Lateral humeral line

Last revised by Daniel J Bell on 20 Feb 2024

The lateral humeral line is used to confirm the alignment of the pediatric radiocapitellar joint in the coronal plane 1. This is particularly important in injuries such as a Monteggia fracture-dislocation or in a radial neck fracture.


The lateral humeral line is drawn on a pediatric AP elbow radiograph. The line runs parallel to the long axis of the humerus at the most lateral extent of the ossified distal humerus. When extended distally, this line should lie lateral to the radial neck to demonstrate a congruent radiocapitellar joint.


The traditional teaching of using radiocapitellar line in the AP projection has been shown to miss the capitellum in 16% of normal pediatric elbow radiographs in children <5 years 2. The lateral humeral line can aid in the evaluation of the pediatric elbow when utilized in conjunction with the radiocapitellar line, but more research is required to establish clinical relevance, as well as sensitivity and specificity. 

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