# Clinical study of modular external fixator for distal humeral metaphyseal-diaphyseal junction fractures in children

## TL;DR

This study shows that modular external fixation is an effective and minimally invasive treatment for certain pediatric elbow fractures, with good recovery and no need for additional surgery.

## Contribution

The study introduces a modular external fixator approach for pediatric distal humeral fractures and provides guidelines for configuration selection based on fracture line height.

## Key findings

- Both linear and triangular fixator configurations achieved similar healing times and functional outcomes.
- Linear configurations were suitable for lower-position fractures (<20 mm), while triangular configurations were better for higher-position fractures (≥20 mm).
- Modular external fixation avoided the need for internal fixation removal and showed high patient satisfaction.

## Abstract

This study evaluated the clinical efficacy of closed reduction with modular external fixation for pediatric distal humeral metaphyseal-diaphyseal junction (MDJ) fractures.

We retrospectively analyzed 45 pediatric patients (mean age 7.87 ± 5.03 years) treated from January 2020 to December 2024. Patients were divided into “linear” (n = 18, two half-pins/one rod) and “triangular” (n = 27, four half-pins/three rods) configuration groups based on external fixator configuration. Outcomes included fracture healing time, radiographic parameters (Baumann angle, shaft-condylar angle), Flynn elbow scores, and complications. Fracture line height (The vertical distance from the highest point of the fracture line to the upper edge of the olecranon fossa) was retrospectively measured to analyze configuration selection.

The mean operative time was 42.8 ± 12.3 min in the “linear” group and 46.5 ± 17.9 min in the “triangular” group. All fractures healed satisfactorily. Healing time (11.0 ± 2.6 weeks vs. 10.2 ± 3.2weeks), final Baumann angles (72.80 ± 3.71 ° vs. 73.81 ± 7.40 °), and shaft-condylar angles (39.38 ± 8.32 ° vs. 35.51 ± 7.67 °) showed no significant differences between groups (P > 0.05). Excellent-to-good Flynn scores were achieved in 94.44% (linear) vs. 92.31% (triangular) of patients, with no statistically significant difference (P > 0.05). Complications included pin tract infections (7 vs. 11 cases) and fixation loosening (2 cases each). The average fracture line height was significantly lower in the “linear” configuration group (17.51 ± 3.35 mm) compared to the “triangular” group (28.02 ± 7.93 mm).

Modular external fixation demonstrated promising outcomes for pediatric distal humeral MDJ fractures, providing a minimally invasive treatment option with favorable functional recovery, and no second surgery is required to remove the internal fixation device. Low-position MDJ fractures (<20 mm) with a linear configuration can be sufficiently stabilized with K-wires, and the “triangular” configuration is more suitable for high-level fractures (≥20 mm).