bone infections (osteomyelitis)
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7/29/2019 Bone Infections (Osteomyelitis)
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BONE INFECTIONS
OSTEOMYELITIS
Infection of bone and bone marrow caused by directinoculation or by blood borne organisms.
Acute hematogenous osteomyelitis
Acute osteomyelitis
Chronic osteomyelitis
Subacute osteomyelitis
Sclerosing Osteomyelitis
Multifocal Osteomyelitis
Osteomyelitis with unusual organisms
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
Pathology
1. Inflammation
2. Suppuration
3. Necrosis 4. New bone formation
5. Resolution
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BONE INFECTIONS
OSTEOMYELITIS
Acute hematogenous osteomyelitis
Pathology
1. InflammationAcute inflammatory reaction with vascular congestion
Rise in intra-osseous pressure causing intense pain
2. SuppurationAt 2-3 days pus forms within the bone and forces its way downthe haversian canals, surface, adjacent joint or into the softtissues
Vertebral infection can spread through the end plate, disc and
into the next vertebral body
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BONE INFECTIONS
OSTEOMYELITISAcute hematogenous osteomyelitis
3. Necrosis
At 7 days, rising pressure, vascular stasis, infectivethrombosis and periosteal stripping compromise the bloodsupply resulting in a sequestrum
4. New bone formation
At 10-14 days this forms from the deep surface of the
stripped periosteum forming the involucrum
5. Resolution
With release of the pressure and appropriate antibioticshealing can occur. There may be permanent deformity
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BONE INFECTIONS
ACUTE HEMATOGENOUS
OSTEOMYELITIS
Clinical features:
Children (invariably)
Pain, malaise, fever
Limp or not weight
bearingInfants
Failure to thrive,
drowsiness, irritable
Adults
The commonest site is thethoracolumbar spine
(Batson's venous complex
from the pelvis) Other bones involved
especially in DM, IVDA,immunosuppressed
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BONE INFECTIONS
ACUTE HEMATOGENOUS OSTEOMYELITIS
Examination:
Local erythema
Swelling and tenderness indicates that the pus has broken
through the periosteum
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BONE INFECTIONS
ACUTE HEMATOGENOUS OSTEOMYELITIS
Investigations:
FBC incr. WCC Differential shows incr. neutrophils
ESR may be normal within the first 48 hours but risesrapidly and may exceed 100mm/hr
CRP raised
Blood cultures Positive in 50% of cases
ASO titres raised in 50%
Antibodies to acid cell wall of S.aureus sensitivity 82% inacute osteomyelitis
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BONE INFECTIONS
ACUTE HEMATOGENOUS OSTEOMYELITIS
Radiographic studies:
Normal in the first 10 days Soft tissue swelling - 2-3 days adjacent to the metaphysis,
with displaced fat planes
Demineralization - 10-14 days, at the site of the infection
New bone formation at the surface10-14 days
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BONE INFECTIONS
ACUTE HEMATOGENOUS OSTEOMYELITISBone scan
99mTechnetium
Positive before any x-ray changes (24-48hrs of infection)
67GalliumUptake related to the local accumulation of PMN
111Indium
Reported specificity 86% and sensitivity 83% and accuracy 83%
MRIIntra and extra osseous changes will be detected early but are notdiagnostic
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BONE INFECTIONS
ACUTE HEMATOGENOUS OSTEOMYELITIS
Aspiration and biopsy
This will yield a positive culture in 80% of cases
Pathogens
S. Aureus in 60-90% of cases H. influenza (Hib) makes up 20% of cases under 4yrs
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BONE INFECTIONS
MANAGEMENTAcute hematogenous osteomyelitis
Antibiotic
Infant < 1yr
Grp B Streptococcus, S.aureus, H.influenza, E.coli
Children 1-16 yr & No underlying disease
S.aureus, Strep.pyogenes, H.influenza
Sickle cell
S.aureus, SalmonellaAdults
S.aureus, E.coli, Serratia marcescens, Pseudomonasaeruginosa
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BONE INFECTIONS
OSTEOMYELITISAcute hematogenous osteomyelitis
Minimum duration of treatment is 6 weeks
20% failure of treatment if antibiotics given for only 3 weeks
Blood levels should be 8 times the minimum bactericidal level
Surgery
If clinical abscess formed or not settling within 48hrs of antibiotics.
Incision and drainage of the affected area
Drilling of bone is not recommended but any soft areas of bone can beprobed
Skin closed over a drain
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BONE INFECTIONS
SUBACUTE OSTEOMYELITIS Patient presents with a painful limp, systemically well and
may have no signs of local infection
There may be signs of a subperiosteal collection, synovitisor pus within a joint
X-rays show a well-established lesion in the bone
Femur and tibia are by far the most common sites
Blood tests
WCC and ESR may be raised but in 50% cases tests arenormal
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BONE INFECTIONS
SUBACUTE OSTEOMYELITIS
Brodie's Abscess Commonly occur in the metaphyses
of tubular bones but can also occur in
flat bones, vertebral body and the
diaphysis They are usually manifestations of
subacute osteomyelitis
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BONE INFECTIONS
CHRONIC OSTEOMYELITIS
Etiology
1. Inadequately treated acute osteomyelitis
2. Haematogenous spread
3. Iatrogenic
4. Penetrating trauma
5. Open fractures
6. Contiguous focus infection, secondary to a breakdown in theoverlying soft tissue e.g. vascular/neuropathic ulcer, DM
7. The adjacent soft tissues are always involved except inBrodies abscess
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BONE INFECTIONS
CHRONIC OSTEOMYELITIS
Causative organism
If secondary to acute osteomyelitis the organism is almostalways S.aureus
Following trauma S.aureus is most common but it may be
polymicrobial
Gramve organisms are now isolated from ~50% ofpatients with osteomyelitis
Animal bitespasturella multocida
Human biteseikenella corrodens
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BONE INFECTIONS
Treatment Principles
Surgical debridement and bony stabilisation
Control of dead space
Soft tissue cover Antibiotics
Surgical debridement
Aim is to remove all dead and infected tissue and bone
Send samples for
Microscopy
Culture
Histology (0.5% will develop SCC, Marjolins ulcer)
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BONE INFECTIONS
GARRS CHRONIC SCLEROSING OSTEOMYELITIS
Children and young adults, average age 16 years
No necrosis or pus present Intense periosteal proliferation leading to bone formation
Aetiology unclear but may be due to anaerobic organisms
Local pain and tenderness in shaft of long bones
Difficult to distinguish from primary osteogenic sarcoma
No satisfactory treatment and antibiotic therapy does not
affect course
Recurrent for years then gradually subsides
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BONE INFECTIONS
SEPTIC ARTHRITIS
In children septic arthritis can occur at any age
50% of cases occur in children under 5years and 30% of cases occur in children under 2years
Hip most commonly affected in infants, and knee in older
children
10% of cases will have more than 1 joint affected
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SEPTIC ARTHRITIS Route of spread
Haematogenous
Spread from metaphyseal osteomyelitis where the metaphysis
is intra-articular
Spread from contiguous soft tissue infection
Direct inoculation
SEPTIC ARTHRITIS Route of spread
Haematogenous
Spread from metaphyseal osteomyelitis where the metaphysis
is intra-articular
Spread from contiguous soft tissue infection
Direct inoculation
BONE INFECTIONS
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BONE INFECTIONS
SEPTIC ARTHRITIS
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BONE INFECTIONSSEPTIC ARTHRITIS
Causative organism
Under 2 yearsS.aureus, E.coli, Group B Strep, Haemophilus
2-16 yearsS.aureus, Strep. Pyogenes, Streptococci (C,G),Haemophilus
16-30 yearsoverS.aureus, Strep. Pyogenes, N.gonorrhoea
30 yearsS.aureus, Streptococci (A,B,C,G,pneumon)
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BONE INFECTIONS
SEPTIC ARTHRITIS
I nvestigations
FBC, ESR, CRP
USS for detection of hip effusion
XR may show subluxation or dislocation
Diagnostic aspiration
Send sample for
Gram stain and microscopy
Septic arthritis strongly suspected if the WCC is
>50,000mm-3 with 90% PMN, even if the cultures are
negative
Culture
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BONE INFECTIONS
SEPTIC ARTHRITIS
Treatment
IV antibiotics broad spectrum aimed at best guess first
then adjusted according to microbiology results
Length of treatment (minimum)
IV 2 weeks
Oral child 2-4 weeks
Adult 4-6 weeks
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BONE INFECTIONS
TREATMENT
Surgical drainage
Hips should always be drained surgically
Best approach anterolateral
Arthroscopic washout acceptable in the knee but open
drainage may be required
Complications
Despite alarming XR changes there is a favorable outcomein many children
AVN
Coxa vara
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