developmental dysplasia of the hip, congenital dislocation of hip

Developmental dysplasia of the hip (DDH) was formerly referred to as congenital dislocation of hip. Now that the condititon is better understood, the former term is preferred to reflect the facts that

DDH is a developmental (ongoing) process, variable in manifestation and not always detectable at birth
DDH involves a dysplasia, or abnormal formation of the hip joint occurring between fetal life and maturity as a result of instability
The hips are not dislocated at birth, but if a dislocation occurs, then the complications of the dislocation - malformation of the hip socket, twisting of the thigh bone (femoral anteversion), and hip muscle shortening (contractures) will develop.
Hips that are found to be normal at birth (and even in the first few months of life) can subsequently be found to be abnormal later. This cannot be overemphasized! The best orthopedist in the world can be fooled by the initial hip exam. We cannot be complacent about your child's hip stability and development.

The cause of DDH is both

physiologic - having to do with the childs basic makeup as well as the child's response to the maternal hormones
mechanical - a result of positional influences in utero

The majority of children with DDH have ligamentous laxity - looseness of the fibrous bands connecting bones together in joints. This predisposes to hip instability; instability allows the hip to slip out of position; and certain mechanical factors such as breech presentation can aggravate the problem. Maternal hormones associated with pelvic relaxation around the time of birth also aggravate the instability of the newborn hip joint by allowing softening and stretching of the baby's hip ligaments.

It has been estimated that only 1 in 100 newborn infants have clinically unstable hips (subluxatable - the ball of the hip is able to be moved around loosely in the hip joint joint - or dislocatable - the ball of the hip is able to be actually slid in and out of joint with a "clunk" that can be felt), whereas only one in 800 to 1,000 of newborn infants eventually experience a true dislocation whereby the ball of the hip lies outside the socket.

There is a 9:1 female predominance; apparently the baby's own female hormones must aggravate the abnormal looseness of the hip ligaments.
Of children with DDH, approximately 60% are firstborn
30-50% develop in the breech position; 2% to 3% of all babies are breech presentations, but about 20% of DDH patients are born breech.

The breech position tends to force the ball of the hip out of the socket, predisposing to dislocation after birth. Highest risk is the frank breech position with the hips flexed and the knees extended - basically feet up by the shoulders. There is also an association of congenital muscular torticollis ("wry neck"), metatarsus adductus (toes bent inward) or talipes equinovarus (club foot) with DDH. A child with any condition caused by intrauterine cramping deserves very careful attention to rule out DDH.

If an abnormal hip remains untreated, the child will develop the long-term complications, including:

osteoarthritis
pain
abnormal gait
unequal leg length
decreased agility

Diagnosis

For this reason, your baby's doctor will carefully examine the hips at every visit. She will perform several tests and inspect the hip area carefully for subtle signs of either hip instability or dislocation.

The Barlow test is the most important maneuver in examining the newborn hip. The examiner attempts to push the ball of the hip rearward out of the socket.
The Ortolani test is a maneuver to reduce a recently dislocated hip. If positive, the examiner feels a "clunk" as it pops back into place. It is most likely to be positive in infants who are 1-2 month old because adequate time must have passed for the true dislocation to have occurred. After 2 mo of age, this test is no longer useful because of the development of soft tissue contractures which prevent the hip from being relocated.
The thigh creases should be symmetrical from side to side; if they are not, possible hip dislocation has to be considered carefully.
Leg length inequality is another tipoff to dislocation, as is uneven knee position from side to side.
Xrays taken before four months old - before the head of the thigh bone (femur) starts to convert from invisible-on-xray cartilage to visible bone (ossification) - are unreliable to rule out hip dysplasia. They must be repeated after ossification has begun to be trusted.
The ultrasound test of the hip is the best under four months. It is unfortunately not available in every hospital.

The examination in the newborn nursery is the critical screening tool to detect loose, dislocatable, and dislocated hips. Up to about 4 to 6 months of age, the Barlow and Ortolani maneuvers done at routine well-baby examinations are most important. Around 6 months of age, a parent might notice differences in the range of motion of the hip with some difficulty with diapering. Perhaps a parent or the doctor might notice a leg length difference or an asymmetric appearance of the two legs (asymmetric skinfolds). The importance of frequent, routine screening hip examinations until walking age by an experienced physician cannot be overemphasized.

A common concern is the presence of hip clicks in infants. Hip clicks per se are usually not due to actual or potential dislocation and are secondary to normal snapping of the tendons and other factors analagous to popping in the normal ankle or cracking knuckles.

Once a child is walking, gait abnormality related to leg length difference is the hallmark for identifying an abnormal hip. Asymmetric intoeing or outtoeing is the clue - one foot points in or out significantly more than the other. If the hip abnormality still remains undiagnosed, pain or more noticeable gait asymmetry ultimately draws attention to the hip as the child becomes older.

In older or walking children, complaints of limping, waddling, increased lumbar lordosis ("swayback"), toe walking, and leg-length discrepancy may indicate an unrecognized DDH, and should obviously be brought to your doctor's attention.

Treatment

If an unstable hip is recognized at birth, treatment consists of maintaining the position of the hip in flexion (knee up towards the head) and abduction (knee away from the centerline) for about 1-2 months. The Pavlik harness is the most widely used device, but the Frejka splint and some other devices are also used. The device chosen for treatment maintains proper position of the femoral head and allows for "tightening up" of the ligamentous structures as well as for stimulation of normal formation of the hip socket. The treatment must be continued until the hip is stable and xrays or ultrasound examinations are normal.

From 1-6 months, true dislocations may develop. As a consequence, treatment is directed toward reduction of the femoral head into the socket (acetabulum), usually with the Pavlik harness or similar device. The harness pushes the femoral head toward the socket, and usually, relocation of the femoral head will occur within 3-4 wk. The Pavlik harness is approximately 95% successful in dysplastic or subluxated hips and 80% successful in true dislocations. Triple diapering is frowned upon now because it promotes hip extension, which is not a good position for normal hip development. If a spontaneous reduction does not occur by splinting, then a surgical closed reduction (manipulation under anesthesia) is done.

In the older infant from 6-18 Mo, surgical closed reduction (manipulation under general anesthesia) is the major method of treatment.

After 18 mo of age, the progressive deformities become so severe that major open surgical intervention is necessary to realign the hip.

Site Information/Disclaimer