervation problem, the disorder resolved within a few months after surgery. In 1 patient, the fracture resulted in fascial compartment syndrome with subsequent Volkmann’s contracture. The above-mentioned patient underwent several reconstructive operations on the forearm as a consequence of the effects of the fracture.
In the Flynn criteria for axis change and mobility restriction subcategories, the most common outcome was very good (80.0% and 77.3% of subjects, respectively) (Tab. 3 and Tab. 4).
Cubitus varus was observed in 6 patients (8%). The Baumann angle was 72.5 degrees on average.

The Mayo Elbow Score turned out to be excellent in 94.7% of the operated patients and good in 4.0%. Patients with a satisfactory score represented only 1.3% of the sample.
In the patient population, the type of fixation was also analysed, comparing the cross and side techniques in terms of the occurrence of current complaints. There was a significantly higher incidence (p = 0.03) of current complaints in the group treated from the side compared to the group treated crosswise (54% vs 32% of patients reported current complaints, respectively).
There was a relevant association between season and the number of falls (p = 0.04). More falls from above own height occur in trauma patients during the summer. In contrast, fractures caused by falls from one’s height occur more frequently in patients with trauma in spring than in other seasons.

In addition, significant but weak correlations were observed between the difference in broken and healthy limb axis and parameters such as the age at the time of injury (p = 0.02, r = 0.28) and age at the time of examination (p = 0.02, r = 0.295). Younger patients had a significantly smaller difference in limb axis between healthy and operated limbs.
There were no relevant differences observed between the type of fixation and the following studied parameters: current VAS pain score, Baumann angle of the operated limb, flexion deficit in the elbow joint of the operated limb, presence of current neurological complications, satisfaction with the current function of the limb, Flynn criteria score, and Mayo Elbow Score.
There was also a lack of significant difference between the age of the patient at the time of examination or at the time of injury and the flexion deficit compared to the healthy limb, or the age at the time of injury and the recovery time.

The association of gender with: the difference in the axis of the healthy and operated limb, postoperative neurological complications, Baumann’s angle, and the indicated recovery time was also non-significant.

Discussion

The results gathered from the retrospective study were analysed and correlated to establish a superiority of surgical technique, as cross K-wire or side K-wire procedures were assessed and compared in the treatment of supracondylar humerus fractures in children. In the presently available research, it has not been clearly established which group of patients would benefit more from a particular K-wire configuration in relation to future limb function and patient satisfaction [19,20]. Traditionally, the K-wire cross method is associated with a larger number of neurological complications, with ulnar paresthesia taking the lead [11]. In contrast, the side K-wire method is more often associated with the instability of the fracture [21]. Interestingly, some authors argue that it is impossible to establish either method’s superiority [22,23]. Statistical analysis of the current study group shows only one relevant correlation in favour of cross K-wire technique over side K-wire surgical technique due to postoperative patients’ complaints. It should be noted that due to the limited study group number and the major disproportion of the popularity of the two surgical techniques, the result may be biased and the surgeon’s experience of the two techniques is considerably different.

The most common type of iatrogenic intra and postoperative neurological complication observed in humerus fractures is ulnar nerve injury, as Dekker et al. stated in their meta-analysis, leading to subsequent ulnar nerve palsy [11]. Other sources state that the most common injury is median nerve injury. [8] The surgeon should keep in mind that there is always the possibility of damaging median nerve. Once recognised early enough, preferably during the operation, it allows to reduce long-term complications resulting fromthe palsy.
Percutaneous cross K-wire technique and side K-wire technique results were compared in 52 patients by Kocher et al., and no iatrogenic nerve injury occurred in either group [19].
A study by Krusche et al. reports findings similar to the group of 36 patients. The authors report only one incident of iatrogenic radial nerve injury, which later resolved completely without intervention [24].

Green et al. found one patient out of the study group of 65 patients with a postoperative ulnar nerve injury which corresponds to a 1,5% iatrogenic injury rate [25].
In our findings, only one patient presented Volkmann contracture, a severe complication that was treated by revision operations resulting in mild improvement of limb function. No patients presented nerve injuries on the day of examination. In literature, contractures generally are placed as some of the most common complications of paediatric supracondylar fractures and occur in around 1,1% of patients, as reported in a meta-analysis by Mitchelson et al.. However, Volkmann ischemic contracture is a rare but extremely difficult to treat complication of supracondylar humerus fractures [26,27].

Perioperative symptoms such as temporary nerve palsy, neurological symptoms of paraesthesia, and vascular problems observed in around 20% of patients have all, but one been resolved or have considerably decreased since surgical treatment. Authors report that neurological complications at a presentation of patients occur at rates from 5-14% of patients, and vascular compromise is present in 7-10% of patients [28-31].

A significant statistical difference has been found in the seasonality of injury resulting from a fall. Falling from own height has occurred statistically more often in spring, whereas falling from heights above own happens statistically more often during the summer. Seasonality of injury has been reported previously in upper limb fractures, specifically in supracondylar fractures, which places summer as the season with the most injury occurrence [32-35].

In addition, correlations were observed between the differences in broken and healthy limb axis and the age of patients at the time of injury, showing that children of younger ages tend to preserve the anatomical limb axis more often than older children. The above findings require careful consideration as the study groups were of unequal proportions and should be confronted with more extensive cohort studies. Auso-Peres et al., in their study, confirmed that a younger age at fracture enables a quicker and less complicated healing process compared with a similar injury in older children [34]. Mitchelson et al. presented a study of 382 paediatric patients where children of older ages and heights sustained a larger number of more severe and complicated injuries than the younger population [26]. Authors highlight that bone mineral density decreases during rapid growth in older children, leading to higher complicated fracture risk [36,37].
An extension of the current study to include a larger cohort of patients with statistically equal study groups would help eliminate bias in future studies and possibly discover additional correlations when divided into smaller age-dependent subgroups. A significant limitation of the study is that patients were recruited voluntarily and asked to travel to examination sites on their own, which excluded some participants due to lack of transport from rural areas. Another limitation of the study is that it is a single tertiary centre study which may not be truly representative of larger demography.

Conclusion

Percutaneous stabilisation of supracondylar fracture of humerus in children makes it possible to obtain good results. Despite the high rate of perioperative complications affecting the nerves of the limbs, the functional deficits are typically transient and resolve independently in a few months. The functional assessment of the upper limb is frequently more than satisfactory. When comparing the treatment results with regards to the method of K-wire introduction, our study has shown statistical significance solely for the current complaints that the patients had. Both methods of pinning provide excellent functional results. The study was limited by the significant disparities in group sizes, which may have, in turn, affected the significance of the results. We believe that further studies with a greater or more homogenous group of patients should be conducted.

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