416 



URIST, MACDONALD, MOSS, AND SKOOG 



TABLE IV. Indicpzs of Physiologic Aging of Bone and Osteoporosis 

 IN White Females between 5th and 7th Decades of Life 



Estimated per cent change 

 Characteristic or component Aging, <65 Osteoporotic 



Authority 



Density (w/v, 10 bones) 



Bone tissue water 



Variation in density of osteons 



No. osteons less than ^4 closed 



Enlarged vascular channels, 

 porosity 



Vascular channels with plugs 

 of amorphous calcium de- 

 posits 



Osteocytolysis 



Osteocyte lacunae filled with 

 calcium salts 



Surface area occupied with 

 resorption 



Rate of retention of bone- 

 seeking isotopes 



Hexosamine/collagen ratio 



EDTA-soluble fraction of 

 mucopolysaccharides 



Degraded acid-insoluble 

 collagen (solid residue) 



Loss of fibrillar form of archi- 

 tecture of collagen 



Bone highly reactive with 

 tetracycline 



-12-30 -33-50 Trotteref aZ. (1960); 



Urist et al. (1962) 



65, and did not progress at an increasing rate with advancing time. 

 The indices hsted in Tables IV and V indicate that all morphological 

 and chemical changes attributed to aging occurred in osteoporotics, 

 probably at an earlier age and to a more extreme degree. These ob- 

 servations were interpreted to suggest that osteoporosis is caused by 

 an aberration or acute development of the aging changes in bone, 

 perhaps in persons who are genetically predisposed to rapid earlier 

 deterioration of the skeletal system. 



