metaphyseal dysostosis

dysostosis /dys·os·to·sis/ (dis″os-to´sis) defective ossification; defect in the normal ossification of fetal cartilages.

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cleidocranial dysostosis  a hereditary condition marked by defective ossification of the cranial bones, absence of the clavicles, and dental and vertebral anomalies.

craniofacial dysostosis  a hereditary condition marked by acrocephaly, exophthalmos, hypertelorism, strabismus, parrot-beaked nose, and hypoplastic maxilla.

mandibulofacial dysostosis  a hereditary disorder occurring in a complete form (Franceschetti syndrome) and a less severe form (Treacher Collins syndrome), with antimongoloid slant of the palpebral fissures, coloboma of the lower lid, micrognathia and hypoplasia of the zygomatic arches, and microtia.

metaphyseal dysostosis  a skeletal abnormality in which the epiphyses are normal and the metaphyseal tissues are replaced by masses of cartilage, producing interference with enchondral bone formation.

dysostosis mul´tiplex  Hurler's syndrome.

orodigitofacial dysostosis  orofaciodigital syndrome.

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metaphyseal dysostosis

[mətaf′izē′əl disostō′sis, met′əfiz′ē·əl disostō′sis]

Etymology: 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. Mental retardation 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.

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dysostosis [dis″os-to´sis]

defective ossification; a defect in the normal ossification of fetal cartilages.

cleidocranial dysostosis an autosomal dominant condition in which there is defective ossification of the cranial bones, complete or partial absence of the clavicles, so that the shoulders may be brought together, or nearly together, in front, and dental and vertebral anomalies. See illustration.

Cleidocranial dysostosis. From Dorland's, 2000.

craniofacial dysostosis an autosomal dominant condition marked by a pointed or conical skull, protruding wide-set eyes, strabismus, parrot-beaked nose, and hypoplastic maxilla with relative mandibular prognathism. Called also Crouzon's disease.

mandibulofacial dysostosis a hereditary disorder occurring in two different forms: the complete form is Franceschetti syndrome and the incomplete form is Treacher Collins syndrome. Persons with the condition have downslanting eyes (antimongoloid palpebral fissures); absence of all or part of the lower lid; underdeveloped cheekbones that appear depressed; a prominent nose, wide mouth, and small receding chin; underdeveloped, malformed, or prominent ears; and small tufts of hair in front of the ears. There is often, but not always, some degree of hearing loss, usually conductive.

metaphyseal dysostosis a skeletal abnormality in which the epiphyses are normal or nearly so, and the metaphyseal tissues are replaced by masses of cartilage, producing interference with endochondral bone formation and expansion and thinning of the metaphyseal cortices.

orodigitofacial dysostosis orofaciodigital syndrome.