ENERGY-DISPERSIVE X-RAY-MICROANALYSIS OF THE BANE MINERAL-CONTENT IN HUMAN TRABECULAR BONE - A COMPARISON WITH ICPES AND NEUTRON-ACTIVATIONANALYSIS

To evaluate the accuracy of bone mineral composition determination by electron microprobe analysis (EDX) the measurements have been compared to instrumental neutron activation analysis (INAA) and chemical analy sis (ICPES). Bone specimens from five femoral heads were used. The tra becular content of calcium (Ca) and phosphorus (P) was analyzed by the three different methods. The EDX method allows for a microstructural analysis of intact, methylmetacrylate-embedded, undecalcified bone and the measuring points can thus be distinctly identified centrally in e ach trabecula. The analysis yielded 25.8 +/- 0.7 wt% Ca and 10.5 +/- 0 .1 wt% P, compared with 22.2 +/- 0.5 and 23.0 +/- 1.0 wt% Ca, and 9.83 +/- 0.21 and 10.02 +/- 0.44 wt% P for INAA and ICPES, respectively. T he EDX analysis was calibrated by consecutive measurements of a hard, pressed tablet of hydroxyapatit of known content. The mean Ca content deviated with -0.38 wt% from the given content and P with -0.89 wt%. W e could not verify any particular interference from the embedding proc edure, however, it is possible that the relatively lower P content sti ll may reflect this. The magnesium (Mg) concentration was 0.31 +/- 0.0 2 wt% by EDX and 0.26 +/- 0.02 wt% by INAA. The EDX analytical method provides a useful tool for simultaneous elemental quantification in bo ne. It has the advantage of permitting the use of regular bone biopsy material and thus allowing for a unique microstructural evaluation of the degree of mineralization. By comparison with other established met hods, the assessment of accuracy and reliability indicates that the me asurements are well in range for the major constituents, Ca and P, whe reas INAA is more sensitive in determining trace elements.