Difference between revisions of "Bones Fractures - Pathology"

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#REDIRECT[[Fractures]]
 
 
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|backcolour =CDE472
 
|linkpage =Musculoskeletal System - Pathology
 
|linktext =Musculoskeletal System
 
|maplink = Musculoskeletal System (Content Map) - Pathology
 
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|sublink1=Bones Degenerative - Pathology
 
|subtext1=BONES DEGENERATIVE
 
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<br>
 
===Fracture classification===
 
 
 
*'''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]]
 
 
 
 
 
*'''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'''
 
 
 
===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 - normal#Normal structure|osteoclasts]]
 
****Continues long after bone has been united by callus
 
**[[Bones - normal#Periosteum and blood supply|Periosteum]] tears, fragments displaced
 
*-> Haematoma formation, necrosis of any isolated fragments
 
*-> Mesenchymal cells proliferate in haematoma - [[Chronic Inflammation - Pathology#Granulation tissue|granulation tissue]]
 
**Invading cells: endothelial, fibroblasts, osteoprogenitor
 
*-> Loose collagenous tissue (primary callus)
 
*-> Mesenchymal cells differentiate to [[Bones - normal#Normal structure|osteoblasts]] and chondroblasts
 
*-> [[Bones - normal#Bone organisation|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 -> [[Bones - normal#Bone development|endochondral ossification]]
 
***Osteoid becomes ossified
 
**Internal callus - from endosteum
 
***Rarely forms cartilage
 
***May occlude the medullary cavity
 
**Osteoid remodelled by [[Bones - normal#Normal structure|osteoclastic resorption]]
 
*-> Mature [[Bones - normal#Bone organisation|lamellar bone]]
 
 
 
 
 
*Early reactive fracture repair may be mistaken for [[Bones Hyperplastic and Neoplastic - Pathology#Osteosarcoma (OSA)|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
 
*[[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===
 
 
 
*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
 
 
 
 
 
<big>Also see [[Healing and Repair - Pathology#Repair in the Bones|'''Repair in the Bones - Pathology''']]</big>
 

Latest revision as of 18:34, 27 February 2011

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