Septic arthritis

Causative organisms:

• Staph. aureus (most common)
• Streptococci
• N. gonorrhoea
• Haemophilus influenzae

Clinical features:

• Is a medical emergency

In the young the joint is:

• Hot
• Swollen
• Red
• Agonisingly painful
• Held immobile by muscle spasm

In the elderly/immunocompromised:

• Clinical picture is less dramatic

Investigations:

Aspirate the joint:

• Send the fluid for urgent Gram stain and culture
• The fluid is usually frankly purulent

Blood cultures:

• Are usually positive

Leucocytosis:

• Is usual, unless the patient is severely immunocompromised

Treatment:

• Should be started IMMEDIATELY on diagnosis as joint destruction occurs in days
• IV antibiotics should be given for a week
• It is usual to give 2 antibiotics to which the organism is sensitive for 6 weeks, then 1 for a further 6 weeks orally
• Immobilize the joint initially
• Physiotherapy should be started early to prevent stiffness and muscle wasting

Empirical treatment in septic arthritis:

Usually give:

• Flucloxacillin 1-2g IV QID, plus
• Fusidic acid 500mg PO TID

If the patient is allergic to penicillin, replace flucloxacillin with:

• Erythromycin 1g IV QID
• Clindamycin 600mg IV TID

In immunocompromised patients:

• Flucloxacillin 1-2g IV QID, plus
• Gentamycin IV (to cover anaerobes)

Prognosis:

• Surgical drainage may be required if there is joint destruction and osteomyelitis
• Patients can start weight-bearing as soon as the inflammation subsides
• Resolution of the arthritis with complete recovery can occur in a few days or weeks