BIOL122 Lecture Notes - Lecture 8: Ossification, Spasm, Medullary Cavity
Fractures:
‘A broken bone occurs when a force exerted against a bone is stronger than the
bone can bear. This disturbs the structure and strength of the bone, and leads to
pain, loss of function and sometimes bleeding and injury around the site.’ (Better
Health Channel, 2014)
Causes of fractures:
• Fall from a height
• Repetitive force
• Low bone mineral density
• Immobility
• Low estrogen levels
• Endocrine disorders
• Previous fractures
• Medications
Fracture healing:
4 stages:
• Haematoma formation:
- Blood vessels lacerated
- Bone cells die
- Blood collects
- Clot forms
- Phagocytic clean up
- Osteoblasts and osteoclasts proliferate
• Fibrocartilaginous callus formation
- New capillaries form
- Fibroblasts lay collagen fibres
- Chondroblasts lay cartilage
- Osteoblasts lay osteoid
• Ossification
- Calcium and mineral salts added to soft callus
- Hard callus formed
- Continues for 3 months
• Remodelling:
- Osteoblasts continue to strengthen structure
- Osteoclasts remove excess bone and reshape
- New medullary cavity formed
- Can take several years
Factors affecting healing:
• Infection
• Poor blood supply
• Poor nutrition
• Movement
• Drug therapy
• Old age
Fracture types:
• Complete fracture- bone breaks into two or more parts
• Incomplete fracture- bone cracks, but does not break all the way through
• Closed (simple) fracture- the broken bone has not pierced the skin
• Open (compound) fracture- the broken bone juts out through the skin
Document Summary
A broken bone occurs when a force exerted against a bone is stronger than the bone can bear. This disturbs the structure and strength of the bone, and leads to pain, loss of function and sometimes bleeding and injury around the site. " (better. Causes of fractures: fall from a height, repetitive force, low bone mineral density. Immobility: low estrogen levels, endocrine disorders, previous fractures, medications. Osteoblasts and osteoclasts proliferate: fibrocartilaginous callus formation. Calcium and mineral salts added to soft callus. Infection: poor blood supply, poor nutrition, movement, drug therapy, old age. Fracture types: complete fracture- bone breaks into two or more parts. Incomplete fracture- bone cracks, but does not break all the way through: closed (simple) fracture- the broken bone has not pierced the skin, open (compound) fracture- the broken bone juts out through the skin. Clinical syndrome characterised by progressive loss of articular cartilage, remodelling and sclerosis of subchondral bone and formation of marginal osteophytes: rheumatoid arthritis:
