Biological Materials

Question 1

What makes up bone?

Answer 1

• Water 25-30% (WET)
• Collagen 30% (DRY)
• Minerals 70% (DRY)

Question 2

How much force can bone withstand maximally in comparison to normal life?

Answer 2

6x

Question 3

What are the characteristics of osteocytes?

Answer 3

• Light
• In a collagen matrix
• Packed with minerals

Question 4

What is the relationship between trabecular and cortical bone in regards to strength:weight ratio?

Answer 4

Total exceeds either of its constituents. Whole is greater than the sum of the parts.

Question 5

Which is stronger, cortical/trabecular and tension/compression?

Answer 5

Cortical & Compression

Question 6

Name the two types of fracture MOI categories

Answer 6

• Traumatic

- Fatigue-induced

Question 7

FP: Diaphyseal impaction

Answer 7

Load: Axial compression

Question 8

FP: Transverse

Answer 8

Load: Bending

Question 9

FP: Spiral

Answer 9

Load: Torsion

Question 10

FP: Oblique transverse/butterfly

Answer 10

Load: Axial compression and bending

Question 11

FP: Oblique

Answer 11

Load: Axial compression, bending, and torsion

Question 12

What % of cartilage tissue volume is cells?

Answer 12

<10%

Question 13

What % of cartilage organic matrix is fibrils? What % is prosteoglycans solution? What % is water, salts, matrix proteins, glycoproteins and lipids?

Answer 13

• 10-30%
• 3-10%
• 60-87%

Question 14

Cartilage is anisotropic, what does this mean?

Answer 14

Mechanical properties depend on direction of loading

Question 15

How does cartilage reduce stress on joints?

Answer 15

Increases load bearing area

Question 16

Name 6 viscoelastic materials.

Answer 16

• Tendons
• Aponeuroses
• Deep fascia
• Intermuscular septa
• Ligaments
• Ligmentous joint capsule

Question 17

What is the ultimate failure strain of tendons? And what’s their viscoelastic behaviour (hysteresis)

Answer 17

• 8-10%

- 2.5-20%

Question 18

Where do most everyday ligament activities occur on the stress-strain curve?

Answer 18

High deformation/low force toe region

Question 19

As force is applied, what happens to the stiffness of ligaments?

Answer 19

Increases

Question 20

At a fast load rate, what type of ligament tear is likely?

Answer 20

Mid-substance tear

Question 21

At a low load rate, what type of ligament tear is likely?

Answer 21

Bony avulsion

Question 22

What are the effects of a ligament tear?

Answer 22

• Loss of stability
• Joint misalignment
• Abnormal contact pressure
• Loss of proprioception.

Question 23

Why is muscle the most susceptible tissue to injure?

Answer 23

Low stiffness

Question 24

What is muscle stiffness related to?

Answer 24

Force produced in relation to length

Question 25

How far can muscle stretch without rupture?

Answer 25

160%

Question 26

How many times stiffer is a muscle in eccentric compared to concentric?

Answer 26

200x