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| + | ===Fracture classification=== |
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| + | *'''Traumatic''' - normal bone broken by excessive force |
| + | *'''Pathologic''' - abnormal bone broken by minimal or no trauma |
| + | **E.g. due to [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]], [[Bones Hyperplastic and Neoplastic - Pathology#Neoplastic|bone neoplasia]] |
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| + | *'''Closed''' - overlying skin and soft tissue is intact |
| + | *'''Compound''' - overlying skin and soft tissue are perforated |
| + | *'''Comminuted''' - bone is shattered at fracture site |
| + | *'''Compresses''' - the ends of the fracture are impacted into each other |
| + | *'''Avulsed''' - due to pull of a ligament |
| + | *'''Transverse''' |
| + | *'''Spiral''' |
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| + | ===Fracture repair=== |
| + | [[Image:Recent healing fracture.jpg|right|thumb|100px|<small><center>Recent healing fracture (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]] |
| + | *Fracture |
| + | **Ruptured blood vessels -> haemorrhage and clot formation, some ischaemic necrosis |
| + | ***Dead marrow liquefies and is phagocytosed |
| + | ***Dead bone is removed by [[Bones - Anatomy & Physiology|osteoclasts]] |
| + | ****Continues long after bone has been united by callus |
| + | **[[Bones - Anatomy & Physiology|Periosteum]] tears, fragments displaced |
| + | *-> Haematoma formation, necrosis of any isolated fragments |
| + | *-> Mesenchymal cells proliferate in haematoma - [[Granulation Tissue|granulation tissue]] |
| + | **Invading cells: endothelial, fibroblasts, osteoprogenitor |
| + | *-> Loose collagenous tissue (primary callus) |
| + | *-> Mesenchymal cells differentiate to [[Bones - Anatomy & Physiology|osteoblasts]] and chondroblasts |
| + | *-> [[Bones - Anatomy & Physiology|Woven bone]] (secondary callus) |
| + | **External callus - from periosteum |
| + | ***Periosteal growth eventually bridges the gap between the fracture ends |
| + | ***Blood supply is outstripped |
| + | ***Cartilage is produced instead of osteoid |
| + | ***Blood vessels invade cartilage -> [[Bone & Cartilage Development - Anatomy & Physiology|endochondral ossification]] |
| + | ***Osteoid becomes ossified |
| + | **Internal callus - from endosteum |
| + | ***Rarely forms cartilage |
| + | ***May occlude the medullary cavity |
| + | **Osteoid remodelled by [[Bones - Anatomy & Physiology|osteoclastic resorption]] |
| + | *-> Mature [[Bones - Anatomy & Physiology|lamellar bone]] |
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| + | *Early reactive fracture repair may be mistaken for [[Bones Hyperplastic and Neoplastic - Pathology#Osteosarcoma (OSA)|osteosarcoma]] on biopsy |
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| + | ===Complications of fracture repair=== |
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| + | *Malnutrition |
| + | *Lack of adequate blood supply (leads to hypoxia) |
| + | **Leads to excess cartilage in callus |
| + | **Healing can still occur since this can turn to bone |
| + | *Excess movement |
| + | **Leads to excess fibrous tissue in callus adn formation of false joint (below) |
| + | *Presence of necrotic bone (may form a sequestrum) |
| + | *Poor alignment |
| + | *[[Bones Inflammatory - Pathology|Bacterial infection]] |
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| + | ===Pseudoarthrosis=== |
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| + | *False joint |
| + | *Non-osseus union |
| + | *From infection, poor imobilisation, avascularity, extensive tearing damage to periosteum |
| + | *Composed of fibrous tissue |
| + | *If mobility continues -> hyaline cartilage forms -> neoarthrosis (formation of new joint) |
| + | *In [[Bones Metabolic - Pathology#Secondary hyperparathyroidism|''Osteodystrophia fibrosa'']], [[Bones Metabolic - Pathology#Osteomalacia|osteomalacia]] and [[Bones Metabolic - Pathology#Rickets|rickets]] - callus forms but does not mineralise |
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| + | ===Head and neck of femur fracture=== |
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| + | *Vascularisation from joint capsule -> if complete separation -> bone and marrow undergo avascular necrosis |
| + | *Fibrovascular tissue and osteogenic cells invade -> deposit new bone |
| + | *Resorption of articular cartilage and subchondral bone -> '''osteoarthropathy''' commonly develops |
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| + | ===Sore shins=== |
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| + | *Dorsal metacarpal disease of racehorses |
| + | *In 2-3 year olds |
| + | *Excessive compressive stress on dorsal cortex of third metacarpal -> microfractures |
| + | *Hyperaemic overlying periosteum - -> new bone production to cover the lesion |
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| ===Causes of Fracture=== | | ===Causes of Fracture=== |
| * The causes of fracture fit into two distinct categories: | | * The causes of fracture fit into two distinct categories: |