Presentation
Two days of pain in the left hip after a martial arts class. On physical examination, there was severe pain in the left hip and the patient was unable to walk. Elevation of C-reactive protein stands out in laboratory tests. Bilateral hip ultrasound was performed.
Patient Data
Effusion in the anterior recess of left hip joint up to 5.4 mm. No hypervascularity of adjacent tissues. Intact femoral bone cortex. Normal right hip joint.
Case Discussion
A child with severe hip pain, elevated CRP, and hip joint effusion is highly suspicious of septic arthritis. At surgery, it was demonstrated pus in the left hip joint. At blood and hip joint effusion cultures, Staphylococcus aureus was isolated. The absence of hypervascularity at the power-Doppler study doesn't rule out septic arthritis: the radiologist should take into count the other variables.