Week 4 Flashcards
two types of bone
Compact
Trabecular (spongy)
Define epiphysis
area within the bone that contains spongy bone
Define diaphysis
Area within the bone that contains compact bone
Define and explain Osteo Blasts
Cells that form new bone
numerical variable is a variable where the measurement or number has a numerical meaning.
Define and explain Osteo Clasts
- Osteoclasts removes bone tissue by removing the mineral matrix of the bone and dissolving the collagen part of the bone and dissolves it into the blood
- Unmineralized bone (osteoid) is protected against osteoclastic resportion
Bone strength is influenced by what 4 factors
- Bone mineral density
- Bone mineral content
- Size
- Geometry
Define load-deformation curve
A curve showing the relationship between the stress or load on a structure, structural member, or a specimen and the strain or deformation that results.
Define stress stain curve
Load-deformation curve but removes the cofounding effects of geometry and size of the material
What does the are under the curve of a load-deformation curve represent
Absorbed energy
What the linear segment in a load-deformation curve represent
Elastic region
What does the plateau represent in a load-deformation curve
Plastic region
What does the slope of the load deformation curve represent
Material stifness
How much tolerance can a cortical bone take for compression, tension and shearing
Compression - 190Mpa
Tension - 130
shearing - 70
How much tolerance can a trabecular bone take for compression and tension
Compression - 50
Tension - 8Mpa
Define anisotropic behaviour of bone
Differences in strength depending on how we load the bone
Bones are strongest…..
if you load them fast
What causes stress fractures
When remodeling can’t keep up with loading related damage
What is wollf’s law
Bone in a healthy person will adapt to the loads under which it is placed
Define growth in regards to wollf’s law
- The cartilaginous nature of the growth or epiphyseal plate renders it prone to damage during period of growth
Define avulsion fractures
- Fractures at the weak/est points in the bone
What are 5 non-modifiable risk factors of osteoporosis
- Female sex, age > 70 years, being Caucasian or Asian, early onset of menopause, longer postmenopausal interval
What are 7 modifiable risk factors of osteoporosis
- Lack of weight bearing exercise, smoking, alcohol abuse, XS caffeine consumption, low dietary Ca2+, lack of sunlight
What are the two types of bone loading
Static
Dynamic
Define static loading
- Static = constant
Define dynamic loading
- Dynamic = intermittent
- High rates of intermittent deformation
- Drives fluid back and forth through lacunar-canalicular network
What type of bone loading stimulates osteogenesis
Dynamic
