Origin of the Medial Ulnar Collateral Ligament on the Pediatric Elbow

OBJECTIVES: Surgical reconstruction of the torn anterior bundle of the medial ulnar collateral elbow ligament (UCL) is an established treatment that yields satisfactory results in adults. 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. METHODS: A retrospective analysis of children with elbow MRI between 2009 and 2012 was performed. Grouped by age (<11, 11-13, and >13) and gender, the exclusion criteria included: poor imaging quality due to motion artifact, elbow flexion beyond 45 degrees, and prior elbow injury obscuring anatomic structures. Measurements of UCL width and UCL midpoint distance from medial epicondyle apophysis were recorded on coronal T1 images utilizing digital PACS software. RESULTS: Ninety children (68 boys, 22 girls), mean age 12.8 years (range 6-18), met criteria. 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 (Table 1). However, the anatomic origin of the UCL always remained medial to the distal periphery of the apophysis. There was, however, a statistical trend in girls between the <11 and >13 groups for the UCL origin to move closer to the medial epicondyle apophysis with maturity (p=0.053). CONCLUSION: Although surgical reconstruction of the UCL in children is infrequent, it may be the best treatment for a given skeletally immature patient with elbow instability. The procedure requires a choice regarding ligament placement on the humerus versus preservation of the medial epicondyle apophysis. This study elucidates the anatomical origin of the UCL across gender and age for the at risk pediatric group and demonstrates no differences in the UCL center of attachment based on skeletal maturity or gender. Therefore, surgical intervention of the pediatric torn elbow UCL does not require specific consideration of age and gender regarding placement of the reconstructed ligament; however, an anatomic reconstruction of the UCL does place the medial epicondyle apophysis at risk for injury.