Skeletal development of the proximal humerus in the pediatric population: MRI features

The purpose of this study was to provide a guideline of normal MRI developmental anatomy of the proximal humerus in a growing child.

Retrospective interpretation of 83 consecutive MRI studies of shoulders in children 2 months to 17 years old was performed in consensus by two radiologists. The following variables were documented: presence, number, and fusion of secondary ossification centers; appearance and closure of the growth plate; presence of the metaphyseal stripe; and proximal metaphyseal marrow signal intensity.

Preossification centers were seen in 2- and 4-month-old patients. Secondary ossification centers appeared in the medial humeral head and greater tuberosity at 4 and 10 months, respectively, originally depicting red marrow and later converting to yellow marrow. A separate lesser tuberosity ossification center was not seen. The ossification centers began fusing by 3 years and gradually conformed to the final shape of the proximal humerus. Ossification was completed by 13 years. The multilaminar growth plate initially had a flat and smooth contour that progressively became irregular and pyramidal, closing at 17 years. The metaphyseal stripe was noted at infancy and disappeared by 15.5 years. The metaphyseal marrow signal intensity was diffusely low in infants but, with conversion to yellow marrow, showed proximal metaphyseal bright patchy or linear signal-intensity, eventually disappearing by 17 years.

The postnatal skeletal development of the proximal humerus in the pediatric population follows distinctive sequential patterns of maturation, which can serve as a guideline for interpreting MRI studies in children.