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icroradiography of Bone Resorption 



JENIFER JOWSEY,* Department of Microradiography, Albert Einstein 

 Medical Center, Northern Division, Philadelphia, Pennsylvania 



FOR a normal skeleton to be maintained there must be a balance 

 between the addition and the removal of bone tissue. This turnover 

 of bone may be taking place rapidly as in a growing individual, or 

 slowly as in young adults, but whatever the rate, the balance must 

 be maintained to result in the compact, well calcified tissue of a 

 normal skeleton. A number of abnormalities of the skeleton are the 

 result of an upsetting of this balance in turnover of bone; there is 

 an increase or decrease in removal of tissue without a corresponding 

 increase or decrease in addition of bone, and the result is a change 

 in the gross structure of the bone, generally a loss of tissue, which 

 seriously affects its supporting function. If the abnormality existing 

 in various bone diseases is to be understood, the immediate cause 

 of the upset in the balance must first be found, and this may be 

 done by measuring the amount of bone formation and bone resorp- 

 tion and also measuring the extent of decrease in mass of the tissue, 

 or its porosity, a figure which will indicate for how long the balance 

 has been upset. 



The Measurement of Bone Turnover 



A number of attempts have been made to measure bone foimation 

 by equating the amount of new bone laid down in the skeleton at 



** Present address: Section of Surgical Research, Mayo Clinic, Rochester, Minnesota. 



447 



