metaphyseal dysostosis /mətaf′izē″əl disostō″sis, met′əfiz″ē·əl disostō″sis/ [Gk, meta + phyein, to grow, dys, bad, osteon, bone] , a condition characterized by abnormal mineralization of the metaphyseal area of the bones, resulting in dwarfism. Metaphyseal dysostosis is classified as the Gansen, Schmidt, or Spahar-Hartmann type or as cartilage-hair hypoplasia. The Gansen type is characterized by metaphyseal alterations similar to those of achondroplasia but not involving the skull or the epiphyses of the long bones. The Schmidt type is characterized by developmental changes from the weight-bearing age to approximately 5 years of age. The metaphyseal alterations associated with this type are similar to those of achondroplasia, resulting in moderate dwarfism. The Spahar-Hartmann type is characterized by skeletal changes and severe bowleg. Cartilage-hair hypoplasia is characterized by severe dwarfism and hair that is sparse, short, and brittle. Intellectual disability is not usually associated with metaphyseal dysostosis. Radiographic examination of all types of the disease reveals characteristic widening of the metaphyses of the tubular bones, with normal diaphyseal and epiphyseal ossification centers. Treatment is supportive and symptomatic. No specific modality is used.
