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

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