The primary purpose of this study was to determine if tibial bone strength is compromised in dystrophic mice and if so, what geometric and material properties contribute. Results of three-point bending tests showed that tibia of mdx and dko (dystrophin- and utrophin-deficient) mice had up to 50% lower strength and stiffness compared to wild-type mice. Micro-computed tomography indicated that dystrophic tibia had reductions of 6-57% in cortical cross-sectional moment of inertia and cross-sectional area. Metaphyseal trabecular bone morphometry was also altered up to 78% in dystrophic mice. Bone-to-muscle functional ratios (i.e., three-point bending measures:muscle strength) indicated that bone strength was relatively high in 7-week-old dystrophic mice compared to muscle strength, but ratios were similar to wild-type mice by 24. months of age. Young dystrophic mice have compromised bone strength; these models may be useful for designing therapeutic regimens aimed at improving the skeleton.
Bibliographical noteFunding Information:
Our research has been supported by grants from the Muscular Dystrophy Association (Research Grant 114071 ) and the National Institutes of Health ( P30-AR057220 ).
- Bone geometry
- Bone strength
- Duchenne muscular dystrophy
- Mdx mouse