This is an acute infection of the joint.

Aetiology

• Haematogenous spread from a primary focus elsewhere in the body

• Direct penetrating injuries into the joint

• Extension from a compound fracture of the neighbouring bone

The commonest causative organisms are staphylococcus, streptococcus, haemophilus influenzae and to a lesser extent salmonella. Large joints such as shoulder, knee, ankle and hip are more often affected. Septic arthritis is most common in children under 3 years of age.

Clinical Features

• Fever, chills and irritability

• Swollen, warm, very tender joint

• Pseudoparalysis of the joint

• Multiple joints may be affected.

Investigations

• Haemogram - anaemia and leucocytosis present

• Pus for C&S

• X-ray of the affected joint shows increased joint space, synovial thickening and later rarefaction of the adjacent bone surfaces.

Management

• Admit the patient

• Start on intravenous antibiotics - cloxacillin 50-100 mg/kg QDS + gentamicin 5-7.5 mg/kg TDS change according to C&S results and continue for 4-6 weeks

• Splint the joint

• Analgesics and antipyretics

• Aspirate the joint and if there is frank pus then refer for arthrotomy

Review daily until discharge.

Refer If

• The fever persists for more than 7 days of full treatment

• The joint swelling does not subside within 3 weeks

• New joints get involved while on treatment

• The affected joint starts to discharge pus spontaneously

• Shortening of the limb occurs

• There is persistent deformity of the joint

• Loss of function related to the infection.

Review monthly after discharge.