A regional approach to the classic metaphyseal lesion in abused infants: the proximal tibia

The purpose of this study was to systematically analyze the spectrum of morphologic alterations of the classic metaphyseal lesion (CML) involving the proximal tibia of abused infants and to identify features that aid in the radiologic diagnosis and assessment of healing. Thirty-one infants who died with evidence of inflicted skeletal injury were studied with high-detail skeletal surveys, resected specimen radiography, and histopathologic analysis. The number of fractures identified, the portions of the proximal tibial metaphyses involved, and the age of the lesions were assessed. Seventeen proximal tibial CMLs were noted. They were bilateral in six instances and unilateral in five. When the lesion was visible radiographically, it always involved the medial aspect of the metaphysis, with involvement of the lateral metaphyseal margin in more extensive injuries. Fractures tended to be less conspicuous when acute and were more easily recognizable with healing, especially with specimen radiography. Histologically, the fracture line consistently undercut the medial subperiosteal bone collar. Extension of hypertrophic chondrocytes from the growth plate into the region of fracture was a common finding. The CML of the proximal tibia has distinctive radiologic and histopathologic characteristics that relate to the anatomy of the region. Because the proximal tibia is a common site for this strong indicator of infant abuse, the region should be carefully evaluated with well-collimated, high-detail skeletal radiographs in all cases of suspected infant abuse.