Metaphyseal lesions

Diagrammatic representation of the relationship of the subperiosteal bone collar to a metaphyseal lesion.
(A) A tangential view of the metaphyseal margin, demonstrating a fracture line that extends adjacent to the chondro-osseous junction centrally. Peripherally, the fracture line (arrows) veers away from the growth plate to undermine a larger peripheral fragment, incorporating the subperiosteal bone collar (corner fracture).
(B) When the fracture line (arrows) is projected obliquely, the thicker peripheral fragment, including the subperiosteal bone collar, is projected as a curvilinear fragment or a bucket-handle lesion.
(C) When the fracture line (arrow) is incomplete (it extends across only a portion of the metaphysis), the appearance suggests a focal, triangularly shaped peripheral fragment encompassing the subperiosteal bone collar (corner fracture).
(D) When the fracture line (arrow) is tipped obliquely, the peripheral margin of the fragment is projected as curvilinear density (bucket handle fracture).