acute osteomylelitis

8/2/2019 Acute Osteomylelitis

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osteomyelitis



• 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



Spread of infection

• Haematogenous spread

• Direct spread

• Neighboring focus• Iatrogenic causes



Clinical types:

Acute osteomyelitis

•

Chronic osteomyelitis• Primary subacute osteomyelitis

• Acute flare up of chronic osteomyelitis



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



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.



• 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.



• 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.



• 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



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



• 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



• 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



• 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



• 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.



• 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.



• 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



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



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



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



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.



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



• 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



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



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



• 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



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



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



• Blood culture is positive in half of the cases of

proven infection

• Antistreptococcal antibody titres maybe raised

• Most useful in atypical cases



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



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



• Acute rheumatism-pain is less severe and tend

to flit from 1 joint to another and there maybe

carditis , rheumatic nodules and erythema

marginatum



treatment

• Four aspects to the management of the

patient

1. Supportive treatment for pain and

dehydration

2. Splintage

3. Antibiotic therapy

4. Surgical drainage



General supportive treatment

• Analgesic to be given at repeated interval

• Septicemia and fever can cause severe

dehydration and fluid must be given

intravenously



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



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)



• 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



• Heroin addicts and immunocompromised

patient- start with chloramphenicol and co-

amoxiclav

drainage



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



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

acute osteomylelitis

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