Irritable hip is a common childhood condition that causes symptoms such as hip pain and limping. Doctors sometimes refer to irritable hip as transient or toxic synovitis. Hip pain isn't usually severe, but your child may be reluctant to place weight on the affected leg. Occasionally, an irritable hip may also cause: pain in the knee or thigh restricted movement in one of the hip joints a slightly higher temperature than normal – a normal temperature is around 37C (98.6F) In younger children who are unable to speak, the only noticeable symptom may be crying at night.