The establishment of a mechanobiology model of bone and functional adaptation in response to mechanical loading.

BACKGROUND

Mechanical stimuli affected bone adaptation, however, the mechanism on a dose-response relationship between mechanical stimuli and bone response is unclear. Therefore, we established a mechanobiology model to evaluated the adaptive response of bone to strain deformation at high-frequencies (5-15 Hz) of externally applied strain.

METHODS

The ulnae of adult female rats were subjected to dynamic axial loading in vivo using Instron materials-testing machine. The applied loading at frequencies of 5 Hz, 10 Hz, and 15 Hz for 10 min with a haversine, low-magnitude waveform for a 2 weeks period, the peak strains is 2000 muepsilon and 3000 muepsilon. Strain was recorded using strain gauge conditioner and compared to physiological values obtained after testing.

FINDINGS: At frequencies of 10 Hz, 15 Hz groups, loading promoted obviously secreted of osteocalcin and collagen; a relative benefit in Bone Mineral Density (BMD) was found compare to the control (P < 0.05) followed the decline of material mechanical properties (modulus of elasticity, ultimate stress) (P < 0.01).

INTERPRETATION: These data show that a mechanobiology model of the axial ulna loading technique had been established successfully in rat. A short daily period of low-magnitude, high-frequency mechanical stimuli results in an osteogenic response related to peak strain magnitude, which do not result in significant differences in mechanical properties between the groups.