Origin of the medial ulnar collateral ligament on the pediatric elbow

Surgical reconstruction of the adult anterior bundle of the medial ulnar collateral elbow ligament (UCL) is a common and established treatment that yields satisfactory results. Children sustain these injuries less frequently, and surgical intervention is complicated by the juxtaposed medial epicondyle apophysis. The purpose of this study was to identify the anatomical origin of the pediatric UCL and determine if this location changes with elbow maturity.

A retrospective analysis of children with an elbow MRI between 2009 and 2012 was performed. Ninety children (68 boys, 22 girls), mean age 12.8 years (range 6-18), were grouped by age (<11, 11-13, and >13) and gender. Measurements of UCL width and UCL midpoint distance from medial epicondyle apophysis were recorded on coronal T1 images utilizing digital PACS software.

Across all groups, boys had a wider UCL than girls (4.05 ± 0.16 mm vs 3.72 ± 0.20 mm, p = 0.03); however, there was no difference in the anatomical origin of the UCL relative to the medial epicondyle apophysis between gender (p = 0.52), between gender age-matched groups, or within gender age-matched groups. Yet, the anatomic origin of the UCL always remained medial to the cartilaginous interface of the apophysis with the osseous distal humerus and was centered approximately 3 mm medial to the lateral edge of the apophysis.

Regardless of age or gender, the humeral origin for the medial ulnar collateral ligament is medial to the interface between the medial epicondyle apophysis and distal humerus, which has surgical implications for anatomic reconstruction in children.