A regional approach to classic metaphyseal lesions in abused infants: the distal tibia.

OBJECTIVE: The purpose of this study was to analyze systematically the spectrum of morphologic alterations of classic metaphyseal lesions (CML) involving the distal tibia of abused infants and to identify features that assist in the radiologic diagnosis and assessment of healing.

MATERIALS AND METHODS: Thirty-one infants who died with evidence of inflicted injury were studied with high-detailed skeletal surveys, resected-specimen radiography, and histopathologic analysis. The number of fractures identified, the portions of the distal tibial metaphyses involved, and the age of the lesion were assessed.

RESULTS: A total of 16 CML of the distal tibia were noted. Eight infants had unilateral injury that always involved the left side, and four had bilateral lesions. When a CML was visible radiographically, it was always seen along the medial aspect of the metaphysis; lateral metaphyseal involvement was evident with more extensive injuries and always accompanied medial involvement. Fractures tended to be less conspicuous when acute and were more easily recognized with healing, especially with specimen radiography. Radiographically, the typical fracture separated a medial fragment that was tall and triangular; this appearance was histologically related to the undercutting of the long subperiosteal bone collar. In healing lesions, extension of hypertrophic chondrocytes from the growth plate into the region of the fracture was a consistent finding.

CONCLUSION: CML of the distal tibia have distinctive radiologic and histopathologic characteristics that relate to the anatomy of the region. Visualization of these fractures depends on the quality of the radiographs obtained. An understanding of the radiologic and histopathologic features of CML should aid in the recognition of this strong indicator of infant abuse.