3. Route of infection
Dissemination of pathogens via the blood, from
distant site…. (most common)
Dissemination from an acute osteomylitic focus
Dissemination from adjacent soft tissue infection,
Entry via penetrating trauma
Entry via iatrogenic means
The causal organism is usually Staphylococcus aureus.
In children under the age of 3 years Haemophilus
influenzae is fairly common
gram-negative bacilli (a group of bacteria, including
Escherichia coli, or E. coli)
streptococci (a group of bacteria that can lead to a
wide variety of diseases)
There is an acute synovitis with a purulent joint effusion
and Synovial membrane becomes edematous, swollen and
hyperemic, and produces increase amount of cloudy
exudates contains leukocytes and bacteria
As infection spread through the joint, articular cartilage is
destroyed by bacterial and cellular enzymes.
If the infection is not arrested the cartilage may be
Pus may burst out of the joint to form abscesses and
The joint may be become pathologically dislocated.
7. With healing there will be:
Complete resolution and return to normal.
Partial loss of cartilage and fibrosis.
Bone destruction and permanent deformity.
8. Clinical presentation
Typical features are acute pain and swelling in a single
large joint ,commonly the hip in children and the knee in
adults, however any joint can be affected.
The most commonly involved joint is the knee (50% of
cases), followed by the hip (20%), shoulder (8%), ankle
(7%), and wrists (7%). interphalangeal, sternoclavicular,
and sacroiliac joints each make up 1-4% of cases.
9. 1. Symptoms in newborns or infants:
The emphasis is on septicemia rather than joint pain.
Irritability ,Fever, refuses to feed, rapid pulse.
Unable to move the limb with the infected joint
Cries when infected joint is moved (diaper changing)
Infection is usually suspected ,but it could be anywhere
so the joints should be carefully felt and moved to elicit
the local signs of warmth ,tenderness and resistance to
Umbilical cord or the site of injection should be
examined for possible source of infection.
If the baby is distressed and wont move his/her leg think
of hip infection.
10. 2. In children:
Acute pain in single large joint.
The joint is swollen (if superficial), warm
All movements are restricted due to muscle
spasm (Pseudo paresis).
11. 3. In adult:
Intense joint pain .
Joint swelling .
Joint redness .
Unable to move the limb with the infected
12. Physical examination
1. Decreased or absent rang of motion.
2. Signs of inflammation: joint swelling, warmth,
tenderness and erythema.
3. Joint orientation as to minimize pain (position
Hip: abducted, flexed and externally rotated.
Knee, ankle and elbow: partially flexed.
Shoulder: abducted and internally rotated
The diagnosis can usually be confirmed by joint aspiration
and immediate microbiological investigation of the fluid.
Blood culture may be positive in about 50% of proven
Non specific features of acute inflammation-
leucocytosis,ESR,CRP-are suggestive but not diagnostic .
14. Ask for:
gram stain, culture, leukocyte count with
differential, and crystal examination
o generally higher than 50,000/µL, with a predominance
of neutrophils more than 75%
are positive in approximately 75% of patients with
staphylococcal infections; however, results are positive in only
50% of patients with gram-negative infections
15. crystal examination:
exclude crystal-induced arthritis (may coexist)
The definitive method
for aerobic and anaerobic organisms.
are positive in 85-95%
• Synovial fluid glucose, protein, and lactic acid
concentration not specific.
17. Imaging studies
The appearance of significant x-ray findings depends upon
the duration and virulence of infection.
Plain radiography findings are generally nonspecific and
may reveal only soft tissue swelling ,widening of the joint
space ( due to the effusion), and periarticular osteoporosis
during the first 2 weeks.
Later ,when the articular cartilage is attacked ,the joint
space is narrowed.(persistent subluxation, destructive
This study is very sensitive in detecting joint effusions
generated by septic arthritis.
Ultrasound can be used to define the extent of septic arthritis
and help guide treatment.
Ultrasound helps to differentiate septic arthritis from other
conditions (e.g., soft tissue abscesses, tenosynovitis) in which
treatment may differ.
23. 3-Radio-isotope bone scan:
Show increase uptake of the isotope in the region of the
joint. (may help in difficult site as sacroiliac &
4- CT scan:
This study may help to diagnose sternoclavicular or
sacroiliac joint infections.
MRI is most useful in assessing the presence of
periarticular osteomyelitis as a causative mechanism.
24. DIFFERENTIAL DIAGNOSIS
Osteomyelitis: near a joint may be indistinguishable from septic
arthritis ;the safest is to assume that both are present.
An acute haemarthrosis :either post-traumatic or due to a
haemophilic bleed ,can closely resemble infection. The history is
helpful and joint aspiration will resolve any doubt.
Transient synovitis(irritable joint) in children: causes
symptoms and signs which are less acute ,but there is always the that
this is the beginning of an infection.
Gout and pseudogout in adults :aspirated fluid may look turbid
but the presence of urate or pyrophosphate crystals will confirm the
Dislocation: a tense effusion may cause dislocation
Epiphyseal destruction: in neglected infants the largely
cartilaginous epiphysis may be destroyed ,leaving an unstable
Growth disturbance: physeal damage may result in shortening or
Ankylosis: if articular cartilage is eroded healing may lead to
The first priority is to aspirate the joint and examine the
fluid, treatment is then started without further delay.
Analgesics and splinting of the involved joint in the
position of maximal comfort alleviate pain.
Fluid replacement and nutritional support may be
Other foci of infection and any coexisting medical
conditions must be identified and treated appropriately.
27. Intravenous antibiotics should be given empirically and
started as soon as joint fluid and blood sample have been
taken for culture.
If gram –positive organisms are identified ,Flucloxacillin is
suitable . If in doubt ,a third generation cephalosporin will
cover both game+ and gram- organisms.
Children less than 4 yr( if suspicion of H.Infl) treated with
Once the bacterial sensitivity is known the appropriate
drug is substituted.
Intravenous administration is continued for several weeks
and is followed by oral antibiotics for a further 2 or 3 weeks.
Indication of Surgical Drainage:
1-Joints that do not respond to antimicrobial therapy and
2-. Any joint with limited accessibility, including the
sternoclavicular or the hip joint
3-Patients with underlying disease, including diabetes,
rheumatoid arthritis, immunosuppression, or other
systemic symptoms, should be treated more aggressively
with earlier surgical intervention