Biological Materials Flashcards
What makes up bone?
- Water 25-30% (WET)
- Collagen 30% (DRY)
- Minerals 70% (DRY)
How much force can bone withstand maximally in comparison to normal life?
6x
What are the characteristics of osteocytes?
- Light
- In a collagen matrix
- Packed with minerals
What is the relationship between trabecular and cortical bone in regards to strength:weight ratio?
Total exceeds either of its constituents. Whole is greater than the sum of the parts.
Which is stronger, cortical/trabecular and tension/compression?
Cortical & Compression
Name the two types of fracture MOI categories
- Traumatic
- Fatigue-induced
FP: Diaphyseal impaction
Load: Axial compression
FP: Transverse
Load: Bending
FP: Spiral
Load: Torsion
FP: Oblique transverse/butterfly
Load: Axial compression and bending
FP: Oblique
Load: Axial compression, bending, and torsion
What % of cartilage tissue volume is cells?
<10%
What % of cartilage organic matrix is fibrils? What % is prosteoglycans solution? What % is water, salts, matrix proteins, glycoproteins and lipids?
- 10-30%
- 3-10%
- 60-87%
Cartilage is anisotropic, what does this mean?
Mechanical properties depend on direction of loading
How does cartilage reduce stress on joints?
Increases load bearing area
Name 6 viscoelastic materials.
- Tendons
- Aponeuroses
- Deep fascia
- Intermuscular septa
- Ligaments
- Ligmentous joint capsule
What is the ultimate failure strain of tendons? And what’s their viscoelastic behaviour (hysteresis)
- 8-10%
- 2.5-20%
Where do most everyday ligament activities occur on the stress-strain curve?
High deformation/low force toe region
As force is applied, what happens to the stiffness of ligaments?
Increases
At a fast load rate, what type of ligament tear is likely?
Mid-substance tear
At a low load rate, what type of ligament tear is likely?
Bony avulsion
What are the effects of a ligament tear?
- Loss of stability
- Joint misalignment
- Abnormal contact pressure
- Loss of proprioception.
Why is muscle the most susceptible tissue to injure?
Low stiffness
What is muscle stiffness related to?
Force produced in relation to length
