RACHITIS. 557 



CHAPTER VI. 



RACHITIS RICKETS. 



ETIOLOGY. The actual changes in the bones in rachitis consist, 

 I . In proliferation of the cartilage of the epiphysis and of the periosteum, 

 which are the sources of the normal growth in length and thickness 

 of the bones. 2. The cartilaginous and fibrous tissues, resulting from 

 this proliferation, ossify more incompletely and later than in the nor- 

 mal growth of bone. Hence, in rachitis, there is not, as was formerly 

 supposed, a morbid softening of tissues previously hard ; but tissues 

 which normally become hard, from deposits of chalky salts, remain ab- 

 normally soft. This view is not in opposition to the fact that rachitic 

 bones bend more readily than they did before the disease. The me- 

 dullary cavity increases in rachitic just as it does in healthy bones ; 

 but, while in the latter the new formation of firm, bony substance 

 at the periphery preponderates over its loss from within, so that, ic 

 spite of the latter, the strength of the bone increases ; in rachitic 

 bones, the loss of firm, bony substance from within is not replaced 

 by a corresponding new formation at the periphery, and conse- 

 quently their resisting power is decreased. The excessive prolifera 

 tion of the cartilages of the epiphysis and of the periosteum, with 

 which rachitis begins, is by some regarded as inflammatory. The 

 great vascularity and infiltration of the affected parts, the pains which 

 accompany the disease from the first, as well as the many analogies 

 of the proliferation, with other undoubtedly inflammatory affections, 

 support this view ; but, on the other hand, it is opposed by the etiol- 

 ogy, course, and constant results of the disease. Many attempt to ex- 

 plain the retarded ossification of the newly-formed cartilage elements, 

 and the fibrous proliferation of the periosteum, by saying that, in ra- 

 chitic children, the calcareous salts taken up with the food cannot be 

 deposited in the terminal and peripheral layers of bone, because they 

 are held in solution by the lactic acid in the blood of the patient, 

 and are excreted through the kidneys. Part of the analyses of urine 

 made favor this explanation, as they showed that the urine of rachitic 

 children was not unfrequently very rich in lactic acid, and that it con- 

 tained four or six times as much phosphate of lime as is contained in 

 normal urine. Another point in favor of this view is, that children 

 who suffer from dyspepsia are especially apt to be attacked with ra- 

 chitis. The active decomposition going on in the stomachs of these 

 children forms quantities of acid, particularly lactic acid, and it is pos- 

 sible that their reabsorption and their presence in the blood hold the 

 phosphate of lime in solution, and that by their excretion with the 



