Biomedical Engineering Reference
In-Depth Information
can be so widespread that it can account for the large changes in mechanical
properties of overloaded trabecular bone. Moreover, its detection in a clinical
environment is more difficult owing to the fact that it can only be seen on a
small scale. It is therefore difficult to evaluate the risk of fracture with this
type of damage. Different factors can affect bone damage, such as strain rate
or age. Loading at higher strain rates reduces the reduction in stress after
the ultimate point is reached (Keaveny
et al
., 1999). Elderly cortical bone,
which is more brittle than younger bone, damages more easily than younger
tissue when subjected to the same strain (Courtney
et al
., 1996). Evidence
in the literature on strain rate and age related effects led Keaveny (2001) to
suggest that biomechanical effects of damage from a non-fracturing fall or
overload may be most severe in elderly individuals who have brittle bone
tissue and low bone density but who are subjected to loads at relatively low
strain rates.
4.4 Conclusions
Bone is an intriguingly complex material with a very organized structure that
confers it with anisotropic properties well adapted to the multiple loading
present throughout human life. The mechanical properties are fundamentally
anisotropic and can be described as a two phase material in which the interstitial
fluid can play a determinant role in the mechanical response depending on
the type of loading applied. Many factors can play a role in the mechanical
properties of bone, in particular strain rate and age effects are very relevant
for bone repair and its study with biomaterials.
4.5 Bibliography
Bilezikian, J.P., Raisz, L.G. and Rodan, G.A. (eds) (1996).
Principles of
bone biology.
academic Press, San Diego.
Buckwalter J.A., Einhorn, T.A. and Simon, S.R. (eds) (2000).
Orthopaedic
basic Science: biology and biomechanics of the Musculoskeletal System
.
2nd Edition, American Academy Orthopaedic Surgurgeons, Rosemont,
illinois.
Cowin, S.C. (ed) (2001).
bone Mechanics Handbook
. 2nd Edition, CRC
Press, Boca raton.
Daniel D.M., Akeson W.H. and O'Connor J.J. (eds) (1990).
Knee Ligaments:
Structure, Function, Injury, and Repair
. Raven Press, New York.
Fung Y.C. (ed) (1981).
biomechanics:
Mechanical Properties of Living
Tissues
. Springer-Verlag, New York.
Martin, R.B. and Burr, D.B. (eds) (1989).
Structure, Function, and adaptation
of compact bone
. Raven Press, New York.
