ETIOLOGY

acute hematogenous osteomyelitis subacute osteomyelitis chronic osteomyelitis

osteomyelitis

Osteomyelitis may occur at any age. Most common in ages 3-12 years. It affected boys twice frequently as girls . A microbial ethiology is confirmed in three

fourth of osteomyelitis and two thirds of cases of septic joint

pathogenesis

1. Hematogenous

2. Direct spread from a contiguous focus of infection.

Osteomylitis in children is most often the consequence of bacterremia.

Pathogenesis (con)

involves growing bone . Particularly the metaphyses of the long bone .

Femur and tibia are equally and together almost half of the all cases .

(distal femur , proximal tibia ,distal humerus , distal radius)

Pathogenesis (con)

Bacteria lodge in nutrient arteries supplying the growth plates of bones.

Blood in the large sinusoidal veins flows slowly No phagocytic cells present in this area. Obstruction of flow by bacterial microemboli

produces small areas of avascular necrosis and metaphyseal abscess .

1. Bacteria lodge in nutrient arteries supplying the growth plates of bones.

2. Blood in the large sinusoidal veins flows slowly.

No phagocytic cells present in this area.3. bstruction of flow by bacterial microemboli produces

small areas of avascular necrosis and metaphyseal abscess .

pathogenesis

Trauma often is noted before the onset of osteomyelitis. (in about one third)

In infant<1 yr the capillaries perforate the epiphyseal growth plate .

Spread across the epiphysis ,which causes a septic arthritis .

(con)

pathogenesis (con)

Pyartheritis complicating osteomyelitis is common in joints :

that capsule inserts to the metaphysis proximal to the epiphyseal plate .

( hip, elbow, shoulder , knee)

capsule inserts to the metaphysis proximal to the epiphyseal plate .( hip, elbow, shoulder , knee)

Chronic osteomyelitis

Involucrum:

Infected periosteum calcify into a shell of new bone around the infected portion of the shaft .

Brodie abscess: a subacute intraosseous

abscess that does not drain into the subperiosteal space and is classically located in the distal tibia

Sequestrum: portions of avascular bone that have separated from adjacent bone, frequenrly are covered with a thickened sheat

Contiguous osteomyelitis

Less common in children Usually occur after the spread of cellulitis as a

result of Infected wound .

■ osteomyelitis also may result from direct inoculation of a penetrating wound

■ Primary viral infection of bones or joints are rare

etiology S.aureus is responsible for most infections in

all age groups. Group B ( neonate) or other streptococci(A)

and pneumococcus , anaerobic microorganism , gram-negative entric bacteria, M,tuberculosis .

furunculosis , infected burns ,varicella, trauma, drug abuse ,prolong IV or central parenteral

alimentation

etiology Sickle cell anemia :

( salmonella , staphylococcus and less common S.pneumonia)

Cat or dog bite ( pasteurella multocida) Puncture wounds ,IV drug abuse (pseudomonas)

H,influ type b account for more than half of all case but is rarely seen in an immunized population .

Clinical manifestations

Hematogenous osteomylitis usually involves a single bone.

The most common presenting complaints are focal pain, exquisite point tenderness over the bone, warmth, erythema, swelling, and decreased use of the affected extremity.

Fever, anorexia, irritability, and lethargy may accompany the focal findings.

Clinical manifestations

Weight bearing and spontaneous or requested motion are refused .( pseudoparalysis)

Hematogenous vertebral osteomyelitis is insidious onset. With little fever or systemic toxicity.

Pelvic osteomyelitis present with limp ,abdominal, hip ,groin ,pain and fever

Clinical manifestations Neonate 40% multiple site local edema GBS,E coli reduced limb motion S,aureus

joint effusion (60-70)

1-24 mo long bones pseudoparalysis S,aureus involve joints fever,limp GBS

2-20 yr metaphysis of focal pain+ fever (90%) S,aureus(60-90%) long bones focal tenderness (70%) strep(10%) rarely vertebral joint effusion (20%) pelvis

diagnosis

Marked tenderness over the involved site.

leukocytosis may be present , ESR ↑, CRP ↑

Blood culture ( 60% positive). Cultures of aspirated cellulitis or priosteal space

before antibiotic therapy.

diagnosis

Radiography :

• finding of acute systemic osteomyelitis, at about 9 days, is loss of the periosteal fat line

• Periosteal elevation and periosteal destruction are later findings

technetium 99m bone scans . MRI is particularly useful for extended of infection or

when infection is a complication of trauma , surgery, sickle cell anemia

treatment

Initial IV antibiotic should be based on result of Gram stain of bone aspiration ,blood culture, age associated disease.

Initial IV antibiotic should cover S.aureus (oxacillin,nafcillin methicillin, clindamycin) Possibility of methicilin –resistant staph should

be considered . Gram- negative organism if wound contamination

or IV drug abuse .

treatment ( con)

sickle cell anemia S.aureus and salmonell must be covered (cefotaxim ,ceftriaxon)

The response to appropriate IV antibiotic usually occur in 48 hr .

Lack of improvement in fever and pain after this time indicates that surgical drainage may be necessary or an unusual pathogen may be present .

Treatment ( con)

surgical drainage may be appropriate at earlier time if :

1. sequestrum is present

2. disease is chronic or atypical

3. the hip joint is involved

4. Presence of spinal cord compression.

standard therapy usually consist of antibiotic for 4-6 weeks

After initial inpatient treatment and a good clinical response, including decreases in CRP or ESR, consideration may be given for home therapy with IV antibiotics or oral antibiotics,

Septic Arthritis

It occurs most commonly during the first 2 yr of life and adolescence.

Half of all cases occur by 2 yr and three fourths occur by 5 yr .

Joints of the lower extremity constitute three fourth of all cases.

pathogenesis

1. Hematogenous dissemination of bacteria.2. Contaguous spread from surrrounding tissues.3. Spread of osteomyelitis through the epiphysis

into the joint space in young children . Presenting in the first 3 days more often

represent the hamatogenous spread of bacteria .

pathogenesis

Post infectious joint effusion :

Which is sterile .

caused by antigen- antibody complex.

Developed after 7 days of bacterial illness.

( bacteremia, meningitis, diarrhea , urethritis)

etiology S.aureus is the most common agent. H.influ type b is the most common factor in 3

month to -4 yr . Streptococci , pneumococci, meningococci that

may occure in the absence of sepsis or meningitis.

Gonococcal arthritis most common cause of polyartheritis and monoarticular artheritis in adolecent.

Clinical manifestation

Erythema , warmth , swelling, and tenderness with a palpable effusion and decreased range of movement . Toddlers demonstrate a limp .

Acute septic arthritis most often involves a single joint .

Multiple joints in 10% .

1. The onset may be sudden with fever and chills 2. Insidious with symptoms noted only when the joint

is moved .

Clinical manifestation( con)

Often difficult to assess septic arthritis of the hip and may cause referred pain the knee .

The hip for minimize pain from pressure ,The limb may be positioned in external rotation and flexion .

The knee and elbow joints usually are in flexion .

diagnosis Leukocytosis , elevated ESR or CRP are

common . Arthrocentesis is the test of choice for rapid

diagnosis . Blood or joint cultures are positive in 70%up to

85% in cases ultraSonography is helpful in detecting joint

effusion and may guide localization for aspiration .

Plain radiographs typically add little information to the physical findings.

Radiographs may show swelling of the joint capsule, a widened joint

space, and displacement of adjacent normal fat lines.

Radionuclide scans are of limited use, although technetium-99m

bone scans may be helpful to exclude concurrent bone infection, eithir adjacint or distant from the infected

joint.

MRI is useful in distinguishing joint infections from cellulitis or deep abscesses.

diagnosis (Synovial fluid analysis)

Synovial fluid analysisfor cell count, diff ,protein and glucose has limited usefulness .

Noninfection inflammatory disease can also increased cells and protein and decreased glucose

(rheumatic fever , and rheumatoid arthritis)

diagnosis

In up to 30% of patients who have never received antibiotic may not reveal bacterial pathogens .

In chronic arthritis synovial biopsy may distinguish between an septic and a non infection process.

Radiography or bone scans of adjacent bone .

Differential diagnosis

Reactive arthritis is immune-mediated synovial inflammation thar follows a bacrerial or viral infection

Non infectious

(Rheumatoid arthritis , SLE,serum sickness , IBD) Henoch –schonlein purpura,

leukemia ,metabolic diseases , foreign bodies , traumatic arthritis

viral infections may cause arthritis

Suppurative arthritis must be distinguished from Lyme disease, osteomyelitis, suppurative bursitis, fasciitis, myositis, cellulitis, and soft tissue abscesses.

Psoas muscle abscess often presents with fever and pain on hip flexion and rotation

Differential diagnosis

Toxic tenosynovitis of the hip Common condition of children age 3-6 years . May be viral in etiology . Selflimited disorder and more common than septic

arthritis .

bacterial infections (TB, syphilis.Lyme disease)

treatment Therapy is based on :1. Likely organism2. Gramstain of joint fluid 3. host immunologic status

Parenteral antimicrobial agents. Surgical intervention reserved for specific

situation.

treatment (CON)

Pyogenic arthritis of the hip or shoulder caused by S.aureus usually necessiatates prompt surgical drainage.

Staphylococcal infection of the knee may be treated with repeated arthrocenteses and countinuation of appropriate IV antibiotics

treatment (CON)

For empirical therapy: in the neonate antibiotic against

staphyloccocci, GBS, and aerobic gram- negative.

( cefotaxim or ticarcillin / clavulanate) Infant 3 month- 4 years antibiotic against S. aureus and H .influ type b until culture results

are known . ( cefotaxim or ampicillin /sulbactam)

treatment (CON)

IV meticillin is the choice for S.aureus . Vancomycin for methicillin- resistant . The length of therapy depends on :

1. Clinical resolation

2. reduction of ESR .

S.Aureus 14-21 days or more .

Gonococcal or meningococcal 7 days of penicillin

treatment (CON)

Oral agents against s.aureus are:

augmentin.cloxacillin , dicloxacillin , cephalexin , clindamycin, and ciprofloxacin these are often used to complete therapy .