Perthes Disease is a disease that affects the hip bone where it meets the pelvis. This disease, is seen in children, usually between the ages of five and ten. Boys tend to get this disease more frequently than girls, although girls can also develop it.
In this disease, the hip bone deteriorates due to decreased circulation to the top of the bone, called the "femoral head." The hip joint becomes weak, and is not able to handle weight. This results in pain in the child's hip or knee. Occasionally, there will be a limp. To diagnose this disease, your doctor needs to do x-rays of the hip.