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Flashcards in Bone pathology Deck (99)
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1

What is the bone matrix composed of?

- Organic component: osteoid (90% type 1 collagen, 10% water, non-collagenous proteins, lipids, proteoglycas)
- Inorganic component of mineralised tissue (hydroxyapatite = hydroxylated calcium phosphate)

2

What is the consequence of the loss of inorganic matrix of the bone?

Flexible bones

3

What is the consequence of the loss of organic matrix of the bone?

Brittle bone

4

Describe the appearance and role of osteoclasts

Multinucleate, remove calcium from bone

5

Describe the histological appearance of osteocytes

Sit in lacunae, surrounded by matrix

6

Compare the ossification of long and flat bones

- Long: endochondral ossification at the metaphyseal growth plates (physes)
- Flat: intramembranous ossification, bone formed directly from he periosteum

7

Briefly describe the histological appearance of the physes of long bones

- Growth starts at hyaline cartilage (dark purple)
- Moves down into medullary cavity
- Then mineralises and ossifies, becomes pink
- Medullar cavity and spongy bone

8

What is the most common response of injured periosteum?

Formation of new bone e.g. around a fracture site

9

What is meant by brachygnathia?

Abnormally short jaw

10

What is meant by prognathia?

Abnormal projection of jaw

11

What is meant by kyphosis?

Dorsal curvature of the spinal column

12

What is meant by lordosis?

Ventral curvature of the spinal column

13

What is meant by scoliosis?

Lateral deviation of the spinal column

14

What is amelia?

Absence of limbs

15

What is hemimelia?

Absence of distal limb part

16

What is polydactyly and which animals are predisposed?

Presence of supranumerary digits, most common in cats, esp. Hemignway cats

17

What is adactyly?

Absence of a digit

18

What is syndactyly?

Fusion of digits

19

What causes chondrodysplasias?

Hereditary disorder of bone growth as a result of primary lesions in the growth cartilage

20

Which bones are affected by chondrodysplasias and why?

Long bones only, as only endochondral ossification is affected

21

Describe the appearance of an animal with chondrodysplasia

- Short legs and normal sized heads (dogs)
- Sheep usually normal length of legs but abnormal appearance of these (aka spider lamb syndrome)
- Also seen in cattle (bulldog cattle)

22

What causes osteopetrosis?

Defect in bone resorption by osteoclasts - plenty of osteoclasts but are not functioning correctly

23

Describe the consequences of osteopetrosis

- Bone mineral density increased, but bones are more fragile
- Not enough collagen

24

Which species are most commonly affected by osteopetrosis?

Cattle, sometimes horses

25

Give examples of congenital bone disorders

- Chondrodysplasia
- Osteopetrosis
- Osteogenesis imperfecta
- Congenital hyperostosis
- Osteochondromatosis

26

Give the main metabolic bone diseases

- Osteoporosis
- Rickets/osteomalacia
- Fibrous osteodystrophy

27

What are common causes of metabolic bone diseases?

Nutritional, toxic or endocrine

28

Describe the structure of bone affected by osteoporosis

Reduced bone mass, normal bone quality, well mineralised

29

List the main causes of osteoporosis

- Malnutrition
Physical inactivity
- Dietary calcium deficiency
- Advanced age
- Glucocorticoid excess (e.g. long term steroid administration)
- Oestrogen or androgen deficiency

30

What are the consequences of osteoporosis?

- Brittle bones
- Fractures