Are your baby's leg lines "symmetrical"?

Author: Yuan Lizhi Zhengzhou Central Hospital

Reviewer: Yan Yuanyuan, Chief Physician, Zhengzhou Central Hospital

Every baby is an angel who has been born. The arrival of an angel brings so much joy to every family, but their growth may not always be smooth sailing. Doctors and parents need to work together to protect them. After the baby is born, regular child health checks are required. When the baby is three or four months old, some babies will have asymmetrical leg lines, especially fat babies. At this time, the doctor will recommend hip ultrasound. The biggest question parents have is "Is the asymmetry of leg lines so serious? Is it necessary to do this examination?" The answer is yes, this examination is very necessary. So what are doctors worried about?

Why do you need a hip ultrasound?

The purpose of pediatric hip ultrasound is mainly to screen for developmental hip dysplasia, including unstable hip joint, acetabular dysplasia, hip subluxation and hip dislocation, with an incidence of about 1/1000. The acetabulum of such children becomes shallow, allowing the femoral head to easily slide in or out of the acetabulum. When the femoral head partially or completely dislocates from the acetabulum, it forms a subluxation or dislocation. If we can detect hip dysplasia in the early stages and treat it early, the hip joint can develop normally. If treatment is delayed, it may lead to varying degrees of joint deformity and dysfunction in children, and osteoarthritis and even spinal curvature deformity may occur in the future. In the late stage, femoral head necrosis and even disability and other irreversible pathological changes may occur, seriously affecting the quality of life.

Clinical manifestations of hip dysplasia

The inguinal lines on the affected side become shorter or disappear, the hip lines or leg lines increase or rise, the hip abduction is limited, there is a snapping sound or snapping sensation when the affected lower limb is pulled, the lower limbs are unequal in length, and the lower limbs have movement disorders, etc. It is usually more common on the left side than on the right side, and more common in women than in men.

What causes hip dysplasia?

The exact cause is still unclear, including internal factors such as loose joint ligaments, female sex (high estrogen levels during pregnancy and childbirth cause loose pelvic ligaments, and female babies may be sensitive to maternal estrogen, leading to loose hip ligaments) and heredity; external factors such as breech presentation, first pregnancy, oligohydramnios, macrosomia, multiple births, and incorrect parenting methods (candle wraps, leggings, etc.). It is now generally believed that hip dysplasia is caused by the combined effects of multiple internal and external factors.

Early diagnosis of developmental dysplasia of the hip is very important

For infants under 6 months old, since the hip joint and femoral head have not yet ossified and are mostly cartilage structures, ultrasound examination is the preferred screening method, which can accurately evaluate the shape of the hip joint, the position of the femoral head and the stability of the hip joint. For infants over 6 months old, the femoral head gradually ossifies, and the first recommended examination method at this time is X-ray.

Pediatric Hip Ultrasound Procedure

The process of pediatric hip ultrasound is very simple. No preparation is required before the examination. The examination can be completed in 2 to 3 minutes with the presence of the parents, keeping the child in a quiet state (preferably sleeping), and cooperating with the ultrasound doctor to complete the corresponding body position (mostly side-lying position).

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Which infants and young children need ultrasound examination of the hip joint?

1. Physical examination suggests hip joint abnormalities.

2. There is a family history of hip dysplasia.

3. Buttocks presentation (especially buttocks presentation with legs extended).

4. The mother has too little amniotic fluid.

5. Swaddling methods that bind the legs of newborns and infants or force the hips to be stretched and the legs to be closed.

6. Neuromuscular diseases, such as congenital torticollis, congenital foot deformity, etc.

For those with the above high-risk factors, parents are advised to have an ultrasound examination 4 to 6 weeks after the birth of their children. Ultrasound screening is available in areas with medical conditions.

Treatment

The severity of hip dysplasia varies from child to child, but the goal of treatment is the same, which is to return the dislocated femoral head to the acetabulum to achieve stable concentric reduction, so that the hip joint can develop normally. The younger the child is when the treatment is given, the better the effect and the shorter the treatment time. Children aged less than 6 months can generally be treated with Pavlik slings. For children with simple hip dysplasia or subluxation, the success rate of early reduction with Pavlik sling treatment is as high as more than 95%. However, the success rate of reduction of children with complete dislocation using this method is low, and they usually prefer closed reduction and plaster pants treatment after direct traction. For children aged 6 to 18 months, non-surgical treatment is often used, with manual reduction under anesthesia and fixation with plaster or stents, which has a better effect. For children aged more than 3 years, the failure rate of manual reduction is high, and surgical incision reduction is often required.

The seemingly insignificant asymmetry of leg lines may affect the healthy growth of the baby, so parents should not take it lightly! Of course, parents do not need to panic too much. It does not mean that once the baby has asymmetric leg lines, there must be problems with the hip joint. Some may be due to simple obesity leading to asymmetric fat distribution. Just cooperate with the specialist for a physical examination and complete relevant examinations when necessary.