2. • A jt can become infected by;
1. Direct invasion through a penetrating wound, inta-
articular injection or arthroscopy.
2. Direct spread from an adjacent bone abscess.
3. Blood spread from a distant site
• in infants infxn start in the metaphyseal bone then
spread to the jt or vice versa
• Causal organism- staph aureus
• In children btn 1 &4 years old; h influenzae,
streptococcus, E-coli, &proteus,
• Predisposing conditions: rh arthritis, chronic
debilitating disorder, iv drug abuse, aids
3. PATHOLOGY
• Haematogenous spread
• Settle in the synovial membrane
• Acute inflammatory rxn with serous or seropurulent
exudate & an increase in synovial fluid .
• Pus appears in the joint.
• Articular cartilage is eroded & destroyed by bacterial
enzymes & proteolytic enzymes released from synovial
cells, inflammatory cells & pus.
• In infants the epiphysis may be severely damaged
4. • Older children, vascular occlusion may lead to necrosis of
epiphyseal bone
• In adults the effects are usually confined to the articular
cartilage, but in the late cases there may be extensive
erosion due to synovial proliferation & ingrowth.
• If untreated, infection spread to the underlying bone or
burst out of the joint to form an abscess & sinuses.
• With healing there may be
1. Complete resolution & return to normal
2. Partial loss of articular cartilage & fibrosis of the joint
3. Loss of articular cartilage & bony ankylosis
4. Bone destruction &permanent deformity of the joint
5. Clinical features
• Differ according to age of the patient
– NEW BORN INFANT
• Emphasis is on septicemia rather than jt pain
• Irritable &refuses to feed.
• Rapid pulse & fever
• JT;
– FEEL
– Move to elicit local signs of warmth & tenderness.
– Resistance to mvt.
– Examine umbilical cord.
6. CHILDREN
• Acute pain in a single large joint
• Reluctance to move the joint(pseudoparesis)
• Looks ill, rapid pulse & a swinging fever.
• Skin redness & superficial joint swelling
• Local warmth & marked tenderness
• All movements are restricted & often completely
abolished by pain & spasm.
• Source of infxn; septic toe, boil or discharge from
ear.
7. Adults
• Often a superficial joint: knee ,wrist, a finger,
ankle or toe that is painful swollen &
inflamed.
• Warmth & local tenderness.
• Mvt are restricted.
• Pt should be questioned & examined for
gonococcal infection or drug abuse
• Pt on r.a rx may develop a silent jt infxn.
8. imaging
• u/s- reveal joint effusion in early cases.
• X-ray;- usually normal
– watch out for;
– Soft tx swelling
– Loss of tx planes
– Widening of the radiographic joint space
– & slight subluxatiobnbecause of fluid in the joint.
– E-coli- gas
– Narrowing & irregularity if joint space
• Mri & radionuclide imaging in obsure sites e.g
sacroiliac
9. Lab investigations
• Raised wcc & esr.
• Blood culture may be +ve
• SPECIAL INVESTIGATIONS
– aspirate joint & examine joint fluid
• May be purulent
• Early-clear
• Aspirate- wcc & gram stain immediately.
• Normal leukocyte count-<300 per ml.
• >10000per ml in non-infective inflammatory disorders
• >50000per ml are suggestive of sepsis.
• Gram –ve cocci; h influenzae or kingella kingae( in
children)gonococcus in adults.
10. Ddx
• Acute om
• Other types of infxn-psoas abscess/ local pelvic infxn
• Trauma-traumatic synovitis/ haemarthrosis/ jt aspiration.
• Irrtable jt; painful & lack mvt. Child is not ill.
• Rh fever- typically the pain flits from jt to jt
• JRA-gradual onset with less severe systemic symptoms.
• Sickle cell dx
• Gauchers pseudo-osteitis. Acute pain & fever without any organism.
• Gout &pseudogout- acute crystal induced synovitis- aspiration;
turbid jt fluid/ raised wcc/ microscopic exam by oplarized
microscope show xtic crystals
• Rx
11. treatment
• Priority- aspirate joint &examine fluid
• Start rx without further delay & follow the same principles as aom
• If aspirate looks purulent- joint should be drained without waiting
for lab results.
• General supportive care
• Analgesics for pain
• Iv fluids-dehydration.
• Splintage
• To rest joint especially in neonates & infants.
• Hip should be abducted & 30 degrees flexed on traction to prevent
dislocation.
12. antibiotics
• As aho.
• Neonates & infants up to 6 months
– penincillinase resisatant penincillins eg-
flucloxacillin & 3rd generation cephalosporins
– Children from 6 months to puberty –similar
– Older teenagers & adults- flucloxacillin & fusidic
acid
– 3 rd generation cephalosporins- iv for 4-7 days
then orally for 3 weeks.
13. DRAINAGE
• Under anaesthesia
• Jt is opened through a small incision, drained & washed out
with physiological saline.
• A small catheter is left in place & the wound is closed.
• Suction- irrigation is continued for 2-3 days
• Advisable in
1. very young infants
2. Involving hip
3. Very thick pus aspirated
• Older children; repeated closed aspiration may work
• If there is no improvement within 48 hours open drainage
is done
14. complications
• Subluxation & dislocation of the hip
• Instability of the knee
• Damage to cartilagenous physis or epiphysis in growing child.
• Sequelae;
– Retarded growth
– Partial or complete destruction of the epiphysis
– Deformity of the joint
– Epiphyseal osteonecrosis
– Acetabular dysplasia
– Pseudoarthrosis of the hip
– Acetabular cartilage erosion( chondrolysis)is seen in older pts & this
may result in restricted mvt or complete ankylosis of the joint.
