8. Bone Biomechanics Flashcards
What is bone?
A living tissue that changes and adapts to requirements of development and activity
Bone is ANISOTROPIC
What is bone comprised of?
60% mineralised - hydroxyapatite
40% organic proteins - collagen and glycosaminoglycins
What components is bone separated into?
Periosteal surface
Cortex
Endosteal bone
Medullary cavity
What are the 1st level bone structures?
Different types of cortical bone:
- woven bone
- plexiform bone
- primary osteonal cortical bone
- secondary osteonal cortical bone (remodelled)
What are the 2nd level bone structures?
Consists of entities which make up the osteons in primary and secondary bone:
- osteoblasts (formers)
- osteocytes (mature cells)
- osteoclasts (destroyers)
What types of bone can be identified microscopically according to the pattern of collagen forming the osteoid?
Woven bone - characterised by haphazard organisation of collagen fibres, mechanically weak
Lamellar bone - regular parallel alignment of collagen into sheets (lamellae), mechanically strong
What are the forces which can act on bone?
Tension Compression Torsion Bending Shearing
How are the speed and focus of force considered?
Speed - dynamic or static?
Focus - narrow or wide?
What is stress?
The measure of forces acting on a body
What is load?
The average force per unit area under which forces act
What is strain?
Deformation of deformable body under the applications of stress
What is the cauchy strain?
The ratio of total deformation to the initial dimension of the material body in which the forces are being applied
