Our baby was examined by his pediatrician who told us he has a true-positive test for hip dislocation. What does true-positive mean? We assume it means there’s no doubt about it, but could they be wrong?

All newborns should be screened for hip dysplasia. Hip dysplasia is a shallow hip socket that may not be able to hold the round head of the femur (thighbone) in place. Partial dislocation called subluxation or complete dislocation can occur.

Dr. Ortolani, an Italian physician, developed a special test to detect hip dislocation in young infants. If the hip is out of the socket, as the doctor moves the child’s leg away from the body, there is a click or clunk felt.

This is the sensation that occurs as the head of the femur slides over the rim of the cartilage around the joint and slips back into the socket. Anytime this hip click is felt, the test is positive for a true hip dislocation.

Sometimes the hip is dislocated and slips back into the socket without the click or clunk. The physician believes the hip is normal based on the Ortolani test. The results would be considered a false negative.

If you have any doubts or would like further confirmation of the test, an ultrasound (US) can be done. The US will show the exact position of the femoral head. Some experts advise doing an US with every child who has a true-positive Ortolani’s test. The US will also show how well the head is reduced in the socket. This information can be helpful in planning treatment.