Septic Arthritis Flashcards
What is septic arthritis?
Septic arthritis is a serious infection of the joint space, which can lead to bone destruction
Who is septic arthritis most common in?
Children less than 2 years old
How many joints are affected in septic arthritis?
Usually only one joint
What joints are most commonly affected in septic arthritis?
Knee > hip > ankle
What joint is of particular concern in septic arthritis in young children?
The hip
What might septic arthritis result from?
- Haematogenous spread (usual mechanism)
- Puncture wound
- Infected skin lesions, e.g. chickenpox
- Spread of adjacent osteomyelitis
When can septic arthritis result from the spread of adjacent osteomyelitis?
In young children
What must be true of the joint in order for septic arthritis to have spread from adjacent osteomyelitis?
It must be a joint where the capsule inserts below the epiphyseal growth plate
What are the causative organisms for septic arthritis in children <12 months old?
- S. Aureus
- Group B streptococcus
- Gram -ve bacilli
- Candida albicans
What are the causative organisms for septic arthritis in children aged 1-5 years?
- S. Aureus
- Haemophilus influenza
- Group A streptococcus (pyogenes)
- Streptococcus pneumoniae
- Kingella kingae
- Neisseria gonorrhoeae
When is haemophilus influenza causing septic arthritis rare?
In immunised children
What does septic arthritis caused by neisseria gonorrhoae raise concerns of?
Child abuse
What are the causative organisms for septic arthritis in children aged 5-12?
- S. Aureus
- Group A streptococcus
What are the causative organisms for septic arthritis in children aged 12-18?
S. Aureus
What are the risk factors for septic arthritis?
- Immunodeficiency
- Sickle cell disease
What is the problem with the diagnosis of septic arthritis in infants?
They typically do not appear ill, with 50% not having a fever
What are the clinical features of septic arthritis 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
When might the clinical picture in septic arthritis be less acute?
If the child has received antibiotics
What investigations are done in septic arthritis?
- Blood tests
- Ultrasound of deep joints
- X-ray
- Aspiration of joint space
What is found on blood tests in septic arthritis?
Increased WBC, ESR, and CRP
What is the purpose of ultrasound of deep joints in septic arthritis?
Helpful to identify effusion
What is the importance of x-ray in septic arthritis?
Exclude trauma and other bony lesions
What may be shown on x-ray in septic arthritis?
Usually normal initially, but later signs include subluxation/dislocation, joint space narrowing, and erosive changes
How is aspiration of the joint space performed?
Under ultrasound guidance
What is the purpose of aspiration of the joint space in septic arthritis?
To get synovial fluid for organisms and culture
What is the importance of aspiration of the joint space in septic arthritis?
It is the definitive investigation
When is aspiration of the joint space ideally performed in septic arthritis?
Immediately, unless it would cause significant delay in giving antibiotics
What further imaging may be useful in septic arthritis?
- MRI scanning
- Radioisotope bone scan
When might further imaging be useful in septic arthritis?
If the infection site is unclear
What are the differential diagnoses of septic arthritis?
- Transient synovitis
- Rheumatic fever
- Kawasaki disease
What is the medical management of septic arthritis?
IV antibiotics for up to 3 weeks (until inflammatory markers normalise), followed by oral antibiotics for a total of 4-6 weeks
What needs to be done before giving IV antibiotics in septic arthritis?
Aspirate needs to be taken
What does the surgical treatment for septic arthritis involve?
Early referral to the orthropaedic team, with potential for irrigation and debridement of the affected joint
Is there a low or high threshold for irrigation and debridement of the affected joint in septic arthritis?
Low
Describe the use of splinting in septic arthritis?
A brief period of splinting may be useful in the acute setting to improve pain and allow inflammation to settle
In what position should you split the joint in septic arthritis?
The position of function
What is the use of physiotherapy in septic arthritis?
It may be useful to avoid joint stiffness
What are the potential complications of septic arthritis?
- Chondrolysis
- Ongoing infection and bone destruction
- Joint incogruity/stiffness
- Growth disturbance
- Avascular necrosis of femoral head
