Acute Osteomylelitis
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Transcript of Acute Osteomylelitis
8/2/2019 Acute Osteomylelitis
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osteomyelitis
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• inflammation of the bone caused by an
infecting organism
• Approximately 20% of adult cases of
osteomyelitis are hematogenous, which is
more common in males for unknown reasons
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Spread of infection
• Haematogenous spread
• Direct spread
• Neighboring focus• Iatrogenic causes
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Clinical types:
Acute osteomyelitis
•
Chronic osteomyelitis• Primary subacute osteomyelitis
• Acute flare up of chronic osteomyelitis
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ACUTE HAEMATOGENOUS
OSTEOMYELITIS
• mainly a disease of children
• When adults are affected it is usually because
their resistance is lowered
• Trauma may determine the site of infection,
possibly by causing a small haematoma or
fluid collection in a bone
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Causal organisms
• Staphylococcus aureus (found in over 70% of
cases)
• other Gram-positive cocci, such as the Group A
beta-haemolytic streptococcus (Streptococcus
pyogenes) -chronic skin infections
• Group B streptococcus (especially in new-born
babies)• the alphahaemolytic diplococcus S. pneumoniae.
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• In children between 1 and 4 years of age the
Gram negative Haemophilus influenzae
Unusual organisms
Seen in drug addicts
Sickle cell anemia
•
Kingella kingae- mainly following upper respiratory infection in young children.
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• Other Gram-negative organisms :
1.Escherichia coli
2.Pseudomonas aeruginosa
3.Proteus mirabilis
4.Bacteroides fragilis
patients with sickle-cell disease are prone toinfection by Salmonella typhi.
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• The blood stream is invaded, perhaps from a
minor skin abrasion, treading on a sharp
object, an injection point, a boil, a septic tooth
• In the newborn –from an infected umbilical
cord
• In adults the source of infection may be a
urethral catheter, an indwelling arterial line or
a dirty needle and syringe
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Pathogenesis
• In children the infection usually starts in the
vascular metaphysis of a long bone
• Most often in the proximal tibia or in the distal
or proximal ends of the femur
• The growth plate (physis) is a barrier to the
terminal branches of the metaphyseal arteries
• Therefore, vascular flow must make a U-turn
at the physis
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• The resultant sluggish circulation, in combinationwith transient bacteremia, creates a setup forbacteria to gain a foothold in the metaphysis
•The relative vascular stasis and consequentlowered oxygen tension are believed to favourbacterial colonization
• The structure of the fine vessels in the
hypertrophic zone of the physis allows bacteriamore easily to pass through and adhere to type 1collagen in that area
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• In infants, in whom there are still anastomoses
between metaphyseal and epiphyseal blood
vessels, infection can also reach the epiphysis
• Adults with diabetes, who are prone to soft-
tissue infections of the foot, may develop
contiguous bone infection involving a variety
of organisms
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• Osteomyelitis that starts in the metaphysisspreads in two directions:
(1) down the medullary cavity
(2) through the relatively thin metaphysealcortex
• The cartilaginous growth plate is a barrier, andthe physis and adjacent epiphysis are typicallyspared
•
When the infectious process penetrates themetaphyseal cortex, pus elevates the looselyadherent periosteum, and a subperiosteal abscess may form
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• The periosteum, however, remains viable and
attempts to limit the spread of infection by
laying down new bone—a process that is
visible on radiographs after 7 to 14 days
• Periosteal new bone formation typically is
observed only in the metaphysis
• however, with a delay in diagnosis and a
relatively virulent organism, the periosteum of
the entire shaft may become elevated
• The resultant new bone formation encircling
the cortical shaft forms an involucrum.
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• Blood flow may be com promised to the
extent that segments of bone become
necrotic.
• An isolated segment of dead bone surrounded
by pus or scar tissue is called a sequestrum.
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• In certain locations, insertion of the joint
capsule occurs below (distal to) the physis
• At these sites, pus perforating the metaphyseal
cortex causes concomitant septic arthritis
•
This situation most commonly occurs with thespread of osteomyelitis from the proximal
femur into the hip joint, but it also may occur at
the proximal humerus, distal lateral tibia, and
proximal radius
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Clinical features
In children• Pain
• Malaise
• Fever• Toxemia(neglected case)
• Refuses to use one limb or to allow it to be
handled or even touched
• There may be a recent history of infection: a
septic toe, a boil, a sore throat or a discharge
from the ear
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signs
• Looks ill and feverish
• Tachycardia
• Raised body temperature
• The limb is held still and there is acute tendernessnear one of the larger joints
• Pseudoparalysis
•
Local redness,swelling, warmth and oedema arelater signs
• Lymphadenopathy
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In children under a year old
• Failure to thrive and is drowsy but irritable
• Suspicion should be aroused by a history of
birth difficulties, umbilical artery
catheterization or a site of infection
• Metaphyseal tenderness and resistance to
joint movement
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In adults
• The commonest site for haematogenousinfection is the thoracolumbar spine
• History of some urological procedure followed
by a mild fever and backache• Local tenderness is not very marked and it
may take weeks before x-ray signs appear
•
when they do appear the diagnosis may stillneed to be confirmed by fine-needleaspiration and bacteriological culture.
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invstigations
Diagnostic imaging
• X ray maybe normal during the 1st 10 days
•
Displacement of the fat planes signifies softtissue swelling but this could be hematoma or
soft tissue infection
• End of 2nd week, they may be faint extra-
cortical outline due to periosteal new bone
formation
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• Later the periosteal thickening become more
obvious and there is patchy rarefactiion of the
metaphysis
• An important late sign is the combination of
regional osteoporosis with a localized segment
of apparently increased density
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ultrasound
• To detect subperiosteal collection of fluid in
the early stage of osteomyelitis but it cannot
distinguish between a hematoma and pus
• Other findings on ultrasonography include
elevation and thickening of the periosteum
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Radioscintigraphy
• 99mTc-HDP reveals increased activity in both
the perfusion phase and the bone phase
• This is a highly sensitive investigation and
even in the very early stages, but it has
relatively low specificity and other
inflammation lesions can show similar
changes
• In doubtful cases, scanning with 67Ga- citrate
or 111In labelled leucocytes maybe more
revealing
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• MRI- extremely sensitive, even in the early
phase of bone infection.
• Can differentiate between soft tissue infection
and osteomyelitis
• Typical feature is a reduced intensity signal in
T1 – weighted images
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CT scan
• useful for guiding needle biopsies in closed
infections and for preoperative planning to
detect osseous abnormalities, foreign bodies,
or necrotic bone and soft tissue
• assist in the assessment of bony integrity,
cortical disruption, and soft-tissue
involvement
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Complete blood cell count
• A complete blood cell (CBC) count is useful for
evaluating leukocytosis and anemia
• Leukocytosis is common in acute osteomyelitis
before therapy
• The leukocyte count rarely exceeds 15,000/µL
acutely and is usually normal in chronic
osteomyelitis
• Erythrocyte sedimentation rate and C-reactive
protein levels are usually increased
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• Blood culture is positive in half of the cases of
proven infection
• Antistreptococcal antibody titres maybe raised
• Most useful in atypical cases
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Bone biopsy•
Open bone biopsy with histopathologicexamination and culture is the criterion
standard for the microbiologic diagnosis of
osteomyelitis
• When clinical suspicion is high with negative
blood cultures and needle biopsy, a repeat
needle biopsy or open biopsy should be
performed
• To obtain accurate cultures, bone biopsy must
be performed through uninvolved tissue
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Differential diagnosis
• Cellulitis-widespread redness and
lymphangitis. Organism usually is
staphyloccous or streptococcus
• Streptococcal necrotizing myositis-Group A
beta hemolytic streptococci invade muslce
and cause an acute myositis
• Acute suppurative arthritis- tenderness is
diffuse, all movement abolish due to muscle
spasm
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• Acute rheumatism-pain is less severe and tend
to flit from 1 joint to another and there maybe
carditis , rheumatic nodules and erythema
marginatum
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treatment
• Four aspects to the management of the
patient
1. Supportive treatment for pain and
dehydration
2. Splintage
3. Antibiotic therapy
4. Surgical drainage
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General supportive treatment
• Analgesic to be given at repeated interval
• Septicemia and fever can cause severe
dehydration and fluid must be given
intravenously
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splintage
• To provide comfort and to prevent joint
contractures
• Skin traction maybe suffice and if hip is
invloved, this will prevent dislocation
• At other site, a plaster slab or half cylinder
maybe used
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antiobiotics
•
Prompt administration of antibiotics isimportant and should not wait for results
• Factors such as the patient’s age , general
state of resistance , renal function and historyof allrgy must be taken into consideration
• For older children and previously fit adults,
start IV flucloxacillin and fusidic acid which areadministered continously until the condition
begins to improve and C reactive protein
values return to normal level( 1-2weeks)
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• Thereafter, antibiotics to be given orally for
another 3-6 weeks
• Fusidic acid is prefered because it is well
concentrated in the bone
• For children under 4 years, start with
cefuroxime or cefotaxime. It is effective
against both staphylococcos and gram
negative bacteria
• Alternative is co-amoxiclav
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• Heroin addicts and immunocompromised
patient- start with chloramphenicol and co-
amoxiclav
drainage
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drainage• If the clinical feature not imprvoing after 36
hours of treatment or if pus Is aspirated,the
abscess should be drained by open operation
under general anaesthesia
• If no obvious abscess, it is reasonable to drill a
few holes into the bone in various direction
• If there is an extensive intramedulallry
abscess, drainage can be achived by cutting a
small window in the cortex
• The wound is closed without a drain and the
splint is reapplied
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complications
• septicemia
• Suppurative arthritis-may occur in :
1. very young children
2. in whom the growth disc is not an
impenetratable barrier
3. the metaphysis is intracapsular
• Altered bone growth-physeal damage lead to
arrest of growth and shortening of the bone
• Chronic osteomyelitis