954 



Osteomalacia. 



Pathogenesis. The commencement of the pathological 

 IDrocess in the bones is probably similar to that in rachitis 

 (see p. 937), whether the trouble l)e dne to a lime deficiency 

 of the organism or to another cause. But since in this disease 

 the process occurs in fully developed bones, the later tissue 

 changes differ more or less from those in rachitis. In osteo- 

 malacia the peculiar proliferative processes are absent which 

 are noted in rachitis at the borders between the epiphyses and 

 the diapliyses of the long bones, and on the other hand the 

 decalcification (osteoporosis) predominates over the new- 

 formation of osteoid tissue, at least in many cases. Still, ex- 

 ceptions are observed not very infrequentl}^, in so far as a 

 decided proliferative process may set in under the influence 

 of certain mechanical factors (see p. 937) and of other agencies 



Fig. 165. Skeleton of the cow witli osteomalaria, illustrated in Fig. 168. The ribs 

 are bent forward, show nmltijile fractures, and callus formation. Both ilia are 

 fractured, tlie fractured ends lieing crowded into one another. Enormous callus for- 

 mation, moderate lordosis of the lumbar vertebrae ; callus formation at the base of 

 the spinal ]jrocesses of the anterior dorsal vertebrae. 



that are not fully known. In other cases the new-formation of 

 osteoid tissue may be entirely lacking. 



The further consequences of the diminution in the firmness 

 of the bones and of the disturbances in the metabolism are 

 the same as in rachitis (see p. 937), except that in osteomalacia 

 the bones are more often brittle ratlier than pliable. 



Relations of Rachitis to Osteomalacia. While Virchow and others 

 differentiated rachitis sharply from osteomalacia, still other authors 

 declared ])oth diseases to he closely related, or identical. Indeed the 

 pathogenesis and the etiological agencies of hgth affections agree in 

 many points, and it appears as though the anatomical or microscopical 

 differences were dependent solely upon the difference in the age of 



