An attempt has been made to include rachitic and osteomalacio pelves under a common head, the deformity in both cases being regarded as due to softening of the bones. But in rachitis the bones fail to harden, in osteomalacia they become softened after being hard; in the former case there is progressive metamorphosis, in the latter, retrograde degeneration.
Pinard affirms that in the lesser degrees of osteomalacia the shape of the pelvis is identical with that of the well-marked rachitic type. Spiegelberg describes two varieties of the pseudo-osteomalacic rachitic pelvis, in which the bones of an already rachitic pelvis undergo secondary softening, so that the same malformations are produced as in osteomalacia. A pelvis of this character is distinguished from a true osteomalacic pelvis, by the solidity of its bones, the smoothness of their surfaces, and by the fact that their size is greater than normal; the distance between the anterior superior iliac spines is increased. The rest of the skeleton, moreover, presents the characteristic changes of rickets. " It is not very rare," says Depaul, " to find localized in a single bone changes that bear the mark of rickets. We can imagine how, in such cases, the pelvic deformity dif fors from that which results from simultaneous malformation of all the bony parts." As a rule, there is in this instance only an unequal distri bution of the rachitic changes, of which we find traces in other bones. This is the case in the pelvis here represented. (Fig. 36.) On examining it carefully, we note in the rest of the skeleton evidences of the disease, which is unequally distributed, and, by reason of its predominance in a single bone, appears at first sight to have been localized in that bone.
Osteomalacie Pelvis.
Osteomalacia is a disease of adult life. It rarely appears before twenty, generally developing between the ages of thirty and fifty; it is oonfined almost exclusively to poor women, who have been enfeebled by residence in damp, unhealthy dwellings, by insufficient nourishment, and repeated pregnancies. Osteomalacia does not attack women alone, but it is limited to adults. According to Ranvier, we must distinguish true osteomalacia in adults from the osteoporosis that occurs in old age. Kilian describes
two varieties, osteomalacia psathyra (fracturosa), and osteomalacia apsa thyros (cohterens); these are really only successive stages of the same di ease, so that both forms may be observed in the same subject. Some times the bones are yellowish, compressible, and rugose on the surface. sometimes they are quite porous, and brittle, the weight of the entire pel vis being greatly diminished. The most characteristic feature of this pelvis, however, is the fact that it presents apparently normal dimensions, the bones being of the usual size and thickness; in short, there are no evidences of arrest of development as in the rachitic pelvis.
Pathologically the disease is to be regarded as an osteomyelitis and pro gressive osteitis; the bone is deprived of its lime-salts, while at the same time all the other softened bone•tissues are compressed by the morbid proliferation of the marrow. When the women are in poor condition, the constant hyperaemia to which the bones are subject during the entire course of pregnancy, (especially when pregnancies follow one another in rapid succession), lead to the outbreak of the disease. Osteomyelitis is the initial process. The marrow is destroyed and is replaced by a young medullary substance of a reddish color, the small round cells of which proliferate under the influence of the excessive hyperaemia. The removal of the lime salts is effected through the agency of the Haversian canals, an osteoid tissue being formed, which in turn becomes' dissolved, and is eventually replaced by the proliferated medullary tissue. This substitu tion of medullary for osteoid tissue is observed a long the Haversian canals, so that in the midst of the marrow there are found islands of intact osse ous lamellae. Finally, the entire bone becomes soft, like wax, and cuts readily, though crackling in some spots. In extreme cases nothing is left but a membranous sac, formed by the periosteum, containing medul lary substance and fat. No trace of glutin or chondrin remains in the bone, while the carbonate and phosphate of lime'are greatly diminished in amount.