Developmental dysplasia of the hip (DDH) is a common disorder that is seen in infants and young children. It may be present at birth or may occur during the first year of life of the infant. As the name suggests, it occurs due to improper development of the hip joint either while the foetus is in the uterus or during the growth phase in the first year of life.
In normal hip, the head of the femur (thigh bone) fits well into the socket (acetabulum) whereas in hip dysplasia, the socket and femoral head are not congruent because of their abnormal development. The exact cause of DDH is not clear. However, there are factors that may contribute to the development of DDH, and may include:
- Abnormal position of the femoral head
- Too shallow or sloping acetabulum rather than normal cup shape
- Laxity or looseness of the ligaments around the joint
- Breech position of the foetus leading to abnormal stress on the hip joint
- Swaddling or wrapping of the infant with both legs tied together and extended out straight
DDH can be mild or severe and can affect one or both hips. It is more common in girls and usually affects the left hip. DDH does not cause any pain and so the condition may not be noticed until the child starts to walk. A child with DDH may walk with a limp (if one hip joint is affected) or waddle (if both hip joints are affected). If both hips are dislocated, the child’s abnormal walk (gait) is difficult to detect.
Appropriate screening should be performed for all new-borns and infants for the early detection of DDH. This is especially important if the baby is born by breech or has a family history of DDH. Usually, Ortolani’s manoeuvre or Barlow’s test are used to detect any hip instability in infants. For infants older than three months, an additional Galeazzi’s test may also be performed. In this test any difference in knee height is examined while the child is made to lie on their back with the legs folded at the knee. If any one of these tests is positive, your child will be closely observed or treated with a brace. During hip examination, the doctor may also look for the difference in range of motion of the hip, presence of uneven skin folds around the thigh and difference in leg length from side to side. In infants less than 6 months, an ultrasound may be advised to confirm the diagnosis.
The treatment for DDH depends on both the age of the child and severity of the condition. The aim of treatment is to keep the femoral head in good contact with the acetabulum so that the hip can develop normally. If detected in the first six weeks double and triple diapering may be required. If the problem continues to exist, use of a pavlik harness to keep the hip in flexion and abduction may be advised. Only when conventional treatment is not effective, surgery to put the hip back into place may be advised.