Variability of the Anterior Humeral Line in Normal Pediatric Elbows.

Background: The anterior humeral line (AHL) is considered a valuable radiographic tool in the assessment of pediatric elbow sagittal plane alignment following injury. However, few studies exist that examine the validity of the AHL. The purpose of this study is to report the variability of the AHL in skeletally immature children with normal elbows.

Methods: A total of 124 true lateral elbow radiographs of normal pediatric elbows were retrospectively identified and examined for the relationship of the AHL to the capitellum. The percentage of AHLs falling outside the middle third of the capitellum was compared among different age and sex groups using Fisher exact tests.

Results: In 100% of patients, the AHL touched the ossific nucleus of the capitellum. In 100% (52/52) of patients ≥5 years the AHL goes through the middle third of the capitellum, but this is significantly different from patients less than 5 years of age in whom 25% (18/72) of patients the AHL fell outside of the middle third of the capitellum (P<0.001). In children less than 2 years of age, the AHL was in the anterior third in 30% of the cases.

Conclusions: Traditional teaching that the AHL touches the capitellum on a lateral radiograph of a normal elbow in a child is correct, so if the AHL does not touch the capitellum it is appropriate to look for pathology. Similarly, in children 5 years and older the AHL goes through the middle third of the capitellum in all patients, so if it does not, it is appropriate to look for pathology. However, with decreasing age variability increases, with the AHL touching the anterior third of the capitellum in almost 1/3 of children.

Level Of Evidence: Level III.