Our god child was just diagnosed with hip dysplasia but only in the left hip. They told us at the clinic where he as examined that the left side is affected most often when this problem occurs. Can you tell us why that is?

Developmental dysplasia of the hip (DDH) develops either in utero (in the uterus) or during the first year of life. It may or may not be present at birth. In this condition there is a disruption in the normal relationship between the head of the femur (thigh bone) and the acetabulum (hip socket).

DDH can be mild to severe. In mild cases called unstable hip dysplasia, the hip is in the joint but easily dislocated. More involved cases are partially dislocated or completely dislocated. A partial dislocation is called subluxation. DDH can affect one or both hips but you are right that the left hip is affected more often.

The reason for this may be the position of the child while in the mother’s uterus. Ultrasound images show a tendency for babies’ left hips to be pressed up against the mother’s sacrum. This effect could contribute to the greater number of cases of left hip dysplasia in infants.