The lesions in the bones resulting from actinomycosis and from mycetoma, have been described with these diseases.
Constitutional Diseases attended with Lesions in the Bones
These include rickets, scurvy-rickets, osteomalacia, ostitis deformans, osteomyelitis fibrosa, fragilitas ossium, and diseases of the nervous system.
Rickets
Rickets or rachitis is a constitutional disease associated with disturbance of nutrition, and attended with changes in the skeleton. The disease is most common and most severe among the children of the poorer classes in large cities, who are improperly fed and are brought up in unhealthy surroundings. There is evidence that the most important factors in the causation of rickets are ill-health of the mother during pregnancy, and the administration to the child after its birth of food which is defective in animal fat, proteids, and salts of lime, or which contains these in such a form that they are not readily assimilated. The occurrence of the disease is favoured, and its features are aggravated, by imperfect oxygenation of the blood as the result of a deficiency of fresh air and sunlight, want of exercise, and by other conditions which prevail in the slums of large towns.
Pathological Anatomy.—The most striking feature is the softness (malacia) of the bones, due to excessive absorption of osseous tissue, and the formation of an imperfectly calcified tissue at the sites of ossification. The affected bones lose their rigidity, so that they are bent under the weight of the body, by the traction of muscles, and by other mechanical forces.
The periosteum is thick and vascular, and when detached carries with it plates and spicules of soft porous bone. The new bone may be so abundant that it forms a thick crust on the surface, and in the flat bones of the skull this may be heaped up in the form of bosses or ridges resembling those ascribed to inherited syphilis.
In the epiphysial cartilages and at the ossifying junctions, all the processes concerned in ossification, excepting the deposition of lime salts, occur to an exaggerated degree. The cartilage of the epiphysial disc proliferates actively and irregularly, so that it becomes softer, thicker, and wider, and gives rise to a visible swelling, best seen at the lower end of the radius and lower end of the tibia, and at the costo-chondral junctions where the series of beaded swellings is known as the “rickety rosary.”
The ossifying zone is increased in depth; the marrow is abnormally vascular; and the new bone that is formed is imperfectly calcified. The result is that the bones may never attain their normal length, and they remain stunted throughout life as in rickety dwarfs ([Fig. 133]), or the shafts may grow unequally and come to deviate from their normal axes as in knock-knee and bow-knee.