45-i J. JOWSEY 



Material and Techniques 



The method adopted for the present stud\ of bone turnover was 

 the quantitative evaluation of bone formation and resorption in 

 microradiographs of bone sections. Both normal and pathological 

 material was used in this studv. Normal material was collected from 

 accident cases and sudden deaths from heart attacks. Gross x-rav 

 pictures were made of 1.0-cm slices through the 5th lumbar vertebra 

 to determine whether any osteoporosis was present in the normal 

 individuals; if such x-rays showed abnormally low density, these 

 individuals were excluded from the studv. Pathological material 

 came from individuals with bone diseases, in particular osteoporosis. 

 This group consisted of 10 individuals with x-rav evidence of osteo- 

 porosis such as decreased density of the skeleton and crush fractures 

 of the spine; about half of the group had also fractured the neck of 

 one femur. The specimens were taken from the mid-shaft of the 

 femur, the neck of the femur, the iliac crest, and the 5th lumbar 

 vertebra, though the results reported here are mainly those from 

 the mid-femoral shaft. 



The specimens are fixed in 70 per cent alcohol, deh)'drated in 

 absolute alcohol for 2 or 3 days, and then put in unpolymerized 

 methyl methacrylate monomer for 24 hours. The specimens are then 

 placed in semipolvmerized monomer and the polymerization is com- 

 pleted by heating at 32 °C for 2 to 3 davs. The blocks are trimmed 

 on a handsaw and sections 100 microns thick are cut on a commercial 

 milling machine using a circular steel saw. The sections are further 

 ground, if necessary, until they are 100 ± 2 microns thick, and con- 

 tact microradiographs are made using Eastman 649-0 spectroscopic 

 plates and an x-ray beam from a copper target. The microradio- 

 graphs are inspected with a microscope and the areas of bone forma- 

 tion, resorption, and inactivity identified. Quantitative measurements 

 are made by making a print at a magnification of 30 times, and since 

 formation and resorption of bone are activities that take place ex- 

 clusively on the surface, the lengths of all bone surfaces that are 

 undergoing formation or resorption or are inacti\'e are measured 

 with a map measure. The results are expressed as the length of 

 surface involved in either formation or resorption in a certain area 



