Toxic (also known as transient) synovitis may present similarly to a septic hip with an acutely antalgic gait or even refusal to walk. Systemic symptoms and signs such as fever are generally absent and bloodwork is normal. The child or parent may recall a viral illness (often upper respiratory) within the prior few weeks. Physical examination reveals pain on hip motion, but usually the range is not as restricted as with a septic hip. Hip aspiration is required in equivocal cases to rule out bacterial infection. This is presumed to be a viral or post-viral syndrome as synovial fluid cultures are negative. Mild or moderate cases are treated with rest (off school, out of sports) and observation.