Septic arthritis

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Septic arthritis
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Medical ppt
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• septic arthritis
• is an inflammatory joint disease caused by
  bacterial, viral, and fungal infection.

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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

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Etiology

• 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)

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Pathology

• 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 completely destroyed.
• Pus may burst out of the joint to form abscesses
  and sinuses.
• The joint may be become pathologically
  dislocated.

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• With healing there will be
• Complete resolution and return to normal.
• Partial loss of cartilage and fibrosis.
• Bone ankylosis
• Bone destruction and permanent deformity.

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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.

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• 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
  (pseudoparalysis) .
• 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 movement.
• 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.

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• In children
• Acute pain in single large joint.
• The joint is swollen (if superficial), warm and
  tender.
• Fever.
• All movements are restricted due to muscle spasm
  (Pseudoparesis).

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• In adult
• Intense joint pain .
• Joint swelling .
• Joint redness .
• Unable to move the limb with the infected joint .
• Low-grade fever.

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Physical examination

• Decreased or absent rang of motion.
• Signs of inflammation joint swelling, warmth,
  tenderness and erythema.
• Joint orientation as to minimize pain (position
  of comfort)
• Hip abducted, flexed and externally rotated.
• Knee, ankle and elbow partially flexed.
• Shoulder abducted and internally rotated

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Investigation

• Lab studies
• 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 cases.
• Non specific features of acute inflammation-leucoc
  ytosis,ESR,CRP-are suggestive but not diagnostic .

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• Ask for
• gram stain, culture, leukocyte count with
  differential, and crystal examination
• leukocyte count
• generally higher than 50,000/µL, with a
  predominance of neutrophils more than 75
• gram stain
• are positive in approximately 75 of patients
  with staphylococcal infections however, results
  are positive in only 50 of patients with
  gram-negative infections

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• crystal examination
• exclude crystal-induced arthritis (may coexist)
• culture
• The definitive method
• for aerobic and anaerobic organisms.
• are positive in 85-95
• Synovial fluid glucose, protein, and lactic acid
  concentration not specific.

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• Imaging studies
• 1-Plain x-ray
• 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 arthritis).

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Septic arthritis of the hip following group B
strep psoas abscess
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Septic arthritis of the ankle
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• 2-Ultrasonography
• 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.

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• 3-Radio-isotope bone scan
• Show increase uptake of the isotope in the region
  of the joint. (may help in difficult site as
  sacroiliac sternoclavicular joints
• 4- CT scan
• This study may help to diagnose sternoclavicular
  or sacroiliac joint infections.
• 5-MRI
• MRI is most useful in assessing the presence of
  periarticular osteomyelitis as a causative
  mechanism.

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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
  diagnosis.
• Rheumatic fever

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complication

• Dislocation a tense effusion may cause
  dislocation
• Epiphyseal destruction in neglected infants
  the largely cartilaginous epiphysis may be
  destroyed ,leaving an unstable pseudarthrosis.
• Growth disturbance physeal damage may result in
  shortening or deformity
• Ankylosis if articular cartilage is eroded
  healing may lead to ankylosis
• Secondary osteoarthritis
• Osteomyleitis/abcess/sinus

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Treatment

• General Measures
• 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
  required.
• Other foci of infection and any coexisting
  medical conditions must be identified and treated
  appropriately.

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• 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 Ampicillin.
• 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.

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• Drainage
• Indication of Surgical Drainage
• 1-Joints that do not respond to antimicrobial
  therapy and daily arthrocentesis
• 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

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• Thank you

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