Fractures through the ages Flashcards
Describe bone growth in utero
Steady increase in bone mass
After birth -> bone mass decreases
Describe normal bone turnover and self-healing
Healthy bone is in constant remodelling
Microdamage:
Osteoclasts find worn down cells and remove them (secretion of enzymes for resorption)
Pre-osteoblasts formed
Mature osteoblasts build new osteoid tissue which is then mineralised
How does menopause affect bone remodelling?
Oestrogen responsible for osteoclast apoptosis
Menopause = no more oestrogen
No apoptosis = excess bone resorption
How do bisphosphonates work?
Treatment for osteoporosis
Inhibit osteoclasts
Bind tightly to bone and released when bone is resorbed
Side effect: Due to no remodelling bone does not repair so increased risk of fractures
How does Denusemab work?
Monoclonal antibody against RANKL
Reduced osteoclast activity
No bone repair -> risk of fracture
Risk factors of fractures in later life?
Lack of exercise/loading
Genetic
Calcium/Vit D intake
What are 2 types of fracture healing process?
Direct healing = surgery + bone fixation using plates and screws
Indirect/natural healing = Callus formation
Describe the 4 healing stages of bone
- Haematoma + inflammation (first week)
- Soft Callus phase (week 1-4)
- Hard Callus formation (week 4-14)
- Remodelling (rest of time)
Describe stage 1
Granulation tissue forms
Progenitor cells invade
Describe stage 2
Chondroblasts/fibroblasts differentiate and form:
Collagen + fibrous tissue
Proteoglycans (to prevent minieralisation)
Chondrocytes (release Ca)
Describe stage 3
Soft callus invaded by blood vessels
Chondroclasts break down calcified callus
Replaced by osteoid (Type 1 Collagen)
Osteoid calcifies forming WOVEN bone
Describe stage 4
Woven -> Lamellar bone
How is remodelling correlated to age?
Faster in children/adolescence than older people
What are the types of fracture?
Spiral = twisting Butterfly = bending Linear Transverse/Oblique = direct compression Greenstick = not whole width of bone
