A two-stage retrospective analysis to determine the effect of entry point on higher exit of proximal pins in lateral pinning of supracondylar humerus fracture in children

Abstract

BackgroundKirschner wire fixation remains to be the mainstream treatment modality in unstable or displaced supracondylar humerus fracture in children, with divergent lateral pins being the most preferred due to their sufficient stability and decreased risk of ulnar nerve injury. However, the entry point at which the proximal lateral pin can be inserted to achieve a more proximal exit and maximum divergence has not been reported. This study retrospectively analyzed the characteristics and factors influencing the entry and exit points of the proximal lateral pins.MethodsThe study was divided into two stages. In stage one, the entry and exit points of the proximal pins of lateral pinning configuration were analyzed from intra-operative radiographs of children treated for extension-type supracondylar humerus fractures. The coronal and sagittal pin angles formed by the proximal pins were also measured. Using the findings of stage one, we intentionally tried to achieve a more proximal exit with the proximal pins in stage two. Comparisons between groups of patients treated by random and intentional pinnings were done statistically.ResultsIn the first stage, 47 (29.2%) of the 161 proximal pins exited above the metaphyseal-diaphyseal junction (MDJ) region. Of these, 85.1% entered from lateral and posterior to the ossific nucleus of the capitellum (ONC). The pin angles averaged 58.4° and 90.5° in the coronal and sagittal planes respectively. In the second stage, 47 (65.3%) proximal pins in the intended group exited above the MDJ region, while only 32 (36%) in the random group exited above the MDJ region.ConclusionWhile aiming at the upper border of the distal MDJ during pinning, lateral pins can easily achieve a higher, proximal exit above the MDJ if inserted from lateral and posterior to the ONC and parallel to the humeral shaft in the sagittal plane. Higher exit can also be easily achieved in younger patients and patients fixated with smaller diameter pins.

Distal Humerus Metaphyseal-Diaphyseal Junctional Fracture of a Four-Year-Old Child Treated With Intramedullary Steinmann Wire Fixation: A Case Report

“…However, when the fracture line crosses above the olecranon fossa, the fracture is termed a distal metaphyseal-diaphyseal junctional (MDJ) fracture [ 5 ]. Fractures in the distal humeral diaphysis and MDJ fractures are considerably rarer when compared to fractures occurring in the supracondylar humeral region [ 6 ]. The treatment of diaphyseal fractures poses significant challenges due to the distal diaphysis’ triangular shape and thinner periosteum compared to the supracondylar area [ 7 , 8 ].…”

Closed Reduction and Percutaneous Pinning in the Treatment of Humeral Distal Metaphyseal-Diaphyseal Junction Fractures in Children: A Technique Note and Preliminary Results

“…This kind of atypical supracondylar fracture has been defined as a distal humeral metaphyseal-diaphyseal junction (MDJ) fracture (7,8). The MDJ fracture in children is rare, and it accounts for only 3.3% of displaced fractures at the distal humerus (9,10). MDJ fractures are problematic to treat because of their instability and tendency to develop postoperative complications (8,9,11).…”