The purpose of this booklet is to provide you with information about DDH. This paediatric hip condition was previously known as congenital dislocation of the hip (CDH). Recently the name was changed to DDH, Developmental dysplasia of the hip, as it was recognized that in this condition the hip may exhibit a spectrum abnormalities, which only in a minority of cases it presents as a dislocated hip at birth (<25%). In most cases the hip shows various degrees of dysplasia or subluxation (partial dislocation). In a small number of cases the hip may actually be normal at birth, but become abnormal later in life.
The incidence of this condition is about 2-4 cases per 1000 live births. Females are more frequently affected than males by 4:1. It may be bilateral in 25% of cases.
The Natural History.
If this condition is left untreated, it would lead to serious complications such as a severe limp, limb shortening or early onset of osteoarthritis as an adult. Following subgroup of children are particularly at risk of DDH:
- Breech presentation.
- Positive family history.
- Babies with lower limb abnormalities at birth.
- Babies with spinal deformities at birth.
- Syndromic children.
If this condition is detected early within the first few months of life, it could easily be treated with a short period of bracing with successful outcome in over 95% of cases.
Late presentation for example in a walking child is associated with a much worse prognosis. Treatment in the walking age group is generally more complex and prolonged, often requiring open surgical procedures. Early detection and treatment is therefore paramount to ensure a successful outcome and to avoid the need for major surgery.
Screening for this condition In United Kingdom is mandatory and is carried out at birth, 6 weeks and 8 months of age. Most cases are therefore detected at an early age and treated appropriately.
Clinical Features of DDH are:
- Limitation of abduction in flexion (all age groups).
- Hip or thigh asymmetry (all age groups).
- Extra deep crease around the back of the thigh.
- Positive Barlow or Ortolani Tests (
- Short leg or limping (walking age group).
It is important to note that these physical signs are more obvious in unilateral cases due to limb asymmetry. In bilateral cases these signs could easily be overlooked. Limited abduction (<60°) in both hips should raise the suspicion that both hips may be abnormal.
In difficult cases or high risk groups further investigations is recommended. For a child younger than 5 months ultrasound examination is indicated and for over 5 months plain radiographs.
Treatment. The basic principals for treatment are:
- Reduce the dislocation or subluxation.
- Hold the reduction until hip stabilises.
- Careful follow-up until skeletal maturity.
In a child less than 6 months of age the reduction can easily be achieved by flexing and abducting the hips (frog position). The reduction is usually maintained using a brace such as a Pavlik harness for a period of 2-3months
In a child in the age group of 6-18 months this condition is associated with major soft tissue contractures. The reduction would require confirmation using an arthrogram (injection of dye into the hip joint under X-ray control). In the cases that there is resistance to reduction, additional surgical procedures such as tenotomy (muscle release) or limited open reduction of the hip may be necessary. Following this procedure the reduction is maintained using a frog plaster for a period of at least 4 months.
In a walking age child (>18 months) major surgery is often required to reduce and stabilise the hip. this could be in the form of an open reduction of the hip +/- pelvic or femoral osteotomy. Postoperatively a period of casting in a hip spica is necessary for 6 weeks.
Prognosis for this condition is directly related to the age of the child at the time of presentation and the severity of the hip dysplasia.
In children less than 6 months of age 98% success rate is generally expected. This is reduced to 95% if the child is within the age group of 6-24 months and 85-90% if the child is over the age of 2 years at the time of treatment.
Careful follow-up until skeletal maturity (age 16 years) is needed to confirm satisfactory progress and to identify complications such as recurrent dysplasia or avascular necrosis (loss of blood supply to femoral head) at an early stage.
Hip ultrasound in newborns:
DDH of the hip is an abnormal formation of the hip joint in which the ball on top of the thighbone (femur head) is not held firmly in the hip socket.
If the hip is not dislocated at birth, the condition may not be noticed until the child begins to walk. With an ultrasound the position of the femur head in the hip joint can be imaged without causing your baby discomfort or put him at risk.
The earlier the condition is detected the better the chances are of correcting the condition with appropriate treatment.
If DDH is left untreated, the condition may lead to pain and osteoarthritis by early adulthood. It may produce a difference in leg length or a “duck like” gait.
The incidence of this condition is about 2-4 cases per 1000 live births. Females are more frequently affected than males by 4:1. It may be bilateral in 25% of cases. The risk of DDH is higher in first-born children and babies born in the breech position (especially with the feet up by the shoulders). Family history of DDH plays a role as well.
An X-ray does not show the bones in a young baby until at least 6 months and are therefore not indicated.
The Ultrasound image shows the cartilage and bone anatomy of the hip socket and the stability of the joint (dynamic examination). The hip dysplasia is then classified according to the Harcke classification:
Type I – normal hip
Type II – hip is immature or mildly dysplastic and has a more shallow hip socket with a round rim, in children younger than 3 months, most of these will spontaneously resolve and in children older than age 3 months, the deformity is expected to persist without treatment;
Type III – dysplasia the hip joint with a shallow hip socket and the cartilaginous roof is displaced (50% cover)
Type IV – dysplastic joint 20-30% cover
Type V a high dislocation of the hip joint with a flat hip socket cup and the femoral head sideways and upwards displaced. This type has the worse prognosis.
Screening of this condition in the United Kingdom is mandatory and is carried out at birth, 6 weeks and 8 months of age. Most cases are therefore detected at an early age and treated appropriately.
In South Africa only the babies more at risk are referred to a paediatric orhopeadic surgeon to be screened.
Dr Stefan Colyn