Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

11. Orthopaedics > Fracture Healing and Avascular Necrosis > Flashcards

Fracture Healing and Avascular Necrosis Flashcards

1
Q

Describe the blood supply to the bone.

A

Endosteal (inner 2/3)

Periosteal (outer 1/3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Young’s modulus?

What is it like in:

a) Cortical bone?
b) Trabecular bone?

A

Measure of a bone’s resistance to torsion/bending

In cortical bone: high
In trabecular bone: low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 types of bone healing?

A

Indirect/secondary - physiological

Direct/primary/artificial - via medical intervention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 main stages in secondary/indirect fracture healing?

A

Inflammation
Repair
Remodelling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the process of inflammation during secondary/indirect fracture healing. (3)

A
  1. Haematoma formation (6-8 hours after injury)
    a. Blood from broken vessels in the bone forms a clot
  2. Swelling occurs at fracture site
  3. Inflammation occurs around dead bone cells at the fracture site
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the processes of repair in secondary/indirect fracture healing. (5)

A
  1. Fibrocartilage (soft) callous formation
    a. New capillaries grow and organise the haematoma into granulation tissue (pro-callous)
    b. Fibroblasts and osteoblasts invade the pro-callus
    c. This leads to collagen production (soft callous)
    d. Chondrocytes produce fibrocartilage
  2. Bony (hard) callous formation
    a. Osteoblasts produce woven bone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the process of remodelling during secondary/indirect fracture healing. (1)

A
  1. Osteoclasts remodel woven bone into compact and trabecular bone
    a. This does NOT leave a scar
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How long does each stage of secondary/indirect fracture healing take?

A

Inflammation: 6-8 hours

Soft callous: 3 weeks

Hard callous: 3-4 months

Remodelling: years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the process of direct/primary/artificial bone healing. (2)

What is the main difference to secondary bone healing?

A
  1. Bones are realigned/compressed by medical intervention
  2. Direct formation of bone occurs via osteoclast resorption and osteoblast formation
    a. This forms cutting cones across the fracture sites
    b. Therefore new bone is laid down directly across the fracture

MAIN DIFFERENCE: no callous formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

List 8 factors which might inhibit normal fracture healing.

A

Patient factors, e.g.

  • Malnutrition
  • Peripheral vascular disease
  • Hypothyroidism
  • Smoking
  • Alcohol

Drugs, e.g.

  • NSAIDs
  • Steroids
  • Bisphosphonates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define avascular necrosis.

A

Bone infarction, i.e. tissue death due to loss of blood supply to the bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

List 4 causes of avascular necrosis.

A 
Sickle cell anaemia (NOTE: rigid RBCs block blood vessels, preventing blood supply)
Vascular damage (e.g. due to fractures)
Increased intraosseous pressure
Mechanical stress
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

List 4 types of fracture which commonly have compromised blood supply.

A

Proximal pole of scaphoid
Talar neck fractures
Intracapsular hip fractures
Surgical neck of humerus fractures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the clinical features of avascular necrosis. (4)

Describe specific features found in:

a) Surgical neck of femur fractures (4)
b) Lunate fracture (3)

A

Asymptomatic
Rest pain
Night pain
Bilateral pain

SURGICAL NECK OF FEMUR:
Groin pain
Limp
Tenderness around joint
Restricted motion (esp. internal rotation, abduction)

LUNATE FRACTURE:
Weak grip strength
Wrist stiffness
Pain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Kienbock’s disease?

A

Avascular necrosis resulting from a fracture of the lunate bone (wrist)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

List the 3 main complications of AVN.

A

Subchondral erosion
Joint surface collapse
End stage arthritis

17
Q

Describe the pathophysiology of avascular necrosis. (5)

A
  1. Bone marrow lesions formed, involving:
    a. Oedema
    b. Haemorrhage
    c. Fibrilloreticulosis
    d. Hypocellularity
  2. Necrosis of medullary bone forms empty lacunae
    a. Surrounding adipocytes undergo necrosis and release fatty acids
    b. FAs bind to calcium to form insoluble calcium salts
  3. Fracture healing occurs via creeping substitution
  4. If creeping substitution not fast enough, there are too many empty lacunae
    a. Structural weakness
    b. Bone collapse
  5. This causes osteoarthritis
    a. Subchondral bone collapse forms incongruent joint surfaces
    b. This causes osteoarthritis
18
Q

List 4 major risk factors for avascular necrosis.

A

History of trauma (esp. dislocation)
Steroid use/Cushing’s syndrome
Alcohol abuse
Sickle cell anaemia/haemoglobinopathies

19
Q

Which 2 investigations would you do for AVN?

A

X-ray

MRI

20
Q

What features of AVN can be seen on an x-ray? (6)

A 
No change
Mild density change
Sclerosis
Cysts
Crescent sign
Osteoarthritis signs
21
Q

What features of AVN can be seen on MRI? (2)

A

Oedema in bone

Inflammation

22
Q

How would you treat AVN? (4)

Consider how treatment differs before/after joint collapse.

A

Reduce risk of AVN, e.g.
-Patient education

Before joint collapse:

  • Reperfusion
  • Core decompression (with/without bone graft)

After joint collapse:
-Total hip arthroplasty

11. Orthopaedics (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions