The Long-Term Residual Effects of Low-Magnitude Mechanical Stimulation On Murine Femoral Mechanics

As an alternative to drug treatments, low-magnitude mechanical stimulation (LMMS) may improve skeletal health without potential side effects from drugs. LMMS has been shown to increase bone health short term in both animal and clinical studies. Long term changes to the mechanical properties of bone from LMMS are currently unknown, so the objective of this research is to investigate the long-term effects of whole body vibration therapy on the elastic and viscoelastic properties of bone. In this study 10-week old female BALB/cByJ mice were given LMMS (15 min/day, 5 days/week, 0.3 g, 90 Hz) for 8 weeks; SHAM did not receive LMMS. Two sets of groups remained on study for an additional 8 or 16 weeks post LMMS (N=17). MicroCT and histomorphology of these femurs were studied and results were published by Bodnyk et al. [1]. Femoral quasi-static bending stiffness trended 4.2% increase in stiffness after 8-weeks of LMMS and 1.3% increase 8-weeks post LMMS compared to SHAM. Damping, tan delta, and loss stiffness, significantly increased by 17.6%, 16.3%, and 16.6% respectively at 8 weeks LMMS compared to SHAM. Finite element models of applied LMMS signal showed decreased stress in the mid-diaphyseal region at both 8-week LMMS and 8-week post LMMS compared to SHAM. Residual mechanical changes in bone during and post-LMMS indicates that LMMS could be used to increase long-term mechanical integrity of bone.