About three to five percent of all newborns suffer from hip dysplasia. This is an innate maturation disorder of the acetabular cup. Without therapy, babies and children develop malformations of the hip joint, which can lead to premature joint wear in adulthood. Since obvious symptoms of hip dysplasia are usually absent, ultrasound of the hip is performed on all babies as part of the check-ups. If detected early and treated properly, hip dysplasia usually heals without consequences - however, surgery may also be necessary.
Girls affected more often
The causes of hip dysplasia in babies are not fully understood. A risk factor seems to be the position of the unborn child in the womb: If the fetus with the pelvis leading in the uterus, it is more likely to hip dysplasia. Even with twin pregnancies or if too little amniotic fluid is present (Oligohydramnion) the risk for a hip dysplasia seems to be increased.
It is also unclear why girls are about five times more likely than boys to be affected by hip dysplasia. In addition, the disorder occurs familial: If the mother has a hip dysplasia, the risk for her child is increased.
Dislocation in immature hip joint
In a hip dysplasia, the ossification of the acetabulum takes place delayed. As a result, the femoral head does not have sufficient support and slips in the joint. The result is damage to the acetabular cup, as the femoral head deforms the still soft bone.
It may even lead to a dislocation (dislocation) of the hip. Then the joint must be re-fixed (repositioned) as quickly as possible, in order to prevent permanent damage and to allow a normal development of the hip.
Missing signs in babies
In infants with hip dysplasia, there are usually no symptoms because the babies are not yet walking and therefore have no pain. Only if a dislocation of the hip is present, signs of hip dysplasia can be seen: Since the femoral head usually slips up out of the pan, there is a visible shortening of the affected leg. This often also an asymmetry of the wrinkles on the thigh and the buttocks can be seen. Some babies also show a striking posture of the legs.
Symptoms in children: pain in the knee
Symptoms of hip dysplasia, however, usually do not appear until the children start to walk: typical for dislocation of the hip is a crooked pelvis and a waddling or limping gait. In some cases, the pelvis tilts forward - the result is a pronounced hollow back.
In addition, the mobility of the hip is usually limited. However, hip pain is atypical of hip dysplasia - children often complain of pain in the knee or groin instead.
A characteristic symptom of hip dislocation is the so-called Trendelenburg sign: In the one-legged position on the affected leg, the pelvis tilts to the healthy side.
Hip dysplasia: ultrasound screening at U3
Since hip dysplasia often causes no symptoms in babies and the disease was often diagnosed too late, a screening for hip dysplasia is now integrated in screening U3 in the fourth to fifth week of life.
In addition to a physical examination, an ultrasound of the hip is performed. In the ultrasound image, the pediatrician can assess the position of the femoral head and measure the angles of the hip joint. This results in a classification of the hip joint maturity in the so-called
Hip types according to Graf:
- I. Normal developed hip
- II. Maturation delay (hip dysplasia)
- III. Subluxation (partially dislocated hip - the femoral head has slipped in the pan)
- IV. Dislocation (complete dislocation - the femoral head is outside the socket)
Diagnostics: X-rays in children and adults
For babies, ultrasound examination is best for diagnosing hip dysplasia: The development of the still cartilaginous hip can be assessed very well in the ultrasound image. After the first year of life, the joint can be better represented in the X-ray image due to the increasing ossification.
A so-called arthrography may be necessary if the hip can not be restrained in a baby with hip dislocation. Contrast agent is injected into the joint and then made x-ray images from different angles. For example, it is possible to determine whether a tendon, for example, prevents it from narrowing.
Hip dysplasia in babies: Spreizhose treatment
If there is only hip dysplasia without dislocation (type II Graf), the therapy can be performed by a spreader, splint or bandage, which holds the leg in a bent and spread position. This forces the femoral head into the pan, promoting maturation of the joint. Such a splint must be worn around the clock for a few weeks to months.
Lowering the hip by means of overhead extension
In a dislocation (type III and IV according to Graf), the hip must first be restocked. This can be done by a so-called overhead extension: The legs are held in a splayed position on a construction mounted above the bed. Due to the train, the femoral head can slip into the right position within a few days to weeks.
OP sometimes necessary
Another possibility is a manual adjustment (manual reduction). For this, a general anesthetic is usually necessary, in which the muscles are relaxed. If the hip still can not be restrained, it is sometimes an obstacle - such as a tendon or fatty tissue - to blame.
Then surgery may be necessary to retract the hips. Sometimes a wire is additionally used for temporary fixation. In any case, the baby must wear a so-called seat squat gypsum for a few weeks after a hip restraint so that the hip joint remains in the correct position.
Surgical correction in older children and adults
Failure to achieve a satisfactory result from spreader, splint, or plaster treatment - a condition known as residual dysplasia - can prevent sequelae in children over the age of two and adults by surgery.
There are different surgical procedures with a similar principle: By cutting through bone parts on the pelvis or thigh and reattachment in an altered position, the femoral head should be "fitted" into the socket so that the joint is loaded as naturally as possible and thus premature wear is prevented.
Good prognosis with early therapy
If a hip dysplasia is detected in good time and treated correctly, in most cases no consequential damage will remain. The earlier the treatment starts, the shorter the duration of treatment. Because the hip joint is more malleable the younger the child is.
However, if left untreated, hip dysplasia can lead to premature hip joint wear (coxarthrosis) - possibly as early as the third decade of life. Not infrequently, an artificial hip joint is necessary early in these cases.
Sports in hip dysplasia
After successful completion of the treatment, affected children usually do not have to restrict their sports activities. However, if there is residual dysplasia or children have pain, hip-related movements should be avoided, depending on the symptoms.
These include sports with jerky loads such as certain ball games, sprint, jump or martial arts as well as breaststroke and downhill skiing. On the other hand, we recommend dynamic movement sequences such as cycling, hiking and crawl swimming as well as specific exercises for strengthening and stretching the hip muscles.