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. Issue 6 (June 2021)

• Record Type: Journal Article
• Authors: Kamara, Allieu; Ji, Xianglu; Liu, Chuang; Liu, Tianjing; Wang, Enbo
• Is Part Of: Injury. Volume 52:Issue 6(2021)
• Page Start: 1310
• Page End: 1315
• Publication Date: 2021-06
• Subjects: Supracondylar humerus fracture -- Pinning fixation -- Biomechanical analysis -- Finite element analysis -- Three-dimensional pediatric bone model; Wounds and injuries -- Surgery -- Periodicals; Accidents -- Periodicals; Wounds and Injuries -- surgery -- Periodicals; Lésions et blessures -- Chirurgie -- Périodiques; Electronic journals; Electronic journals; 617.1
• DOI: 10.1016/j.injury.2021.01.012
• Languages: English
• ISSNs: 0020-1383

Abstract

Highlights: This study is the first to demonstrate the influence of entry point, exit point, pin number and trajectory on the stiffness of K-wire fixation in pediatric transverse supracondylar humerus fractures using child specific anatomic humerus model. Two-cross pins were only superior to 2-divergent-lateral pins in torsional loadings. Two-cross pins exiting at the upper border of the distal metaphyseal-diaphyseal junction of the humerus provided the best stability against torsional forces. Two-lateral pins with a mid-capitellar distal pin in maximum divergence provided better stability against translation forces Three-cross pins with a mid-capitellar distal lateral pin however offered the best stability against both translation and torsional forces for these fractures. Abstract: Purpose: This study aimed at finding out the effect of exit height, trajectory and number of pins on the stability of cross and divergent-lateral pins used in the fixation of extension-type, transverse supracondylar humerus fracture (SHF) in children, based on finite element analysis. 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 divergent-lateral pinning 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-divergent-lateral pins were more stable against torsional and translation forces respectively, while 3-cross pins were the most stable against all forces. 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 middle third ONC distal pin provided the best stiffness among the 2-lateral pins. A third olecranon fossa pin greatly enhanced stability of the 2-lateral pins. Conclusion: For typical transverse fractures, 2-cross pins are found to be superior to 2-divergent lateral pins only against torsional forces. Pins exiting at the upper border of the MDJ provides the best mechanical stability with 2-cross pins. Two-divergent-lateral pins with a distal pin going through the middle third of the ONC provides the best mechanical stability against translation forces for these transverse fractures. Three-cross pins however offer the best mechanical stability against both translation and torsional forces. This study offers important clues in the preoperative evaluation and management of extension-type supracondylar fractures in children.