Mechanical stability study of three techniques used in the fixation of transverse and oblique metaphyseal-diaphyseal junction fractures of the distal humerus in children: a finite element analysis

Abstract

Background: Management of distal humerus metaphyseal-diaphyseal junction (MDJ) region fractures can be very challenging mainly because of the higher location and characteristics of the fracture lines. Loss of reduction is relatively higher in MDJ fractures treated with classical supracondylar humerus fractures (SHFs) fixation techniques. Methods: Three different fracture patterns including transverse, medial oblique and lateral oblique fractures were computationally simulated in the coronal plane in the distal MDJ region of a pediatric humerus and fixated with Kirschner Wires (K-wires), elastic stable intramedullary nails (ESIN), and lateral external fixation system (EF). Stiffness values in flexion, extension, valgus, varus, internal, and external rotations for each fixation technique were calculated. Results: In the transverse fracture model, 3C (1-medial, 2-lateral K-wires) had the best stiffness in flexion, varus, internal, and external rotations, while 3L (3-divergent lateral K-wires) was the most stable in extension and valgus. In the medial oblique fracture model, EF had the best stiffness in flexion, extension, valgus, and varus loadings, while the best stiffness in internal and external rotations was generated by 3MC (2-medial, 1-lateral K-wires). In the lateral oblique fracture model, 3C (1-medial, 2-lateral K-wires) had the best stiffness in flexion and internal and external rotations, while ESIN had the best stiffness in extension and valgus and varus loadings. Conclusion: The best stability against translational forces in lateral oblique, medial oblique, and transverse MDJ fractures would be provided by ESIN, EF, and K-wires, respectively. K-wires are however superior to both ESIN and EF in stabilizing all three fracture types against torsional forces, with both 2-crossed and 3-crossed K-wires having comparable stability. Depending on the fracture pattern, a 3-crossed configuration with either 2-divergent lateral and 1-medial K-wires or 2-medial and 1-lateral K-wires may offer the best stability.

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][34][35][36] and clinical [37][38][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][34][35][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][34][35][36] and clinical [37][38][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][34][35][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%).…”

The effect of the angle between fracture line and Kirschner wires on stability in supracondylar humerus fractures treated with Kirschner wire fixation: A finite element analysis

“…In this context, we believe that modeling and simulation techniques developed for engineering purposes would be helpful. Liu et al[ 6 ] compared fixation methods used in SHFs through a simulation program (3D FEA) and found cross K-wiring to be effective, particularly in transverse SHFs, as it increased resistance against rotation, flexion, and varus loading. They also compared their findings with other relevant studies and concluded that their findings were compatible with the literature.…”

“…The most accepted one is two lateral and one medial K-wires crossing the fracture line. [ 5 , 6 ] However, the importance of the angle between the fracture and the K-wires in SHFs is still a question that needs to be answered.…”

Prevalence and Treatment Outcome of Displaced High-Long Oblique Supracondylar Humeral Fractures in Children

“…Elastic stable intramedullary nailing for high supracondylar MDJ fractures have been reported due to the difficulty in achieving bicortical fixation with Kirschner wires (K-wires) (5,(9)(10)(11). Lateral external fixator, another surgical option, has also demonstrated superior outcome for oblique or comminuted fracture (6). The traditional percutaneous pinning for the pediatric supracondylar fracture should be modified based on more precise classification and diverse treatment methods, not just on the severity of displacement (4,8,9).…”