It may be time for a follow-up exam with her orthopedic surgeon. Depending on the shape and condition of the femoral head, changes can occur as the child grows and matures. Perthes disease is a condition that first affects the hip in children between the ages of four and eight.
The condition is also referred to as Legg-Calve-Perthes disease. The full name is in honor of the three physicians who each separately described the disease. In Perthes disease, the blood supply to the capital femoral epiphysis (growth center of the hip) is disturbed, causing the bone in this area to die. The blood supply eventually returns, and the bone heals.
How the bone heals determines how the condition will affect the child later in life. The main problem with Perthes disease is that it changes the structure of the hip joint. The amount and type of deformity will determine way the hip joint works. The greater the deformity after the condition has healed, the more difficulties the child may have with walking.
Toeing-in or toeing-out is rare with Perthes disease. It occurs because of a hump deformity of the femoral head left over after treatment. Instead of a nice, smooth, round head at the top of the femur (thigh bone), the disease leaves the child with a misshapen
femoral head. It can become more of an oval or egg shape. The leg rotates in (or out) in order to avoid pinching the hump part of the uneven femoral head against rim of the acetabulum (hip socket).
This type of pinching during hip movement is referred to as impingement. If the hump is small enough, no changes occur. But when a large enough anterior hump is present (toward the front of the femoral head), the hump comes up against the rim of the hip socket, thus preventing further hip flexion.
A large hump along the lateral (outside) half of the femoral head limits hip abduction. As the leg moves away from the body, now the laterally located hump bumps up against the acetabulum. Rotating the femur changes the location of the hump in the socket and reduces or eliminates the impingement. In other words, the hump deformity of the femoral head forces the upper part of the femur to adapt to keep motion as normal as possible.
Children who toe-in as a result of Perthes disease are more likely to seem like they are tripping over their own feet. If available, special three-dimensional CT scans can be taken to identify the cause of the problem. The surgeon will be able to advise you regarding further treatment if it’s needed.