Infants under the age of six months are treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. The idea is to take a child with a poorly formed hip socket or dislocated hip joint and position the head of the femur (thigh bone) right in the hip socket. Then hold it there until the joint forms properly. That’s where the Pavlik harness comes in. This soft harness positions and holds the infant/child with the hips bent or flexed and abducted (leg apart).
Studies show that this conservative method of treatment works about 79 to 96 per cent of the time. But that’s a pretty broad range of success. Researchers are looking for some specific predictive factors like age or gender that make the difference in outcomes.
The goal in finding predictive factors of failure in the conservative treatment of developmental dysplasia of the hip is to identify children who will benefit from therapy with the harness versus those who won’t be helped. No sense using a treatment that you know right from the beginning won’t work.
Some of the most commonly studied factors include the child’s age, gender, side of the hip dysplasia, severity of the dislocation, and ability to reduce the hip before treatment. Amount of hip abduction (leg moved away from the midline) and distance of the femoral head from the hip socket (as measured by X-rays) are also taken into consideration when looking at children as potential candidates for conservative care with the harness.
In a recent study on this topic, an analysis of over 200 children with this condition showed that age at the time of treatment was not a predictor of failure. This was true so long as the child was younger than six months when use of the harness was started. Having a bilateral condition (present in both hips) was a predictor of harness failure. Children with developmental dysplasia in both hips were six times more likely to fail to get reduction of the hip using the harness when compared with children who had only one hip involved.
The starting position of the hip (as seen on X-ray before treatment) was a negative predictive factor. In other words, the farther the hip was from the socket, the less likely it would reduce with the harness and then remain stable in the hip socket. Of the two directions tested (hip displaced proximally or upwards versus hip displaced laterally — away from the socket), reduction was more likely to fail using a Pavlik harness when proximal displacement was a bigger problem.
One other factor that helped predict who would have a failed versus successful response to the Pavlik harness was how far the child’s hips would abduct (move away from the midline). Loss of hip abduction is usually a sign of an adduction contracture. Contracture means the muscle is so tightly contracted, the leg can’t move (or moves minimally). The fact that the hip could not be reduced manually by moving the leg into a flexed and abducted position before treatment had no bearing on the success of the harness to accomplish reduction over time.
And finally, even though one-third of the children with developmental dysplasia of the hip had a family history of this condition, family predisposition was not a predictor of treatment success with the Pavlik harness. In other words, having a family history of dysplasia didn’t necessarily mean treatment would fail.
Look at all the predictive factors and talk with your physician about your child’s case. He or she may have a better idea what to expect given all of the individual variables to consider and how your child falls in the range of possibilities for a successful treatment.