Developmental dysplasia of hip (DDH) is a problem with the way a baby’s hip joint forms. Sometimes, the condition starts before the baby is born and sometimes, it happens after birth as the child grows. It can affect one hip or both. It is also known as hip dysplasia or congenital dislocation of the hip.
Most infants treated for DDH develop into active healthy kids and have no hip problems. Early diagnosis is the most crucial aspect of the treatment of children with DDH.
The use of ultrasonography and other diagnostic imaging modalities, and the implementation of improved education programmes have most likely decreased the number of children with DDH who are diagnosed late, which can cause impaired function and degenerative joint disease.
The hip joint is a ball and socket joint. The top part of the thigh bone (femur), which is the ball part of the hip, sits inside a socket that’s part of the pelvic bone called the acetabulum.
The ball moves around in different directions but always stays inside the socket. This lets us move our hips to the front, back and side to side. It also supports our body weight for walking and running. However, in DDH, the hip does not form well. The ball part of the joint may be completely or partly out of the socket. If this is not fixed, the hip joint will not grow well. This can lead to pain while walking and hip arthritis at a young age.
When the dislocation is not recognised early, the muscle tightens and limits movement of the hip joint, which causes the acetabulum to become dysplastic because it lacks the stimulus of the femoral head. In turn, the ligamentous structure stretches and fibro-fatty tissue occupies the acetabulum, making it impossible to return the femoral head into the acetabulum.
Signs and symptoms
DDH does not cause pain in babies, so it can be hard to notice. The paediatrician checks the hips of all newborns and babies during child examination to look for signs of DDH. A careful physical examination remains the universal screening test for DDH and is therefore critical to diagnosis.
DDH does not cause pain in babies, so it can be hard to notice. A careful physical examination remains the universal screening test for DDH and is therefore critical to diagnosis.
On visual inspection, the dislocated hip shows asymmetric skin folds and shortening of the affected thigh. The knee is lower in the position on the affected side, when the child is in a supine position and knees are flexed. This is known as the Galeazzi sign.
Apart from this, there are two basic manoeuvres that are helpful in the diagnosis of DDH – the Barlow Maneuver and the Ortolani Test.
In Barlow Maneuver, the baby lies in the supine position with the hip flexed at 90 degrees and adducted (brought close). Downward and outward pressure is applied. If the hip can be dislocated, the examiner would feel the femoral head out of the acetabulum with his or her finger.
In the Ortolani Test, the baby lies supine. The hip is flexed at 90 degrees and the thigh is adducted (pushed apart). In case of DDH, a ‘clunk’ is heard as the femoral head returns into the acetabulum. Each hip should be examined individually.
What parents need to watch out for
Baby’s hip makes a popping or clicking that is heard or felt
Baby’s legs are not the same length
One hip does not move the same as the other side
The skin folds under the buttocks, or the thighs don’t line up compared to the opposite side, may have extra creases on the side of DDH
The child has a limp when starting to walk
Babies with any of these signs should see a doctor to have their hips checked. Finding and treating DDH early usually means there is a better chance for a baby’s hip to develop normally.
Hip laxity
Some babies are born with hips that feel loose when moved around. This is called neonatal hip laxity. It happens because ligaments around the joints are extra stretchy. Neonatal hip laxity gets better on its own by 4-6 weeks of age and is not considered to be DDH.
A baby whose hip ligaments are still loose after six weeks might need treatment, so follow-up doctor visits for babies with hip laxity are important.
Hip instability may resolve after 4-6 weeks, due to waning maternal hormones. Therefore, neonates with a slightly positive or inconclusive physical examination, and newborns with risk of DDH should be examined with sonography after this period to reduce false positive results.
Causes of DDH
The exact etiology is not known. Hormonal, mechanical and genetic factors are thought to play a role.
The maternal, hormonal effect of estrogen, which increases muscle laxity later in pregnancy is thought to account for increased risk among female neonates, as this effect is reduced by male sex hormones in male neonates.
Mechanical causes of DDH are oligohydramnios, breech presentation, primigravida uterus before birth and improper swaddling of infants after birth
Genetic factors also play a role. There is a 5% chance that a child will be affected if a sibling has DDH, 36% chance if one sibling and parent has been affected and a 12% chance if one parent has been affected.
Two tests that help doctors check for DDH
Ultrasound of the hip: It uses sound waves to make a picture of the baby’s hip joint. This works best with babies under 4-6 months of age. That’s because most of the baby’s hip joint is still a cartilage, which won’t show up on X-ray.
X-ray of the hip: This works best in babies older than 4-6 months. At this age their bones have formed enough to see them on an X-ray.
How is development DDH treated?
A peadiatric orthopaedic surgeon , handles DDH cases efficiently & chooses the treatment based on the child’s age . The goal of the care is to secure baby's hips in a stable position and allows them to develop normally.
The options include:
Bracing
Treatment for babies younger than six months of age is usually a brace. The brace used most often is a Pavlik harness. It puts the baby’s legs into a position that guides the ball of the hip joint into the socket. Treatment lasts for 6 to 12 weeks. While wearing the harness, the baby has a checkup every 1 to 3 weeks with hip ultrasounds and exams. During the visit, the medical team can adjust the harness if needed.
Closed reduction and casting
A child may need closed reduction (manually moving the ball back into the socket) and casting under general anesthesia if:
The harness was not successful at keeping the ball of the hip in the socket
The baby starts care after 6 months of age
The baby wears the cast for 2 to 4 months
Open reduction (surgery) and casting
Surgically relocating the ball back into the socket of the hip joint can be done if:
The closed reduction was not successful at keeping the ball of the hip in the socket
The child is older than 18 months when starting treatment
Outcome
If diagnosed early and treated successfully, children are able to develop a normal hip joint and should have no limitation in function. Left untreated, DDH can lead to pain and osteoarthritis by early adulthood. It may produce a difference in leg length or decreased agility.
Even with appropriate treatment, hip deformity and osteoarthritis may develop later in life. This is especially true when treatment begins after the age of 2 years.
The writer is Specialist Pediatrics and Head of Department at Burjeel Day Surgery Center, Al Reem Island
Visit Burjeeldaysurgery.com for more details or call 800 55
