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» Abnormal Walking Pattern in Children with Perthes Disease
Abnormal Walking Pattern in Children with Perthes Disease

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Physical Therapy in Cleburne for Pediatric

In this study, surgeons look into the cause of toeing-in or toeing-out while walking for children with Perthes disease. Nine children with this condition were included. They didn't develop this change in how they walked until they were older (between seven and 15-years old). 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. The nine children included in this study started toeing-in or toeing-out 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 left them with a misshapen femoral head. It was more of an oval or egg shape. The leg rotated 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. Because of its location in the hip, the impingement was labeled femoroacetabular impingement (FAI).

Using three-dimensional (3-D) CT scans, they found that in-toeing was to compensate for a laterally deviated(rotated) femoral hump. And out-toeing occurred in hips with an anteriorly deviated femoral hump. Lateral means the hump was to the side. Anteriorly tells us the hump was more forward along the front of the femoral head. By comparing the deformed side to the normal hip, they were able to measure how much rotation there was of the femur in relation to the acetabulum.

The 3-D CT scans were helpful because they took cross-sectional slices of the femoral head and hip joint as if viewed from above (bird's-eye view). The shape of the femoral head was clearly seen. The size, shape, and location of the hump was measured and described. Hip range-of-motion measurements were taken and compared to the impingement pattern based on whether the child toed-in or toed-out during walking.

They found that the hips of children who toed-out rotated out on the affected side when they walked while the pelvis rotated in on the other (unaffected) side. At the same time, hip flexion on the involved side was decreased compared to the uninvolved hip. Several children in the toe-out group also had limited hip extension.

The opposite was true for the in-toeing group. The affected hips were internally rotated while the pelvis on the opposite side was externally rotated. There was a significant loss of external rotation in the Perthes hip of the in-toeing patients. An equal number of children in the in-toeing group had a loss of hip extension. Movement of the leg away from the body called abduction was also limited in all children in the in-toeing group.

The authors make note of the fact that out-toeing and especially in-toeing are normally rare in children with Perthes disease. The fact that there were only nine children over nine years at their clinic with this problem was proof of that. This type of abnormal gait pattern comes about because of changes in the shape of the femoral head. The location, shape, and size of the hump determines where and how much femoroacetabular impingement occurs. The upper portion of the femur rotates as a way to avoid impingement when walking.

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.

The 3-D CT scan helped the researchers understand the biomechanical changes in the hips of children with Perthes who had an in-toed or out-toeing gait pattern. Basically, the hump deformity of the femoral head forces the upper part of the femur to adapt to keep motion as normal as possible. The pattern of change will depend entirely on the hump size, shape, and location.

The authors suggest using 3-D CT to map details of the femoral head before surgery. Getting an even, round shape of the femoral head is important in the treatment of advanced Perthes. Avoiding an ovoid-shaped deformity of the femoral head can also prevent gait disturbances.

Reference: Won Joon Yoo, MD, et al. Out-Toeing and In-Toeing in Patients with Perthes Disease. In Journal of Pediatric Orthopaedics. October 2008. Vol. 28. No. 7. Pp. 717-722.

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