238 VITAMIN D GROUP 



shafts of the long bones, and in the membranous bones, there is produced 

 instead of endosteal and periosteal bone an excessive amount of uncalcified 

 bone, called osteoid. This osteoid is the framework of bone, without lime 

 salt addition, so that it is both soft and radiotranslucent. The amount of 

 this osteoid laid down varies at different points, increasing at areas of stress 

 and strain, but decreasing at points of tension. An example of the former, 

 is the excessive osteoid at the tendinous insertions into the bone, within 

 the angles of a fracture, and on the concave side of bone generally. 



When this soft bone is subjected to various and changing stresses and 

 pressures such as those that occur in walking, sitting, etc., many types of 

 deformities result. The deformities depend on the severity and extent of 

 the disease process, its duration, the age of the child,'^" and the stresses and 

 strains the bones are subject to. The age is important because it influences 

 other factors. The first of these is the rapidity of growth of the various 

 bones: the more active the growth, the greater the liability to damage. 

 Second, the child's age and stage of development will determine which of 

 the bones are particularly subjected to strain and stress. For example, dur- 

 ing the first few months, the child lies on its back, and the stresses on the 

 bones during these early months are those of gravity. During that period 

 also the head and chest are growing most rapidly. For these two reasons, 

 ricketic deformities encountered in the earliest period of life are most con- 

 spicuous in these two anatomic structures. 



Changes in the skull are thus among the earliest manifestations of rickets. 

 First there is flattening of the occipital bones from the pull of gravity. The 

 lack of calcification in circumscribed areas of the skull (craniotabes) is due 

 to the failure of calcification in portions of this membranous bone. In the 

 areas where the bending of the bone is most pronounced, on the parietal 

 and frontal bones, there are accumulations of osteoid tissue which give rise 

 to the bossae which are typical of this disease. 



Deformity of the chest and consequent physiological inadequacy of the 

 respiratory organs represent some of the most dramatic and serious conse- 

 quences of severe rickets.^^ In the advanced case, as the child lies in bed, 

 the front of the chest is seen as a blunt wedge protruding forward, with 

 the sternum and adjacent ends of the ribs corresponding to the prow of a 

 ship. The anterolateral portions of the ribs, corresponding to the costo- 

 chondral junctions, have sunk inward, producing the depressions running 

 the vertical length of the chest. The clavicles are exceedingly prominent 

 and bowed, giving undue prominence to the manubrium sternum. Often 

 there are multiple fractures of the ribs. When these fractures ai'e anterior, 

 they form small mounds of callus; if posterior, they tend to eliminate the 



'" M. M. Eliot and E. A. Park, Brennemann's Practise of Pediatrics. W F. Prior Co., 



Hagerstown, Md., 1950. 

 " E. A. Park and J. Howland, Bull. Johns Hopkins Hosp. 32, 101 (1921). 



