- Cells • (osteoblasts, lining cells, osteocytes, osteoclasts) – Matrix (mostly type 1 collagen) – gives bone flexibility

Bone Flashcards by Aaron Keshwala

What tissues make up the musculo-skeletal system?

Bone
Cartilage
Muscles and tendons
Ligaments

How well did you know this?

Not at all

Perfectly

Bone characteristics

Mechanical

Physiological

How well did you know this?

Not at all

Perfectly

Mechanical structures

Structural

Protective

How well did you know this?

Not at all

Perfectly

Physiological Structures

CA2+ Regulation

Blood Cell production in bone marrow

How well did you know this?

Not at all

Perfectly

Components of bone

organic (35%) and inorganic (65%)

How well did you know this?

Not at all

Perfectly

Organic

Cells
• (osteoblasts, lining cells, osteocytes, osteoclasts)
– Matrix (mostly type 1 collagen) – gives bone flexibility

How well did you know this?

Not at all

Perfectly

Inorganic

– Mineral content – hydroxyapatite – makes bone strong

– Hydroxyapatite = complex salt of calcium and phosphate

How well did you know this?

Not at all

Perfectly

Locations on a bone

Diaphysis

Two Epiphyses

How well did you know this?

Not at all

Perfectly

Types of Bone

Cortical/Compact

Cancellous/ Trabecular

How well did you know this?

Not at all

Perfectly

Characteristics of cancellous/trabecular

Lattice of fine bone plates
– Epiphyses of long bones, vertebral bodies and flat
bones
– Intercommunicating spaces in mesh filled with bone
marrow
– Reduces skeletal mass without compromising strength

How well did you know this?

Not at all

Perfectly

Physical properties of bone

Material

Structural

How well did you know this?

Not at all

Perfectly

Material properties

– Properties of the material itself independent of
specimen
– i.e. stress at which a sample of cortical bone breaks under
compression
• Density of bone
– Cortical bone 1700-2000 kg/m3
– Lumbar vertebra 600-1000 kg/m3
• Compressive strength of bone
– Femur (cortical) 131-224 MPa
– Wood (oak) 40-80 MPa
– Limestone 80-180 MPa
– Steel 370 MPa

How well did you know this?

Not at all

Perfectly

Structural

– Properties of a specific specimen
i.e. breaking force for tibia
– Much more difficult to define

How well did you know this?

Not at all

Perfectly

Bone Skeletal Processes

Longitudinal Growth
Circumferential Growth
Bone Remodelling

How well did you know this?

Not at all

Perfectly

Longitudinal Growth

– Endochondral ossification
– Primary ossification centre
– Secondary Ossification centre (Epiphyseal plates)
– Ceases when secondary growth plates fuse at adulthood (~18yrs)

How well did you know this?

Not at all

Perfectly

Circumferential Growth

– Diameter increases throughout lifespan

– Rapid prior to adulthood then very slow

Bone Remodelling

– Bone mass is maintained, increased and decreased
– Continuous repair of micro-damage
– Ensure that bone is fit for purpose
– Functional adaptation
Wolff’s Law (1882) - Structural and
Material properties of bone are
determined by forces acting on it

What type of feedback informs the bone of microdamage

Sensory

What is the bones response to the sensory feedback

2 types of cells

osteoblasts- bone formations
osteoclasts- resorption

in a coupled process

Definition of Functional Adaptation

Bone adapts to the load placed upon it

What is bone atrophy

if the load is reduced, reduction in bone mass.

decrease in activity
predominance in osteoclast activity

What is bone hypertrophy

if the load is increased, increase in bone mass

increase in activity
trabeculae alignment can change to adapt new load

Why can a bone fracture?

if the stress on the bone exceed the strength of the material.
e.g. excessive force, weak material, cumulative damage due to repetitive loading

What is the formula for stress?

Force/Cross sectional area

What can cause excessive stress?

Large external force | Inappropriate dimensions

Types of fractures

``` complete/incomplete transverse spiral comminuted avulsed impacted greenstick compression ```

What 2 types of xray can investigate fractures?

Plain Xrays | Computerised tomography

What are the characteristics of a plain xray?

- 2D imaging - High spatial resolution - Maneuvering of patient - Simple, available and affordable - Low radiation dose

What are the characteristics of CT scan

- 3D imaging - Very high resolution - Fast-20s for whole body scan - moderately expensive - High radition dose (200x that of a chest xray)

Bone Repair

- Haematoma leads to clot formation - cartilage fills gap which is ossified to form new woven bone (callous) - callous then remodels over time

What is osteoporosis?

A common bone disease in post menopausal women - reduction in oestrogen levels disrupts bone remodelling - reduction in trabecular bone - reduction in bone mineral density --> increased risk of fracture

how would you monitor Bone mineral density?

Dual energy X-ray Absorptiometry

What are stress fractures?

When the remodelling process cannot keep up with damage - dependent on the magnitude of the load and number of cycles - common in metatarsals or tibia

What way can you investigate stress fractures?

Bone scan (nuclear medicine) - Patient injected with radioactive tracking marker (technetium 99 bound to diphosphate) - Functional (identifies areas of remodelling) - Low spatial resolution/ high sensitivity - high dosage and moderately expensive

Name 4 extrinsic risk factors of stress fractures

1) Specific sports 2) Change in training 3) Sudden increase in load 4) Change in equipment

Name 3 intrinsic risk factors of stress fractures

1) small bone geometry 2) Relative energy deficiency syndrome 3) High load rate due to technique

Name and describe bone injuries?

- Osgood Schlatter Disease - Sever's Disease Repetitive tension on changing growth plates