The term developmental dysplasia of the hip (DDH) refers to an abnormality in the size, shape or orientation of the acetabulum, the femoral head or both, or the relationship between them, which are the bones that make up the hip joint.
It comprises a wide spectrum of alterations ranging from acetabular dysplasia (with a shallow and immature acetabulum that can condition the appearance of a subluxation or dislocation of the femoral head), a hip subluxation (displacement of the femoral head without losing contact with the acetabulum) or a dislocation, with loss of contact between both articular surfaces.
This disorder may be present at birth or develop later and may affect one or both hips.
How does it manifest itself?
CDD does not produce pain in children who suffer from it, so it is sometimes more difficult to diagnose.
In newborns or neonates, parents may notice:
- Noises or protrusions (“clunk”) upon mobilization of the hip.
- Decreased abduction (separation) of one leg with respect to the other.
- Different length of both legs.
- Asymmetry in the folds of the legs.
Children who walk may present:
- Decreased abduction (separation) of one leg with respect to the other.
- Different length of both legs
- Asymmetry in the folds of the legs.
- Limping during ambulation.
The cases with bilateral affectation can be more complicated to detect since there would not exist differences between both legs.
How is it diagnosed? What tests are performed?
All newborns should be examined at birth.
The initial diagnosis in newborns is clinical, using the Ortolani and Barlow maneuvers, which allows us to check whether the hip is dislocated or unstable.
In older children -mainly from 3 months of age- a limitation of abduction (hip opening) or a difference in leg length (Galeazzi’s sign) may be evidenced.
These examinations should be repeated at the health check-ups until the child is one year old.
Diagnostic confirmation is made by means of an ultrasound scan that will give us information on the severity of the affectation and will allow us to assess the effectiveness of the treatment. From 4-6 months of age, pelvic radiographs can be taken.
In newborns with risk factors it is advisable to perform a control ultrasound scan between the first 4-6 weeks of life, even if the examination is normal.
What are the risk factors?
Several risk factors have been identified that influence the development of hip dysplasia. The most important are:
- Breech or breech presentation.
- Family history of hip dysplasia (parents and siblings).
- Female sex, since they are more sensitive to maternal hormones that produce greater elasticity.
- Left hip, due to intrauterine posture in adduction as it is supported against the sacrum.
- Firstborns, due to the greater rigidity of the maternal uterus.
Other risk factors include limited fetal mobility, fetal macrosomia, oligohydramnios, multiple gestations, limited fetal mobility, presence of congenital postural deformities, advanced maternal age or postpartum immobilizations with legs in extension and hips in adduction.
How is dysplasia treated?
Early diagnosis is essential for the successful treatment of hip dysplasia.
In children under six months of age and with reducible hips, treatment consists in the placement of an abduction splint that keeps the hip reduced. The most commonly used device is the Pavlik harness. The duration of the treatment will depend on the severity of the CDD and the evolution, generally it is maintained for 3 months. If the ultrasound or X-ray shows a good reduction, this will be the treatment. If, on the other hand, after one week of treatment (up to three weeks according to some authors), the hip is not in place (reduced), it will be necessary to consider another type of treatment, such as closed reduction under anesthesia and placement of a pelvic cast, after traction.
In children older than 6 months, closed reduction treatment under anesthesia and placement of pelvic casts is generally the treatment of choice.
In those children in whom it is not possible to achieve a reduction by these methods or in children older than 18 months it is necessary to perform an open reduction, i.e. a surgical intervention that allows the correct positioning of the hip, to prevent future sequelae. Patients with teratological dislocations (before birth) or dislocations associated with polymalformative syndromes often require this treatment, and have a worse prognosis.
For more information on hip dysplasia, please consult a pediatric orthopaedic surgeon.