osteomyelitis Flashcards

1
Q

What is osteomyelitis?

A

Infection of bone characterised by PROGRESSIVE INFLAMMATORY DESTRUCTION and APPOSITION OF NEW BONE

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2
Q

What are the risk factors for developing OM?

A
Recent trauma /surgery
Immunocompromised patient
iv drug use
Poor vascular supply
systemic conditions- DM / SICKLE CELL
Periphery neuropathy
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3
Q

Describe the pathophysiology of OM?

A

mechanism of spread;
HAEMATOGENOUS- originated or transported in blood, aetiology 20% of OM, vertebra most common
CONTIGUOUS- FOCUS: assoc previous surgery, trauma, wounds, poor vascularity
can be bacterial (most common)
DIRECT-INOCULATION- penetrating injuries

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4
Q

What is the most common organism in adults?

A

staph aureus

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5
Q

What does the bacteria form?

A

Biofilm that covers necrotic bone and hard wear
made of extracellular polymeric substance or exopolysaccharide
antibiotics have difficulty penetrating the film

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6
Q

What organisms are common in newborns?

A

S aureus, Enterobacter species, Group A and B Streprococcus

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7
Q

What organisms are common in children 4mo-4y?

A

S. aureus, Group A strep, Kingella Kingae, enterobacter species

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8
Q

What organisms are common in children 4y - adolescents?

A

S aureus 80%, group a strep, H influenza, enterobacter

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9
Q

What organisms are common in adults?

A

S aureus, occasionally enterobacter, streptococcus

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10
Q

What organisms are common in pt with sickle cell?

A

S aureus, but salmonella is PATHOGNOMIC

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11
Q

What is the prognosis for osteomyelitis?

A

Despite surgical debridement and long term antibiotics- RECURRENCE RATE OF CHRONIC OM IN ADULTS = 30%

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12
Q

Who described the classification of OM?

A

Cierny

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13
Q

What does the Cierny classification describe?

A

The anatomical involvement

The host

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14
Q

Can you describe the Cierny classification

A
Antaomical location 
stage 1- Medullary
stage 2 - Superficial 
stage 3- localised
stage 4- Diffuse

Host
A- normal
B- COMPROMISED
C-TREATMENT WORSE TO PT THEN INFECTION

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15
Q

Do you know any other classifications?

A

Acute- within 2 weeks
subacute- within 1 month to several months
chronic- after several months

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16
Q

What do pt with OM present with?

A

pain

fever- more common in acute om

17
Q

What is found on physical exam in a pt with om?

A
ERYTHERMA
TENDERNESS
OEDEMA
LIMP- pain preventing weight bearing
DRAINAGE SINUS TRACT- in chronic om
18
Q

What imaging is useful to aid dx?

A

Orthogonal plain X-rays-
LYTIC surrounded by SCLEROSIS
MINIMC neoplasm
BONE loss must be 30-40% b4 evident on X-ray
sequestrum- necrotic bone acts as nidus for infection
invlurum- formation of new bone area of bone necrosis

CT- useful for surgical planning
MRI- soft tissue evaluation
bone scan - sensitivity to mri, but specificity poor

19
Q

What lab studies are helpful?

A

WBC- elevated in acute om
normal in chronic om
ESR- elevated both acute and chronic om
Decrease in ESR - favourable prognostic sign
CRP- Decrease faster than ESR in successfully tx pt

microbiology-
blood cultures - used to guide therapy
sinus tract cultures- guide antibiotics
BIOPSY- GOLD STANDARD to guide antibiotics

20
Q

What are the goals of tx of om?

A

Success dependent on
Pt factors- immunocompetent pt and nutrition status
injury factors- severity by segmental bone loss
infection location- metaphyseal infections better to heal than mid-diaphyseal infections
other factors
residual foreign material + ischaemic and necrotic tissues
inappropriate antibiotic coverage
lack of patient cooperation/desire

21
Q

What are the tx options for OM?

A
1)NON OP
   IV or Oral antibiotic therapy for 4-6 wks
   rate of reoccurrence 30%
2) HYPERBARIC O2
   used as adjunct in refractory OM

3) OPERATIVE
IRRIGATION,DEBRIDEMENT + ORGANISM SPECIFIC ANTIBIOTICS
when combined with post anti tx is often successful

22
Q

Can you describe the overall surgical technique?

A

antibiotic- tailored to specific organism- preferable after bone biopsy
chronic suppressive antibiotics may be useful in patients who are immunocompromised or whom surgery is not feasible

surgery- 
Debridement of all devitalised and necrotic tissue
removal of any non essential hard wear 
Goal is to replace dead bone and scar tissue with vascularised tissue for which
vascularised bone grafts
local tissue flaps /free flaps
antibiotic impregnated acrylic beads
vacuum assisted closure
Stabilise bone by EXT FIX