How is Perthes disease different in children?

Perthes disease affects the blood supply to the rounded top of the thigh bone inside the hip. A child may limp, avoid running, or describe pain in the hip, groin, thigh or knee. Knee pain can therefore be referred from the hip. Stiffness may limit how far the leg moves out or rotates. Symptoms can vary from day to day, and some children have little pain despite restricted movement. The condition is managed with the child’s age, hip movement, symptoms and examination findings in mind.

Arrange evaluation if a child develops an unexplained limp, persistent hip or knee pain, or difficulty keeping up with normal play. Until assessed, avoid activities that cause limping or pain and choose calm movement within comfort. Follow the orthopaedic plan about activity, exercises, follow-up imaging and any walking support. Keeping appointments matters because the shape and movement of the developing hip can change during the condition.

Seek urgent medical advice if the child cannot bear weight, has sudden severe hip pain, fever, appears very unwell, or the joint becomes markedly swollen or hot. A new limp after an injury also needs assessment. Do not rely on the child pointing to the knee to locate the problem; a hip examination may be needed even when the knee is the painful area.

Ask which activities are allowed, how to protect hip movement, what follow-up is planned, and which changes should prompt an earlier visit. Share when the limp began, whether pain occurs at rest or at night, and whether the child has stopped particular games or movements.