Achondroplasia. (Lugeol.)
Prognosis.
—The prognosis is unfavorable, because it seems impossible to undo the faults of the intra-uterine condition. The disease, however, is not incompatible with a long life.
Rachitis.
—This also is a constitutional condition, and has been described in Chapter XIII. So far as the manifestations in the bones are concerned it is a constitutional dystrophy caused by improper deposition of calcareous material in the softened and somewhat perverted fetal cartilages. It is a condition, however, pertaining rather to postnatal life, and while inconspicuous at birth becomes more and more marked as the child develops. It is essentially a disease of malnutrition, and consequently may be seen in all walks of life, as well in the bottle-fed babies of the wealthy as in the best-nourished children of the poor. The subject should be studied also in connection with the facts set forth in the chapter on the Status Lymphaticus, which bear on the relation of the ductless glands to tissue growth, and especially to rickets. The lesions are widely distributed. The disease is divided by some writers into three periods: (a) Rarefaction of bone tissue; (b) softening of same; (c) re-ossification.
The first stage is the intra-uterine part; the second and third stages are postnatal. To fetal rarefaction have been attributed intra-uterine fractures, even by Hippocrates.
The general dyscrasia and visceral alterations of rachitis interest us here less than deformities of the various bones. The head is disproportionately large, the vertex flattened, the frontal and parietal eminences pronounced; the anterior fontanelle closes very late. To the atrophic alterations of the head have been given the name craniotabes. The face is disproportionately small, the lower jaw assuming a polygonal shape. The palatal vault is of the Gothic type, dentition irregular and retarded. In the thorax the clavicular curves are exaggerated, by which the bones are shortened and the shoulders made narrow. The costochondral junctions are enlarged, the result being the so-called rachitic rosary. The sternum projects and gives the peculiar appearance known as pigeon-breast. The pelvis is often deformed, and frequently distorted to such an extent as in after years to make normal delivery impossible. The spinal column may either be distorted early or is likely to undergo alterations of curvature, due to the combined results of pressure and traction upon softened vertebræ. The joint ends of the long bones are enlarged or clubbed, this being true even of the phalanges. Joint movements are often accompanied by crepitation. The axes of the long bones are distorted, and more or less marked deviations and curvatures result, giving rise to such deformities as knock-knee, bow-leg, etc. (See [pp. 161] and [162].)
Osteomalacia.
—As rickets is essentially a disease of early childhood, osteomalacia is practically confined to adults. The name implies a peculiar softening of the bones, by which their resistance and rigidity are weakened and deformity permitted. The disease is common to man and to animals in confinement, and is frequently noted among wild animals dying in zoölogical gardens. It commonly occurs in pregnant women, where it would appear as if the mineral elements needed for the growing fetus were abstracted from the mother’s bones rather than from the food ingested. It is brought about also by starvation, possibly by lactation, especially among those who nurse their children for unusual periods.