osteomyelitis Flashcards
What is osteomyelitis?
Infection of bone characterised by PROGRESSIVE INFLAMMATORY DESTRUCTION and APPOSITION OF NEW BONE
What are the risk factors for developing OM?
Recent trauma /surgery Immunocompromised patient iv drug use Poor vascular supply systemic conditions- DM / SICKLE CELL Periphery neuropathy
Describe the pathophysiology of OM?
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
What is the most common organism in adults?
staph aureus
What does the bacteria form?
Biofilm that covers necrotic bone and hard wear
made of extracellular polymeric substance or exopolysaccharide
antibiotics have difficulty penetrating the film
What organisms are common in newborns?
S aureus, Enterobacter species, Group A and B Streprococcus
What organisms are common in children 4mo-4y?
S. aureus, Group A strep, Kingella Kingae, enterobacter species
What organisms are common in children 4y - adolescents?
S aureus 80%, group a strep, H influenza, enterobacter
What organisms are common in adults?
S aureus, occasionally enterobacter, streptococcus
What organisms are common in pt with sickle cell?
S aureus, but salmonella is PATHOGNOMIC
What is the prognosis for osteomyelitis?
Despite surgical debridement and long term antibiotics- RECURRENCE RATE OF CHRONIC OM IN ADULTS = 30%
Who described the classification of OM?
Cierny
What does the Cierny classification describe?
The anatomical involvement
The host
Can you describe the Cierny classification
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
Do you know any other classifications?
Acute- within 2 weeks
subacute- within 1 month to several months
chronic- after several months
What do pt with OM present with?
pain
fever- more common in acute om
What is found on physical exam in a pt with om?
ERYTHERMA TENDERNESS OEDEMA LIMP- pain preventing weight bearing DRAINAGE SINUS TRACT- in chronic om
What imaging is useful to aid dx?
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
What lab studies are helpful?
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
What are the goals of tx of om?
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
What are the tx options for OM?
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
Can you describe the overall surgical technique?
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
