Developmental dislocation of the hip (DDH) in newborns refers to a spectrum of conditions involving the femoral head and hip socket. DDH was formerly called congenital dislocation of the hip (CDH). In a complete dislocation, the femoral head is not located in the hip socket and may or may not be manually reintroduced into the socket by the examining doctor. In some cases the hip is located within the socket at rest, but during the exam can be popped in and out of the socket by the physician. This is referred to as a dislocatable hip. In either of these two conditions, the key to treatment is early diagnosis. The diagnosis is commonly made in the newborn nursery by the examining pediatrician. Predisposing factors include a positive family history for dislocation, breech presentation during pregnancy or delivery, female sex of the child, or first-born child. There are also many other syndromes of multiple birth defects that include dislocation of the hip as part of the general syndrome.
The dislocated hip in a newborn is asymptomatic. It is not a painful condition and can be easily overlooked if it is not specifically sought out. Some signs of dislocation of the hip would be an apparently shortened limb, the presence of extra thigh folds or creases on the involved leg, or decreased range of motion of the limb on examination. Unfortunately these signs often develop late, and in many cases of dislocation, are completely absent.
The key to diagnosis is examination soon after birth by a qualified, experienced examiner. If during routine hip exam on a newborn baby the physician feels any instability of the hip or detects a sensation of the hip popping in and out of the socket, the diagnosis of hip dislocation or dislocatable hip can be established. X-rays are typically not helpful in the newborn and are usually not used until the child is at least 3 months of age. More recently, ultrasound has become standard diagnostic method for assessing the stability of the newborn hip, but it is usually not used before the child is at least 2 weeks of age. Ultrasound in the newborn has too many false positives if done too early. The bottom line is, if the hip feels unstable to an experienced examiner, it is unstable until proven otherwise, and treatment should be instituted. After the child is at least 2 weeks of age, ultrasound examination is the gold standard for establishing stability of the hip. This can usually be performed as an outpatient if the child has already gone home from the hospital.
When diagnosed as a newborn, the treatment of a dislocated hip is very simple and usually consists of placing the patient into a special harness that keeps the hips flexed and abducted and allows normal kicking and moving around. The usual device is called a Pavlik harness and is worn 24 hours a day for approximately a month and the patient is checked on a regular interval during that time with outpatient ultrasound exam. The success rate with this simple harness is approximately 90% in all unstable hips and is the first line of treatment in virtually all cases. In the small number of patient’s whose hips do not stabilize with the harness, the next line of treatment would be to place them in a special cast called a hip spica cast that holds the hip in the reduced position for approximately 6 weeks or so. The casting can be repeated for as long as 3 months, if necessary. In rare resistant cases of hip dislocation, surgery may be required and can range from simple tendon lengthening to major realignment of the femur and pelvis. In the vast majority of cases, however, closed treatment without surgery is successful.