X-ray of the hip joint in childhood: features and rules

What is hip dysplasia?

Most often, an X-ray of the hip joint

in an infant or an older child. The pathology is quite common; it is detected in one out of seven children. Girls get sick more often - cases of the disease make up 80% of the total number. If the X-ray of the child’s hip joints is not interpreted on time, the disease is not detected and eliminated before the age of one year, it will lead to disability. Detection of the disease before the age of one month allows it to be completely eliminated. Diagnosis is quite complex and requires a high level of competence from the doctor, so you cannot rely solely on a visual examination; it is necessary to perform an x-ray for hip dysplasia in an infant to confirm or refute the diagnosis.

The disease is an underdevelopment of the head of the joint, cartilage, and ligaments, which is noticeable on x-rays of the pelvis in children. Heredity, polyhydramnios, malpresentation of the fetus and its high weight often play a role. Subluxation can occur directly during childbirth with malpresentation, and diseases related to gynecology and thyroid disease contribute to underdevelopment of the joints. The disease can be a consequence of tight swaddling or rickets of the baby.

Stages of development of hip dysplasia

There are three stages of this disease: preluxation, subluxation and dislocation. The sooner you find out how infants are given X-rays of the hip joints and undergo an examination, the more optimistic the prognosis.

Pre-luxation

Represents the mildest degree of the disease. At this moment, the head of the joint is unstable, it moves in the articular cavity, and subluxation or dislocation may develop.

Subluxation

An X-ray of the pelvis in newborns determines this stage when changes occur in the joint that are difficult to reverse. The head extends from the acetabulum, but does not extend beyond the limbus. At this stage, the ligament and capsule are stretched, the limbus is everted and cannot perform a supporting function. Because of this, the head moves freely up and to the sides. Proper treatment can provide relief from the disease. Progression leads to transition to the third stage of dysplasia.

Congenital dislocation

Often parents and doctors realize it at the last moment. An X-ray (hip dysplasia in children is not treated at this stage) can show the most serious stage of the disease - congenital dislocation. The head of the joint moves completely out of the acetabulum, the limbus moves downward, and the capsule and ligaments are stretched.

Pathology correction methods

A pediatric orthopedist deals with correction of hip dysplasia. After the most informative diagnosis and understanding of the degree of pathology in a particular patient, it is important to prescribe an appropriate treatment method.

The basic principle of any type of treatment is early initiation. Mild forms such as subluxation can be treated conservatively. The wide swaddling technique, exercise therapy, massage, and Pavlik stirrups are used. All techniques involve long-term holding of the legs in abduction and flexion positions and active movements within the permitted range.

For more complex or advanced forms, surgical treatment is used. It consists of correcting defective components of the hip joint - either the socket itself or the head (the operation never concerns the neck of the femur).

X-ray of a child's hip joint

X-ray of the hip joint

for infants it can be prescribed by an orthopedic doctor while still in the maternity hospital. Based on the results of this diagnostic method, appropriate treatment tactics will be prescribed.

What does normal look like?

The normal x-ray of the hip joint in an infant is when the doctor can visualize the articular head. It should be located in the acetabulum, and attached to it above and in the center by the round ligament. The head is held in place by a capsule; displacement from above is prevented by cartilaginous tissue called the limbus. The entire structure is supported by the thigh muscles.

Type of dysplasia

An X-ray of the hip joint in an infant, the norm of which differs sharply from the pathological condition, allows us to determine how advanced the condition is and what treatment tactics will be optimal. Subluxation and dislocation are characterized by displacement of ossification nuclei in different planes. In general, ossification points should appear at four months in girls and six months in boys. They are visible in children on x-rays of the hip joints.

Dislocation or subluxation occurs during childbirth, since most of the joint consists of cartilage, and the surfaces do not fully correspond to each other. The enlargement of the head often does not correspond to the socket, and childbirth results in a rupture of the femoral tissue.

What is hemolytic disease of the newborn?

Only 10% of all jaundices are pathological. This means that they may require more careful monitoring of the newborn, additional examination and treatment. In approximately 1% of newborns, jaundice is caused by hemolytic disease of the newborn (HDN).

Why does HDN occur? The reasons are differences in blood group, Rh factor or other factors of incompatibility between the blood of the fetus and mother. So, HDN occurs if:

• a Rh-negative mother has a fetus with Rh-positive blood;
• The mother has blood type 1, and the baby has 2 or 3.

Such differences lead to the formation of substances in the mother’s blood that destroy the red blood cells of the fetus. As a result, excessive amounts of hemoglobin and then bilirubin are released into the fetal blood.

How are hip x-rays done for young children?

An X-ray of the hip joint is taken for a newborn lying down, the baby’s legs are specially stretched and straightened. Bending at the knees or pelvis is unacceptable and will not provide the necessary information. The legs also need to be moved slightly inward.

Before X-raying a newborn's hip joint, it is best to have him sedated. This will ensure that the clarity of the image does not deteriorate due to movement. The child's genitals are covered with a lead apron, which avoids future reproductive problems.

What is physiological jaundice of newborns?

Up to 90% of the total number of jaundices are physiological. This means that they do not require medication correction, do not harm the child’s health and go away on their own over time.

Features of physiological jaundice are:

• the appearance of signs of jaundice no earlier than 2-3 days of life. Earlier onset of symptoms often has an unfavorable course;
• increasing manifestations by the end of the first week of life;
• the duration of the course is no more than 2-3 weeks. If jaundice persists, it makes sense to look for the cause;
• low intensity of skin coloring. Physiological jaundice is characterized by a change in skin color on the face and torso, as well as staining of the sclera. In this case, the baby’s arms and legs usually remain pink;
• no other symptoms other than skin coloring;
• no change in the color of urine and feces;
• no changes in the general blood test;
• in a biochemical blood test, the level of blood bilirubin increases due to indirect. At the same time, the level of liver enzymes (ALT, AST) remains normal;
• The blood bilirubin level never reaches critical values ​​sufficient for the development of neurological disorders.

Interpretation of radiographs for hip dysplasia

Interpretation of x-rays of the hip joints in a child should be performed by a specialist radiologist. This is painstaking work with a lot of subtleties. The structure consists of cartilage, so the doctor will use the Hilgenreiner diagram to decipher and establish the condition of the joint. The decryption is done like this:

• a vertical line is drawn through the center of the sacrum;
• a horizontal line is drawn along the lower edge of the iliac bones, they are visible very well;
• two perpendiculars descend through the upper outer edges of the iliac bones;
• A tangent line is drawn horizontally from the depression to the line, resulting in an acetabular angle, which had to be determined.

Based on the angle obtained, a conclusion will be drawn up regarding whether dysplasia was detected on x-rays of the hip joints in children. Up to one year, the norm for girls is considered to be an angle of 20 degrees, for boys - 18.4 degrees. At the age of five, an angle of fifteen degrees is considered normal for children of both sexes.

Alternative research methods for suspected dysplasia

A child up to three months old can undergo an ultrasound examination. Ultrasonography of the hip joints is a fairly accurate diagnostic method and is absolutely safe for a small patient. The information content of ultrasound in the case of detecting a congenital dislocation is not inferior to x-rays for children under six months of age, since thanks to this method the structure of the cartilage is visible. Indications for its implementation are the presence of risk factors for the development of dysplasia.

Today, a program to conduct ultrasound for all newborns as a screening method is being actively implemented.

X-ray examination

The main role in diagnosing congenital hip dislocation belongs to x-ray examination. We cannot support those doctors who keep a child with symptoms of hip dysplasia or dislocation from X-ray examination until 3 months of age (in the absence of an ultrasound method), explaining this by the negative impact of radiation on the baby. However, late diagnosis of the disease has an even worse impact on the child’s health.

An x-ray is taken with the child in the supine position with the legs extended and parallel. I would like to emphasize that in no case should you bend the limbs at the hip joints (which is also encountered during this study), since this changes the relationship in the hip joint in the frontal plane and, as a result, can complicate the correct interpretation of the main x-ray indicators.

As is known, most of the skeleton in young children consists of cartilage, and therefore the contours of the femoral head and acetabulum remain invisible on the x-ray image. In this regard, certain schemes are used to decipher radiographs.

It can be difficult to decipher a radiograph in newborns and young infants, since it is quite difficult to distinguish a moderately severe disorder of joint development from a lower variant of the norm. Therefore, auxiliary lines are drawn on the radiograph, with the help of which the distance and angles are measured.

The X-ray method of research plays a significant role in the diagnosis of dysplasia of the hip joint in newborns. During radiography, the child lies on his back with his legs extended and adducted in a position of some inward rotation, strictly symmetrically. The pelvis should fit snugly against the cassette. It is necessary to protect the genitals with a lead plate, which, if positioned correctly, does not interfere with radiography. When X-ray diagnosing diseases of the hip joints, it should be taken into account that newborns do not have ossification nuclei of the femoral heads and the acetabulum is also cartilaginous and does not provide a contrasting shadow. When reading radiographs, particular importance is attached to the condition of the upper edge of the acetabulum, the relationship of the upper end of the femur and the acetabulum. For this purpose, special diagrams are used, which, using special lines, establish the normal arrangement of the elements of the hip joint and, accordingly, make it possible to determine the displacement of the hip in relation to the socket and its degree. Various schemes have been proposed for early radiological diagnosis of congenital hip dysplasia.

Schemes for diagnosing VVB

Hilgenreiner scheme

Rheinberg circuit

Ombredan Scheme

Calvet and Shenton scheme

Rheinberg circuit

The distance between the midline and line B is measured, and line B1 is drawn at the same distance from the midline. In case of unilateral hip dislocation, a vertical line is first drawn on the healthy side and then on the diseased side.

With congenital dislocation of the hip, the proximal end is located outward from the vertical line B and above the horizontal line A. Another identifying feature is the lower edge of the femoral neck, the contour of which in the medial direction should smoothly intersect the lower contour of the horizontal branch of the pubic bone and form the correct line - Shenton's line.

Ombredan Scheme

Calvet and Shenton scheme

Hilgenreiner scheme

In our opinion, Hilgenreiner’s scheme is quite informative and at the same time simple. In our practice, to read radiographs we use a special transom grid proposed by Ter-Egiazarov G.M., Yukina G.P.

First of all, the value of the acetabular angle is calculated, which is normally less than 300 in children under 3 months of age and decreases to 20 degrees by the age of one year. The acetabular angle is the angle of the roof of the socket, formed by the intersection of a line drawn through the Y-shaped cartilages and a tangent running along the upper edge of the glenoid cavity.

The value h, which tells us about the vertical displacement of the head relative to the acetabulum, is the distance from the horizontal Hilgenreiner line to the middle of the metaphyseal plate of the proximal femur. Normally, this value is the same on both sides and ranges from 9 to 12 mm. A decrease in this indicator and its difference on the right and left indicate the presence of pathology.

Value d, indicating the lateral displacement of the femoral head relative to the acetabulum - the distance from the bottom of the acetabulum to the vertical line (value h). With normal development of the hip joints, it is also the same on both sides and should be no more than 15 mm. Hilgenreiner's scheme is convenient, reliable, gives an objective view of the hip joint, and is quite simple if you know how to read radiographs. Its great advantage is that it allows early detection of minor displacements of the femur outward and upward.

Other causes of jaundice in a newborn

Other reasons are extremely rare. These include:

1. Increased destruction of red blood cells due to medications, bleeding, or hereditary diseases. In this case, the clinic of the underlying disease comes to the fore, and jaundice acts as an additional symptom.
2. Rare genetic abnormalities that interfere with the functioning of liver enzymes. Some of them undergo screening tests of newborns in the maternity hospital. As a rule, jaundice is not their only symptom.
3. Impaired bile outflow associated with the abnormal structure of the biliary tract. For example, jaundice can occur due to congenital blockage of the bile ducts. Such jaundice is manifested by an increase in symptoms by 1 month of life, a characteristic greenish skin color, discoloration of feces and darkening of urine, a predominance of conjugated bilirubin in the blood, and the appearance of neurological symptoms. It is easily diagnosed by ultrasound of the abdominal cavity. Requires surgical treatment!