Hip dysplasia is a congenital or acquired malformation of the acetabular cup. As a result, the still cartilaginously soft femoral head of the thigh cannot be held firmly in the acetabular cup. In the most severe case of hip dysplasia, hip dislocation, the head of the femur slips out of the socket.
Hip dysplasia and hip dislocation can only occur on one hip joint or on both joints. With one-sided malformation, the right hip joint is affected much more often than the left.
Two to three out of 100 newborns have hip dysplasia. Hip dislocation is significantly less common with a frequency of around 0.2 percent. Girls are affected more often than boys.
Unrecognized or too late treated hip dysplasia in babies significantly limits mobility in later life and can cause pain even in adolescents. There can be premature wear-related changes, which restrict the choice of profession and can result in early disability. Malformations of the hip joint such as hip dysplasia favor early joint wear (arthrosis).
Hip dysplasia alone does not cause any symptoms at first. However, if it is not recognized in time, damage to the acetabulum and head (such as hip arthrosis in later life) or hip dislocation can occur.
With a hip dislocation, the femoral head (i.e. the head of the femur) jumps out of the socket. In this case, the baby can only partially spread the legs. The leg on the affected side appears shorter than the other. The anal furrow and pubic fold are shifted towards the affected side. The shortening of the legs and the asymmetry of the folds can, however, be absent in the case of bilateral hip dislocation.
As a result of hip dislocation, the "empty" socket can gradually deform. In some cases, the head of the thigh bone can no longer be moved into the normal position.
Older children may experience a hollow back or "waddle walk" as a result of hip dysplasia. If such signs appear, parents with their child should immediately see a pediatrician or orthopedic surgeon.
The exact causes of hip dysplasia are not known. But there are risk factors that favor the development of this malformation:
As part of the preventive check-up, the pediatrician routinely checks every child for hip dysplasia at U2 (third to tenth day of life). For a reliable diagnosis, he then carries out an ultrasound examination of the hip at the U3 (in the 4th to 6th week of life). An x-ray examination to clarify hip dysplasia is usually unnecessary and also less reliable, since the still cartilaginous bones of the infant can be seen less precisely on the x-ray than on ultrasound.
During the physical exam, the following signs may indicate hip dysplasia:
Treatment for hip dysplasia depends on the severity of the changes. Both conservative and operational measures are available.
Every child is already examined for hip dysplasia as part of the preventive medical check-up (third to tenth day of life). This is diagnosed with an ultrasound examination, shortly after birth, or in the 12th to 16th week. Ultrasound is usually done on newborns because it is best suited to diagnosing hip dysplasia. Because this is the best place to assess the development of the still cartilaginous hip. From the age of 1, the joint can be better visualized on an X-ray because of the increasing ossification.
Arthrography becomes necessary if the hip cannot be straightened in the infant. A contrast medium is then injected into the joint and X-rays are taken from several angles. In this way, it can be seen whether a tendon is preventing the patient from contracting.
If there is only hip dysplasia without dislocation (type II), this can be treated with spreading pants, splint or bandage. This keeps the leg constantly in a bent and spread position. This allows the femoral head to be pressed back into the socket and supports the maturation of the joint. Such a splint has to be worn around the clock for a few weeks to months.
In the event of dislocation (type III and IV), the hip must be straightened again immediately. One method of this is the overhead extension. The treatment is to retract the femoral head and fix it in the socket. This is done with the help of a so-called extension device. Here the child's legs are spread apart with a plaster cast to keep the femoral head stable and permanent in the acetabular cup. Through the re-establishment of contact, the head and pan can develop normally. In this variant, the legs are held in a spread position on a fixed structure. With this pull, the femoral head will slide into the correct position within a few days to weeks.
The hip is then matured using splints, where the child's legs are held in a spread position. The duration of treatment is approximately twelve weeks until the joint has been turned on ultrasound. Together, the treatment of hip dislocation takes about seven months.
The conservative treatment of hip dysplasia or hip dislocation consists of three pillars: maturation treatment, reduction and retention.
At birth, instability in the hip joint due to a delay in maturation resolves on its own within 80 months of normal motor development in 80 percent of cases. Monitoring by ultrasound is usually sufficient as a medical measure. The maturation can be supported by wrapping the child with particularly wide diapers.
With higher-grade hip dysplasia, but with the femoral head still in the socket, the baby is fitted with spreader pants or spreader bars. The duration of treatment depends on the severity of the dysplasia and continues until a normal acetabular cup is formed. This process is checked at regular intervals using ultrasound. In rare cases, the doctor takes an x-ray of the hip as soon as the acetabular cup has matured at the age of twelve months. He can check whether the femoral head and acetabulum are well shaped.
If the femoral head of a child with hip dysplasia has slipped out of the socket (dislocation), it must be "lowered" into the socket (reduction) and then held there (stabilized / retention). In children who are not older than nine months, a reduction bandage can be applied, in which the hip joints can spontaneously retract by the child's kicking and can then be stabilized in this position for a long time.
Another option is to manually retract the "slipped" femoral head and then put on a plaster in the sitting / squatting position for several weeks. It keeps the femoral head stable and permanent in the acetabular cup. The restored contact allows the head and pan to develop normally.
If the restraint has not worked or the affected child is older, preparatory treatment is often carried out. It serves to loosen the hip joint and stretch the shortened muscles.
If the hip dysplasia was recognized too late to carry out conservative treatment options, the femoral head must be brought back into the acetabulum by surgery. Numerous surgical procedures can be used for surgical treatment. For example, in children aged 2-8 years, the Salter osteotomy is used to improve the femoral head mechanically and orthopedically. It is considered a proven method of triple pelvic osteotomy. The acetabular cup is completely separated from the hip bone and brought into a normal covered position. Depending on the severity and severity of the disease, various hip joint endoprostheses are used. As part of the technical development in orthopedics, more and more effective methods are being developed to destroy as little bone material as possible during a hip operation.
If conservative measures to treat hip dysplasia remain unsuccessful or if the deformity is recognized too late (in children who are three years old or older, or in adolescents or adults), surgery is necessary. Various operative procedures are available for this.
Unlike babies, adults with hip dysplasia have no choice but to undergo surgery. This is because the malposition of the hip joint must be corrected to prevent further damage to the joint. There are various surgical procedures that aim to better "fit" the femoral head into the socket and thus achieve the most natural joint position possible. The earlier hip dysplasia is detected, the easier and more effective the therapy. As long as the joint does not show any arthrotic changes, the chances of a prosthesis-free life are very high. When wear begins, it is quite possible to delay the need for an endoprosthesis for 10 to 15 years, or even longer. In adults, hip dysplasia is usually easy to diagnose using an x-ray. Here the shape and position of the hip joint can be clearly recognized and whether there is already arthrosis of the hip. The success of the surgical treatment of hip dysplasia in adults largely depends on how badly the hip joint is already damaged. If the arthrosis has not progressed so far, surgery can significantly alleviate the symptoms. With severe signs of wear, however, an artificial hip joint is often the only way to live as an adult with hip dysplasia without pain in the long run. Based on a questioning of the patient's symptoms (anamnesis) and a physical examination, the doctor can assess the severity of the complaints in order to choose the right treatment method.
There are basically two operational strategies:
A joint-preserving surgical intervention is usually carried out in patients whose ailments can be attributed to various pre-arthrosis in childhood. In the case of early hip arthrosis, these surgical procedures often succeed in delaying the progression of the disease for a certain period of time. The basic idea behind the joint-preserving surgical procedure is to change the malposition surgically so that the natural joint position is restored as well as possible. One hopes to slow down cartilage loss at least in the long term. During the operation, an attempt is made to turn the femoral head in the socket in such a way that areas where there are selective pressure peaks are relieved. If the load can be distributed over a larger joint surface of the femoral head and socket, the rapid loss of cartilage is accordingly slowed down. The aim of a conservative operation is to create a distribution of the acting joint pressure over the largest possible joint surface. In individual cases, the chances of success of these interventions cannot always be predicted exactly, however, extensive post-treatment is necessary. The physiotherapeutic exercises must be carried out consistently and regularly in order to achieve therapeutic success. The operation also results in an optical “artificial leg shortening” on one side. Which must then be compensated for by appropriate measures.
If an adult is diagnosed with severe hip dysplasia, the triple osteotomy is usually used as an operation. This operation is known as a joint-preserving intervention by doctors. The triple osteotomy was specially developed for the therapy of hip dysplasia. However, it is often unclear whether a three-dimensional correction of the pan is suitable and the only way to treat a malposition. Since this operation can cause serious complications, most patients always think twice before whether the procedure is really the only surgical option. Because with the triple osteotomy, the ilium, as well as the pubic bone and the ischium are severed. Then the pan is brought into the correct position and finally screwed on again. With triple osteotomy, there is always the question of whether this complicated and serious operation is necessary or whether the simpler hip TEP is the treatment of choice and thus the second real treatment alternative.
The artificial hip joint is an endoprosthesis and is called TEP (total endoprosthesis). TEP is most commonly used by all endoprostheses in medicine and is the most widely used surgery in orthopedics. Both a part of the thigh and a part of the hip bone are replaced - that is, a complete restoration of the joint. With a successful intervention, an almost complete function and possibility of movement of the hip can be achieved. The materials used must therefore meet the highest requirements. Good lubricity with minimal friction and low abrasion is important. That is why two different materials are used for the artificial femoral head and the acetabulum. These are high-strength alloys made of different metals for the head replacement and for the socket replacement, ceramic or special plastic. The size of the selected endoprosthesis must be adapted to the nature of the patient.
The new acetabular cup can usually be easily screwed into the hip bone. To achieve enough stability of the new femoral head, the new head must be added to the thigh bone together with a long shaft. The old, worn femoral head is removed during the operation and a cavity is created in the middle of the thigh bone using suitable tools. The stem of the new femoral head is inserted into it. There are basically three methods of attaching the endoprosthesis. Which one is used depends on the individual circumstances. In order to achieve the greatest possible stability and quick loading, the endoprosthesis can be attached with bone cement. The second option is a fixation without cement - here the stem is cemented in and the cup is implanted without cement.
An x-ray is checked six weeks after the hip dysplasia operation. If the result is positive, you can finally sit again from this point in time and start spreading the operated leg. This spreading trains the muscles that serve to stabilize the hip and are responsible for the gait later on.
A second follow-up is carried out a further six weeks later. If everything is OK here, you can start building muscle and stress under physiotherapy guidance. Starting with a 10kg load and adding a further 10kg weekly, you should finally come back to full load. One should pay attention to doing intensive muscle building training. Ideally, even in the course of a rehabilitation, in which further exercises in muscle building can be carried out under supervision.
Depending on the degree of wear of the joint, a hip joint endoprosthesis can also be considered.
Hip dysplasia cannot be prevented. However, wide diapers cause babies and toddlers to spread their legs more apart. This is considered beneficial for the hip joints.
For complete healing of hip dysplasia, it is crucial whether it was recognized early. A doctor should therefore check babies for hip dysplasia at the U2 check-up, but at the latest at the U3. Therapy that is started early reduces the risk of permanent damage to the femoral head or the socket.
The sooner hip dysplasia is treated, the faster it can be remedied and the greater the chances of recovery. With consistent treatment in the first weeks and months of life, the hip joints develop normally in over 90 percent of the affected children. If, on the other hand, hip dysplasia is recognized late, surgery can usually not be avoided. There is also a risk of hip dislocation and premature wear and tear of the hip joint - this can result in osteoarthritis even in young adulthood.
The risks of surgery and restraint include growth disorders of the femoral neck and what is known as femoral necrosis, which means that the femoral head dies.
However, if hip dysplasia is not treated, the joint socket becomes deformed and later walking becomes difficult.
In hip dysplasia, physiotherapy helps to counter limping. In particular, muscles are trained that stabilize the hip.