Clinical significance of anterior humeral line in supracondylar humeral fractures in children.

INTRODUCTION: Anterior humeral line (AHL) location is commonly used to evaluate sagittal alignment after fracture reduction in children with supracondylar humeral fractures. However, the position of the AHL for acceptable fracture reduction has not been validated by clinical outcome. The purpose of this study was to investigate the relationship between the location of AHL and range of elbow motion.

PATIENTS AND METHODS: We retrospectively reviewed 101 children who underwent closed reduction and percutaneous pinning for Gartland type III supracondylar humeral fractures between January 2009 and June 2014. There were 67 boys and 34 girls, with a mean age of 7 years. The children were classified according to the location of the AHL three months postoperatively into five groups: anteriorly loss (n=6), anterior third (n=25), middle third (n=47), posterior third (n=21), and posteriorly loss (n=2). Range of elbow motion was measured by attending paediatric orthopaedic surgeons with a goniometer. Clinical and radiographic outcomes were compared among the five groups.

RESULTS: The mean elbow extension angle was not significantly different among the groups (p=0.21). However, children with AHL anterior to the capitellum had less elbow flexion angle (125.8° vs. 131.2°, p=0.046) and less total range of elbow motion (128.3° vs. 135.7°, p=0.048) than children with AHL crossing the capitellum. When the AHL crossed the capitellum, the elbow flexion angle and total range of elbow motion were significantly decreased in children with AHL crossing the anterior third of the capitellum. The Flynn criteria were not significantly different among the central three groups (p=0.131). However, the Flynn criteria were significantly worse in children whose AHL missed the capitellum (p<0.001). The mean Baumann angle measured 3 months postoperatively was not significantly different among the groups (p=0.12).

CONCLUSIONS: These findings demonstrate that children with AHL crossing the middle and posterior thirds of the capitellum appear to have slightly better early elbow flexion and total range of elbow motion. AHL crossing the anterior third of the capitellum can be an underreduction that has similar elbow motion as AHL anterior to the capitellum. AHL posterior to the capitellum is a warning sign of overreduction and should be avoided.