Difference between revisions of "Bones Fractures - Pathology"

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#REDIRECT[[Fractures]]
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{{review}}
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{{toplink
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|backcolour =CDE472
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|linkpage =Musculoskeletal System - Pathology
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|linktext =Musculoskeletal System
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|maplink = Musculoskeletal System (Content Map) - Pathology
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|pagetype =Pathology
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|sublink1=Bones Degenerative - Pathology
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|subtext1=BONES DEGENERATIVE
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<br>
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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
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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 shatteed 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 - normal#Normal structure|osteoclasts]]
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****Continues long after bone has been united by callus
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**[[Bones - normal#Periosteum and blood supply|Periosteum]] tears, fragments displaced
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*-> Haematoma formation, necrosis of any isolated fragments
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*-> Mesenchymal cells proliferate in haematoma - [[Chronic Inflammation - Pathology#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 - normal#Normal structure|osteoblasts]] and chondroblasts
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*-> [[Bones - normal#Bone organisation|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
 +
***Blood supply is outstripped
 +
***Cartilage is produced instead of osteoid
 +
***Blood vessels invade cartilage -> [[Bones - normal#Bone development|endochondral ossification]]
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***Osteoid becomes ossified
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**Internal callus - from endosteum
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***Rarely forms cartilage
 +
***May occlude the medullary cavity
 +
**Osteoid remodelled by [[Bones - normal#Normal structure|osteoclastic resorption]]
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*-> Mature [[Bones - normal#Bone organisation|lamellar bone]]
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*Early reactive fracture repair may be mistaken for [[Bones Hyperplastic and Neoplastic - Pathology#Osteosarcoma (OSA)|osteosarcoma]] on biopsy
 +
 
 +
===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]]
 +
 
 +
===Pseudoarthrosis===
 +
 
 +
*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
 +
 
 +
===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
 +
 
 +
===Sore shins===
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*Dorsal metacarpal disease of racehorses
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*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
 +
 
 +
 
 +
<big>Also see [[Healing and Repair - Pathology#Repair in the Bones|'''Repair in the Bones - Pathology''']]</big>

Revision as of 21:15, 13 August 2009

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()Map MUSCULOSKELETAL SYSTEM (Map)
BONES DEGENERATIVE



Fracture classification

  • Traumatic - normal bone broken by excessive force
  • Pathologic - abnormal bone broken by minimal or no trauma


  • Closed - overlying skin and soft tissue is intact
  • Compound - overlying skin and soft tissue are perforated
  • Comminuted - bone is shatteed at fracture site
  • Compresses - the ends of the fracture are impacted into each other
  • Avulsed - due to pull of a ligament
  • Transverse
  • Spiral

Fracture repair

Recent healing fracture (Image sourced from Bristol Biomed Image Archive with permission)
  • Fracture
    • Ruptured blood vessels -> haemorrhage and clot formation, some ischaemic necrosis
      • Dead marrow liquefies and is phagocytosed
      • Dead bone is removed by osteoclasts
        • Continues long after bone has been united by callus
    • Periosteum tears, fragments displaced
  • -> Haematoma formation, necrosis of any isolated fragments
  • -> Mesenchymal cells proliferate in haematoma - granulation tissue
    • Invading cells: endothelial, fibroblasts, osteoprogenitor
  • -> Loose collagenous tissue (primary callus)
  • -> Mesenchymal cells differentiate to osteoblasts and chondroblasts
  • -> 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 -> endochondral ossification
      • Osteoid becomes ossified
    • Internal callus - from endosteum
      • Rarely forms cartilage
      • May occlude the medullary cavity
    • Osteoid remodelled by osteoclastic resorption
  • -> Mature lamellar bone


  • Early reactive fracture repair may be mistaken for osteosarcoma on biopsy

Complications of fracture repair

  • 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
  • Bacterial infection

Pseudoarthrosis

  • 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 Osteodystrophia fibrosa, osteomalacia and rickets - callus forms but does not mineralise

Head and neck of femur fracture

  • 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

Sore shins

  • 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


Also see Repair in the Bones - Pathology

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