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8/17/2019 Bone Pathology - Infective
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Introduction
Normal Anatomy & Histology
BONE PATHOLOGY
Dr. Sura !ain" #.D
Asst. Pro$%ssor
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Normal anatomy
Parts o$ a long on%s' • diaphysis (shaft),
• epiphysis (ends of bone, partially covered byarticular cartilage),
• metaphysis (junction of diaphysis and epiphysis,most common site of primary bone tumors)
(ross s%ction'
• periosteum
• cortex (composed of cortical or compact bone)
• medullary space (composed of cancellous orspongy bone)
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Normal )istology
Lam%llar Bon% * #atur%+ layered bone with concentric parallel lamellae;
gradually replaces woven bone
Cortical - 8!of s"eleton
- 8-#! calci$ed - relatively low metabolic activity
Cancellous or trabecular or spongy
- %! of s"eleton
- &-%! calci$ed - relatively high metabolic activity
,o-%n on% *immatur% on%+
irregular non-minerali'ed bone
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Types of Bone Cells
• Osteocytes : Mature bone cells• present in bone matrix
• Osteoblasts : Bone-forming cells• located on surface of bone, involved in
minerali'ation eceptors for *+, vit .estrogen
• Osteoclasts : Bone-destroying cells
• Break down bone matrix for remodeling & release
of calcium M!"C, derivate of /0- precursorcell from bone marrow
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#tages in t$e %ealing of a Bone
racture
Bone remodeling is a process in w$ic$ bot$
osteoblasts and osteoclasts participate
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BONE PATHOLOGY (lassication
• In$%ctious dis%as%s
*Ost%omy%litis+• #%taolic dis%as%s
• Tumours• Art)ritis
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In$%cti-% / Ost%omy%litis
BONE PATHOLOGY
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1n2ammation of bone (osteo) .marrow (myelo)
34+5306571+14
Bact%rial ost%omy%litis'Acut% su00urati-% ost%omy%litis
Ha%matog%nous 1 non/)a%matog%nous
()ronic ost%omy%litis'non/s0%cic 1 s0%cic *TB & Sy0)ilis+
Non/ act%rial ost%omy%litis'2iral ost%omy%litis 1 Sarcoidosis 1 3adiation
ost%omy%litis
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PYOGENI( OSTEO#YELITIS'
is almost always caused by bacteria
• 4tapylococcus aureus (8-#!)
• 5coli, lebsiella and *seudomonas in patientswith /9 tract infections : 1 drug abusers
• 0ixed bacterial infections can be seen in thesetting of direct spread during surgery or open <
• 1n neonatal period, H. infuenzae and group =streptococci are fre>uent pathogens
• 4almonella infections - common in sic"le celldisease patients
• 1n &! of the cases no organisms can be isolated
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Sit%s o$ in-ol-%m%nt'
1n2uenced by the vascular
circulation, which varies with age• N%onat%s? the metaphyseal vessels
penetrate the growth plate, resulting
in fre>uent infection of themetaphysis, epiphysis or both
• ()ildr%n' metaphyseal
• Adults' epiphyses and subchondral
regions
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Pat)og%n%sis
@ ematogenous spread
% 5xtension from a contiguous siteA irect implantation
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Pat)og%n%sis'
• 3nce locali'ed in bone, the bacteriaproliferate and induce an acutein2ammatory reaction
• 4pread of bacteria and in2ammation leads
to suppuration• *us within bone reaches periosteum . forms
a subperiosteal abscess in %-A days
• Bithin medullary cavity it obstructs the
periosteal . endosteal blood supply causingbone necrosis in approx days
• ead pieces of bone are "nown as these>uestrum
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• upture of the periosteumDsoft tissue abscessformationDdraining sinuses
• Efter @st wee", chronic in2ammatory cells arenumerous with release of cyto"ines anddeposition of new bone at the periphery
• +his new bone formation from the strippedsurface of periosteum is "nown as the1nvolucrum
• 1n infants epiphyseal infection may spread tothe adjacent joint and causes septic orsuppurative arthritis; may lead to permanent
disability
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S%4u%nc% o$ c)ang%s as $ollo5s '
+ransient bacteraemia
Focus of acute in2ammation in
metaphysis
Gecrosis of bone forming45H954+90
eactive new bone formationI1G379C90
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#icrosco0y
In6ammation o$ on%
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Acut%ost%omy%litis
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(linical (ours%'
• Fever ,chills, malaise . throbbing pain
over the aJected region
Diagnosis'
• 4ign:symptoms• K-ray
' lytic focus of bone destruction
surrounded by 'one of sclerosis• =lood : *us culture
• biopsy
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(om0lications?
• *athologic fracture
• Chronic suppurative osteomyelitis? includingse>uestrum formation and s"in sinus formation
• 7ocal 4pread of infection? Erthritis : myositis :
neuritis• 4ystemic 4pread of infection - toxaemia,
septicaemia or 5ndocarditis
• amage to the growth plate causing subse>uentgrowth deformity
• 4econdary amyloidosis
• 4>uamous cell carcinoma in longstanding cases
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• Brodi%s asc%ss' ' 7ocalised form of acute osteomyelitis
' small intraosseus abscess thatfre>uently involves the cortex and iswalled oJ reactive bone
• Scl%rosing ost%omy%litis o$ Garr%
' +ypically develops in the jaw
' a:w extensive new bone formation thatobscures much of the underlyingosseous structure.
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T7BE3(7LO7S OSTEO#YELITIS
outes of entry?
• 9sually blood borne and originate
from a focus of active visceraldisease
• irect extension (eg from a
pulmonary focus into a rib)• spread via draining lymphatics
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• spine (L! of cases, especially thoracic .lumbar vertebrae) followed by the "neesand hips are the most common sites
• *ott disease - involvement of spine
• 1nfection brea"s through the intervertebraldiscs . extends into the soft tissuesforming abscesses
• *ain, Fever, weight loss• +uberculous arthritis
• 1n patients with E14 fre>uently multifocal
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*ott disease
• presentation of extra-pulmonary tuberculosis thataJects the spine
• lower thoracic and upper lumbar vertebrae aremost often aJected
• +ypically present with pain on motion, locali'edtenderness, low-grade fevers, chills, and weight
loss
• *araspinal mass, sometimes a:w numbness,paraesthesia or muscle wea"ness of the legs
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Pott8s Dis%as%
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iagnosis
• =lood tests I 54
• +uberculin s"in test
•adiographs of the spine• =one scan
• C+ of the spine
• =one biopsy• 01
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Complications
• ertebral collapse resulting in"yphosis : 4coliosis
• neurologic de$cits secondary to4pinal cord or nerve compression(*ott paraplegia)
• 4inus tract formation
• tuberculous arthritis
• psoas abscess
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