What is dysplasia of hip? Its forms and treatment
What is dysplasia of hip?
The expression “congenital hip dislocation” is not currently used. Instead, terms are used that show that hip dislocation, is not a congenital condition. Development of the hip joint occurs during the prenatal period, at birth, and after delivery. Because hip dislocation can occur during each of these periods, the term dysplasia of hip (DDH – Developmental Dysplasia of the Hip) is used today. Dysplasia of hip can be caused by subluxation of the femoral head, dysplasia of acetabulum, and total release of the head of femoral bone from the acetabulum.
There is another type of hip dislocation that is mainly related to chromosomal abnormalities and neuromuscular disease, and it is called teratogenic hip dislocation. Hip dislocation is congenital and is not reduced on examination. This type of dislocation is more severe. It cannot be reduced by conservative treatment methods. On the X-ray we can see the following picture: the acetabulum is small, its angle is too high and the femoral head is supralateral. The treatment is mostly open reduction and/or osteotomy.
The picture shows a left hip dislocation
Pathophysiology
The acetabulum of a newborn child is completely covered by cartilage, and the fibrous cartilage, called the labrum, has a very thin margin. The cartilaginous surface of the acetabulum plays a role in growth, and damage to this area causes impaired growth. Most of the acetabulum completes its development at eight years of age.
Clinical examination methods for dysplasia of hip
Newborn children
If dysplasia of hip is detected, Ortalani and Barlow tests can be performed and the hip can be reduced and righted. When performing hip reduction in newborns, it is important to feel the sound of the reduction with your hands. This examination should be repeated at least 3-4 times. A positive result on the Klisic test also indicates the presence dysplasia of hip.
Klisic test: During the test, the 2nd finger of the hand should be placed on the greater trochanter and the 3rd finger on the anterior iliac axis. If the imaginary axis connecting these two points goes through the umbilicus, the joint is normal, but if it goes between the umbilicus and the pubis, the hip joint is dislocated (positive test).
Infants
Check abduction limitation, Galeazzi test, pili asymmetry. Ortolani test, Barlow provocation test and Klisic test may be positive, as well as in newborn children.
The figures show: A – pili asymmetry, B – Galeazzi test, C – abduction limitation.
Children who walks
In the presence of hip dislocation, limitation of abduction, positive Klisic and Galeazzi tests, lameness, and Trendelenburg gait can be found. During bilateral hip dislocation, patients have increased lumbar lordosis and a “duck-like” gait. These children have negative Galeazzi test results and pili asymmetry. For this reason, a Klisic test should be performed.
Risk factors
- Genetic factors
- Problems during childbirth
- First child (girl)
- Congenital Clubfoot (Metatarsus adductus) and Torticolysis
How is the diagnosis made?
- X-ray
- Magnetic resonance imaging
- Arthrography
X-rays: X-rays of the hip joint can be taken at 3-6 months of age. The most commonly used X-rays to evaluate X-rays are the inferior lines.
The Hilgenreiner line is the line that runs between the lower sides of both three radial (Y) cartilages of the acetabulum.
The Perkins line runs through the outer edge of the acetabulum, and runs perpendicular to the Hilgenreiner line.
Center-edge angle: this is a right angle that is formed by a line connecting the center of the head of femoral bone and the most extreme point of the acetabulum.
The Shenton line is an oval line that begins at the acetabulum, passes to the neck of the femur, and continues through the inner edge of the pubic bone. In a normal (healthy) pelvis, the Shenton line is correct.
The acetabular index is the angle that is formed by the Hilgenreiner line and a line drawn across the upper surface of the acetabulum. The acetabular index in a healthy newborn baby averages 27.5 degrees. At 6 months of age it averages 23.5 degrees, and by two years of age it decreases to 20 degrees. An angle of 30 degrees or more is considered to be greater than the norm.
The figure shows the alpha angle of the acetabular index
In the presence of a hip dislocation, there are factors that interfere with a reduction. These include:
- Lengthening and thickening of the round ligament, during an open reduction, it must necessarily be cut and removed.
- The transverse ligament of the acetabulum, during an open reduction, you must be sure to cut it off.
- The iliopsoas muscle (hourglass), which is located between the head of femoral bone and the acetabulum, must always be cut during open surgery.
- The articular lip, which is inverted (invert limbus), must always be cut during open surgery.
- The cushion (pulvinar) formed by the scar tissue inside the acetabulum (fibrofatty tissue). During open surgery, the cavity must always be cleared.
Treatment
Children of age 1-6 months
In the treatment of hip dysplasia in children 1-6 months of age, the Pavlik bandage is used. The hip joint is brought to a position: an angle of 80-90 degrees of flexion and an angle of 45 degrees of abduction. The bandage should be worn for 24 hours. Later methods are used: closed reduction, open reduction, osteotomy of the femur and acetabulum. You can use one single type of fixation or a combination of them. The doctor selects the method of treatment based on the clinical symptoms and age of the patient. For each unsuccessful step, further treatment tactics are based on the physician’s choice.
Children under the age of 6 months
If a reduction can be made, a stable hip joint can be formed within 4-6 weeks while wearing a Pavlik bandage. After this stage, the Pavlik bandage time is gradually reduced and a night orthesis is applied. The wearing of the night orthesis should continue until the results of the ultrasound and X-rays of the hip joint are normalized.
Children of age 6-18 months
Tests are performed with closed reduction until 12 months of age, and if they are successful, a pelvic cast is used. If the closed reduction is unsuccessful, an open reduction is started. Open reduction can be performed in children under 12 months of age, using a medial access. For children over 12 months of age, an anterolateral access is recommended.
Children of age over 18 months
Open reduction is used in the first instance. If necessary, a Salter osteotomy and/or a proximal varus-derotation osteotomy may be added to the surgical procedure. Closed reduction is performed under general anesthesia or deep sedation. A pelvipedal plaster cast is applied within the “safe zone”. Tight reduction can be achieved with at least 90 degree flexion and 40-45 degree abduction. The angle of internal rotation to which the pelvis will be brought should not exceed 10-15 degrees. The duration of immobilization in a cast is not standardized. In general practice, a patient is kept in a cast for three months. After immobilization lasting 6 weeks, the patient and the cast undergo X-ray examination. If there is contamination and expansion in the cast, it is replaced under anesthesia.
Surgical treatments for dysplasia of hip
Osteotomy of the pelvic bones that reshape the acetabulum.
Salter osteotomy
A pelvic osteotomy is performed over the acetabulum, and the acetabulum index is normalized. A bone socket, cut from the ridge of the iliac bone, is placed in the cavity and fixed with two spokes. Later, a pelvipedal cast is applied. This type of osteotomy is used more often than others.
Pemberton osteotomy
After the osteotomy, a curved osteotomy is made to the three radial (Y) cartilage, thus normalizing the angle of the acetabulum. A bone graft, obtained from the crest of the iliac bone, is placed in the bone cavity. No spokes are used for fixation.
Osteotomy according to the Ganz method
A Ganz osteotomy (triple osteotomy) is used in children who have completed the formation of the acetabulum. After an osteotomy on three sides of the acetabulum (iliac, sciatic and pubic bones), the completely freed acetabulum is brought to the correct (desired) angle, rotated, and then fixed with spokes and screws.
Osteotomy according to the Dega method
A Dega osteotomy is performed as shown in the figure below. A bone graft is placed in the cavity that was created after the osteotomy. After a Dega osteotomy, a plaster cast is not necessary.
Steel and Tonnis osteotomy
After performing a three edge osteotomy of the acetabulum, traction and rotation are performed under X-ray monitoring in order to overlap the surface of the acetabulum, the anterior and lateral surfaces of the femoral head. Two 3.5-mm K-spikes are inserted over the iliac wing into the cavity after the iliac osteotomy and a titanium plate is fixed with screws.
