bone pathology - infective

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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bone pathology - infective

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