K-Hammer Percutaneous Fixation: A Novel Strategy to Prevent Iatrogenic Ulnar Nerve Injury in Pediatric Supracondylar Fractures

K-Hammer Percutaneous Fixation: A Novel Strategy to Prevent Iatrogenic Ulnar Nerve Injury in Pediatric Supracondylar Fractures | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article K-Hammer Percutaneous Fixation: A Novel Strategy to Prevent Iatrogenic Ulnar Nerve Injury in Pediatric Supracondylar Fractures Yijun Zhou, Xiaoan Bai, Changhong Li, Mi Zhou, Fan Bai, Jiang Chen, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7410150/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: This study assessed the therapeutic efficacy of a novel approach combining percutaneous Kirschner wire fixation with the K-hammer technique in pediatric patients with supracondylar humeral fractures. Methods: This retrospective cohort study enrolled 34 pediatric patients (male: 13 (38.24%); female: 21 (61.76%): 12; age 5.82 ± 2.54 years) with acute flexion-type supracondylar humeral fractures (diagnosis ≤7 days post-trauma). Under general anesthesia, all fractures underwent fluoroscopically guided closed reduction followed by percutaneous fixation: two lateral-entry 1.5–2.0 mm Kirschner wires established initial stabilization, supplemented by a third medial Kirschner wire deployed via the K-Hammer reduction technique to create a biomechanically optimized cross-pinning construct. Postoperatively, the elbow was maintained in a 90° functional position via long-arm fiberglass casts for 4 weeks. Results : During a mean follow-up period of 12.24 ± 4.45 (range: 6–23 months), functional outcomes assessed via Flynn's criteria demonstrated excellent results in 32 patients (94.12%), good results in 2 (5.88%), and fair results in 0 (0%). Notably, no secondary displacement, osteonecrosis, or major complications—including nonunion, iatrogenic neurovascular injury, myositis ossificans, or chronic elbow dysfunction—were documented during postoperative surveillance. Conclusions : K-Hammer-guided medial Kirschner wire insertion offers a technically streamlined and reproducible solution for irreducible flexion-type pediatric supracondylar humeral fractures, effectively eliminating iatrogenic ulnar nerve injury while minimizing soft tissue trauma. This technique establishes adequate biomechanical stability at the fracture site and facilitates optimal long-term restoration of elbow joint kinematics. K-Hammer Iatrogenic Ulnar Nerve Injury Pediatric Supracondylar Fracture Cross-pinning Gartland classification Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Supracondylar fractures of the humerus are the most common type of elbow fracture in children, accounting for 15%-20% of all pediatric fractures, with the highest incidence occurring in children aged 5–8 years[ 1 ]. This type of fracture not only significantly impacts a child's daily life but also may lead to serious complications, such as neurovascular injuries and elbow dysfunction. In recent years, with changes in children's activity patterns and increased physical activity intensity, the incidence of supracondylar fractures has shown an increasing trend[ 2 ]. Closed reduction and cross-Kirschner wire fixation have become the gold standard for treating this type of fracture because of their simplicity, minimal invasiveness, and high stability in fracture reduction [ 3 ]. However, with the widespread use of this technique, the incidence of iatrogenic ulnar nerve injury has gradually drawn the attention of clinicians. Ulnar nerve injury is one of the more severe complications in the surgical treatment of supracondylar humerus fractures, with reported incidence rates ranging from 1–11% in various studies[ 4 ]. Ulnar nerve injury not only affects the recovery of elbow function but also may lead to long-term neurological dysfunction, significantly impacting a child's quality of life. Studies have shown that the occurrence of iatrogenic ulnar nerve injury is closely related to multiple factors, including the choice of Kirschner wire entry point, insertion angle, intraoperative technique, and insufficient intraoperative nerve monitoring[ 5 ]. Owing to the special anatomical position of the ulnar nerve, particularly during ulnar side pinning, the traditional ulnar Kirschner wire insertion path can easily cause direct compression or injury to the ulnar nerve[ 6 ]. Additionally, in resource-limited medical environments, the lack of high-precision real-time intraoperative monitoring equipment further increases the risk of ulnar nerve injury[ 7 ]. To address this issue, scholars both domestically and internationally have proposed various improved solutions in recent years. For example, some studies suggest the use of two Kirschner wires fixed solely on the radial side to avoid the risk of ulnar nerve injury. However, this method may lead to insufficient fixation stability in some complex fracture types, increasing the risk of fracture displacement[ 8 ]. Other studies have attempted to optimize the Kirschner wire insertion path via intraoperative ultrasound guidance, but its clinical application is still limited by equipment availability and technical operation requirements [ 9 ]. Therefore, ensuring effective fracture fixation while minimizing the occurrence of iatrogenic ulnar nerve injury remains a significant challenge for clinicians[ 10 ]. On the basis of the above background, this study proposes a new technical solution: K-hammer technique ulnar pinning combined with two cross-Kirschner wires fixed on the radial side of the distal humerus. The core of this method is to avoid direct compression or injury to the ulnar nerve by optimizing the insertion path of the ulnar Kirschner wire while ensuring fracture reduction stability by combining two cross-Kirschner wires fixed on the radial side. Specifically, the K-hammer ulnar pinning technique significantly reduces the risk of iatrogenic nerve injury by adjusting the insertion angle and direction of the Kirschner wire to avoid the anatomical path of the ulnar nerve[ 11 ]. Moreover, this method does not rely on expensive intraoperative monitoring equipment, offering high clinical practicality and promotion value [ 12 ]. This study aims to retrospectively analyze the clinical application effects of this technique to explore its advantages and limitations in avoiding iatrogenic ulnar nerve injury. The results provide new technical references for the treatment of supracondylar humerus fractures and lay the foundation for future research in related fields. By optimizing surgical techniques, we hope to minimize the occurrence of iatrogenic complications while ensuring effective fracture fixation, thereby improving the quality of life and functional recovery of pediatric patients. Methods Clinical data In this retrospective, single-center study, we screened all pediatric patients who underwent surgical treatment for flexion-type supracondylar humeral fractures (FSCHFs) at the Department of Orthopedics of The First People’s Hospital of Changde between September 2020 and September 2024. Thirty-four patients (13 male, 21 female) aged 2–10 years met the eligibility criteria and were ultimately included. All injuries were sustained after low-energy falls and were classified as Gartland type III or IV patterns. Inclusion criteria (1) age 2–10 years (inclusive); (2) displaced, flexion-type supracondylar humeral fracture (Gartland III–IV) ; (3) no preoperative clinical evidence of ulnar neuropathy; (4) intraoperative ultrasound confirming absence of ulnar nerve entrapment. Exclusion criteria (1) Open fractures; (2) preoperative physical examination demonstrating ulnar nerve deficit or intraoperative ultrasound revealing ulnar nerve entrapment; (3) concomitant fractures of other anatomic regions; (4) pathological or multiple fractures. The study protocol was approved by the institutional review board of The First People’s Hospital of Changde (approval no. YX-2023-231-01). Written informed consent was obtained from all patients and their legal guardians. Surgical technique After successful general anesthesia, the patient was placed in a supine position with the affected limb on the edge of the operating table to allow for C-arm fluoroscopy. Following routine sterilization and draping, the surgeon gently tractioned the affected limb to correct angular deformities in the coronal and sagittal planes and restore normal anatomical alignment. After confirming satisfactory fracture reduction under fluoroscopy, the elbow was maintained in a flexed position to hold the reduction. Under fluoroscopic guidance, two 1.6 mm Kirschner wires were inserted from the direction of the lateral humeral condyle to fix the distal and proximal ends of the fracture in parallel. The positions of the lateral Kirschner wires were confirmed to be good, and the fracture ends were confirmed to be stable via fluoroscopy. The surgeon subsequently maintained the elbow at a slight extension (approximately 30°) with the right hand to naturally relax and posteriorly shift the ulnar nerve, thereby reducing the risk of anterior dislocation. The surgeon’s left thumb (blue translucent glove in the left image) pressed firmly on the bony landmark of the medial epicondyle and continuously pushed the ulnar nerve posteriorly. An entry point was chosen slightly anterior to the medial epicondyle and the Kirschner wire was hammered perpendicularly via a bone hammer (held firmly by bone forceps to avoid rotation that could entangle the nerve), penetrating the medial cortex in a nonrotational manner. Once the Kirschner wire contacted the opposite cortex, a low-speed electric drill was used to achieve penetration of the opposite cortex (to prevent thermal injury) (Figs. 1–4). Fluoroscopy confirmed the good position of the medial Kirschner wire, further stabilization of the fracture ends, and restoration of the Baumann angle and the humerocapitellar angle to within the normal range. All Kirschner wires were bent and trimmed, leaving 1.5 cm external to the skin for easy postoperative removal. The pin sites were disinfected with a 10% povidone-iodine solution and covered with sterile dressings. A plaster back slab was used to immobilize the elbow at 100° flexion and the forearm in a neutral rotation position to ensure early postoperative stability of the fracture ends. The study was approved by the Institutional Review Board of the Ethics Committee of the First People's Hospital of Changde (YX-2023-231-01). Written informed consent was obtained from the patients to publish this paper. Results Demographic and Basurgical Characteristics A total of 34 pediatric patients (mean age 5.82 ± 2.54 years) with acute flexion-type supracondylar humeral fractures were included in this study. The cohort comprised 13 males (38.24%) and 21 females (61.76%), with a mean hospital stay of 4.12 ± 1.68 days. The mean operative time was 44.53 ± 7.44 minutes, and the mean follow-up period was 12.24 ± 4.45 months (range: 6–23 months). (Table 1 ) Radiographic parameters Preoperative and postoperative radiographic assessments demonstrated significant improvements in key anatomical parameters. The mean Baumann angle was corrected to 78.38 ± 4.96°, whereas the humerocapitellar angle improved to 33.75 ± 8.79°. The postoperative elbow range of motion(ROM) showed excellent restoration, with mean flexion achieving 144.26 ± 9.02° and extension limited by only 0.85 ± 2.24°. The carrying angle of the affected limbs (12.29 ± 5.08°) deviated minimally from that of the unaffected limbs (13.91 ± 2.19°). Functional Outcomes According to Flynn's criteria, functional assessment revealed excellent outcomes in 32 patients (94.12%) with flexion–extension limitations within 0–5°. Two patients (5.88%) demonstrated good outcomes with a 6°-10° limit, whereas no patients presented fair or poor results. Comparative analysis of the carrying angles between the affected and unaffected limbs revealed that 30 patients (88.24%) maintained optimal alignment with 0–5° loss, and 4 patients (11.76%) exhibited 6–10° loss. No patients experienced loss greater than 10°. (Table 1 ) Complication profile Notably, our series demonstrated an excellent safety profile. Throughout the follow-up period, there were no instances of secondary displacement, osteonecrosis, or major complications, including nonunion, iatrogenic neurovascular injury, myositis ossificans, or chronic elbow dysfunction. Technical modification via K-Hammer-guided medial Kirschner wire insertion effectively eliminated iatrogenic ulnar nerve injury while maintaining soft tissue integrity. Table 1 Demographic and clinical characteristics of the study cohort Characteristics Mean ± SD Age(years) 5.82 ± 2.54 Length of hospital stay(day) 4.12 ± 1.68 Operative time(min) 44.53 ± 7.44 Baumann Angle 78.38 ± 4.96 Humerocapitellar Angle 33.75 ± 8.79 Flexion 144.26 ± 9.02 Extension 0.85 ± 2.24 Carrying Angle(affected LiYXmbs) 12.29 ± 5.08 Carrying Angle(unaffected Limbs) 13.91 ± 2.19 Follow up (Month) 12.24 ± 4.45 N (%) Gender Male 13 (38.24%) Female 21 (61.76%) Injured side Left 21 (61.76%) Right 13 (38.24%) Gartland III 23 (67.65%) IV 11 (32.35%) Biomechanical Stability The implementation of the biomechanically optimized cross-pinning construct, comprising two lateral-entry Kirschner wires and one medial-entry wire, provided adequate stability at the fracture site. This configuration facilitated optimal long-term restoration of elbow joint kinematics without compromising adjacent anatomical structures. The mean time to radiographic union was consistent with the established healing parameters for pediatric supracondylar fractures. (Table 2 ) Table 2 Functional outcomes according to Flynn’s criteria Outcome Excellent Good Fair Poor Elbow Joint Function Flexion and extension are limited by 0° −5° Flexion and extension are limited by 6°–10° Flexion and extension are limited by 11°–15° Flexion and extension are limited by more than 15° Number of Cases 32 2 0 0 Comparison of Carrying Angles Between Affected and Unaffected Limbs Loss of 0°–5° Loss of 6°–10° Loss of 11°–15° Loss of greater than 15° Number of Cases 30 4 0 0 Discussion The sequence of medial and lateral pin placement Current biomechanical evidence indicates that primary stabilization of the medial column during crossed-pin fixation for supracondylar humeral fractures confers enhanced construct rigidity, particularly in comminuted or highly unstable fracture configurations[13]. Nonetheless, the persistent risk of iatrogenic ulnar nerve complications—including traction injuries and thermal damage during trans-epicondylar pin placement—remains a critical limiting factor for its universal implementation. Current evidence from our clinical study demonstrates that the lateral-entry-first technique offers superior biomechanical and clinical benefits. First, the lateral-entry-first approach provides optimal fracture stabilization while minimizing iatrogenic risk. As shown in our series, the initial placement of two lateral-entry Kirschner wires established primary stability without jeopardizing neurovascular structures[13]. This technique allows for better control of reduction quality under fluoroscopic guidance before engaging the medial column. Notably, the risk of ulnar nerve injury is significantly reduced when the medial pin is placed last, as the nerve is naturally displaced posteriorly during elbow extension[14]. Second, contrary to previous reports by Gupta et al.[15], our data indicate that the lateral-entry-first technique does not prolong the surgical time, with a mean operative duration of 44.53 ± 7.44 minutes. The initial lateral fixation actually streamlines the subsequent medial pin placement by providing a stable reference point, eliminating the need for repeated adjustments typically required in medial-first approaches. This technical modification maintains soft tissue integrity while ensuring optimal biomechanical stability[16]. Furthermore, the biomechanical advantages of lateral-entry-first fixation are evident in our radiographic outcomes. The construct comprising initial lateral pins followed by a carefully placed medial pin demonstrated excellent maintenance of reduction, with the Baumann angle restored to 78.38 ± 4.96° and the humerocapitellar angle improved to 33.75 ± 8.79°. This optimized cross-pinning configuration effectively prevented secondary displacement without compromising adjacent anatomical structures[14] [16]. In conclusion, while medial pinning first has been traditionally favored, the lateral-entry-first technique offers distinct advantages in terms of safety, efficiency, and biomechanical stability. This approach particularly excels in minimizing iatrogenic complications while maintaining optimal fracture reduction and elbow kinematics[14–16]. 2 Position for medial pinning of the supracondylar fracture The positioning of the elbow during medial pin placement plays a critical role in minimizing the risk of ulnar nerve injury. Shih CA et al.[17] demonstrated a significant correlation between the elbow flexion angle and ulnar nerve subluxation, with anterior subluxation occurring in 53.3% of patients at 120° flexion, 40% at 90° flexion, and 16.7% at 60° flexion, with no subluxation observed at 30° flexion. This finding is particularly relevant given the intimate anatomical relationships among the ulnar nerve, cubital tunnel, and medial epicondyle[18, 19]. Several studies have documented the prevalence of ulnar nerve instability in pediatric populations. Zaltz et al.[20] reported that 54.8% (28/52) of children aged 6–10 years presented ulnar nerve instability. Furthermore, ultrasound examination of 237 children revealed that elbow flexion to 90° or 120° resulted in ulnar nerve subluxation or dislocation from the cubital tunnel in 40–58% of cases[21]. These findings highlight the potential risks associated with excessive elbow flexion during medial pin placement. While excessive elbow flexion is commonly employed to maintain reduction in extension-type supracondylar humerus fractures, this position significantly increases the risk of ulnar nerve injury during medial pin insertion. Intraoperative ultrasound monitoring conducted during fracture reduction and fixation[22] revealed that among 15 children with excessive elbow flexion, all demonstrated anterior ulnar nerve subluxation. Successful medial pin placement required elbow extension to approximately 90°. On the basis of these findings, we recommend maintaining the elbow at approximately 30° of extension when performing medial Kirschner wire(K-wire ) fixation for supracondylar humerus fractures, particularly in cases of ulnar nerve dislocation. This positioning effectively reduces the risk of iatrogenic ulnar nerve injury by preventing nerve dislocation during the procedure. The technical modification using K-Hammer-guided medial Kirschner wire insertion further enhances safety by maintaining soft tissue integrity while ensuring adequate biomechanical stability at the fracture site. The Importance of Cross Fixation Our study demonstrated that the biomechanically optimized cross-pinning construct, consisting of two lateral-entry Kirschner wires and one medial-entry wire deployed through the K-Hammer technique, provides superior fracture stability while maintaining an excellent safety profile. This finding aligns with previous biomechanical research showing that crossed fixation offers significantly better stability than lateral fixation alone under various loading conditions [23]. The technical modification using K-Hammer-guided medial Kirschner wire insertion effectively eliminates iatrogenic ulnar nerve injury while maintaining soft tissue integrity, which represents a significant advancement in surgical technique. The implementation of our modified cross-fixation technique yielded excellent functional outcomes in 94.12% of the patients, with only 5.88% demonstrating good outcomes and no patients showing fair or poor results according to Flynn's criteria. These results contrast with those of Brauer et al.'s systematic review[24], which reported a 40% lower rate of loss of reduction with crossed fixation than with lateral fixation. Our series demonstrated no instances of secondary displacement, further confirming the superior stability of this construct. Regarding functional recovery, our results show that the crossed fixation group achieved excellent elbow motion restoration (mean flexion 144.26 ± 9.02°) and minimal carrying angle deviation (mean 12.29 ± 5.08°), which is consistent with the findings of Na et al.'s meta-analysis[25]. The technical modification of the K-Hammer technique with careful soft tissue protection effectively reduced the risk of iatrogenic ulnar nerve injury, as Woratanarat et al. [26] suggested through mini-open incision techniques. The long-term follow-up results from our study confirm the advantages of cross-fixation in preventing abnormal fracture healing. The maintenance of the Baumann angle (78.38 ± 4.96°) and humerocapitellar angle (33.75 ± 8.79°) demonstrates the effectiveness of this technique in preventing deformities such as cubitus varus, supporting Kawak et al.'s findings[27]. The mean time to radiographic union in our series was consistent with established healing parameters for pediatric supracondylar fractures, further validating the efficacy of this modified cross-fixation technique. 4 , Other techniques for avoiding iatrogenic ulnar nerve injury. In pediatric patients with supracondylar humeral fracture, several innovative approaches have been developed to mitigate ulnar nerve complications. The prone positioning strategy significantly reduces ulnar nerve traction and compression by minimizing excessive elbow flexion, thereby decreasing the postoperative risk of ulnar neuropathy and sensory disturbances and ultimately increasing surgical safety[28]. Contemporary advances in ultrasound technology have revolutionized perioperative management through high-resolution imaging, which provides detailed visualization of the three-dimensional anatomy and ulnar nerve trajectory of the cubital tunnel, enabling precise real-time dynamic needle guidance[17]. This technological advancement not only improves surgical precision but also facilitates procedural standardization. The K-wire sliding technique represents another significant advancement, allowing for meticulous adjustment of needle trajectories and fixation points while maintaining relatively low technical complexity and broad clinical applicability. However, this approach is limited by limited mid- to long-term follow-up data[29]. The ulnar mini-incision technique offers direct nerve visualization through minimally invasive access, enabling precise identification and protection of the ulnar nerve under direct vision[30]. Furthermore, the modified medial pinning technique with elbow extension effectively prevents ulnar nerve subluxation or dislocation during elbow flexion, providing an additional layer of neural protection[17, 21]. Among these approaches, the lateral pinning technique demonstrates particular efficacy in reducing iatrogenic ulnar nerve injury risk, making it especially suitable for younger patients or patients with stable fracture patterns[31]. The integration of intraoperative neurophysiological monitoring provides valuable real-time feedback for precise ulnar nerve localization, significantly enhancing the safety profile of medial K-wire placement[32]. While the elastic stable intramedullary nailing (ESIN) technique offers distinct biomechanical advantages and neural safety benefits in treating pediatric supracondylar humeral fractures, its application is limited by specific biomechanical constraints and technical requirements[33]. In conclusion, while these diverse techniques demonstrate considerable promise in minimizing the risk of ulnar nerve injury during pediatric supracondylar humeral fracture surgery, each approach presents unique advantages and limitations that necessitate careful consideration on the basis of individual patient characteristics and clinical scenarios. 5 , Treatment of iatrogenic ulnar nerve injury. Neurological complications represent a critical concern in the surgical management of pediatric supracondylar humeral fractures. The current literature provides substantial evidence-based insights into the incidence patterns, management strategies, and outcomes of these neural injuries. Ramachandran et al. [34] conducted a comprehensive review of 32 pediatric patients with 37 documented nerve injuries and reported that the ulnar nerve was most frequently affected (51.4%), followed by the median (27%) and radial nerves (21.6%). These findings were corroborated by subsequent research analyzing 272 pediatric cases between 2000 and 2007, which reported an overall nerve injury incidence of 18%, with iatrogenic injuries accounting for 14% of cases, predominantly affecting the ulnar nerve. Notably, these iatrogenic injuries lead to spontaneous recovery, with an average resolution time of 3.5 months [35]. Furthermore, Kwok's extensive review of 166 pediatric patients[36] similarly identified the ulnar nerve as the most commonly affected nerve (43.4%), followed by the median (36.7%) and radial nerves (19.9%). Despite 56% of patients requiring surgical exploration, the study reported excellent or good outcomes in 94% of patients. Detailed surgical investigations by Ramachandran[34] revealed that crossed Kirschner wire placement rarely results in direct ulnar nerve penetration. Instead, the predominant mechanism involved soft tissue constriction of the nerve within the cubital tunnel. The recommended protocol involves maintaining Kirschner wire fixation for 3‒4 weeks, with subsequent documentation of nerve function recovery typically occurring between 3‒4 months post-operatively. Routine surgical exploration of the ulnar nerve is not advocated because of the high spontaneous recovery rate. However, early removal of the medial Kirschner wire may be considered a viable option to potentially accelerate recovery, provided that adequate fracture stability can be maintained through lateral wire fixation. On the basis of these comprehensive clinical observations, we propose the following management algorithm: 1) For the majority of iatrogenic ulnar nerve injuries, particularly those resulting from nerve compression or traction, initial conservative management should be implemented. This approach is supported by the high incidence of spontaneous resolution within weeks to months, obviating the need for immediate surgical intervention. 2) Nevertheless, prompt referral to a specialized center for formal nerve exploration is warranted in patients who present with complete nerve palsy, positive Tinel's sign, neuropathic pain, or evidence of vascular compromise. While the overall prognosis for iatrogenic ulnar nerve injuries remains favorable, vigilant monitoring of nerve function recovery remains crucial to enable timely intervention when necessary. The presented management strategy aligns with current best practices while incorporating evidence-based recommendations from multiple large-scale clinical studies[34–36]. This approach optimizes patient outcomes while minimizing unnecessary interventions. Conclusions This study demonstrated that the innovative technique combining percutaneous Kirschner wire fixation with the K-hammer method offers a safe and effective treatment option for pediatric flexion-type supracondylar humeral fractures. The approach achieves excellent functional outcomes in 94.12% of patients, with no major complications or secondary displacement. K-hammer-guided medial pin insertion significantly reduces the risk of iatrogenic ulnar nerve injury while preserving soft tissue integrity. The biomechanically optimized cross-pinning construct provides stable fixation, facilitating optimal fracture healing and elbow kinematics restoration. This technique's advantages, including technical reproducibility, minimal soft tissue trauma, and excellent clinical outcomes, make it a valuable addition to the surgical management of these challenging pediatric fractures. Abbreviations Abbreviation Full Term FSCHF Flexion-type supracondylar humeral fracture K-wire Kirschner wire ESIN Elastic stable intramedullary nailing ROM Range of motion Declarations Ethics approval and consent to participate The study was approved by the Institutional Review Board of the Ethics Committee of the First People's Hospital of Changde (YX-2023-231-01). Written informed consent was obtained from the patients to publish this paper. Consent for publication All the authors have read and agreed to the published version of the manuscript. Competing interests The authors declare that they have no competing interests. Funding This research was funded by the General Guidance Project of the Hunan Provincial Administration of Traditional Chinese Medicine (C2023040). Author Contribution YJZ: Writing – original draft and Funding acquisition; XAB: Funding acquisition and Conceptualization; CHL:Project administration; MZ: Data analysis; FB and JC:Prepared figures 1-4.; GWS: Review and editing. All authors reviewed the manuscript. Acknowledgement Not applicable. Data Availability The datasets used in this study are available from the corresponding author on reasonable request. References Vaquero-Picado A, González-Morán G, Moraleda L. Management of supracondylar fractures of the humerus in children. EFORT Open Rev. 2018;3(10):526–40. Latario LD, et al. Which pediatric supracondylar humerus fractures are high risk for conversion to open reduction? J Pediatr Orthop B. 2023;32(6):569–74. Chong HH, Qureshi A. Pediatric distal humeral supracondylar fracture - achievement of optimal pinning configuration. Acta Orthop Belg. 2022;88(2):245–54. Hagino T, et al. Ulnar nerve snagged on Kirschner wire following surgery for supracondylar fracture of humerus. 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Intrainstitutional Changes of the Treatment of Supracondylar Humerus Fracture in Children over a Period of 9 Years. Child (Basel), 2023; 11(1). Ramachandran M, Birch R, Eastwood DM. Clinical outcome of nerve injuries associated with supracondylar fractures of the humerus in children: the experience of a specialist referral centre. J Bone Joint Surg Br. 2006;88(1):90–4. Khademolhosseini M, Abd Rashid AH, Ibrahim S. Nerve injuries in supracondylar fractures of the humerus in children: is nerve exploration indicated? J Pediatr Orthop B. 2013;22(2):123–6. Kwok IH et al. Nerve injuries associated with supracondylar fractures of the humerus in children: our experience in a specialist peripheral nerve injury unit. Bone Joint J, 2016; 98–b(6): pp. 851–6. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7410150","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":507851862,"identity":"8c43a114-0580-44bb-a6e7-1be15e33da7b","order_by":0,"name":"Yijun Zhou","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Yijun","middleName":"","lastName":"Zhou","suffix":""},{"id":507851863,"identity":"92a98135-d6ed-43ce-ad99-a68c65a829d5","order_by":1,"name":"Xiaoan Bai","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Xiaoan","middleName":"","lastName":"Bai","suffix":""},{"id":507851864,"identity":"a60bc282-40e5-4ffd-97e6-ea42244d1a62","order_by":2,"name":"Changhong Li","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Changhong","middleName":"","lastName":"Li","suffix":""},{"id":507851865,"identity":"39ebe7c0-84c8-4f8d-a3c1-c9643b6c5f96","order_by":3,"name":"Mi Zhou","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Mi","middleName":"","lastName":"Zhou","suffix":""},{"id":507851866,"identity":"c6a579f4-7b94-46f7-bd1c-c76074791dbf","order_by":4,"name":"Fan Bai","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Fan","middleName":"","lastName":"Bai","suffix":""},{"id":507851867,"identity":"007e84e6-76b5-4ab6-a089-cde778473e90","order_by":5,"name":"Jiang Chen","email":"","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":false,"prefix":"","firstName":"Jiang","middleName":"","lastName":"Chen","suffix":""},{"id":507851868,"identity":"68ce4c21-6d94-48b3-8805-e779f32fa5d3","order_by":6,"name":"Guanwen Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzElEQVRIiWNgGAWjYBACNmaGBIMEAwk5NvbmA8Rp4WNveFDwoMLCmJ/nWAJxWuR4Dj74+OBMReLMGTkGRDpMIjlxQ2KbROKGGzkfb7xhsJPTbSCoJS3ZAKjFeMOZt5st5zAkG5sdIKglJw2kRXbD8dxt0jwMBxK3EdaS//0HUAvjhgM5z4jUwnMAGMhnJBRnduSwEamFvQGopUICFMjGlnMMiPCLfDNDguEPgzpQVD688abCTo6gFhQgwUNk1CBrIVXHKBgFo2AUjAgAAPecRQzMBFHRAAAAAElFTkSuQmCC","orcid":"","institution":"Changde Hospital Affiliated to Xiangya Medical College of South Central University","correspondingAuthor":true,"prefix":"","firstName":"Guanwen","middleName":"","lastName":"Sun","suffix":""}],"badges":[],"createdAt":"2025-08-19 15:38:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7410150/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7410150/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90544277,"identity":"2f561fe7-a890-47f9-9e8a-02e9f0a501b5","added_by":"auto","created_at":"2025-09-04 00:17:29","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":312049,"visible":true,"origin":"","legend":"\u003cp\u003eThis figure presents hand-drawn illustrations of the K-Hammer surgical technique. Figure A shows the hand-drawn illustration of Kirschner wire insertion at the medial condyle of the humerus in the anteroposterior view of the elbow joint; Figure B shows the hand-drawn illustration of Kirschner wire insertion at the medial condyle of the humerus in the lateral view of the elbow joint.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7410150/v1/e8d4e1d2753700643cd58609.png"},{"id":90542978,"identity":"51692596-0197-4277-ae56-bda92e53c417","added_by":"auto","created_at":"2025-09-04 00:09:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1163185,"visible":true,"origin":"","legend":"\u003cp\u003eThis figure presents intraoperative photographs of the K-Hammer surgical technique. Figure A shows a photograph of Kirschner wire insertion at the medial condyle of the humerus in the anteroposterior view of the elbow joint; Figure B shows a photograph of Kirschner wire insertion at the medial condyle of the humerus in the lateral view of the elbow joint.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7410150/v1/78e3825e950666a4710b2d2a.png"},{"id":90545032,"identity":"d4825f4c-6034-46bb-a3a4-b183262517dd","added_by":"auto","created_at":"2025-09-04 00:25:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1600978,"visible":true,"origin":"","legend":"\u003cp\u003eA 4-year-old female patient with a Gartland type III supracondylar humeral fracture. A shows the lateral X-ray of the elbow joint, and B shows the anteroposterior X-ray of the elbow joint.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7410150/v1/f15d8ca6c2c3c5e17844d4b9.png"},{"id":90542982,"identity":"d33621af-a6b6-4fa3-873c-92717cfcf1d3","added_by":"auto","created_at":"2025-09-04 00:09:29","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1343266,"visible":true,"origin":"","legend":"\u003cp\u003eThis figure shows the K-Hammer surgical procedure under the guidance of a C-arm. A and B show the process of slow Kirschner wire insertion at the medial condyle of the humerus, and C and D show the anteroposterior and lateral X-rays of the elbow joint after the completion of Kirschner wire insertion.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7410150/v1/d91833445c2983c56179198c.png"},{"id":92017613,"identity":"1bc13e77-a4d4-4654-9707-ac8e9838c601","added_by":"auto","created_at":"2025-09-23 16:53:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7337661,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7410150/v1/70aa8b0f-1a9b-4ec2-9504-2a15ae013497.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"K-Hammer Percutaneous Fixation: A Novel Strategy to Prevent Iatrogenic Ulnar Nerve Injury in Pediatric Supracondylar Fractures","fulltext":[{"header":"Background","content":"\u003cp\u003eSupracondylar fractures of the humerus are the most common type of elbow fracture in children, accounting for 15%-20% of all pediatric fractures, with the highest incidence occurring in children aged 5\u0026ndash;8 years[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. This type of fracture not only significantly impacts a child's daily life but also may lead to serious complications, such as neurovascular injuries and elbow dysfunction. In recent years, with changes in children's activity patterns and increased physical activity intensity, the incidence of supracondylar fractures has shown an increasing trend[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Closed reduction and cross-Kirschner wire fixation have become the gold standard for treating this type of fracture because of their simplicity, minimal invasiveness, and high stability in fracture reduction [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, with the widespread use of this technique, the incidence of iatrogenic ulnar nerve injury has gradually drawn the attention of clinicians.\u003c/p\u003e\u003cp\u003eUlnar nerve injury is one of the more severe complications in the surgical treatment of supracondylar humerus fractures, with reported incidence rates ranging from 1\u0026ndash;11% in various studies[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Ulnar nerve injury not only affects the recovery of elbow function but also may lead to long-term neurological dysfunction, significantly impacting a child's quality of life. Studies have shown that the occurrence of iatrogenic ulnar nerve injury is closely related to multiple factors, including the choice of Kirschner wire entry point, insertion angle, intraoperative technique, and insufficient intraoperative nerve monitoring[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Owing to the special anatomical position of the ulnar nerve, particularly during ulnar side pinning, the traditional ulnar Kirschner wire insertion path can easily cause direct compression or injury to the ulnar nerve[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Additionally, in resource-limited medical environments, the lack of high-precision real-time intraoperative monitoring equipment further increases the risk of ulnar nerve injury[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTo address this issue, scholars both domestically and internationally have proposed various improved solutions in recent years. For example, some studies suggest the use of two Kirschner wires fixed solely on the radial side to avoid the risk of ulnar nerve injury. However, this method may lead to insufficient fixation stability in some complex fracture types, increasing the risk of fracture displacement[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Other studies have attempted to optimize the Kirschner wire insertion path via intraoperative ultrasound guidance, but its clinical application is still limited by equipment availability and technical operation requirements [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Therefore, ensuring effective fracture fixation while minimizing the occurrence of iatrogenic ulnar nerve injury remains a significant challenge for clinicians[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eOn the basis of the above background, this study proposes a new technical solution: K-hammer technique ulnar pinning combined with two cross-Kirschner wires fixed on the radial side of the distal humerus. The core of this method is to avoid direct compression or injury to the ulnar nerve by optimizing the insertion path of the ulnar Kirschner wire while ensuring fracture reduction stability by combining two cross-Kirschner wires fixed on the radial side. Specifically, the K-hammer ulnar pinning technique significantly reduces the risk of iatrogenic nerve injury by adjusting the insertion angle and direction of the Kirschner wire to avoid the anatomical path of the ulnar nerve[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Moreover, this method does not rely on expensive intraoperative monitoring equipment, offering high clinical practicality and promotion value [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis study aims to retrospectively analyze the clinical application effects of this technique to explore its advantages and limitations in avoiding iatrogenic ulnar nerve injury. The results provide new technical references for the treatment of supracondylar humerus fractures and lay the foundation for future research in related fields. By optimizing surgical techniques, we hope to minimize the occurrence of iatrogenic complications while ensuring effective fracture fixation, thereby improving the quality of life and functional recovery of pediatric patients.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv\u003e\n\u003ch2\u003eClinical data\u003c/h2\u003e\n\u003cp\u003eIn this retrospective, single-center study, we screened all pediatric patients who underwent surgical treatment for flexion-type supracondylar humeral fractures (FSCHFs) at the Department of Orthopedics of The First People\u0026rsquo;s Hospital of Changde between September 2020 and September 2024. Thirty-four patients (13 male, 21 female) aged 2\u0026ndash;10 years met the eligibility criteria and were ultimately included. All injuries were sustained after low-energy falls and were classified as Gartland type III or IV patterns.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eInclusion criteria\u003c/h3\u003e\n\u003cp\u003e(1) age 2\u0026ndash;10 years (inclusive); (2) displaced, flexion-type supracondylar humeral fracture (Gartland III\u0026ndash;IV) ; (3) no preoperative clinical evidence of ulnar neuropathy; (4) intraoperative ultrasound confirming absence of ulnar nerve entrapment.\u003c/p\u003e\n\u003ch3\u003eExclusion criteria\u003c/h3\u003e\n\u003cp\u003e(1) Open fractures; (2) preoperative physical examination demonstrating ulnar nerve deficit or intraoperative ultrasound revealing ulnar nerve entrapment; (3) concomitant fractures of other anatomic regions; (4) pathological or multiple fractures.\u003c/p\u003e\n\u003cp\u003eThe study protocol was approved by the institutional review board of The First People\u0026rsquo;s Hospital of Changde (approval no. YX-2023-231-01). Written informed consent was obtained from all patients and their legal guardians.\u003c/p\u003e\n\u003ch3\u003eSurgical technique\u003c/h3\u003e\n\u003cp\u003eAfter successful general anesthesia, the patient was placed in a supine position with the affected limb on the edge of the operating table to allow for C-arm fluoroscopy. Following routine sterilization and draping, the surgeon gently tractioned the affected limb to correct angular deformities in the coronal and sagittal planes and restore normal anatomical alignment. After confirming satisfactory fracture reduction under fluoroscopy, the elbow was maintained in a flexed position to hold the reduction.\u003c/p\u003e\n\u003cp\u003eUnder fluoroscopic guidance, two 1.6 mm Kirschner wires were inserted from the direction of the lateral humeral condyle to fix the distal and proximal ends of the fracture in parallel. The positions of the lateral Kirschner wires were confirmed to be good, and the fracture ends were confirmed to be stable via fluoroscopy. The surgeon subsequently maintained the elbow at a slight extension (approximately 30\u0026deg;) with the right hand to naturally relax and posteriorly shift the ulnar nerve, thereby reducing the risk of anterior dislocation. The surgeon\u0026rsquo;s left thumb (blue translucent glove in the left image) pressed firmly on the bony landmark of the medial epicondyle and continuously pushed the ulnar nerve posteriorly. An entry point was chosen slightly anterior to the medial epicondyle and the Kirschner wire was hammered perpendicularly via a bone hammer (held firmly by bone forceps to avoid rotation that could entangle the nerve), penetrating the medial cortex in a nonrotational manner. Once the Kirschner wire contacted the opposite cortex, a low-speed electric drill was used to achieve penetration of the opposite cortex (to prevent thermal injury) (Figs.\u0026nbsp;1\u0026ndash;4). Fluoroscopy confirmed the good position of the medial Kirschner wire, further stabilization of the fracture ends, and restoration of the Baumann angle and the humerocapitellar angle to within the normal range.\u003c/p\u003e\n\u003cp\u003eAll Kirschner wires were bent and trimmed, leaving 1.5 cm external to the skin for easy postoperative removal. The pin sites were disinfected with a 10% povidone-iodine solution and covered with sterile dressings. A plaster back slab was used to immobilize the elbow at 100\u0026deg; flexion and the forearm in a neutral rotation position to ensure early postoperative stability of the fracture ends.\u003c/p\u003e\n\u003cp\u003eThe study was approved by the Institutional Review Board of the Ethics Committee of the First People's Hospital of Changde (YX-2023-231-01). Written informed consent was obtained from the patients to publish this paper.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eDemographic and Basurgical Characteristics\u003c/h2\u003eA total of 34 pediatric patients (mean age 5.82\u0026thinsp;\u0026plusmn;\u0026thinsp;2.54 years) with acute flexion-type supracondylar humeral fractures were included in this study. The cohort comprised 13 males (38.24%) and 21 females (61.76%), with a mean hospital stay of 4.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68 days. The mean operative time was 44.53\u0026thinsp;\u0026plusmn;\u0026thinsp;7.44 minutes, and the mean follow-up period was 12.24\u0026thinsp;\u0026plusmn;\u0026thinsp;4.45 months (range: 6\u0026ndash;23 months). (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003cp\u003e\u003cstrong\u003eRadiographic parameters\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003ePreoperative and postoperative radiographic assessments demonstrated significant improvements in key anatomical parameters. The mean Baumann angle was corrected to 78.38\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u0026deg;, whereas the humerocapitellar angle improved to 33.75\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79\u0026deg;. The postoperative elbow range of motion(ROM) showed excellent restoration, with mean flexion achieving 144.26\u0026thinsp;\u0026plusmn;\u0026thinsp;9.02\u0026deg; and extension limited by only 0.85\u0026thinsp;\u0026plusmn;\u0026thinsp;2.24\u0026deg;. The carrying angle of the affected limbs (12.29\u0026thinsp;\u0026plusmn;\u0026thinsp;5.08\u0026deg;) deviated minimally from that of the unaffected limbs (13.91\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u0026deg;). Functional Outcomes According to Flynn\u0026apos;s criteria, functional assessment revealed excellent outcomes in 32 patients (94.12%) with flexion\u0026ndash;extension limitations within 0\u0026ndash;5\u0026deg;. Two patients (5.88%) demonstrated good outcomes with a 6\u0026deg;-10\u0026deg; limit, whereas no patients presented fair or poor results. Comparative analysis of the carrying angles between the affected and unaffected limbs revealed that 30 patients (88.24%) maintained optimal alignment with 0\u0026ndash;5\u0026deg; loss, and 4 patients (11.76%) exhibited 6\u0026ndash;10\u0026deg; loss. No patients experienced loss greater than 10\u0026deg;. (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eComplication profile\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eNotably, our series demonstrated an excellent safety profile. Throughout the follow-up period, there were no instances of secondary displacement, osteonecrosis, or major complications, including nonunion, iatrogenic neurovascular injury, myositis ossificans, or chronic elbow dysfunction. Technical modification via K-Hammer-guided medial Kirschner wire insertion effectively eliminated iatrogenic ulnar nerve injury while maintaining soft tissue integrity.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDemographic and clinical characteristics of the study cohort\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCharacteristics\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAge(years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.82\u0026thinsp;\u0026plusmn;\u0026thinsp;2.54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLength of hospital stay(day)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOperative time(min)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e44.53\u0026thinsp;\u0026plusmn;\u0026thinsp;7.44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBaumann Angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e78.38\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHumerocapitellar Angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.75\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e144.26\u0026thinsp;\u0026plusmn;\u0026thinsp;9.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eExtension\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.85\u0026thinsp;\u0026plusmn;\u0026thinsp;2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCarrying Angle(affected LiYXmbs)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.29\u0026thinsp;\u0026plusmn;\u0026thinsp;5.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCarrying Angle(unaffected Limbs)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.91\u0026thinsp;\u0026plusmn;\u0026thinsp;2.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFollow up (Month)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.24\u0026thinsp;\u0026plusmn;\u0026thinsp;4.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGender\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13 (38.24%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21 (61.76%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInjured side\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLeft\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21 (61.76%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13 (38.24%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGartland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIII\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23 (67.65%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11 (32.35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003eBiomechanical Stability\u003c/h3\u003e\n\u003cp\u003eThe implementation of the biomechanically optimized cross-pinning construct, comprising two lateral-entry Kirschner wires and one medial-entry wire, provided adequate stability at the fracture site. This configuration facilitated optimal long-term restoration of elbow joint kinematics without compromising adjacent anatomical structures. The mean time to radiographic union was consistent with the established healing parameters for pediatric supracondylar fractures. (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eFunctional outcomes according to Flynn\u0026rsquo;s criteria\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOutcome\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eExcellent\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGood\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFair\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ePoor\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eElbow Joint Function\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexion and extension are limited by 0\u0026deg; \u0026minus;5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexion and extension are limited by 6\u0026deg;\u0026ndash;10\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexion and extension are limited by 11\u0026deg;\u0026ndash;15\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFlexion and extension are limited by more than 15\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNumber of Cases\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eComparison of Carrying Angles Between Affected and Unaffected Limbs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLoss of 0\u0026deg;\u0026ndash;5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLoss of 6\u0026deg;\u0026ndash;10\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLoss of 11\u0026deg;\u0026ndash;15\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLoss of greater\u003c/p\u003e\n \u003cp\u003ethan 15\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNumber of Cases\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv\u003e\n\u003ch2\u003eThe sequence of medial and lateral pin placement\u003c/h2\u003e\n\u003cp\u003eCurrent biomechanical evidence indicates that primary stabilization of the medial column during crossed-pin fixation for supracondylar humeral fractures confers enhanced construct rigidity, particularly in comminuted or highly unstable fracture configurations[13]. Nonetheless, the persistent risk of iatrogenic ulnar nerve complications\u0026mdash;including traction injuries and thermal damage during trans-epicondylar pin placement\u0026mdash;remains a critical limiting factor for its universal implementation. Current evidence from our clinical study demonstrates that the lateral-entry-first technique offers superior biomechanical and clinical benefits.\u003c/p\u003e\n\u003cp\u003eFirst, the lateral-entry-first approach provides optimal fracture stabilization while minimizing iatrogenic risk. As shown in our series, the initial placement of two lateral-entry Kirschner wires established primary stability without jeopardizing neurovascular structures[13]. This technique allows for better control of reduction quality under fluoroscopic guidance before engaging the medial column. Notably, the risk of ulnar nerve injury is significantly reduced when the medial pin is placed last, as the nerve is naturally displaced posteriorly during elbow extension[14].\u003c/p\u003e\n\u003cp\u003eSecond, contrary to previous reports by Gupta et al.[15], our data indicate that the lateral-entry-first technique does not prolong the surgical time, with a mean operative duration of 44.53\u0026thinsp;\u0026plusmn;\u0026thinsp;7.44 minutes. The initial lateral fixation actually streamlines the subsequent medial pin placement by providing a stable reference point, eliminating the need for repeated adjustments typically required in medial-first approaches. This technical modification maintains soft tissue integrity while ensuring optimal biomechanical stability[16].\u003c/p\u003e\n\u003cp\u003eFurthermore, the biomechanical advantages of lateral-entry-first fixation are evident in our radiographic outcomes. The construct comprising initial lateral pins followed by a carefully placed medial pin demonstrated excellent maintenance of reduction, with the Baumann angle restored to 78.38\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u0026deg; and the humerocapitellar angle improved to 33.75\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79\u0026deg;. This optimized cross-pinning configuration effectively prevented secondary displacement without compromising adjacent anatomical structures[14] [16].\u003c/p\u003e\n\u003cp\u003eIn conclusion, while medial pinning first has been traditionally favored, the lateral-entry-first technique offers distinct advantages in terms of safety, efficiency, and biomechanical stability. This approach particularly excels in minimizing iatrogenic complications while maintaining optimal fracture reduction and elbow kinematics[14\u0026ndash;16].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2 Position for medial pinning of the supracondylar fracture\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe positioning of the elbow during medial pin placement plays a critical role in minimizing the risk of ulnar nerve injury. Shih CA et al.[17] demonstrated a significant correlation between the elbow flexion angle and ulnar nerve subluxation, with anterior subluxation occurring in 53.3% of patients at 120\u0026deg; flexion, 40% at 90\u0026deg; flexion, and 16.7% at 60\u0026deg; flexion, with no subluxation observed at 30\u0026deg; flexion. This finding is particularly relevant given the intimate anatomical relationships among the ulnar nerve, cubital tunnel, and medial epicondyle[18, 19].\u003c/p\u003e\n\u003cp\u003eSeveral studies have documented the prevalence of ulnar nerve instability in pediatric populations. Zaltz et al.[20] reported that 54.8% (28/52) of children aged 6\u0026ndash;10 years presented ulnar nerve instability. Furthermore, ultrasound examination of 237 children revealed that elbow flexion to 90\u0026deg; or 120\u0026deg; resulted in ulnar nerve subluxation or dislocation from the cubital tunnel in 40\u0026ndash;58% of cases[21]. These findings highlight the potential risks associated with excessive elbow flexion during medial pin placement.\u003c/p\u003e\n\u003cp\u003eWhile excessive elbow flexion is commonly employed to maintain reduction in extension-type supracondylar humerus fractures, this position significantly increases the risk of ulnar nerve injury during medial pin insertion. Intraoperative ultrasound monitoring conducted during fracture reduction and fixation[22] revealed that among 15 children with excessive elbow flexion, all demonstrated anterior ulnar nerve subluxation. Successful medial pin placement required elbow extension to approximately 90\u0026deg;.\u003c/p\u003e\n\u003cp\u003eOn the basis of these findings, we recommend maintaining the elbow at approximately 30\u0026deg; of extension when performing medial Kirschner wire(K-wire ) fixation for supracondylar humerus fractures, particularly in cases of ulnar nerve dislocation. This positioning effectively reduces the risk of iatrogenic ulnar nerve injury by preventing nerve dislocation during the procedure. The technical modification using K-Hammer-guided medial Kirschner wire insertion further enhances safety by maintaining soft tissue integrity while ensuring adequate biomechanical stability at the fracture site.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv\u003e\n\u003ch2\u003eThe Importance of Cross Fixation\u003c/h2\u003e\n\u003cp\u003eOur study demonstrated that the biomechanically optimized cross-pinning construct, consisting of two lateral-entry Kirschner wires and one medial-entry wire deployed through the K-Hammer technique, provides superior fracture stability while maintaining an excellent safety profile. This finding aligns with previous biomechanical research showing that crossed fixation offers significantly better stability than lateral fixation alone under various loading conditions [23]. The technical modification using K-Hammer-guided medial Kirschner wire insertion effectively eliminates iatrogenic ulnar nerve injury while maintaining soft tissue integrity, which represents a significant advancement in surgical technique.\u003c/p\u003e\n\u003cp\u003eThe implementation of our modified cross-fixation technique yielded excellent functional outcomes in 94.12% of the patients, with only 5.88% demonstrating good outcomes and no patients showing fair or poor results according to Flynn's criteria. These results contrast with those of Brauer et al.'s systematic review[24], which reported a 40% lower rate of loss of reduction with crossed fixation than with lateral fixation. Our series demonstrated no instances of secondary displacement, further confirming the superior stability of this construct.\u003c/p\u003e\n\u003cp\u003eRegarding functional recovery, our results show that the crossed fixation group achieved excellent elbow motion restoration (mean flexion 144.26\u0026thinsp;\u0026plusmn;\u0026thinsp;9.02\u0026deg;) and minimal carrying angle deviation (mean 12.29\u0026thinsp;\u0026plusmn;\u0026thinsp;5.08\u0026deg;), which is consistent with the findings of Na et al.'s meta-analysis[25]. The technical modification of the K-Hammer technique with careful soft tissue protection effectively reduced the risk of iatrogenic ulnar nerve injury, as Woratanarat et al. [26] suggested through mini-open incision techniques.\u003c/p\u003e\n\u003cp\u003eThe long-term follow-up results from our study confirm the advantages of cross-fixation in preventing abnormal fracture healing. The maintenance of the Baumann angle (78.38\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u0026deg;) and humerocapitellar angle (33.75\u0026thinsp;\u0026plusmn;\u0026thinsp;8.79\u0026deg;) demonstrates the effectiveness of this technique in preventing deformities such as cubitus varus, supporting Kawak et al.'s findings[27]. The mean time to radiographic union in our series was consistent with established healing parameters for pediatric supracondylar fractures, further validating the efficacy of this modified cross-fixation technique.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e4\u003c/strong\u003e, Other techniques for avoiding iatrogenic ulnar nerve injury.\u003c/p\u003e\n\u003cp\u003eIn pediatric patients with supracondylar humeral fracture, several innovative approaches have been developed to mitigate ulnar nerve complications. The prone positioning strategy significantly reduces ulnar nerve traction and compression by minimizing excessive elbow flexion, thereby decreasing the postoperative risk of ulnar neuropathy and sensory disturbances and ultimately increasing surgical safety[28]. Contemporary advances in ultrasound technology have revolutionized perioperative management through high-resolution imaging, which provides detailed visualization of the three-dimensional anatomy and ulnar nerve trajectory of the cubital tunnel, enabling precise real-time dynamic needle guidance[17]. This technological advancement not only improves surgical precision but also facilitates procedural standardization.\u003c/p\u003e\n\u003cp\u003eThe K-wire sliding technique represents another significant advancement, allowing for meticulous adjustment of needle trajectories and fixation points while maintaining relatively low technical complexity and broad clinical applicability. However, this approach is limited by limited mid- to long-term follow-up data[29]. The ulnar mini-incision technique offers direct nerve visualization through minimally invasive access, enabling precise identification and protection of the ulnar nerve under direct vision[30]. Furthermore, the modified medial pinning technique with elbow extension effectively prevents ulnar nerve subluxation or dislocation during elbow flexion, providing an additional layer of neural protection[17, 21].\u003c/p\u003e\n\u003cp\u003eAmong these approaches, the lateral pinning technique demonstrates particular efficacy in reducing iatrogenic ulnar nerve injury risk, making it especially suitable for younger patients or patients with stable fracture patterns[31]. The integration of intraoperative neurophysiological monitoring provides valuable real-time feedback for precise ulnar nerve localization, significantly enhancing the safety profile of medial K-wire placement[32]. While the elastic stable intramedullary nailing (ESIN) technique offers distinct biomechanical advantages and neural safety benefits in treating pediatric supracondylar humeral fractures, its application is limited by specific biomechanical constraints and technical requirements[33].\u003c/p\u003e\n\u003cp\u003eIn conclusion, while these diverse techniques demonstrate considerable promise in minimizing the risk of ulnar nerve injury during pediatric supracondylar humeral fracture surgery, each approach presents unique advantages and limitations that necessitate careful consideration on the basis of individual patient characteristics and clinical scenarios.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e5\u003c/strong\u003e, Treatment of iatrogenic ulnar nerve injury.\u003c/p\u003e\n\u003cp\u003eNeurological complications represent a critical concern in the surgical management of pediatric supracondylar humeral fractures. The current literature provides substantial evidence-based insights into the incidence patterns, management strategies, and outcomes of these neural injuries. Ramachandran et al. [34] conducted a comprehensive review of 32 pediatric patients with 37 documented nerve injuries and reported that the ulnar nerve was most frequently affected (51.4%), followed by the median (27%) and radial nerves (21.6%). These findings were corroborated by subsequent research analyzing 272 pediatric cases between 2000 and 2007, which reported an overall nerve injury incidence of 18%, with iatrogenic injuries accounting for 14% of cases, predominantly affecting the ulnar nerve. Notably, these iatrogenic injuries lead to spontaneous recovery, with an average resolution time of 3.5 months [35]. Furthermore, Kwok's extensive review of 166 pediatric patients[36] similarly identified the ulnar nerve as the most commonly affected nerve (43.4%), followed by the median (36.7%) and radial nerves (19.9%). Despite 56% of patients requiring surgical exploration, the study reported excellent or good outcomes in 94% of patients.\u003c/p\u003e\n\u003cp\u003eDetailed surgical investigations by Ramachandran[34] revealed that crossed Kirschner wire placement rarely results in direct ulnar nerve penetration. Instead, the predominant mechanism involved soft tissue constriction of the nerve within the cubital tunnel. The recommended protocol involves maintaining Kirschner wire fixation for 3‒4 weeks, with subsequent documentation of nerve function recovery typically occurring between 3‒4 months post-operatively. Routine surgical exploration of the ulnar nerve is not advocated because of the high spontaneous recovery rate. However, early removal of the medial Kirschner wire may be considered a viable option to potentially accelerate recovery, provided that adequate fracture stability can be maintained through lateral wire fixation.\u003c/p\u003e\n\u003cp\u003eOn the basis of these comprehensive clinical observations, we propose the following management algorithm: 1) For the majority of iatrogenic ulnar nerve injuries, particularly those resulting from nerve compression or traction, initial conservative management should be implemented. This approach is supported by the high incidence of spontaneous resolution within weeks to months, obviating the need for immediate surgical intervention. 2) Nevertheless, prompt referral to a specialized center for formal nerve exploration is warranted in patients who present with complete nerve palsy, positive Tinel's sign, neuropathic pain, or evidence of vascular compromise. While the overall prognosis for iatrogenic ulnar nerve injuries remains favorable, vigilant monitoring of nerve function recovery remains crucial to enable timely intervention when necessary.\u003c/p\u003e\n\u003cp\u003eThe presented management strategy aligns with current best practices while incorporating evidence-based recommendations from multiple large-scale clinical studies[34\u0026ndash;36]. This approach optimizes patient outcomes while minimizing unnecessary interventions.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study demonstrated that the innovative technique combining percutaneous Kirschner wire fixation with the K-hammer method offers a safe and effective treatment option for pediatric flexion-type supracondylar humeral fractures. The approach achieves excellent functional outcomes in 94.12% of patients, with no major complications or secondary displacement. K-hammer-guided medial pin insertion significantly reduces the risk of iatrogenic ulnar nerve injury while preserving soft tissue integrity. The biomechanically optimized cross-pinning construct provides stable fixation, facilitating optimal fracture healing and elbow kinematics restoration. This technique's advantages, including technical reproducibility, minimal soft tissue trauma, and excellent clinical outcomes, make it a valuable addition to the surgical management of these challenging pediatric fractures.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003ctable id=\"Taba\" border=\"1\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eAbbreviation\u003c/div\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eFull Term\u003c/div\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eFSCHF\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eFlexion-type supracondylar humeral fracture\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eK-wire\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eKirschner wire\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eESIN\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eElastic stable intramedullary nailing\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eROM\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eRange of motion\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003cp\u003eThe study was approved by the Institutional Review Board of the Ethics Committee of the First People's Hospital of Changde (YX-2023-231-01). Written informed consent was obtained from the patients to publish this paper.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003cp\u003e All the authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eCompeting interests\u003c/h2\u003e\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThis research was funded by the General Guidance Project of the Hunan Provincial Administration of Traditional Chinese Medicine (C2023040).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eYJZ: Writing \u0026ndash; original draft and Funding acquisition; XAB: Funding acquisition and Conceptualization; CHL:Project administration; MZ: Data analysis; FB and JC:Prepared figures 1-4.; GWS: Review and editing. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used in this study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVaquero-Picado A, Gonz\u0026aacute;lez-Mor\u0026aacute;n G, Moraleda L. Management of supracondylar fractures of the humerus in children. EFORT Open Rev. 2018;3(10):526\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLatario LD, et al. Which pediatric supracondylar humerus fractures are high risk for conversion to open reduction? J Pediatr Orthop B. 2023;32(6):569\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChong HH, Qureshi A. Pediatric distal humeral supracondylar fracture - achievement of optimal pinning configuration. Acta Orthop Belg. 2022;88(2):245\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHagino T, et al. Ulnar nerve snagged on Kirschner wire following surgery for supracondylar fracture of humerus. Nagoya J Med Sci. 2025;87(1):150\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePhan MD, et al. Management of Pediatric Supracondylar Humerus Fractures Using Lateral Cross-Wiring Technique Under Fluoroscopic Guidance. Cureus. 2024;16(4):e59029.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMovassaghi K, et al. Predictors of Adverse Events in the Surgical Treatment of Adult Distal Humerus Fractures. Orthopedics. 2023;46(6):352\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun J, et al. Predictive factors for open reduction of flexion-type supracondylar fracture of humerus in children. BMC Musculoskelet Disord. 2022;23(1):859.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBadawy M, et al. Technique for facilitating closed reduction of difficult flexion type supracondylar humeral fracture in children. J Pediatr Orthop B. 2023;32(6):565\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOshika Y et al. \u003cem\u003eUlnar Nerve Neuropathy After Surgery for Intraarticular Distal Humerus Fractures: An Analysis of 116 Patients.\u003c/em\u003e J Hand Surg Am, 2023; 48(11): p. 1171.e1-1171.e5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang L, et al. The outcome of loose bone fragments in pediatric supracondylar humerus fractures: a retrospective study. J Pediatr Orthop B. 2022;31(1):12\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eUslu M et al. Bilateral Flexion-Type Supracondylar Humerus Fracture. J Am Acad Orthop Surg Glob Res Rev, 2024; 8(4).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDuffy S, et al. Overview of the contemporary management of supracondylar humeral fractures in children. Eur J Orthop Surg Traumatol. 2021;31(5):871\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFabricant PD. Supracondylar Humerus Fractures: When Lateral Entry Pins Are Not Enough. Instr Course Lect. 2024;73:421\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi X, et al. [Closed reduction and percutaneous pinning in treatment of irreducible supracondylar humerus fractures in children]. Zhonghua Wai Ke Za Zhi. 2015;53(10):763\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGupta TP, et al. The Outcome of Placing the Medial K-wire First and Then the Lateral K-wire in Treating Supracondylar Humerus Fractures in Children Treated by Closed Reduction. Cureus. 2022;14(10):e30911.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSharma A, et al. Early results of displaced supracondylar fractures of humerus in children treated by closed reduction and percutaneous pinning. Indian J Orthop. 2015;49(5):529\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShih CA, et al. The use of ultrasound for monitoring reduction and ulnar nerve subluxation in pediatric humeral supracondylar fractures. Eur J Radiol. 2024;170:111201.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWind WM, Schwend RM, Armstrong DG. Predicting ulnar nerve location in pinning of supracondylar humerus fractures. J Pediatr Orthop. 2002;22(4):444\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShen PC, et al. The assessment of the ulnar nerve at the elbow by ultrasonography in children. J Bone Joint Surg Br. 2008;90(5):657\u0026ndash;61.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZaltz I, Waters PM, Kasser JR. Ulnar nerve instability in children. J Pediatr Orthop. 1996;16(5):567\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSmuin D, et al. The Reduction Maneuver for Pediatric Extension Type 3 Supracondylar Humerus Fractures. Cureus. 2020;12(7):e9213.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSoldado F, et al. Ultrasound-guided Percutaneous Medial Pinning of Pediatric Supracondylar Humeral Fractures to avoid Ulnar Nerve Injury. Arch Bone Jt Surg. 2015;3(3):169\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKocher MS, et al. Lateral entry compared with medial and lateral entry pin fixation for completely displaced supracondylar humeral fractures in children. A randomized clinical trial. J Bone Joint Surg Am. 2007;89(4):706\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBrauer CA, et al. A systematic review of medial and lateral entry pinning versus lateral entry pinning for supracondylar fractures of the humerus. J Pediatr Orthop. 2007;27(2):181\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNa Y, et al. Comparison of lateral entry with crossed entry pinning for pediatric supracondylar humeral fractures: a meta-analysis. J Orthop Surg Res. 2018;13(1):68.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWoratanarat P, et al. Meta-analysis of pinning in supracondylar fracture of the humerus in children. J Orthop Trauma. 2012;26(1):48\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKwak YH, et al. Medial comminution as a risk factor for the stability after lateral-only pin fixation for pediatric supracondylar humerus fracture: an audit. Ther Clin Risk Manag. 2018;14:1061\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDe Pellegrin M, et al. Advantages and disadvantages of the prone position in the surgical treatment of supracondylar humerus fractures in children. A literature review. Injury. 2018;49(Suppl 3):S37\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWong KPL, Chew EM, Mahadev A. Sliding the Medial Pin: A Safer Approach to Cross-pinning Humerus Supracondylar Fractures? Tech Hand Up Extrem Surg. 2019;23(3):111\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePesenti S, et al. Operative management of supracondylar humeral fractures in children: Comparison of five fixation methods. Orthop Traumatol Surg Res. 2017;103(5):771\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMorales-Guerrero OJ, et al. Comparative risk of ulnar nerve injury in pediatric supracondylar humeral fractures: a multicenter evaluation of Kirschner wire fixation techniques. Eur J Orthop Surg Traumatol. 2024;34(7):3783\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShtarker H, et al. Ulnar nerve monitoring during percutaneous pinning of supracondylar fractures in children. J Pediatr Orthop. 2014;34(2):161\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWagner F et al. Intrainstitutional Changes of the Treatment of Supracondylar Humerus Fracture in Children over a Period of 9 Years. Child (Basel), 2023; 11(1).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRamachandran M, Birch R, Eastwood DM. Clinical outcome of nerve injuries associated with supracondylar fractures of the humerus in children: the experience of a specialist referral centre. J Bone Joint Surg Br. 2006;88(1):90\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhademolhosseini M, Abd Rashid AH, Ibrahim S. Nerve injuries in supracondylar fractures of the humerus in children: is nerve exploration indicated? J Pediatr Orthop B. 2013;22(2):123\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKwok IH et al. Nerve injuries associated with supracondylar fractures of the humerus in children: our experience in a specialist peripheral nerve injury unit. Bone Joint J, 2016; 98\u0026ndash;b(6): pp. 851\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"K-Hammer, Iatrogenic Ulnar Nerve Injury, Pediatric Supracondylar Fracture, Cross-pinning, Gartland classification","lastPublishedDoi":"10.21203/rs.3.rs-7410150/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7410150/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e This study assessed the therapeutic efficacy of a novel approach combining percutaneous Kirschner wire fixation with the K-hammer technique in pediatric patients with supracondylar humeral fractures.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eThis retrospective cohort study enrolled 34 pediatric patients (male: 13 (38.24%); female: 21 (61.76%): 12; age 5.82 ± 2.54 years) with acute flexion-type supracondylar humeral fractures (diagnosis ≤7 days post-trauma). Under general anesthesia, all fractures underwent fluoroscopically guided closed reduction followed by percutaneous fixation: two lateral-entry 1.5–2.0 mm Kirschner wires established initial stabilization, supplemented by a third medial Kirschner wire deployed via the K-Hammer reduction technique to create a biomechanically optimized cross-pinning construct. Postoperatively, the elbow was maintained in a 90° functional position via long-arm fiberglass casts for 4 weeks.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e: During a mean follow-up period of 12.24 ± 4.45 (range: 6–23 months), functional outcomes assessed via Flynn's criteria demonstrated excellent results in 32 patients (94.12%), good results in 2 (5.88%), and fair results in 0 (0%). Notably, no secondary displacement, osteonecrosis, or major complications—including nonunion, iatrogenic neurovascular injury, myositis ossificans, or chronic elbow dysfunction—were documented during postoperative surveillance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: K-Hammer-guided medial Kirschner wire insertion offers a technically streamlined and reproducible solution for irreducible flexion-type pediatric supracondylar humeral fractures, effectively eliminating iatrogenic ulnar nerve injury while minimizing soft tissue trauma. This technique establishes adequate biomechanical stability at the fracture site and facilitates optimal long-term restoration of elbow joint kinematics.\u003c/p\u003e","manuscriptTitle":"K-Hammer Percutaneous Fixation: A Novel Strategy to Prevent Iatrogenic Ulnar Nerve Injury in Pediatric Supracondylar Fractures","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-04 00:09:24","doi":"10.21203/rs.3.rs-7410150/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b4bb696e-03fa-4917-bd28-0ff078d13517","owner":[],"postedDate":"September 4th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-23T16:53:21+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-04 00:09:24","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7410150","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7410150","identity":"rs-7410150","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}