Download MBBS Orthopaedics PPT 13 Osteomyelitis Lecture Notes

Osteomyelitis

Department of Orthopaedics

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Learning objectives

? Definition
? Aetiology
? Pathogenesis

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? Clinical picture
? Investigations
? Differential diagnosis
? Treatment

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Definition

? Inflammation of bone
? Osteo= bone ,myelitis = inflammation of marrow

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? Rapid destructive pyogenic infection
? Most frequently in infants and children

Aetiology

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? Bacterial infection but at times can be fungal infection

? Causes can be ?
1. Diabetes
2. Intravenous drug use

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3. Trauma to the part
4. Immunocompromised status of the host.
5. Poor nutrition ,unhygienic surroundings

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Aetiology

? Sex: Male /female -4:1

? Location :metaphysis of long bone

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due to rich blood supply to that
area

? Hairpin bent of the metaphyseal

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vessels

? Metaphyseal hemorrhage

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? Defective phagocytosis

? Vasospasm of the end arteries

preventing the antibiotics to reach

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there.

Micro-organism

? In Infants : Staphylococcus aureus ,S. agalactiae and E.coli

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? In children >1 yr. : Staphylococcal Aureus , Streptococcus pyogenes ,H.

influenzae

? In adults : S.aureus and streptococcus species

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? In patients of sickle cell anemia ? salmonella species
CLASSIFICATION

? According to duration of symptoms
Acute (<2 weeks)

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Subacute (2-3 weeks)
Chronic (>3 weeks)

Pathophysiology

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Mechanism of spread :
? Hematogenous ? MC aetiology in children
? Contiguous spread ?associated with previous surgery ,trauma,

cellulitis

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? Direct inoculation ?in penetrating injuries ,open injuries, orthopaedic

surgeries like joint replacement and fixation of fractures.

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? Preexisting focus / Exogenous Infection
? Infective embolus enters nutrient artery
? Trapped in a vessel of small Caliber(metaphysis)
? Blocks the vessel

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? Active hyperemia + PMN cells exudate
? In order to engulf the bacteria they release
enzymes and lyse the bone around.

? Hyperemia and immobilization causes decalcification.

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? Proteolytic enzymes destroy bacteria and medullary

elements.

? The debris increase and intramedullary pressure

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increases.


Cont.

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? Enter subperiosteal space.
? Strips periosteum.
? Perforation of periosteum / reach joint by piercing capsule.
? Enters soft tissue and may drain out

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Clinical presentation

? Severe pain ,malaise ,fever
? Recent history of infection

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? Child looks ill and feverish
? temperature raised
? Limb held still and acute tenderness present over the involved limb
? Manipulation of limb painful :pseudo paralysis

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? Infants:
Failure to thrive and drowsy
h/o birth difficulties ,umblical

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artery catherization or site of
infection

Laboratory investigations

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? Elevations in the peripheral white blood cell count (WBC),
? Erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP)
? Blood culture is positive in half of cases.

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Radiological findings

? Negative for 1st week or 10 days
? Localised area of bone destruction
? Periosteal shadow is elevated

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? multiple lamination of bone deposition
? Periosteal new bone formation is seen after 2
weeks.

? Ultrasonography ? juxtacortical soft tissue swelling with periosteal

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thickening

? Radionuclide scanning ? sensitive but not specific

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increased uptake

? Magnetic resonance imaging ? hypointense on T1 weighted image

hyperintense on T2

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Differential diagnosis

? Rheumatic fever : Onset -more gradual,

pain and tenderness less intense.

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polyarticular.

Response to salicylates

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? Acute suppurative arthritis : Pain and tenderness limited to the joint,

joint movements -restricted

aspiration reveals purulent synovial fluid.

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? Ewing's sarcoma : biopsy demonstrates tumor cells

Treatment

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? General management-

Rest in bed

Elevation of the part

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Systematic treatment- IV fluids, correct shock

Treatment with antibiotics

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Surgery
Principles of antibiotic therapy

? Appropriate drug
? Appropriate route

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? Appropriate dose
? Appropriate time to stop
? Appropriate adjunctive measures.

Treatment

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? Local management
Well timed surgery
Nade's indication for surgery-
? Abscess formation

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? Severely ill and moribund child.
? Failure to respond to intravenous antibiotics for more than 48 hours.


Surgical methods

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? Aspiration

? Incision and drainage

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? Multiple drill holes

? Small bone window

? Bone abscess

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? Septic Arthritis
? Septicemia
? Fracture
? Growth arrest
? Overlying soft-tissue cellulitis

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? Chronic infection


Subacute osteomyelitis

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? insidious onset, mild symptoms, lack of systemic reaction
? Its relative mildness is due to:

Organism being less virulent OR

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Patient more resistant OR

(Both)

? Most common site: Distal femur, Proximal & Distal Tibia

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Causative organism

? Staphyloccocus aureus (30-60%)
? Others (Streptococcus, Pseudomonas, Haemophilus influenzae)

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? Pseudomonas aeruginosa (IV drug user)
? Salmonella (patient with sickle cell anemia)
Radiographic findings

Brodie's abscess

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- circumscribed, round/oval cavity containing pus and pieces of dead

bone (sequestra) surrounded by sclerosis.

? MC in tibial / femoral metaphysis.

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? May occur in epiphysis / cuboidal bone (eg: calcaneum).
? Metaphyseal lesion cause no / little periosteal reaction.
? Diaphyseal lesion may be associated with periosteal new bone

formation and marked cortical thickening.

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Clinical features

? Pain (several weeks / months)
? Limping

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? Swelling & Local tenderness
? Muscle wasting
? Body temperature usually normal (no fever)

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A circumscribed, oval cavity

This is a lateral view X-ray of left

surrounded by a zone of

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tibia and fibula. There is a marked

sclerosis at the proximal

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periosteal reaction at the

tibia (Brodie's abscess)

diaphysis.

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Investigations

? X-ray (may resemble osteoid osteoma / malignant bone tumor)
? Biopsy

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? Fluid aspiration & culture
? ESR raised
? WBC count may be normal

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Treatment

Conservative :

a)

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Immobilization

b) Antibiotics for 6weeks

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Surgical (if the diagnosis is in doubt / failed conservative treatment) :

a)

Open biopsy

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b) Perform curettage on the lesion

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BRODIE'S ABSCESS

? Subacute osteomyelitis persist for many years before progressing to

chronic osteomyelitis.

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? Classically it is abscess formation surrounded by fibrous tissue or host

tissue.

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? Causative organism is staphylococcal aureus in most of the cases.
Presentation

? Localized pain
? Often nocturnal

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? Alleviated by aspirin.

location

? Metaphysis of long bones

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Upper end of tibia
Lower end of tibia
Lower end of femur
Lower end of fibula
Radiographic findings

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Brodie's abscess
- circumscribed, round/oval cavity containing pus and pieces of dead

bone (sequestra) surrounded by sclerosis.

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? MC in tibial / femoral metaphysis.
? May occur in epiphysis / cuboidal bone (eg: calcaneum).
? Metaphyseal lesion cause no / little periosteal reaction.
? Diaphyseal lesion may be associated with periosteal new bone

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formation and marked cortical thickening.

Radiologically

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? Oval, elliptical, or serpentine radiolucency usually greater than 1 cm

surrounded by a heavily reactive sclerosis.

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Radiologically

? lytic lesion in the distal

metaphysis with a narrow zone

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of transition more caudally

? with a faint sclerotic rim and a

wide zone of transition more

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cephalad.

Radiologically

? hyper intense edema in the calf

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musculature, marrow edema,
and sub-periosteal pus.

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Radiologically

? The thin hypointense rim

surrounding the intramedullary

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collection represents the
reactive interface between the
abscess and the body's attempt
to wall it off.

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Radiologically

? post gadolinium image showing

the extent of the multiloculated

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intramedullary abscess.
Treatment

? In the majority of cases surgery has to be performed.
? If the cavity is small then surgical evacuation and curettage is

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performed under antibiotic cover.

? If the cavity is large then the abscess space may need packing

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with cancellous bone chips after evacuation.

SALMONELLA OSTEOMYELITIS

? Seen in patient with sickle cell anemia and thalassemia.

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? Clinical features ?
Several bones involved
Symmetrical involvement of bones
Severe osteomyelitis
Spine may be involved

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Sickle cell anemia present.
Stool may be positive.
Treatment

? The most commonly used antimicrobials are

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chloramphenicol,
third generation cephalosporin's
Fluoroquinolones (ciprofloxacin)

In unresponsive cases surgical resection along with prolonged antibiotic therapy needs to be

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performed.

Question 1

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Chronic Osteomyelitis

? Definition:

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" A severe, persistent and incapacitating infection of bone and bone

marrow "

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Etiological Agents

Usual organisms (with time there is always a mixed infection)
? Staph.aureus(commonest)

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? Strep.pyogenes
? E.coli
? Pseudomonas
? Staph.epidermidis (commonest in surgical implant)

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Clinical Features

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a)

Pain

b) Low grade fever

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c)

Mild Redness

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d) Mild Tenderness

e)

Discharging sinus

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(seropurulent discharge)

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Pathogenesis

Inadequate treatment of acute OM /Foreign implant /

Open fracture

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Inflammatory process continues with time

together with persistent infection by infecting organism

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Persistent infection in the bone leads to increase in

intramedullary pressure due to inflammatory exudates

(pus)

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stripping the periosteum

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Pathogenesis (Contd.)

Vascular thrombosis

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Bone necrosis (Sequestrum formation)

New bone formation occur (Involucrum)

Multiple openings appear in this

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involucrum, through which exudates

& debris from the sequestrum pass via

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the sinuses

(Sinus formation)

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Staging Of Osteomyelitis:

? The Cierny-Mader staging system.

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? Determined by the status of the disease process.
? It takes into account the state of the bone,
? the patient's overall condition and factors affecting the development of

osteomyelitis.

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Cierny-Mader Classification

? 1: Medullary Osteomyelitis - Infection

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confined to medullary cavity.

? 2: Superficial Osteomyelitis -

Contiguous type of infection. Confined

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to surface of bone.

? 3: Localized Osteomyelitis - Full-

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thickness cortical sequestration which

can easily be removed surgically.

? 4: Diffuse Osteomyelitis -Loss of

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bone stability, even after surgical

debridement.

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Radiographic Findings

1) X-ray examination

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-

Usually show bone resorption (patchy loss of density / osteolytic lesion)

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-

Thickening & sclerosis around the bone

-

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Presence of sequestra

-

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Occasionaly it may present as a Brodie's abscess surrounded by vascular tissue and
area of sclerosis

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2) Radioisotope scintigraphy

-

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Sensitive but not specific

-

Technetium labelled hydroxymethylene diphosphonate (99mTc-HDP) may

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show increased activity in both perfusion phase and bone phase

3) CT scan & MRI

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Show the extent of bone destruction, reactive oedema, hidden abscess and
sequestra

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MRI of Osteomyelitis of metatarsal

Decreased signal in T1
weighted images

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Appears bright in T2

weighted images.

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Treatment -

? Antibiotics
? Host immunity

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? Surgical ? sequestrectomy and debridement

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Complications

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1) Pathological Fracture

-

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This occurs in the bone weakened by chronic osteomyelitis

2) Deformity

?

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In children the focus of osteomyelitis destroys part of the epiphysis growth
plate.

3) Shortening/ lengthening

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-

Destruction of growth plate arrest growth.

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-

Stimulation of growth plate due to hyperemia.

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