Assessment of ulnar nerve stability at the elbow by ultrasonography in children

BACKGROUND:Elbow fractures are common in children. While Kirschner wire (K-wire) is the most commonly used fixation material in children, medial entry pins may be needed for fracture stability. This study aimed to assess ulnar nerve instability by ultrasonography in children. METHODS:We enrolled 466 children aged 2 months to 14 years between January 2019 and January 2020. There were at least 30 patients in each age group. Ulnar nerves were observed under the ultrasound equipment with the elbow fully extended and flexed. If ulnar nerves were subluxated or dislocated, they were considered to have ulnar nerve instability. The children's clinical data, including sex, age, and elbow sides, were analyzed. RESULTS:Of 466 enrolled children, 59 had ulnar nerve instability. Ulnar nerve instability rate was 12.7% (59/466). Instability was prevalent in children aged 0-2 years (P = .001). Among 59 children with ulnar nerve instability, 52.5% (31/59) had bilateral ulnar nerve instability, 16.9% (10/59) had right ulnar nerve instability, and 30.5% (18/59) had left ulnar nerve instability. Logistic analysis of the risk factors of ulnar nerve instability showed no significant difference in terms of sex and left or right ulnar nerve instability. CONCLUSIONS:Ulnar nerve instability correlated with age in children. Children aged <3 years had a low risk of ulnar nerve instability.