Difference between revisions of "Bones Inflammatory - Pathology"

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#REDIRECT[[:Category:Bones - Inflammatory Pathology]]
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===Bone infections in general===
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*'''Caused by''':
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**Bacteria most commonly (e.g. [[Mandibular Osteomyelitis|lumpy jaw]] in cattle due to ''[[Actinomyces bovis]]'')
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**Viruses, fungi and protozoa less commonly
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*'''Routes of infection''':
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**“Inoculated” at time of [[Bones Fractures - Pathology|fracture]]
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**Extension from other infected sites ([[Paranasal Sinuses Inflammatory - Pathology|sinuses]], middle ear, [[Joints Inflammatory - Pathology|joints]])
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**Haematogenous (young farm animals)
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*'''Gross lesions'''
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**Suppurative exudate (in bacterial infection), necrosis, bone proliferation, pathological fractures
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**Dead bone portions may be separated from blood supply and form bone sequestra
 +
 
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*'''Consequences'''
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**Extension to adjacent bone
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**Haematogenous spread to other bones and soft tissue
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**Pathologic fractures
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**Sinus tracts to exterior
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*'''Osteitis''' = inflammation of bone
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*'''Periostitis''' = inflammation of periosteum, usually develops from infection in adjacent tissues
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*'''Osteomyelitis''' = inflammation of medullary cavity
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===Osteitis===
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*E.g.: [[Fusobacterium necrophorum|''Fusobacterium necrophorum'']] in the foot, [[Respiratory Bacterial Infections - Pathology#Necrotic laryngitis|calf diphteria]], bite wounds, extension from paranasal sinuses, compound fractures, extensions from infections in the joints, [[Alveolar Periostitis|periodontal disease]], [[Respiratory Bacterial Infections - Pathology#Atrophic Rhinitis|Atrophic rhinitis]]
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===Osteomyelitis===
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[[Image:Cattle localised osteomyelitis with sequestrum.jpg|right|thumb|100px|<small><center>Localised osteomyelitis plus sequestrum (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*Mainly due to haematogenous spread in young animals
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*Often as an extension from [[Joints Inflammatory - Pathology#Arthritis|suppurative arthritis]]
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*Usually isolated: ''[[Actinomyces pyogenes]]'', [[Salmonella|''Salmonella'']], [[Escherichia coli|''E.coli'']], [[Klebsiella|''Klebsiella'']], [[:Category:Streptococcus species|''Streptococci'']]
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*Metaphyses and epiphyses mostly affected
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*Most infections are exacerbated by host response
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*Pathogenesis:
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**Prostaglandin and cytokines stimulate [[Bones - normal#Normal structure|osteoclastic]] bone resorption
 +
**Blood vessel occlusion and tissue necrosis -> lack of removal of agent and cartilage -> cartilage thickening + persistance of infection
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*Affected area may be surrounded by fibrous inflammatory tissue
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*Metaphyseal abscesses may develop
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*Sequestra may also develop -> surrounded by [[Granulation Tissue|granulation tissue]]
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**Isolated from osteoclastic resorption
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**May persist for long time
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**Obstruct repair
 +
 
 +
 
 +
*'''Vertebral osteomyelitis'''
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**Lesions may affect the spinal cord
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**Usually due to ''[[Actinomyces pyogenes]]''
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**Suppurative inflammation may cause fracture of vertebral body -> dorsal displacement -> damage to spinal cord
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**May form encapsulated abscess protruding into spinal canal -> spinal cord compression
 +
 
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*'''''Actinomycosis'''''
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**= '''Lumpy jaw''' in cattle
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**Caused by ''[[Actinomyces bovis]]''
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***Gram positive, branching, filamentous
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***Obligatory parasite of mucous membranes of [[Oropharynx - Anatomy & Physiology|oropharynx]]
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***Surface tissue is usually injured for infection to occur
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***[[Mandibular Osteomyelitis|Osteomyelitis of mandible]] -> destruction of bone -> replacement by fibrous tissue with pyogranulomatous nodules cotaining 'club colonies' of bacteria
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***Suppurative osteomyelitis
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***Fistulous tracts may discharge onto skin and into [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]
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***Excessive periosteal bone formation
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***Greatly enlarged mandible
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===Periostitis===
 +
 
 +
*Chronic periostitis - pockets of exudate and irregular new bone fomation
 +
 
 +
===Panosteitis===
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[[Image:Panosteitis.jpg|right|thumb|100px|<small><center>Panosteitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*Typically young large or giant breeds
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*75% of cases in German shepherd dogs, 5-12 months old
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*Clinical signs:
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**Shifting lameness
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**Often eosinophilia in peripheral blood
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*Usually self-limiting in one to several months
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*Grossly:
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**Foreleg long bone '''diaphyses''' affected (multiple bones in 50% of cases)
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**Increased bone formation in the medullary cavity and often in the periosteum
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*Contast with [[Bones Hyperplastic and Neoplastic - Pathology#Hypertrophic osteodystrophy|'''hypertrophic osteodystrophy''']]
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[[Category:Musculoskeletal System - Pathology]]

Revision as of 12:35, 14 February 2011

Bone infections in general

  • Routes of infection:
    • “Inoculated” at time of fracture
    • Extension from other infected sites (sinuses, middle ear, joints)
    • Haematogenous (young farm animals)
  • Gross lesions
    • Suppurative exudate (in bacterial infection), necrosis, bone proliferation, pathological fractures
    • Dead bone portions may be separated from blood supply and form bone sequestra
  • Consequences
    • Extension to adjacent bone
    • Haematogenous spread to other bones and soft tissue
    • Pathologic fractures
    • Sinus tracts to exterior
  • Osteitis = inflammation of bone
  • Periostitis = inflammation of periosteum, usually develops from infection in adjacent tissues
  • Osteomyelitis = inflammation of medullary cavity

Osteitis

Osteomyelitis

Localised osteomyelitis plus sequestrum (Image sourced from Bristol Biomed Image Archive with permission)
  • Mainly due to haematogenous spread in young animals
  • Often as an extension from suppurative arthritis
  • Usually isolated: Actinomyces pyogenes, Salmonella, E.coli, Klebsiella, Streptococci
  • Metaphyses and epiphyses mostly affected
  • Most infections are exacerbated by host response
  • Pathogenesis:
    • Prostaglandin and cytokines stimulate osteoclastic bone resorption
    • Blood vessel occlusion and tissue necrosis -> lack of removal of agent and cartilage -> cartilage thickening + persistance of infection
  • Affected area may be surrounded by fibrous inflammatory tissue
  • Metaphyseal abscesses may develop
  • Sequestra may also develop -> surrounded by granulation tissue
    • Isolated from osteoclastic resorption
    • May persist for long time
    • Obstruct repair


  • Vertebral osteomyelitis
    • Lesions may affect the spinal cord
    • Usually due to Actinomyces pyogenes
    • Suppurative inflammation may cause fracture of vertebral body -> dorsal displacement -> damage to spinal cord
    • May form encapsulated abscess protruding into spinal canal -> spinal cord compression
  • Actinomycosis
    • = Lumpy jaw in cattle
    • Caused by Actinomyces bovis
      • Gram positive, branching, filamentous
      • Obligatory parasite of mucous membranes of oropharynx
      • Surface tissue is usually injured for infection to occur
      • Osteomyelitis of mandible -> destruction of bone -> replacement by fibrous tissue with pyogranulomatous nodules cotaining 'club colonies' of bacteria
      • Suppurative osteomyelitis
      • Fistulous tracts may discharge onto skin and into oral cavity
      • Excessive periosteal bone formation
      • Greatly enlarged mandible

Periostitis

  • Chronic periostitis - pockets of exudate and irregular new bone fomation

Panosteitis

Panosteitis (Image sourced from Bristol Biomed Image Archive with permission)
  • Typically young large or giant breeds
  • 75% of cases in German shepherd dogs, 5-12 months old
  • Clinical signs:
    • Shifting lameness
    • Often eosinophilia in peripheral blood
  • Usually self-limiting in one to several months
  • Grossly:
    • Foreleg long bone diaphyses affected (multiple bones in 50% of cases)
    • Increased bone formation in the medullary cavity and often in the periosteum
  • Contast with hypertrophic osteodystrophy
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