Bone growth and fracture healing Flashcards
What does the basic long bone anatomy consist of?
- Diaphysis (shaft)
- Metaphysis (flare at end of shaft)
- Epiphysis (on joint side of physis)
- Physis (plate)
- Medullary canal
What are the features of cortical bone?
- Diaphysis (shaft)
- Resists bending/torsion
- Laid down circumferentially
- Less biologically active
What are the features of cancellous bone?
- Metaphysis
- Resists/absorbs compression
- Site of longitudinal growth
- Very biologically active
What is a fracture?
Break in structural continuity of bone. Can be crack/split/break/crumpling
Why do bones fail?
- High energy transfer in normal bones
- Repetive stress in normal bones (stress fracture)
- Low energy transfer in abnormal bones (osteoporosis/osteomalacia/metastatic tumour/other bone disorders)
In fracture repair there are 4 stages. What are these?
- Inflammation
- Soft callus
- Hard callus
- Bone remodelling
Discuss Stage 1 of bone healing
- Begins immediately after fracture. Haematoma and fibrin clot. Involves lots of cell types in inflammation mentioned in slides
- Angiogenesis also involved
Stage one affected by:
>NSAIDs
>Loss haematoma (open fracture/surgery)
>Extensive tissue damage (poor blood supply)
Name some platelet concentrates which may help in bone regeneration
- Platelet-derived growth factor
- Transforming growth factor-beta
- Insulin like growth factor
- Vascular endothelial growth factor
Discuss stage 2 of bone healing
- Begins when pain and swelling subside lasting until bony fragments are united by cartilage/fibrous tissue
- Angulation can still occur. Continued inc. in vascularity
Can be affected by
- Demineralised bone matrix (cartilage)
- Bone graft/substitutes (bone)
Discuss stage 3 of bone healing
- Conversion of cartilage to woven bone (endochondral/membranous bone formation)
- Increasing rigidity
Discuss stage 4 of bone healing
- Conversion of woven bone to lamellar bone
- Medullary canal is reconstituted
Why does delayed union (failure to heal in expected time) happen?
- High energy injury
- Distraction
- Instability
- Infection
- Steroids
- Immunosuppressants
- Smoking
- Warfarin
- NSAIDs
- Ciprofloxacin
Discuss non union (failure to heal)
- Excessive osteoclasis (instability)
- Abundant callus formation
- Pain and tenderness
- Persistent fracture line
- Sclerosis
Alternative management of delayed union?
- Different fixation
- Dynamisation
- Bone grafting
