In adults

Differential diagnosis includes:

In children

Acute hip pain differential is usually primarily between septic arthritis and "transient synovitis"

n.b. Both of the above can present with acute hip pain, fever, limp or unwillingness to bear weight, limited ROM, and joint effusion

Ultrasound be effective in identifying the effusion.

I. Septic arthritis

  1. Bacterial infection of the joint space
  2. Rarer than transient synovitis, but more dangerous

II. "Transient Synovitis"

  1. A syndrome of acute hip pain in children, thought possibly to be viral; self-limited and without serious sequelae

Distinguishing SA from TS: