Rheumatological disease in a child: Infective arthritis Flashcards
Define infective arthritis.
An infectious arthritis of a synovial joint, mostly affecting the lower limb (75%) Knee> Hip> Ankle.
Other 25% are in upper limbs.
Explain the aetiology of infective arthritis?
Septic arthritis can develop from osteomyelitis especially in neonates where infection spreads from the metaphysis via transepiphyseal vessels. It may also arise due to haematogenous spread of infection or by direct inoculation.
What are the causes of infective arthritis aged <12 months?
Staphylococcus aureus
Group B streptococcus
Gram –ve bacilli
Candida albicans
What are the causes of infective arthritis aged 1-5 years?
Staph. aureus
Haemophilus influenza (rarely in immunized children)
Group A streptococcus (pyogenes)
Streptococcus pneumonia
Kingella Kingae
Neisseria gonorrheae (child abuse)
What are the causes of infective arthritis aged 5-12 years?
Staph aureus
Group A streptococcus
What are the causes of infective arthritis aged 12-18 years?
Staph. aureus
Neisseria gonorrhoeae (sexually active)
Which cause of infective arthritis is increasing worldwide?
Community acquired MRSA (CA-MRSA)
Summarise the epidemiology of infective arthritis.
The frequency is highest in young children with half of all cases presenting in the first 2 years.
Males > female (2:1).
What are the signs and symptoms of infective arthritis?
Infants characteristically do not appear ill. 50% do not have fever.
In the older child—acute onset; decreased range of movements or pseudoparalysis; pain on passive motion; hot, warm, swollen joint; inability to weight bear; systemic symptoms of infection.
In <10% of cases more than one joint affected (except gonococcal infections). The clinical picture may be less acute if the child has received antibiotics.
What are appropriate investigations for infective arthritis?
Bloods: FBC, ESR, CRP, blood cultures; Lyme titres if exposure.
X-ray of joint: Usually normally initially (widened joint space suggests an effusion). Subluxation/dislocation, joint space narrowing and erosive changes are later signs.
Joint aspiration: Most useful diagnostic investigation. Send aspirate for microscopy and culture. PCR may be useful if already on antibiotics.
US: To detect effusion and guide aspiration.
MRI: If diagnosis in doubt to exclude osteomyelitis, (do not delay treatment while waiting for MRI).
CT: To image sternoclavicular and sacroiliac joints. Psoas abscess.
Bone scan: If multiple sites and child too unwell to localize pain.
Lumbar puncture: If a septic joint with Haemophilus influenza (increased incidence of meningitis).
What is the management for infective arthritis?
Medical: IV antibiotics, after aspirate is taken, for up to 3 weeks (until inflammatory markers normalize) , followed by oral antibiotics for a total of 4-6 weeks. Outcome of treatment is time dependent.
Surgical: Early referral to orthopaedic team as there is low threshold for irrigation and debridement of the affected joint (+ drainage of any associated osteomyelitis).
Splintage: In the acute setting a brief period of splintage improves pain and allows inflammation to settle. Splint in position of function.
Physiotherapy: To avoid joint stiffness.
What are possible complications associated wtih infective arthritis?
Chondrolysis
Ongoing infection and bone destruction
Joint incongruity/stiffness
Growth disturbance
Avascular necrosis of the femoral head can occur
What is the prognosis of infective arthritis?
Usually good unless the diagnosis is delayed. Recurrence of disease and development of chronic infection occur in <10%.
Long-term follow-up is needed as growth-related sequelae may not become apparent for months or years. Hip joint infection has the worst prognosis for anatomical and functional impairment.
