Hip dysplasia, also known as developmental dysplasia of the hip (DDH), is an abnormality of the hip joint that may take three forms:
- unstable hip dysplasia, in which the hip can be dislocated manually
- incomplete dislocation, in which the femoral head is on the edge of the acetabulum, the rounded cavity on the outer surface of the hip bone that receives the femur
- complete dislocation, in which the femoral head is outside the acetabulum
It is more common in females.
The cause is not known; however, it tends to run in families. Hip dislocation may result if the fetus is not positioned correctly within the uterus before and during birth.
Signs and Symptoms
Physical examination shows asymmetric folds in the thigh of neonates with limited abduction of the affected hip. A shortening of the femur is noted when the knees and hips are flexed at right angles. The signs are typically quite obvious when children attempt to walk, if the condition has not been discovered before that time.
Observations during physical examination may suggest the diagnosis, but a positive Ortolani sign will confirm the diagnosis. Ortolani sign is the “clunk” felt when an examiner abducts (draws away from the body) and lifts the femurs of a supine infant. The “clunk” indicates a partial or an incomplete displacement of the hip. X-ray may be used.
It is important for treatment to begin as soon as possible. Before 3 months of age, treatment requires closed reduction of the dislocation, followed by the use of a splint-brace or cast for 2 to 3 months. If the child is much older, open reduction followed by casting may be necessary.
No significant complementary therapy is indicated.
Families will need support and teaching on how to care for an infant or a child with a cast or splint, if necessary.
When treatment occurs before age 5, the prognosis is excellent. If not treated promptly, abnormal development of the hip and permanent disability may result.
There is no known prevention for congenital hip dysplasia.