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DEN303 - IHD > Bones and Joints > Flashcards

Bones and Joints Flashcards

1
Q

Normal bone

Constituents and purpose of each

A 
Outer solid cortical bone - mechanical
Inner trabecular (spongy) bone - mechanical and hosts bone marrow for metabolic fx
Outer surface - periosteum 
Inner space (medulla) contains fat or haemopoietic marrow

65% inorganic (mineralised) - mainly calcium salts
35% organic

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2
Q

Functions

A

Mineral homeostasis - bone acts as vessel for calcium

Houses haemopoietic system i.e bone marrow

Mechanical - differentiates us from vertebrates - not a static scaffold - constantly remodelled

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3
Q

Bone diseases - consists of

A

Infection
Tumours
Trauma/degeneration
Specific derangements of bone’s particular specialised processes and function

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4
Q

Specific bone diseases

A

Infections
Tumour
Trauma

Disorders of matrix formation
Disorders of mineralisation
Disorders of bone turnover

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5
Q

Bone remodelling cycle

A 
Activation of osteoclasts
Resorption of bone
Death of osteoclasts
Formation of new matrix by osteoblasts
Mineralisation of new matrix
Quiescence = BASIC MULTICELLULAR UNIT
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6
Q

Two cell types run bone

Key to maintaining bone strength

What can go wrong - what happens in osteoporosis

A

Osteoblasts and clasts are coupled
Coupling lost in osteoporosis –> loss of bone volume
Calcium physiology

Defective matrix/ matrix formation
Mineralisation problems
Turnover problems

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7
Q

Bone matrix formation diseases - rare

A 
Mutations in collagen 
- type 1 --> Osteogenesis imperfecta, affects ears, eyes, skin and teeth 
- greater risk of fractures 
Other abnormalities 
- mucopolysaccharidoses 
--> morquio syndrome 
--> Hurler syndrome
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8
Q

Cartilage matrix formation disorders - uncommon

Bone usually grows longitudinally at the growth plates

A

Achondroplasia

  • autosomal dominant
  • failure of cartilage maturation at the growth plate
  • mutation of fibroblast growth receptor 3
  • -> continually activated negative regulator of growth
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9
Q

Diseases of mineralisation - uncommon

Vit D is activated in kidney

A

Osteomalacia/Rickets

  • deficiency in Vit D or calcium
  • dietary or metabolic
  • failure to mineralise to cartilage overgrowth –> failure of longitudinal growth

If deficient, skeleton is not mineralised properly

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10
Q

Bone remodelling problems

A
  1. osteoporosis - Increased porosity of bone due to a reduction in bone mass
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11
Q

Osteoporosis

Risk factors

A

Increased porosity of bone due to a reduction in bone mass

  1. Age
  2. Hormonal influences - loss of sex steroids
  3. Lifestyle
  4. Activity
  5. Genetics
  6. Nutrition
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12
Q

Osteoporosis - mechanism

Which bone is lost first

A

Uncoupling of bone resorption and formation

  • too much resorption
  • too little formation
  • loss of trabecular bone initially
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13
Q

Osteoporosis - complications and treatment e.g??

A
  • fragility fractures (vertebrae, femoral neck, distal radius)
  • kyphosis (Dowager’s hump)
  • Loss of height
  • Inhibit bone resorption with BISPHOSPHONATES
  • increase bone formation with experimental treatment e.g parathyroid hormone
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14
Q

Disorders of abnormal turnover

Which disease?

Common in

A

PAGET’S disease aka OSTEITIS DEFORMANS
Excess turnover
Progressive deformity of individual bones

3 phases :
Osteolytic ->
Mixed ->
Osteosclerotic

Pain, chalkstick fracture,
Tumours : benign / or Sarcoma - 5% of patients with severe disease

North of England, NZ and Australia

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15
Q

General pathology affecting bone

A

Infection

Tumours

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16
Q

Bone infections e.g

What is it
Contraction

A

Osteomyelitis

  • complication of compound fractures
  • blood borne
  • necrosis of bone fragments
  • new bone formation
  • sinuses drain pus
17
Q

Tumours

A

Most tumours are metastases

  • lung
  • breast
  • prostate
  • thyroid
  • kidney
  • myeloma
18
Q

Primary bone tumours are either (nature)

A

Chondrogenic

Osteogenic

Usually benign
Malignant ones potentially rapidly fatal

19
Q

Chondrogenic tumours

A

60% benign - osteochondroma (many sites) and chondroma (mainly fingers)

40% malignant - chondrosarcoma (femur, pelvis and skull base)

20
Q

Osteogenic tumour

B and M types and common sites

A

13% benign
Osteoid osteoma - any site small tumours in cortex
Osteoblastoma - larger lesions e.g spinal

87% malignant
Osteosarcoma - femur

21
Q

Malignant bone tumours

A

Osteosarcoma
Chondrosarcoma
Ewing’s sarcoma
Undifferentiated sarcoma

22
Q

Osteosarcoma occurence

Chondrosarcoma

Ewing’s sarcoma

Undifferentiated sarcoma

A

15-30 y/o metaphyses e.g knee - chemosensitive

Middle age-elderly e.g pelvis, ribs, proximal long bones

<20 y/o Diaphyses

Middle aged-elderly mainly metaphyses

23
Q

Other joint diseases

A 
Infections
Crystal arthropathies
Chronic inflammatory arthritis
Osteoarthritis
Tumours – these are rare so don’t worry about them
24
Q

Joint infections

Septic arthritis

A

Insect bites, small wounds near joints
Very painful
IV antibiotics and drainage

25
Q

Joint infections

Crystal arthropathies

False presentations?

A

Gout - urate crystals precipitated in joints due to raised serum uric acid

Pseudogout

  • calcium pyrophosphate crystals
  • age related
26
Q

Chronic inflammatory arthritis

Other types

A

Generally autoimmune
Rheumatoid is commonest form

Ankylosing spondylitis and psoriatic arthritis and systemic lupus

27
Q

Rheumatoid arthritis

A

Systematic inflammatory disorder
Auto-antibodies to immunoglobulins
- rheumatoid factor
- more of a marker of a loss immune self tolerance

28
Q

What does R.A involve

In the joint

What is pannus

A

Inflammation of synovium
Lymphocytyes / plasma cells / macrophages
‘Pannus’ formation (inflamed fibrous tissue) - tumour like layer of fibrous tissue which grows over surface and destroys cartilage

Multiple joints

Extra articular features

Joint destruction caused by a cascade of cytokines driven by tumour necrosis factor-alpha

Anti-TNF-alpha antibodies are an effective treatment of severe rheumatoid disease

29
Q

Osteoarthritis/arthrosis

Rare?
What kind of disease?

Mechanism

A

Common
Degenerative disease

Erosion of cartilage

  • Minimal inflammation
  • Leads to changes in underlying bone

Mechanical

Predisposed by previous joint damage e.g. inflammation, intra-articular fracture

30
Q

Features of osteoarthritis

Why are osteophytes dangerous in spine

A
  • Fragmentation of cartilage
    (‘fibrillation’)
  • Osteophyte formation - outgrowths of bone on outside of joints - can trap nerve roots in spine

Cysts in underlying bone

Represents a final common pathway of joint failure

The only effective treatment is arthoplasty (surgical removal of the joint and replacement with a prosthesis)

DEN303 - IHD (58 decks)

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