Introduction

Introduction to congenital dislocation of the hip

Congenital dislocation of the hip is one of the more common congenital malformations in children. It is more common in later dislocations. It exists at birth, more women than men, about 6:1, the left side is twice as much as the right side, and the bilateral side is less. . Mainly due to congenital dysplasia or abnormality of the acetabulum, femoral head, joint capsule, ligament and nearby muscles, resulting in joint relaxation, subluxation or dislocation. In addition, the fetal position in the uterus is abnormal, the hip joint is excessively flexed, and it is easy to cause Disease, and genetic factors are also more obvious.

basic knowledge

The proportion of illness: 0.004%

Susceptible people: infants and young children

Mode of infection: non-infectious

Complications: femoral head necrosis

Pathogen

Causes of congenital dislocation of the hip

Mechanical factor (45%)

The breech position has abnormal mechanical stress on the hip, which can cause dislocation of the femoral head. At birth, the humerus, ischium and pubis are only partially fused, and the acetabular fossa is extremely shallow, so the fetal hip joint has a large range of activity during childbirth, so that the fetus can easily pass through the birth canal. Therefore, the fetus is most prone to hip dislocation during the period before and after birth.

Endocrine factors (25%)

Ligament relaxation has been considered as an important disease factor. The increase of estrogen secretion in the mother during the late pregnancy will relax the pelvis, which is conducive to childbirth. It also causes the fetus ligaments to relax in the uterus, and the femoral head dislocation is more likely to occur in the neonatal period.

Genetic factors (25%)

Genetic and primary germplasm defects are thought to play an important role in the pathogenesis. The hip joint of the fetus begins with a fissure formed by interstitial cartilage, which is firstly deep and concave, then gradually shallower and semi-circular. If the lower extremity of the fetus is placed in the straight position, the femoral head is not easily placed in the depth of the acetabulum and is easily dislocated.

Pathogenesis

At birth, joint capsule relaxation is the main pathological change. As the age increases and the degree of dislocation increases, especially after walking, the following pathological changes can gradually occur:

1. The joint capsule is elongated and adheres to the tibia. The middle part is dumbbell-shaped.

2. The acetabular lip is thickened and begins to be everted. It becomes inversion with increasing walking. The round ligament grows thicker and the transverse ligament is thicker. The acetabulum is poorly developed due to the lack of normal pressure stimulation of the femoral head. Slope shaped.

3. Delayed development of femoral condyle, even ischemic necrosis, femoral neck anteversion and neck dry angle.

4. The femoral adductor muscle contracture, gluteal muscle relaxation.

5. False sacs are formed at the humeral wing, pelvic tilt and compensatory scoliosis.

Prevention

Congenital dislocation of the hip

This disease is a common malformation disease in the neonatal period. It is easy to find early, diagnose, and timely treatment.

If the disease is discovered after the child walks, then a series of surgical treatments are needed. The earlier the treatment of congenital dislocation of the hip, the better. If you are treated in infancy, your child will walk normally and will not have any influence in later life. However, if the treatment is delayed, it may cause permanent lameness or hip arthritis.

Complication

Congenital dislocation of the hip Complications femoral head necrosis

Both conservative treatment and surgical treatment can be complicated by avascular necrosis of the femoral head, and re-dislocation and joint stiffness can occur after surgery, and attention should be paid to prevention during treatment.

1. Avascular necrosis of the femoral head This is a iatrogenic complication, mainly caused by mechanical stress-induced arterial ischemia. Salter proposed five diagnostic criteria:

(1) One year after the reduction, the femoral epiphysis of the femoral head still does not appear.

(2) One year after the reduction, the existing bone nucleus grew stagnant.

(3) One year after the reduction, the femoral neck is widened.

(4) The femoral head is flattened, the density is increased or fragmentation occurs.

(5) residual deformity of the femoral head, including head flattening and enlargement, flat hip, hip varus, short neck and wide neck.

2. Postoperative dislocation after dislocation, although the incidence is not high, but once it occurs, the prognosis is poor, femoral head necrosis and joint stiffness can occur, should be prevented as much as possible, the main reason is that the joint capsule is not ideal, this is The most common cause; followed by the anteversion angle is too large and not corrected; there are head, sputum asymmetry, poor treatment, etc., should be strengthened prevention, once it occurs, should be treated early.

3. Hip joint movement is limited or stiff. This complication is more common. The older the patient is, the higher the incidence is. The higher the dislocation of the femoral head is, the heavier the contraction around the hip joint. If it is not corrected, the hip joint movement is very prone to occur. Restricted or stiff, especially after the application of hip herringbone plaster fixation is more likely to occur, should strengthen the early joint function exercise after surgery, take the hip abduction gypsum stent fixation, 1 week after surgery should sit up practice activities, can also Without cast immobilization, continuous passive activity (CPM) was used for joint function exercise.

Symptom

Congenital dislocation of the hip Symptoms Common symptoms Hip dislocation weakness Lower extremity shortening

Clinical manifestation

(1) Performance of newborns and infancy:

1 symptom:

A. Joint movement disorder: The affected limb is often flexed, the activity is worse than the healthy side, the pedaling force is on the other side, and the hip abduction is limited.

B. Short-term injury of the affected limb: the affected femoral head is dislocated to the posterior superior position, and the corresponding lower limb shortening is common.

C. Changes in the skin and perineum: The skin wrinkles on the buttocks and inner thighs are asymmetrical, the affected side skin is deeper than the healthy side, and the number increases. The baby's labia majora is asymmetrical and the perineum is widened.

2 check:

A. Ortolani trial and Barlow trial: for congenital dislocation of the hip from birth to 3 months, first proposed by Ortolani in 1935, modified by Barlow, Ortolani's method is to treat the child's knees and hips When it is bent to 90°, the examiner puts the thumb on the inner side of the thigh of the child, the index finger and the middle finger are placed on the greater trochanter, and the thigh is gradually abducted and externally rotated. If there is dislocation, the femoral head can be felt to be embedded in the acetabular rim. Slight abduction resistance, then lift the greater trochanter with the index finger and middle finger, the thumb can feel the bullet when the femoral head slides into the acetabulum, which is the Ortolani test positive, the Barlow test is opposite to the Ortolani test operation, the examiner The child's thighs are passively adducted, internal rotation, and the thumb is pushed outwards and pressed against the greater trochanter of the femur, and can feel a spring again.

B.Allis sign (Galezzi sign): make the newborn supine, knees 85 ° ~ 90 °, legs together, double heel alignment, if there is this disease, can see the height of the knees, this is the affected side of the femur up Caused.

C. Nesting test: the child is supine, the hip and knee joints of the affected side are flexed by 90°, the examiner holds the distal femur and the knee joint in one hand, and the other hand presses the groin of the affected limb. If the large rotor is moved up and down, it is positive for the nesting test.

D. Hip-knee flexion abduction test: the baby in the test is supine, the hip and knee joints are flexed, the examiner holds the knees with both hands, the thumb is on the inner side of the knee, and the other four fingers are on the outside of the knee. Normal infants can generally If the abduction is about 80°, if it is only 50° to 60°, it is positive, and only abduction 40° to 50° is strong positive.

(2) Early childhood performance:

1 symptom:

A. Minhang gait: Minhang is often the only complaint of the parents at the time of pediatric treatment. When one side dislocation, the performance is limp; when the dislocation is bilateral, it is duck step. The child's buttocks are obviously protruding and the lumbar lordosis is enlarged.

B. Short-term deformity of the affected limb: In addition to shortening, there is also an adduction deformity.

2 check:

A. Nelaton line: The anterior superior iliac spine and the ischial tuberosity are normally connected through the apex of the greater trochanter, called the Nelaton line, and the greater trochanter is above the line when the hip is dislocated.

B.Trende lenburg test: Children stand on one leg, the other leg bends hips as much as possible, bends the knee to make the foot off the ground, and the contralateral pelvis rises when standing normally; after the hip dislocation, the femoral head can not hold the acetabulum, gluteus medius The weakness, the contralateral pelvis descends, especially from the back, known as the Trende lenburg test positive, is a sign of hip instability.

(1) According to the relationship between the femoral head and the acetabulum: generally can be divided into the following three types:

1 congenital dysplasia: the femoral head only moves slightly outward, the Shenton line is basically normal, but the CE angle can be reduced, the acetabulum becomes shallow, and Dunn calls this a congenital dislocation of the hip.

2 congenital subluxation: the femoral head is displaced outwards, but still forms joints with the lateral part of the acetabulum, the Shenton line is discontinuous, the CE angle is less than 20°, and the acetabulum becomes shallow, belonging to the Dunn classification II.

3 congenital complete dislocation: the femoral head is completely outside the true acetabulum, forming a joint with the lateral aspect of the humerus, gradually forming a false acetabulum, the original joint capsule is embedded between the femoral head and the tibia, belonging to the Dunn classification III .

(2) Classification according to the degree of dislocation: Sun Caikang is divided into the following 4 degrees according to the standard of Zients:

1I degree dislocation: the femoral head nucleus is below the Y line, outside the upper rim of the acetabulum.

2 degree II dislocation: the femoral head nucleus lies between the parallel line of the upper edge of the y-line and the y-line.

3III degree dislocation: the femoral head nucleus is located at the height of the parallel line of the upper edge of the iliac crest.

4IV degree dislocation: the femoral head nucleus is located above the parallel line of the upper edge of the iliac crest and has false sputum formation.

Examine

Congenital dislocation of the hip

1.Von-Rosen (outreaching rotation) filming method

The baby is supine, the two hips are straightened and abducted 45°, and the endoscopic position is taken as far as possible. Normally, the upward extension of the femoral axis intersects the lumbosacral plane through the outer edge of the acetabulum, but when the hip is dislocated, This line intersects the anterior superior iliac spine above the lumbosacral plane. However, the hip dislocation of individual children is abducted, the internal rotation has the possibility of natural reduction, and the results are normal. This method is more reliable and suitable for newborns. The femoral skulling center has not yet appeared.

2.Perkin quadrant

After the occurrence of nucleus ossification of the femoral skull, the Perkin quadrant can be used to determine the dislocation of the hip joint, that is, a line between the acetabular centers on both sides, called the H line, and then a vertical line from the outer edge of the acetabulum to the H line. P line), the hip joint is divided into four quadrants, the normal femoral condyle is located in the inner lower quadrant, subluxation in the outer lower quadrant, and full dislocation in the outer upper quadrant.

3. The acetabular index is connected from the outer edge of the acetabulum to the center of the acetabulum. The acute angle formed by the intersection of the acetabular index and the H line is called the acetabular index. The normal value is 20° to 25°. After the child begins walking, the competition is The annual decrease is almost constant at around 15° at 12 years of age, and the angle is significantly increased when the hip is dislocated, even above 30°.

4. The CE angle is also called the center edge angle, which is the angle formed by the line connecting the center line of the femoral head to the YY line and the line connecting the outer edge of the acetabulum and the center of the femoral head. The relative position of the iliac crest and the femoral head is valuable for the diagnosis of acetabular dysplasia or hip subluxation, and is normally below 20°.

5. When the Shenton line is normal, the curved line on the upper edge of the obturator is connected with the curved line on the inner side of the femoral neck to form a continuous arc called the Shenton line. This line is interrupted when the hip joint is dislocated.

6. The Simon line is the outer superior edge of the humerus to the outer upper edge of the acetabulum. Then, a downward longitudinal arc is formed along the outer edge of the femoral neck. The arc is also interrupted when the hip is dislocated.

7. Hip arthrography

In infancy, the femoral head has not been ossified, most of the hip joints are cartilage, and are not developed on the X-ray film. Therefore, hip arthrography is beneficial to observe the translucent part and soft tissue structure of the joint. The method is: the child is in a supine position. General anesthesia, under aseptic operation, insert the 18th needle with a needle core 1.5 to 2 cm below the anterior superior iliac spine. After entering the skin, align the acetabulum downwards and inward until it touches the acetabulum, then turn External access to the joint capsule, injection of contrast agent, can be observed in normal hip joints:

(1) The size and shape of the femoral head.

(2) The cartilage margin of the acetabulum.

(3) The annular region, that is, the region surrounding the joint capsule, the transparent region surrounding the femoral neck is visible, and the contrast agent is divided into two.

(4) Transverse ligament, which is expressed as the indentation under the contrast agent.

(5) Round ligaments.

Congenital dislocation of the hip, such as the inversion of the joint rim, can have a filling defect between the femoral head and the acetabulum, the joint capsule has obvious contraction, and there is a band shadow in the acetabulum, indicating a thick round ligament.

8. CT examination Recently, some scholars have used CT to examine the congenital dislocation of the hip in infants and young children. The bone defect can be seen, the acetabular deformation causes dislocation, and the bone changes can be seen. The soft tissue is embedded and the femoral neck is tilted forward. The degree of dislocation of the femoral head.

Diagnosis

Diagnosis and diagnosis of congenital dislocation of the hip

Diagnosis can be established based on medical history, clinical manifestations, signs, X-ray examination and measurement.

Note that it should be differentiated from hip synovitis. Hip synovitis, also known as transient (temporary) synovitis of the hip, is a multiple disease. Children under 3-10 years of age are prone to hip synovitis, with men being more common and most children having a sudden onset. The peak incidence was 3 to 6 years old, the right side was more than the left side, and the bilateral hip joints accounted for 5%. The cause of the disease may be related to viral infection, trauma, bacterial infection and allergic reactions (allergic reactions). Onset is either anxious or slow. The child described the pain in the front or side of the thigh and knee joint. The body can be found to avoid painful gait, there is tenderness in front of the hip joint, and the range of motion is limited and uncomfortable.