Limits of the musculoskeletal system 1 - Lecture 3 Flashcards
What function does bone perform?
Mechanical - Structural & Protective
Physiological - Ca2+ regulation & blood cell production in bone marrow
What gives bones flexibility?
Matrix (type 1 collagen)
What makes bones strong?
Mineral content - hydroxyapatite
complex salt of calcium and phosphate
What structures does a long bone have?
Long bone has a diaphysis and two epiphyses
What are the two different types of bone?
Cortical (compact)
Cancellous (spongey)
What percentage of bone is cortical, or cancellous?
Cortical (80%)
Cancellous (20%)
How can we measure bone strain?
In vivo
What is the process of longitudinal growth?
- Endochondral ossification
- Primary ossification centre
- Secondary ossification centre
- Ceases when secondary growth plates fuse at adulthood
What is the process of circumferential growth?
- Diameter increases throughout life span
2. Rapid prior to adulthood then very slow
What happens when a bone breaks?
- Repair
- Haematoma leads to clot formation
- Cartilage fills gap which is ossified to form new woven bone
- Callous then remodels over time
What do osteoclasts and osteoblasts do?
osteoclasts - bone resorption
osteoblasts - bone formation
What is bone atrophy?
Inactivity - bone mass and mineral content decrease due to osteoclast activity
What is bone hypertrophy?
Increase in activity where bone mass and mineral content can increase
How can we predict when a bone will break?
It is difficult to predict the stress at which a bone will break at
Why is it difficult to predict when a bone will break?
Individual differences
Bone constantly changing
Dependant on loading rate
Why does a bone fracture occur?
Excessive forces
Weak material
Cumulative damage from repetitive loading
What are the physics of X-rays?
Electro-magnetic spectrum
0.1-10nm wavelength
Form of ionising radiation
Bones absorb the protons of the x-ray as they are electron dense
What are the characteristics of plain radiography (2D)?
Spatial resolution (2D)
Simple, available, affordable
High reproducibility
Low radiation does
What are the characteristics of computerised tomography (3D)?
Very high resolution of bone
Fast - 20s for whole body
Moderately expensive
High radiation does
What is osteoporosis?
A common disease which occurs in post menopausal women
Reduction in oestrogen disrupts bone remodelling
Reduction in bone mineral density
Why would a stress fracture occur?
When the remodelling process cannot keep up with the damage
Most common in metatarsals and tibia
How would a stress fracture be most common?
Change in training type
Sudden increase in training intensity
Change in equipment
