Background: Shoulder pain is a common problem among adolescent athletes. A possible cause of such pain that can be diagnosed on MRI is a stress injury to the proximal humerus known as Little Leaguer's shoulder (proximal humeral epiphysiolysis).
Objective: Our objective was to describe the MRI appearance of Little Leaguer's shoulder.
Materials and methods: Four patients (all boys; age range 11-15 years; median 13 years) with clinical, plain radiographic, and MR imaging findings of Little Leaguer's shoulder were studied retrospectively.
Results: MRI demonstrated focal physeal widening in all four boys with extension of physeal signal intensity into the metaphysis on T1-weighted and gradient echo coronal and sagittal sequences. T2-weighted sequences were of limited use in demonstrating the physeal widening, which is critical to the diagnosis. Abnormal high T2-signal intensity was seen in the metaphysis adjacent to the focal physeal widening in all the boys.
Conclusion: Focal extension of normal physeal T1-weighted and gradient echo signal intensity into the adjacent metaphysis is a sign of stress injury in the proximal humeral physis (Little Leaguer's shoulder). Children should suspend the offending sport to allow healing.