Congenital dysplasia of the hip Congenital dislocation of the hip (CDH), also known as developmental dislocation of the hip (DDH), is a lesion that has a significant impact on the health of children, and if diagnosed and treated early the clinical outcome is satisfactory. Congenital dislocation of the hip, also known as developmental hip dislocation, is one of the major disorders that cause physical disability in children. There are obvious differences in the incidence of congenital hip dislocation in different regions of the world, and there is no complete statistical information in China, about 0.91‰ in some maternity hospitals in Shanghai, 3.8‰ in Beijing, 1.75‰ in a hospital in Shenyang and 0.07‰ in Hong Kong.
These data are not comprehensive enough and do not reflect the incidence rate in China, which is estimated to be about 1 per 1,000. About 20% of the prelapsed hips have family history; 80% of the prelapsed hips are the first child; the family inheritance of a newborn census in a hospital in Shenyang is 1/14, and only 4 cases out of 226 cases in Toronto Children’s Hospital in Canada have genetic history; genetic factors are not important factors in the development of prelapsed hips. The incidence rate of anterior hip dislocation is absolutely dominated by girls, and the ratio of men to women in China is 1:4.75. The incidence rate varies greatly by region and race, which is related to genetic factors, environmental influences and living habits; the incidence rate is low in ethnic groups that are used to carrying babies on their backs, such as South Africa, some regions in Central Africa, Eskimos, Koreans and Guangdong and Hong Kong; ethnic groups that prefer to use binding methods to fix the hip joint of newborns The incidence is significantly higher for those who prefer to bind the hip joint in an extended, inward position, such as North Italy, North American Indians, Germany and North Scandinavia, as well as the habits of the Han Chinese in China. The incidence is significantly higher in infants born in winter. The incidence of breech birth is higher, about 23% in foreign countries, 26% in Shanghai, 28.5% in Shenyang, and only 5% in normal births; the incidence of anterior hip dislocation is 10 times higher in breech births than in cephalic births; the incidence of anterior hip dislocation is higher in cesarean births than in vaginal births, accounting for 30% in Shanghai statistics, with significant differences, and the incidence of babies with heavy body weight in cesarean births is found to be high.
The main pathological features of congenital hip dislocation are.
1, tension and contracture of the iliopsoas muscle, which compresses the entrance of the acetabulum.
2, deformation of the joint capsule in a gourd-like pattern.
3. deformation of the femoral head and neck, mainly with an oval-shaped femoral head, short femoral neck and increased anterior femoral neck inclination.
4, deformation of the acetabulum, mainly with a shallow and triangular acetabular fossa, increased acetabular index and involution of the glenoid lip of the joint.
5, thickening and lengthening of the femoral round ligament, degeneration of articular cartilage, etc.
Subtypes of congenital hip dislocation.
1, simple congenital hip dislocation
(1) hip dysplasia: also known as hip instability, X-ray films are often characterized by an increase in the acetabular index, most of which are self-healing with an external hip booth, about 1/10 will develop into congenital hip dislocation in the future, and a few cases persist with acetabular dysplasia and develop symptoms when they grow older.
(2) Hip subluxation: X-ray has an increased acetabular index with the acetabulum covering part of the femoral head, which is an independent type that can persist for a long time without transforming into total dislocation.
(3) Total dislocation of hip joint: the femoral head is completely dislocated from the acetabulum, which can be divided into four degrees according to the height of the dislocation of the femoral head: degree I: the femoral head is only displaced outward and is located at the same level of the acetabulum; degree II: the femoral head is displaced outward and upward, which is equivalent to the level of the outer upper part of the acetabulum; degree III the dislocated femoral head is located at the part of the iliac wing; degree IV the dislocated femoral head is displaced upward to the level of the sacroiliac joint.
2.Deformed congenital
The typical hip dislocation is double hip dislocation, both knees are stiff in the extension position and cannot be flexed, both feet are flat-footed in the external rotation position, and often combined with upper limb deformity.
A, newborn and infant congenital hip dislocation
1, congenital hip dislocation in the neonatal period is more difficult to diagnose, once diagnosed treatment is easy, and will get the ideal treatment effect.
Because the pathological changes in the neonatal period are the lightest and easy to correct; the pelvis develops the fastest in the first year after birth, especially in the neonatal period.
2.Clinical symptoms
Appearance: thighs and calves are asymmetrical with the opposite side), which can be manifested as thickening and shortening or thinning, external rotation (unilateral); buttocks widening (bilateral). Dermatoglyphic pattern: increased, deepened and upwardly displaced asymmetric limb movement in the buttocks, groin and thighs: little movement in the affected limb, most easily detected during diaper changes.
3. physical signs weakened or absent femoral artery of the affected limb.
The positive Barlow’s test (only for newborns), because hip instability decreases with age and abduction restriction increases with age. positive Ortolani’s sign or abduction test, which is reliable. destruction of Nelaton’s line sign.
4.X-ray examination
Von-Rosen position pelvic plain radiograph: normal extension line through the outer edge of the acetabulum intersecting below the plane of lumbar 5 and sacral 1.
Pelvic plain radiograph: acetabular index normal at 20-25°, basically constant at 15° by age 12, abnormal at >30°.
Perkin’s square: normal located in the lower inner quadrant
Shenton’s line: the distance from the apex of the Hilgenereiner femoral epiphysis to the horizontal line is measured as H, normal is 10 mm; the distance from the apex of the femoral epiphysis to the innermost edge of the acetabulum is d, normal is 12 mm. When the H value is less than 10 mm or the d distance is greater than 12 mm, hip dysplasia should be suspected.
Bertol measurement: normal upper gap a is 9.5 mm and medial gap b is 4.3 mm. if a is less than 8.5 mm and b is greater than 5.1 mm hip dislocation should be suspected. If a is less than 7.5 mm and b is more than 6.1 mm, it can be diagnosed as hip dislocation.
5. Differential diagnosis
(1) congenital hip inversion
(2) pathological hip dislocation
(3) paralytic and spastic hip dislocation
(4) Rickets
6.Treatment of congenital hip dislocation in newborn and infancy
(1) diaper pillow
(2) Dressing device
(3) Pavlik harness
(4) Von-Rosen aluminum splint
(5) Continuous traction repositioning
(6) Plaster fixation with closed reduction of the adductor muscle + brace Pavlik fixation belt, which should be used for 3-4 months.
Second, congenital hip dislocation in early childhood and children
1.Clinical symptoms
Late walking, abnormal gait: unstable gait at the beginning of walking with waddling, swaying or rocking gait (unilateral); duck walking gait in bilateral cases, unequal limbs, compensatory scoliosis of the trunk
2. Physical signs
Positive Allis sign (unilateral)
Positive Ortolani sign or abduction test
Nelaton line sign destruction
Positive Trendelenburg sign
3.X-ray examination
Acetabular index
CE angle: normal value +15° or more at age 4, +20° or more at age 15
Perkin’s square
Shenton’s line
Sharp’s angle: this angle >40° means acetabular dysplasia.
Measurement of femoral neck anteversion angle: X-ray double plain film
Head socket index (AHI): The distance A from the inner edge of the femoral head to the outer edge of the acetabulum is greater than the transverse diameter B of the femoral head, indicating a state in which the size of the femoral head is not proportional to the depth of the acetabulum. It is characterized by the decrease of the head socket index with age, and the normal value is generally around 84-85. Its calculation formula is AHI=A/B×100.
Hip joint gap: compared with the normal side, bilateral patients were compared with the same age hip joint. The distance between the face of the highest point of the femoral head and the base of the acetabular cartilage was measured and divided into 5 levels, with level 4 being the normal gap, level 3 being 1/4 narrower than normal, level 2 being 1/2 narrower than normal, level 1 being 3/4 narrower than normal, and level 0 having a completely disappeared joint gap. It is used as a criterion to determine the presence or absence of traumatic arthritis.
4.Other examinations: arthrography, CT, MRI can have their diagnostic value for congenital hip dislocation.