Distal humeral physeal separation: radiographic findings in infants and toddlers

Distal humeral physeal separation is an uncommon but frequently misdiagnosed injury of the immature elbow in infants and toddlers that carries a strong association with non-accidental trauma; its largely unossified anatomy makes radiographic diagnosis challenging.

To evaluate radiographic features that can aid in the diagnosis of distal humeral physeal separation among infants and toddlers.

This retrospective comparative study included 19 children under 3 years of age with clinically or surgically confirmed distal humeral physeal separation and available pretreatment elbow and forearm radiographs, identified from the imaging database of a tertiary-care children's hospital (January 2008 to December 2024). Thirty-two age- and sex-matched control children without elbow fracture were selected from the same source population. Two radiologists independently reviewed all examinations, blinded to fracture status, and recorded the presence or absence of soft tissue swelling, joint effusion, abnormal ossific fragmentation, and abnormal medial or posterior forearm alignment. Findings were compared between children with and without separation injury.

This study group included 51 children (32 boys, 19 girls; median age, 17 days, range, 0-1186 days). Soft-tissue swelling (anteroposterior: 94.7% vs 34.4%, P<.001; lateral: 78.9% vs 12.5%, P<.001), abnormal ossific fragmentation (78.9% vs 3.1%, P<.001), and abnormal forearm alignment (medial: 89.5% vs 0%, P<.001; posterior: 78.6% vs 0%, P<.001) were more common in children with physeal separation than those without. On multivariable analysis, abnormal medial forearm alignment remained associated with physeal separation (OR=104.2; 95% CI, 3.9-2775.5; P=.001).

In our study group, several radiographic findings were associated with distal humeral physeal separation in infants and toddlers; however, only abnormal medial forearm alignment remained strongly associated with physeal separation.