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Acute Osteomyelitis

Acute osteomyelitis
is infection
of bone.
Osteo = bone
Myelo = bone marrow
Itis = inflammation

Anatomy Review - FYI

Etiology
• • Staphylococcus aureus is the most common organism in all age groups
• • Salmonella is commonest organism in sickle cell anemia

patients

• • Pseudomonas aeurogenosa is commonest organism in Drug
abusers
• • Animal bite – Pasteurella multiocida
• • Human bite – Eikenella corrodens
• • Diabetic ulcer and Fight bites – Anaerobes
• • Immunocompromised (HIV) – Staphylococcus aureus
• • Post -traumatic osteomyelitis/Post -surgical osteomyelitis –
• S. aureus
• • Open injuries – Staphylococcus
• • Foot injuries – Pseudomonas

Pathology

• • Most common mode of
infection is
hematogenous
• • In children metaphysis
of long bone (usually
lower end femur > upper
end tibia) is earliest and
most commonly involved
site
• • In adults commonest
site of infection is
thoracolumbar spine

Starts in Metaphysis Because of:

• • Defective phagocytosis in metaphysis (Inherently
depleted Reticuloendothelial System)
• • Rich blood supply
• • Hair pin bend of metaphyseal vessels (leads
to vascular stasis)
• • Metaphyseal hemorrhage due to repeated
trauma (acts as culture media)

Pathophysiology

• i. Metaphyseal Abscess is formed initially and it
spreads Subperiosteally in children
because periosteum is loosely
attached to bone in children and
in adults pus spreads to
Medullary cavity involving the
Diaphysis.
• ii. Infection rarely crosses growth plate
because it has no blood
vessels and periosteum is firmly
attached to the plate at this
level.
• iii. Joint involvement can take place
if metaphysisis intracapsular (e.g. hip,
shoulder, elbow).
• iv. The pathological sequence is
inflammation, suppuration, necrosis,
reactive new bone formation and
ultimately resolution and
healing. (Same sequence is seen in HIV
positive patient also).

Clinical Feature

• • Fever (> 38.3 °C),
• swelling of the limb,
• pain,
• systemic symptoms (Toxic child)
• Note: Systemic signs are absent in
immunocompromised and neonates.
• • Absent movements of a limb after
ruling out trauma in pediatric
population is osteomyelitis till proved
otherwise.

Investigation

• increased levels of Total leucocyte counts,
• ESR and CRP.
• X -rays in < 24 hours is normal
• • 1 st change on X -rays is loss of soft tissue planes.
• • 1 st bony change is Periosteal reaction seen on day 7 – 10
(2 nd week or day 10 ) Solid Periosteal Reaction.

• • Later features of

bone destruction
appear.

• MRI is considered

the best radiological
investigation for
bone infections because
it can identify
marrow edema (seen
within 6 hours)
and soft tissue
extension in bone
infections.

• • Tc 99 -MDP, Ga -67 - citrate or

Indium 111 labelled leucocytes
(Best out of 3 ) are the
2 nd best radiological investigation.

Bone scans, both anterior (A) and lateral (B), showing the

accumulation of radioactive tracer at the right ankle
(arrow). This focal accumulation is characteristic of
osteomyelitis.

• • Gold standard is always tissue diagnosis (from the lesion)

hence growth of organism on culture media is the best
investigation for infections.
• • Blood Culture is positive in 60 % cases.

“Criteria for Diagnosis of Osteomyelitis”

• Definite : Pathogen isolated from bone or
adjacent soft tissue or there is
histologic evidence of osteomyelitis. –
Probable : Blood culture positive +
Clinical (absent movements of
the limb) + Radiological diagnosis. –
• Likely: Typical clinical findings and
definite radiographic evidence of
OM + Response to antibiotics.

Treatment

• Osteomyelitis < 24 Hours
• • X -ray – No Loss of Soft tissue planes
• • MRI – Marrow changes in metaphysis
• • Bone Scan – Increased activity
• • Treatment is started with, IV antibiotics
until condition begins to improve or
CRP values return to normal,
usually for 2 weeks. There after
antibiotics are given orally for another 4
weeks.

• The CRP increases within 6 hours of

infection, reaches a peak elevation 2 days after
infection, and returns to normal within 1
week after adequate treatment has begun. So CRP
is better indicator of infection as compared
to ESR.
• • Peak elevation of the ESR occurs at 3 – 5 days
after infection and returns to normal
approximately 3 weeks after treatment is
begun. • If antibiotics are given early (< 24
hours), drainage is often unnecessary.

• • Change of antibiotics or Surgery is

considered if no improvement occurs within
48 hours of antibiotics.
• Osteomyelitis > 24 Hours
• • X -ray – Loss of Soft tissue planes
• • MRI – Marrow changes in metaphysis
• • Bone Scan – Increased activity

Treatment

• Evacuation and Exploration of pus drainage is
followed by antibiotics course of antibiotics is
same as Osteomyelitis < 24 Hours, i.e. for 2 weeks
I/V and 4 weeks oral. The antibiotics that
cover staphylococcus aureus are preferred and
ones that have both Oral and injectable preparation
are preferred, e.g. Amoxy -Clavulanic

SUBACUTE OSTEOMYELITIS (Brodie’s Abscess)

• Seen in Immuno -Competent Host!
• • It is long standing localized pyogenic
abscess in the bone (long standing
because of strong defence
mechanism of body).
• • It usually involves long bones
(metaphysis or diaphysis) e.g. Upper
end tibia.

• • Classical Brodie’s

abscess looks like a
small walled off
(Sclerotic margins)
cavity in bone
with little or no
periosteal reaction.

Treatment

• Trial of injectable antibiotics is given if it fails
curettage of the cavity is carried out.

CHRONIC OSTEOMYELITIS

• “USUALLY A SEQUELAE OF
INADEQUATELY TREATED ACUTE
OSTEOMYELITIS”
• Sequestrum : Avascular piece of
bone surrounded by
granulation tissue, it is
pathognomic of
chronic osteomyelitis.
• • It acts as nidus of
infection and is most
common cause of non -
healing sinus in chronic
osteomyelitis.

• Involucrum is dense sclerotic

new bone surrounding the
sequestrum formed from
deep layers of stripped
periosteum (usually obvious
by the end of 2 nd
week). At least 2 / 3 rd
surface of sequestrum
should be surrounded by
involucrum before carrying
out sequestrectomy (Removal
of Sequestrum).

• If infection persists, pus

and tiny sequestrated
spicules of bone may
continue to discharge
through perforations in
involucrum (cloacae ).

• TREATMENT

• 1 . Remove the sequestrum from Cavity or
Saucerization of cavity (Leaving the Cavity
open).
• 2 . Identify the organism and control the infection
(most important step).
• 3 . Fill the gap in Cavity with Bone graft/Bone
cement (Poly Methyl MethAcrylate ).

• 4 . Provide a good soft tissue coverage — Local closure or

by Myoplasty or Composite graft of Bone, Muscle and skin.
Instillation -suction technique for the treatment of
chronic bone infection is described in which
infected bone is first exposed and all sequestra
removed. Two drainage tubes are inserted. One tube
is connected to a drip containing antibiotic
solution and the second to a continuous
suction pump. Closed continuous steady flow
instillation -suction is established to do lavage
of cavity.

Complications of Chronic Osteomyelitis:

• i. Acute excacerbation
• ii. Growth abnormalities due to
damage to adjacent growth
plate
• iii. Pathological fracture
• iv. Joint stiffness
• v. Sinus tract malignancy (very rare):
Squamous cell carcinoma
• vi. Amyloidosis


رفعت المحاضرة من قبل: Ahmed monther Aljial
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