Septic left hip in 2 year old. Image source: L. Davidson

The child with a septic hip is acutely ill, often with a fever as well as laboratory evidence of infection (elevated white blood cell count, increased % neutrophils on differential, elevated ESR and C-reactive protein). The illness comes on quickly and may be characterized either by an antalgic gait or by refusal to walk (especially in very young children).

Physical examination reveals extreme pain and guarding upon passive motion of the affected hip. Radiographs are usually normal; an ultrasound scan will reveal fluid in the hip joint.

Hip aspiration (done under x-ray guidance) is diagnostic. The fluid is grossly abnormal (thick, yellow). Gram stain, joint fluid cell count and culture (which takes 48 hours) are generally diagnostic. Blood cultures are also recommended. The organism responsible for most septic hips in otherwise healthy children is staphylococcus aureus.

A septic hip is a surgical emergency requiring urgent surgical drainage in the operating room as well as hospitalization for intravenous antibiotics. A 3-4 week cours of antibiotics is required.