What it means?
It is condition characterized by the hip joint is partially or completely out of its place. The hip joint is a ball and socket joint which allows full range of movements in many directions. The upper end of thigh bone (femur) forms the ball and the cavity in the pelvic bone outer aspect forms the socket. In this condition, the ball may be loosely lying in the socket or the ball may be partially or completely out of the socket.
What causes it?
The socket that is acetabulum which forms the cup for the femoral head. The socket is not formed normally hence it will not be deep or curved. As a result, the ball that is femoral head does not fit tightly in the joint. Thus, the ball remains loose in the socket, or the ball can slip out of the socket partially or lies completely out of the socket.
DDH can run in families. It is more common in girls and first born children. Babies who are in breech position and low amniotic fluid during pregnancy have a risk of DDH.
How child will present like?
- Baby will have difference in leg length affected side will be short
- Difference in thigh skin folds increased on affected side
- Difference in hip joint movement that means difficulty to take the lower limb away from the midline which will decreased on the affected side
- Baby walks with a limp on the affected side if one side involved or waddling walk if both sides involved
What are the tests required?
- On careful examine of the hip joint, need to assess the hip range of movements, leg length, skin folds in the thigh, stress test to see whether the hip dislocates or subluxates
- Ultrasound screening of both hip joint helps to assess the status of hip joint whether reduced, subluxated, or dislocated. Baby who are at high risk for DDH like female baby with breech presentation should undergo ultrasound screening of both hip joints
- X-ray is the best choice of test for older infants and toddlers which gives details of the bony anatomy of hip joint
What are the treatment options?
The treatment of DDH depends upon the age
- Baby aged between 0 to 6 months can be treated with PAVLIK HARNESS which is a soft brace that keeps the hip in place for 1 to 3 months during that time tissue around the hip tightens, and when femoral head remains inside the acetabulum develops more normally.
- If the hip continues to sublux or dislocate with Pavlik harness treatment, then the baby will need closed reduction under anaesthesia.
- Baby aged between 6 months to 2 years can be treated with CLOSED REDUCTION UNDER ANAESTHESIA that means the hip joint is positioned back into its place and its position is confirmed by injecting a dye into the hip joint and then placed in a body cast, known as SPICA CAST to hold the hip in position. After that a CT scan or MRI will be performed to check that the hip stayed in the joint
- If closed reduction fails to reduce the hip joint then an OPEN REDUCTION OF HIP JOINT is needed
- Baby aged more than 2 years can be treated with OPEN REDUCTION OF HIP JOINT WITH SHORTENING OF THE FEMUR AND PELVIC OSTEOTOMY that means the hip joint will be opened and the structures which preventing the femoral head from staying inside the acetabulum were removed. Even after removal of obstructing soft tissues, if it is very difficult to place femoral head back in place then femur bone needs to be shortened or the pelvic bone needs to be cut and shifted to make acetabular cavity deep in order to position the femoral head into acetabulum. This reduction maintained in position by spica cast for 2 months.
What will be outcome?
- Child needs to be kept under long term follow up with x-rays to keep watch on the hips developing normally after treatment
- Most of the children with DDH who are treated early will have a normal full functional hip joint
- Some children may have hip dysplasia even after took treatment for which they may require future surgery
- If hip dysplasia left untreated will cause pain and arthritis in young adulthood