Mineral to matrix ratio determines biomaterial and biomechanical properties of rat femur -application of Fourier transform infrared spectroscopy-

Abstract

We studied the changes of biomaterial and biomechanical properties of the rat femur during development. Thirty male Wistar rats were allocated to 6 groups: aged 6 weeks (n=5), 9 weeks (n=5), 12 weeks (n=5), 15 weeks (n=5), 24 weeks (n=5), and 36 weeks (n=5). The mineral to matrix ratio (M/M ratio) of rat femur by Fourier transform infrared spectroscopy was 0.97±0.10 at the age of 6 weeks, and reached the maximum of 1.52±0.17 at the age of 36 weeks. Total bone mineral density (BMD) by peripheral quantitative computed tomography of the femoral shaft aged 6 weeks was 479.1±58.7 mg/cm³, and reached the maximum of 1022.2±42.3 mg/cm³ at the age of 36 weeks. The ultimate load to failure of the femur of the rat aged 6 weeks by the three-point bending test was 29.6±6.1 N. At the age of 36 weeks, the ultimate load to failure of the rat femur increased to the maximum of 283.5±14.7 N. The results showed that the M/M ratio increased with development as total BMD and bone strength increased. The results suggest that the M/M ratio is one of the determinants of the biomaterial and biomechanical properties of bone. J. Med. Invest. 58: 197-202, August, 2011