BONE LESIONS OF SMALLPOX. 555 



during infancy and childhood followed by gradual development of the 

 deformities, and in the absence of any other apparent cause, makes it 

 fairly certain that the condition is caused by smallpox. Additional evi- 

 dence of some value is found in the popular recognition of the condition 

 as one of the complications of variola to such an extent that it is one of 

 the occurrences most dreaded by mothers when they find that their 

 children are suffering from the disease. The nature of the lesions could 

 better be determined by the use of radiographs or by autopsies. 



However, from the nature of the deformities and as a result of 

 physical examination, the process appears to be due to destructive lesions 

 in the epiphyses of the bones. The shafts of the ulna and radius seem 

 to be normal, except in length. The ends of the bones are enlarged and 

 irregular in shape and similar changes may be encountered in the carpal, 

 metacarpal and phalangeal bones. 



One of the most striking features of the deformities is the constant 

 location of the lesions in the upper extremities, they usually being con- 

 fined to one or both forearms, although they occasionally extend to the 

 hands, as is shown in the illustrations. 



The reason for not studying our cases with the X ray has already been 

 given, and up to the present time we have not been able to examine any 

 individual postmortem. However, in spite of the absence of radio- 

 graphic pictures of the bones in question, it may be determined with 

 considerable accuracy that the probable seat of the primary lesion which 

 has prevented the further longitudinal growth of the bones is produced 

 by the nature of the gross anatomical changes in the bone itself. To 

 begin with, we have the following facts on which to base our, argument : 



I. The circumferential growth of these bones is not disturbed in the 

 least. There is no sign of underdevelopment in diameter, as can be 

 proved by comparing them with normal bones. This shows that the 



"periosteum upon which the circumferential growth depends, was not 

 affected. 



II. The bones are markedly shortened and stunted in longitudinal 

 growth, in some instances they are reduced to more than one-half the 

 length of the normal bone. 



The obvious conclusion from this fact is that the seat of the primary 

 lesions is in that active part of the bone between the epiphysis and 

 diaphysis which grows ex utero. This center of ossification consists 

 of cartilage cells, upon which the longitudinal growth depends and 

 which do not become calcified or ossified until late in life. Complete 

 ossification of the ulna takes place from the twentieth to the twenty- 

 third year; of the radius from the twentieth to the twenty- fifth year; 

 and of the metacarpal and phalangeal bones at about the twentieth year. 

 At the the end of these periods of time, the diaphyses and epiphyses 

 become firmly united and longitudinal growth ceases.. 



