DevelopmentalDysplasiaoftheHip (DDH) is a condition in which the acetabulum becomes shallow or the head of the femur prolapses outside the acetabulum at birth or during development. It is also called congenital hip dysplasia and congenital dislocation of the hip joint. Chen Houping, Department of Pediatric Surgery, Guiyang Maternal and Child Health Hospital
Characteristics of hip dislocation in newborns and infants.
1. Congenital hip dislocation
It is more difficult to diagnose in the neonatal period, but once diagnosed, it is easy to treat and will get the ideal treatment effect. Because the pathological changes are the lightest in the neonatal period, it is 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).
Skin lines: increased, deepened and asymmetrical upward movement of skin lines on the buttocks, groin and thighs.
Limb movement: the affected limbs have little movement and are most easily detected during diaper changes.
3. Physical signs
Weakening or disappearance of the femoral artery of the affected limb.
Tension spasms of the innominate muscles.
Positive Barlow test Ortolani sign or positive abduction test, these 2 methods are only used within 3 months of age.
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: normal acetabular index of 20-25°, basically constant at 15° by 12 years of age, abnormal for >30°.
Perkin’s square normally located in the lower inner quadrant.
Shenton’s line Nelaton’s line sign disruption.
The distance from the apex of the Hilgenereiner femoral epiphysis to the horizontal line was measured as H, with a normal of 10 mm; the distance from the apex of the femoral epiphysis to the innermost edge of the acetabulum was d, with a normal of 12 mm. When H value is less than 10mm or d distance is more than 12mm should be suspected of hip dysplasia.
Bertol measurement method: the normal upper gap a is 9.5mm and the medial gap b is 4.3mm. if a is less than 8.5mm and b is more than 5.1mm, hip dislocation should be suspected. If a is less than 7.5mm and b is greater than 6.1mm, hip dislocation can be diagnosed.
What is the value of ultrasound in the early diagnosis of DDH?
Ultrasound hip examination technology is recognized as the preferred method for early diagnosis of DDH in many developed medical countries and regions, and has become an important tool for early detection and intervention in the treatment of DDH in children.
Ultrasound has the ability to penetrate cartilage, which makes it particularly suitable for examination in newborns and infants whose femoral heads have not yet ossified. As the ossification center of the femoral head forms and increases in size, the usefulness of ultrasound decreases. Ultrasound hip examination is highly sensitive and precise in its ability to detect morphologic changes in the acetabulum more accurately than radiographs to measure the acetabular index (AI), and its ability to detect changes in the glenoid labrum and garden ligament is comparable to that of hip arthrography, according to Graf: ultrasound offers the possibility of early identification of hip maturation, selection of the best treatment and the possibility of surveillance.
The Graf method is commonly used internationally: the probe is placed on the greater trochanter, with the longitudinal axis parallel to the longitudinal axis of the torso, and the probe is moved back and forth in parallel to obtain a clearer frontal section of the hip, and the alpha and beta angles are measured. Then the hip was divided into 4 types according to the size of α and β angles.
Type I: α>60°, β<55°, which is a normal hip joint with well-developed bony acetabulum.
Type II: α43° to 60°, β55° to 77°, i.e. hip dysplasia.
Type III: <43°, β>77°, semi-dislocation.
Type IV: complete dislocation.
Alpha angle (bone apex angle) is the angle made by the intersection of the bone apex line (BD) and the baseline (AB); β angle (cartilage apex angle): the angle made by the intersection of the cartilage apex line (BC) and the baseline (AB).