The most stable pinning configurations in transverse supracondylar humerus fracture fixation in children: A novel three-dimensional finite element analysis of a pediatric bone model

Abstract

Background: This study aimed at finding out the effect of exit height of pins, pin trajectory and pin number on the stability of cross and lateral pinning configurations used in the fixation of extension-type supracondylar humerus fracture (SHF) in children, through finite element analysis of a novel pediatric humerus bone model. Methods: Distal humerus model consisting of the ossific nucleus of the capitellum (ONC) and distal cartilage of a 6-year-old boy was developed via three-dimensional finite modeling. Various cross and lateral pinning fixation models with either two or three pins were simulated on an extension-type, transverse SHF and tested in six loading directions. Results: Two-cross pins and 2-lateral pins were respectively more stable in rotation and compression loadings, while 3-cross pins were the most stable in all loading directions. The cross pins exiting at the upper border of the distal metaphyseal-diaphyseal junction (MDJ) had the best stiffness among the 2-cross pins, while the lateral pins with a mid-ONC distal pin provided the best stiffness among the 2-lateral pins. A third pin however, going through the olecranon fossa led to improved stability of the 2-lateral pins in flexion, extension, internal and external rotations. Conclusion: In the fixation of extension-type, transverse supracondylar humerus fractures, 2-cross pins are only superior to 2-divergent lateral pins in rotational loadings. Two-cross pins exiting at the upper border of the MDJ provides the best stability, whereas 2-lateral pins with a distal pin going through the middle third of the ONC provides the best stability against compression forces for these fractures. Three-cross pins however offer the best stability against both compression and rotation forces. This study offers important clues in the preoperative evaluation and management of extension-type supracondylar fractures in children.

Current trends in the treatment of supracondylar fractures of the humerus in children: Results of a survey of the members of European Paediatric Orthopaedic Society

“…Nevertheless, no clear preference was revealed by the survey about pin configuration as crossed pins (33.7%) and two divergent lateral (23.9%) pins were mostly done. This result reflects the uncertainty of the literature with several biomechanical 33–36 and clinical 37–39 studies reporting the superiority of a pin configuration over the others. Crossed pinning has been found to be the most stable configuration in different fracture patterns, 33–36 especially when three k-wire (two lateral and one medial) are used; 33 however, a recent metanalysis 39 reported 4.9% of iatrogenic ulnar nerve injury in crossed pinning, but the performance of safe procedure for the medial pin 40 can significantly reduce the risk of injuring the nerve.…”

“…This result reflects the uncertainty of the literature with several biomechanical 33–36 and clinical 37–39 studies reporting the superiority of a pin configuration over the others. Crossed pinning has been found to be the most stable configuration in different fracture patterns, 33–36 especially when three k-wire (two lateral and one medial) are used; 33 however, a recent metanalysis 39 reported 4.9% of iatrogenic ulnar nerve injury in crossed pinning, but the performance of safe procedure for the medial pin 40 can significantly reduce the risk of injuring the nerve. 37,38 To avoid ulnar nerve injury, lateral pinning is the preferred fixation technique by 50% of respondents; in particular, most surgeons use two lateral pins (38.6%) and the remaining three (11.4%).…”

Finite element analyses of lateral condyle fracture fixation in paediatrics regarding configuration of Kirschner-wire

“…FEA is more applicable in paediatric fracture studies since paediatric clinical trials have more limitations than an adult study. Previous researchers have focused on K-wire configurations in paediatric supracondylar humerus fractures, both biomechanically and computationally [28][29][30][31][32][33][34]. Kamar et al [34] investigated FEA of supracondylar fractures, but the study of lateral condyle fractures with FEA has not yet been performed.…”

“…Previous researchers have focused on K-wire configurations in paediatric supracondylar humerus fractures, both biomechanically and computationally [28][29][30][31][32][33][34]. Kamar et al [34] investigated FEA of supracondylar fractures, but the study of lateral condyle fractures with FEA has not yet been performed. With regard to the research on lateral condyle fractures, a few studies were limited to biomechanical tests of K-wire configurations, and differing fixation materials such as screws or large K-wires [35].…”