bone infections (osteomyelitis)

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



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BONE INFECTIONS

OSTEOMYELITIS



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BONE INFECTIONS

OSTEOMYELITIS



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OSTEOMYELITIS



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BONE INFECTIONS

OSTEOMYELITIS


Pathology

1. Inflammation

2. Suppuration

3. Necrosis 4. New bone formation

5. Resolution


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BONE INFECTIONS

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


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


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


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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bone infections (osteomyelitis)

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