Effect of human trabecular bone composition on its electrical properties

Sierpowska, J.; Lammi, M.J.; Hakulinen, M.A.; Jurvelin, J.S.; Lappalainen, R.; Töyräs, J.

doi:10.1016/j.medengphy.2006.09.007

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Volume 29, Issue 8 , Pages 845-852, October 2007

Effect of human trabecular bone composition on its electrical properties

J. Sierpowska
- Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
- Corresponding author. Tel.: +358 17 162541; fax: +358 17 162585.
M.J. Lammi
- Institute of Biomedicine, Department of Anatomy, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
M.A. Hakulinen
- Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
J.S. Jurvelin
- Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
- Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, University of Kuopio, P.O. Box 1777, FIN-70211 Kuopio, Finland
R. Lappalainen
- Department of Physics, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland
J. Töyräs
- Department of Clinical Neurophysiology, Kuopio University Hospital, University of Kuopio, P.O. Box 1777, FIN-70211 Kuopio, Finland

Received 23 March 2006; received in revised form 15 September 2006; accepted 19 September 2006. published online 15 November 2006.

Abstract

Mechanical properties of bone are determined not only by bone mineral density (BMD), but also by tissue trabecular structure and organic composition. Impedance spectroscopy has shown potential to diagnose trabecular bone BMD and strength, however, the relationships between organic composition and electrical and dielectric properties have not been systematically investigated. To investigate these issues organic composition of 26 human trabecular bone samples harvested from the distal femur and proximal tibia was determined and compared with relative permittivity, loss factor, conductivity, phase angle, specific impedance and dissipation factor measured at wide range (50Hz to 5MHz) of frequencies. A strong linear correlation was found between the relative permittivity at 1.2MHz and trabecular bone fat content (r=−0.85, p<0.01, n=26). On the other hand, relative permittivity measured at 200Hz served as a good predictor of water content (r=0.83). Phase angle, specific impedance and especially conductivity were strongly related to the trabecular bone dry density and water content (|r|≥0.69). Variation in bone tissue collagen content was strongly related to the relative permittivity measured at 1.2MHz (r=0.64), but only moderately to other parameters. Glycosaminoglycan content showed no significant relations with any investigated electrical parameters. The present study indicates that if the trabecular bone composition is known, the relationships presented in this study could facilitate calculation of current field distribution, e.g. during electrical stimulation of osteogenesis. On the other hand, our results suggest that permittivity measured at low (<1kHz) or high (>100kHz) frequencies could be used, e.g. during implant surgery, for prediction of trabecular bone water or fat contents, respectively.