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| − | ===Fracture classification===
| + | #REDIRECT[[Fractures]] |
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| − | *'''Traumatic''' - normal bone broken by excessive force
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| − | *'''Pathologic''' - abnormal bone broken by minimal or no trauma
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| − | **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
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| − | *'''Compound''' - overlying skin and soft tissue are perforated
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| − | *'''Comminuted''' - bone is shattered at fracture site
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| − | *'''Compresses''' - the ends of the fracture are impacted into each other
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| − | *'''Avulsed''' - due to pull of a ligament
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| − | *'''Transverse'''
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| − | *'''Spiral'''
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| − | ===Fracture repair===
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| − | [[Image:Recent healing fracture.jpg|right|thumb|100px|<small><center>Recent healing fracture (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Fracture
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| − | **Ruptured blood vessels -> haemorrhage and clot formation, some ischaemic necrosis
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| − | ***Dead marrow liquefies and is phagocytosed
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| − | ***Dead bone is removed by [[Bones - Anatomy & Physiology|osteoclasts]]
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| − | ****Continues long after bone has been united by callus
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| − | **[[Bones - Anatomy & Physiology|Periosteum]] tears, fragments displaced
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| − | *-> Haematoma formation, necrosis of any isolated fragments
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| − | *-> Mesenchymal cells proliferate in haematoma - [[Granulation Tissue|granulation tissue]]
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| − | **Invading cells: endothelial, fibroblasts, osteoprogenitor
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| − | *-> Loose collagenous tissue (primary callus)
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| − | *-> Mesenchymal cells differentiate to [[Bones - Anatomy & Physiology|osteoblasts]] and chondroblasts
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| − | *-> [[Bones - Anatomy & Physiology|Woven bone]] (secondary callus)
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| − | **External callus - from periosteum
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| − | ***Periosteal growth eventually bridges the gap between the fracture ends
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| − | ***Blood supply is outstripped
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| − | ***Cartilage is produced instead of osteoid
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| − | ***Blood vessels invade cartilage -> [[Bone & Cartilage Development - Anatomy & Physiology|endochondral ossification]]
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| − | ***Osteoid becomes ossified
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| − | **Internal callus - from endosteum
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| − | ***Rarely forms cartilage
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| − | ***May occlude the medullary cavity
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| − | **Osteoid remodelled by [[Bones - Anatomy & Physiology|osteoclastic resorption]]
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| − | *-> 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
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| − | *Lack of adequate blood supply (leads to hypoxia)
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| − | **Leads to excess cartilage in callus
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| − | **Healing can still occur since this can turn to bone
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| − | *Excess movement
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| − | **Leads to excess fibrous tissue in callus adn formation of false joint (below)
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| − | *Presence of necrotic bone (may form a sequestrum)
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| − | *Poor alignment
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| − | *[[Bones Inflammatory - Pathology|Bacterial infection]]
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| − | ===Pseudoarthrosis===
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| − | *False joint
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| − | *Non-osseus union
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| − | *From infection, poor imobilisation, avascularity, extensive tearing damage to periosteum
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| − | *Composed of fibrous tissue
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| − | *If mobility continues -> hyaline cartilage forms -> neoarthrosis (formation of new joint)
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| − | *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
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| − | *Fibrovascular tissue and osteogenic cells invade -> deposit new bone
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| − | *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
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| − | *In 2-3 year olds
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| − | *Excessive compressive stress on dorsal cortex of third metacarpal -> microfractures
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| − | *Hyperaemic overlying periosteum - -> new bone production to cover the lesion
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| − | <big>Also see [[Healing and Repair - Pathology#Repair in the Bones|'''Repair in the Bones - Pathology''']]</big>
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| − | [[Category:Musculoskeletal System - Pathology]] | |