15 



Rarefying Disease of the Skeleton: 

 Observations Dealing with Aged and 

 Dead Bone in Patients with Osteoporosis 



MARSHALL R. URIST, Division of Orthopedics, Department of Surgery, 

 School of Medicine, Center for the Health Sciences, University of Cali- 

 fornia, Los Angeles, California 



NORMAN S. MacDONALD, Departments of Nuclear Medicine, Bio- 

 physics, and Radiology, School of Medicine, Center for the Health Sci- 

 ences, LTniversity of California, Los Angeles, California 



MILTON J. MOSS, Division of Orthopedics, Department of Surgery, 

 School of Medicine, Center for the Health Sciences, University of Cali- 

 fornia, Los Angeles, California 



WILLIAM A. SKOOG, Department of Medicine, School of Medicine, 

 Center for the Health Sciences, University of California, Los Angeles, 

 California 



THE subject of rarefying disease of bone in clinical medicine in- 

 cludes at least ten relatively uncommon conditions and one very 

 common disorder. Some of the uncommon conditions are: osteo- 

 malacia, osteitis fibrosa generalisata, renal osteodystrophy, hypo- 

 phosphatasia, metastatic bone disease, osteitis deformans, fibrous 

 dysplasia of bone, multiple myeloma, scurvy, and osteogenesis im- 

 perfecta. The one common disorder is osteoporosis, a condition very 

 difficult to diagnose at an early stage and often superimposed upon 

 physiological atrophy of bone of old age. In the advanced stage, 



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