Limits of the musculoskeletal system 1 - Lecture 3

Question 1

What function does bone perform?

Answer 1

Mechanical - Structural & Protective

Physiological - Ca2+ regulation & blood cell production in bone marrow

Question 2

What gives bones flexibility?

Answer 2

Matrix (type 1 collagen)

Question 3

What makes bones strong?

Answer 3

Mineral content - hydroxyapatite

complex salt of calcium and phosphate

Question 4

What structures does a long bone have?

Answer 4

Long bone has a diaphysis and two epiphyses

Question 5

What are the two different types of bone?

Answer 5

Cortical (compact)

Cancellous (spongey)

Question 6

What percentage of bone is cortical, or cancellous?

Answer 6

Cortical (80%)

Cancellous (20%)

Question 7

How can we measure bone strain?

Answer 7

In vivo

Question 8

What is the process of longitudinal growth?

Answer 8

1. Endochondral ossification
2. Primary ossification centre
3. Secondary ossification centre
4. Ceases when secondary growth plates fuse at adulthood

Question 9

What is the process of circumferential growth?

Answer 9

1. Diameter increases throughout life span

2. Rapid prior to adulthood then very slow

Question 10

What happens when a bone breaks?

Answer 10

1. Repair
2. Haematoma leads to clot formation
3. Cartilage fills gap which is ossified to form new woven bone
4. Callous then remodels over time

Question 11

What do osteoclasts and osteoblasts do?

Answer 11

osteoclasts - bone resorption

osteoblasts - bone formation

Question 12

What is bone atrophy?

Answer 12

Inactivity - bone mass and mineral content decrease due to osteoclast activity

Question 13

What is bone hypertrophy?

Answer 13

Increase in activity where bone mass and mineral content can increase

Question 14

How can we predict when a bone will break?

Answer 14

It is difficult to predict the stress at which a bone will break at

Question 15

Why is it difficult to predict when a bone will break?

Answer 15

Individual differences
Bone constantly changing
Dependant on loading rate

Question 16

Why does a bone fracture occur?

Answer 16

Excessive forces
Weak material
Cumulative damage from repetitive loading

Question 17

What are the physics of X-rays?

Answer 17

Electro-magnetic spectrum
0.1-10nm wavelength
Form of ionising radiation
Bones absorb the protons of the x-ray as they are electron dense

Question 18

What are the characteristics of plain radiography (2D)?

Answer 18

Spatial resolution (2D)
Simple, available, affordable
High reproducibility
Low radiation does

Question 19

What are the characteristics of computerised tomography (3D)?

Answer 19

Very high resolution of bone
Fast - 20s for whole body
Moderately expensive
High radiation does

Question 20

What is osteoporosis?

Answer 20

A common disease which occurs in post menopausal women
Reduction in oestrogen disrupts bone remodelling
Reduction in bone mineral density

Question 21

Why would a stress fracture occur?

Answer 21

When the remodelling process cannot keep up with the damage

Most common in metatarsals and tibia

Question 22

How would a stress fracture be most common?

Answer 22

Change in training type
Sudden increase in training intensity
Change in equipment