This section is from the book "A Manual Of Pathology", by Guthrie McConnell. Also available from Amazon: A Manual Of Pathology.
Osteomalacia is a condition of softening and flexibility of the fully formed bone following absorption of the bone salts. It is most common in women of the poorer classes, and frequently appears in connection with pregnancy. It is more common in certain regions - along the Rhine and in central Germany - than elsewhere. As a result of the flexibility of the bones, fractures are very common and all varieties of deformities may appear. The pelvis is often the seat of a typical deformity. As a result of the pressure of the spinal column from above and from the femurs below, the pubes are pushed upward and forward like a beak, the sides of the pelvis inward, and the iliac crests outward. From above, the opening in such a pelvis is triangular. Microscopically it is seen that the loss of bone salts takes place first at the periphery and extends toward the center. The laminated condition remains unchanged until late in the disease. The marrow is congested and red, the fat absorbed, and there is an extensive collection of small, round cells. The marrow may become gelatinous in appearance. Where the bones are much bent or there has been a fracture, the regular histologic structure is not retained. The bones are soft and easily broken or cut. Cachexia appears eventually, and the patient usually dies from exhaustion following repeated fractures or from some intercurrent disease.
Atrophy of the bones occurs constantly, but regeneration continues also, except when the atrophy is due to senile changes. In various conditions the destruction is too rapid and actual atrophy takes place - either general or local. Local atrophy is usually the result of pressure causing obstruction of the periosteal blood-vessels, thus interfering with the nutrition of the bone. This is not really an atrophy but a rarefying osteitis. When the bones become very brittle as a result of atrophy, the condition is known as fragilitas ossium.
Hypertrophy may be general or local, the latter being due to increased work brought upon certain areas of muscular attachment. General enlargement seems to be due to various nerve disturbances, and is frequently associated with lesions of the pituitary body, as in a akromegaly.
Inflammation may involve the covering of the bone - periostitis - the bone itself - ostitis - or the marrow - osteomyelitis. It is due to traumatism and infection.