Bone Disorders Flashcards
what’s bone made of?
non-cellular mineralised matrix
- type 1 collagen = osteoid
- calcium phosphate
- protein and growth factors
- osteoblasts
- osteocytes
- osteoclasts
why is mineralisation important?
to make the osteoid hard, makes bone stiff and strong
what is the function of bone?
- physical integrity and support
- protection for organs
- attachment for muscles and tendons
what are the 3 main cellular elements of bone and their functions?
osteoblasts
- secrete collagen/osteoids
- mineralisation
osteocytes
- inactive osteoblasts
- trapped inside bone
osteoclasts
- stem from macrophages
- resorb bone
what is the difference between woven and lamellar bone?
woven bone = immature bone
- random osteoid
- rapid turnover
- remodelled to lamellar bone
lamellar bone
- parallel sheets
- normal healthy adult bone
- compact or trabecular/cancellous
which is stronger, woven or lamellar bone?
lamellar bone
- due to regular arrangement
the 2 types of bone
compact/cortical
trabecular/cancellous
describe cortical bone
hard outer shell
organised and regular
haversion system
surrounds cancellous bone
describe cancellous bone
spongy
marrow
describe the bone remodelling cycle
- activation
- hormones or damage activate osteoblast
- cytokines secreted
- osteoclasts sticks to surface of bone - resorption
- osteoclasts secrete substance and resorb bone
= pits on surface
- apoptosis or migration of clasts - reversal
- monocytes clear debris - formation
- osteoblasts secrete matrix
- mineralisation
- some blast incorporate as osteocytes
what is osteoarthritis?
give aetiology.
progressive erosion of articular cartilage
aetiology
- primary - just happens
- secondary - pre-existing joint damage, metabolic disease, systemic disease
what is the pathogenesis of osteoarthritis?
- erosion of articular cartilage
- bone exposed
- abnormal growth = osteophytes
- cysts in the bone
- narrow joint space
how does osteoarthritis clinically feature?
symptoms
- pain
- limited function
signs
- bony enlargements
- crepitus - crunch
- instability
how is osteoarthritis investigated and treated?
blood test
x-ray
physical
medications
surgery - joint replacement
what is rheumatoid arthritis
autoimmune condition with persistent inflammation
describe the pathogenesis of rheumatoid arthritis.
- citrullination of arginine to citrulline
- protein modification, becomes foreign
- autoimmune response
- T cells and cytokines
- macrophages
- fibroblasts
- synovium proliferation and inflammation
- synovitis
how is rheumatoid arthritis investigated and managed?
blood tests
x-rays
no cure
medications - DMARDS
= disease modifying anti-rheumatic drugs
what is padgets disease?
bone turnover is disordered
- more woven bone
describe the pathogenesis of padgets disease.
- hot phase
- osteoclast activity - mixed phase
- osteoblast and osteoclast activity - cold phase
- no activity
how does padgets disease clinically present?
bone deformations
high fracture risk
bone pain
hypercementosis - cotton wool appearance
nerve compression - hydrocephalus
how is pagets disease treated? also used for osteoporosis
bisphosphonates
- inhibit clasts resporption
= slow bone loss
what is the biggest worry of using bisphosphonates?
the chance of developing BRONJ
- hinders bone healing
what is osteomyelitis?
give aetiology.
inflammation of bone marrow
aetiology
- from infection
- staphlococcus aureus
how does osteomyelitis clinically present?
fever
bone pain
tenderness
treatment for osteomyelitis?
immobilise
antibiotics
what is osteonecrosis?
- aetiology.
infarction of bone marrow
aetiology = vascular insufficiency
- alcohol
- steroids
- fractures
osteonecrosis is asceptic, wym?
not due to infection
describe the pathogenesis of osteonecrosis.
how does osteonecrosis clinically present?
give management
joint pain
collapse of articular bone
- grafts
- joint replacement
what is osteomalacia AKA rickets?
give aetiology.
defective mineralisation of bone osteoid
rickets = kids
osteomalacia = adults
aetiology - anything that interferes with bone mineralisation
- vitamin D deficiency - blood calcium drops
- renal failure
dental complications of rickets
hypophosphataemia
- thin enamel
- globular dentine
- dental abscess more common
hypoplasia
missing teeth
osteogenesis imperfecta
- definition
- aetiology
brittle bone disease
- type 1 collagen has gene mutation
describe the clinical features of osteogenesis imperfecta
increased fractures
small discoloured teeth
achrondoplasia
- definition
- aetiology
frank from always sunny has achondroplasia
woven bone remodelled to lamellar bone
= endochondral ossification
- short limbs
intramembral ossification
- in the maxilla, skill and mandible
aetiology
- FGFR-3 mutation
- impairs cartilage growth
define fracture
a loss of bone integrity and loss of the mechanical strength
how are fractures classified?
simple
comminuted - fragments
compound - out of the skin
displaced - ends not aligned
describe the phases of fracture healing
- inflammatory phase
- haematoma forms - blood
- lump of haemopoietic cells
- macrophages, neutrophils, platelets activate cytokines
- fibroblasts at site
- granulation tissue
- neovascularisation
- fibrosis = callus formation - a scar within the site - reparative phase
- primary callus
- endochondral ossification converts soft cartilage to woven bone - remodelling phase
- woven bone into cortical bone
