Synonymous
artificial hip joint, total hip joint prosthesis, hip prosthesis, total hip prosthesis, hip arthroplasty
Definition
The name total hip joint prosthesis stands for "artificial hip joint". The artificial hip joint is based on the human hip joint and therefore consists of the same parts in principle.
When implanting an artificial hip joint, you replace the joint cavity of the pelvis by a socket prosthesis (= "artificial socket"). The femoral head and the femoral neck themselves are being replaced by the prosthesis shaft with an artificial femoral head on top.
There is the possibility of fixing the mentioned components in the bone either with or without bone cement.
Preparation
Since all surgeries concerning artificial joints are so-called "interventions by choice" and the appointment is therefore known over a longer time period, preparations for the surgery can be made early and well thought about. Part of the preparations, besides obtaining information, are for example:
Information conversations with the attending doctor, maybe even with the operating doctor
Obtaining information with regard to the question: Which artificial limb model is suitable for me?
Obtaining information with regard to the question: Are there specialists / special clinical complexes?
Is there the possibility of the autohemodonation?
With regard to the possibility for the autohemodonation you shall point out in this place that it can particularly come to a high loss of blood at the artificial hip joint operation. A donation of your own blood then has the advantage that one "donates blood to himself" before surgery in case you might be in need.
This is possible particularly due to the fact that this is a “intervention by choice” (see above). The donation of one’s own blood takes place about two to six weeks before the planned operation appointment in the hospital which carries out the operation. It has the advantage that the risk of an illness assignment can be excluded actually over the blood way since one gets his own blood again. A blood transfusion from somebody else is connected to a certain remaining risk also at all control authorities which the blood must pass through.
An artificial hip joint operation leads to an approximately two till three-week stay in hospital in general. This stay is followed by rehabilitative treatments which can be carried out ambulant or on the ward and be made individually very different.
The first mobilization takes place in general on the first day after the operation. You must point out that this has to happen under instructions. A physiotherapist in general is responsible for the first mobilization, and who furthermore explains the patient which movements can be done and how and which movements you shouldn’t do.
Artificial joint models
Which different artificial joint models are there?
Radiograph with an artificial hip joint
Socket of the hip artificial joint
Artificial joint shaft
Artificial femoral head
Since high requirements are made on artificial hip joints and they must meet these requirements also in a special way, to the qualification profile of artificial joints belongs that prosthesis have to be
corrosion-resistant
abrasion resistant
well- tolerated (no allergies !!!)
robust to the pressure and bending strains of the body movements. Only few, quite certain metal based alloys do justice to this qualification profile generally. For example specific synthetic materials, titanium, ceramic and high-grade steel, are part of these special alloyings.
The aim is always restoring an undisturbed, painless and first of all things durable function of the hip joint. One therefore distinguishes three different artificial joint types which are different in the endogenous bone in the way of the artificial limb anchorage.
These are:
The cement free artificial joint
The cemented artificial joint
The hybrid artificial joint,
which is a combination of cemented and not- cemented artificial joint parts.
The advantage, that there are different possibilities of the artificial joint anchorages in the endogenous bone, is that the patient can have implanted three - under circumstances even more- different types of artificial joints. Despite all requirements an artificial limb model must fulfill, changing operations can not be excluded and get due within a certain time period (see below).
The different artificial limb types shall be represented and described in their qualities followingly.
1. The cement free artificial joint
Other than at a cemented artificial joint, at a non- cemented prosthesis the femoral shaft and the artificial socket of the hip is either screwed into the bone or clamped into the bone. In the first case one talks about a so-called “screwing socket”, in the last case you talk about a “press – fit prosthesis".
A fixation of cement-free artificial joints, which as a rule consist of titanium, can be achieved in a special way by the special surface coating, which consists of a bone basic substance, the Hydroxylapatit. The surrounding bone grows up to the artificial joint so that a close connection is formed between the two substances. Therefore the direct assignment of the strain strengths is ensured first of all.
2. The cemented artificial joint
Cemented artificial joints can be distinguished from the not- cemented artificial joint, because both the artificial joint shaft and the socket of the hip can be implanted with the help of a fast hardening, containing antibiotics bone cement. Therefore they do not have any roughened surface, which shall cause growth.
At cemented artificial joints it is necessary to avoid possible gaps, which can appear between cement and artificial joint and under circumstances can be responsible for the loosening of the artificial joint.
3. The hybrid artificial joint
A hybrid artificial joint is a combination of a cement free and cemented artificial joint. Therefore either the artificial joint shaft is fixed with the help of a fast hardening and - to prevent infections - as a rule antibitotic- containing cement, while the socket of the hip is fixed without cement, or the other way round. For all artificial joint types different model variants exist. It requires the determination of size, weight and bone form of the patient as well as the demands which he makes to his new hip joint to determine the right model.
As a rule, the operating doctor makes drawings of the hip to be operated prior to the operation using the pictorial methods with whose help he then can determine the exact size and the model of the artificial hip joint.
Different components of the hip joint prosthetic are shown followingly. One recognizes that according to the model variants and the manufacturers different models are on the market whose advantages and disadvantages can be investigated only after many years and are dependent always also on individual events.
The socket of the hip joint
The following pictures shall clarify the differences between cemented and cement available hip joint sockets. As mentioned already, cement- free artificial joints always imply a screwed socket.
Cement- free artificial joint imply the use of a socket with metal based alloy (for example in the form of titanium).
Screwed socket
"press fit” - socket
"press fit” - socket with rotation taps (with inlay)
Polyethylene socket for cemented artificial joints
The artificial joint shaft
To the variety of the different socket types analogously there also exists a great choice the artificial joint shaft. One distinguishes also here:
Cemented sockets and
Not- cememted sockets
The not- cemented sockets are especially being distinguished with regard to their main anchorage zones again. According to the artificial joint design the artificial hip shafts are anchored mainly in the upper part of the prosthesis. The remaining part of the artificial joint also contributes to the anchorage, however, it is not seen as a percentage so decisively. It is important in any case that the artificial joint shaft is attached here as narrowly as possible to the hard part (compacta) of the tube bone and is there accepted by the bone of its own in the course of the further weeks after the artificial joint operation. Therefore, between the artificial joint and the bones a biological - synthetic combination occurs, which can be stably combined for a life time.
At this type of the prosthesis the main part of the artificial joint anchorage in the middle / lower part of the artificial joint. Seen as a percentage the upper part of the shaft contributes only less to the anchorage in the thigh bone. This artificial joint type is completely installed in a lower quantity than the artificial joint type listed above.
The shaft types
The manufacturers advertise with different designs also here. Comparative examinations between the different types and their advantages and disadvantages are carried out only restrictedly. An arbitrary choice of different shaft models was compiled followingly.
A cement free titanium artificial limb, the head is already are put on.
A modular system, i.e. the shaft length can be chosen modularly, depending on the patient.
Another model with macroporous upper and microporous lower shaft share.
The hip artificial joint head:
The femoral head is the part of the complete artificial limb to which you can adapt situationally and individually, said more exactly: must be adapted. So this is as described already above a modular share of the whole prosthesis.
Modular shares of a whole prosthesis, either in the area of the artificial hip joint head or in the area of the shaft types, help to be able prepare better for individual events (see above). These components make it possible for the surgeon, for example, to compensate for leg length differences provided that it can be considered to be sensible.
There are different materials which are used for the production of the artificial hip joint heads. Steel based alloys or femoral head artificial of ceramic joints are frequently used.
Advantages and disadvantages can be found at the two materials. Although one accuses artificial hip joint heads made of ceramic are said to be less abrasion sensitive, but also more sensitive for fractures, while steel practically cannot break, however.
A final assessment, which material is to be categorized as better, is not yet cleared up until now. The investigation of new or surely the improvement of the previous materials will further make progress.
Operation course
In briefs in the context of an artificial hip joint operation bones, which have been damaged operatively or cartilage parts of the hip joint will be removed and replaced by artificial parts.
The hip joint consists of the thigh bone (= femur), a long tube bone which ends in ball at the top side. This "ball" is under guarantee of a room to move embedded into the socket of the hip (= acetabulum) of the pelvis. By this construction a maximum freedom of movement in the kinds of walking walk, sitting, ...becomes possible ..
Patients with whom a prosthesis of the hip joint must be taken into consideration have lost this maximum freedom of movement or are strongly restricted in their possibilities to do everyday movements. Which causes regarding this it can be based on shall not be mentioned at this place. Here you shall rather show how such an operation proceeds.
As already mentioned above, bone or cartilage parts damaged in the context of the hip joint prosthesis are being removed and trying to save healthy fabric. The taken- out components are replaced by artificial "spare parts". On the one hand, these artificial parts are the acetabulum, the socket of the hip joint, the hip shaft with the artificial hip joint head (example see above).
Aim of a hip artificial joint operation is the achievement of maximum quality of life in the form of painless movement of the hip joint.
The access
Every operation requires an access to the area to be operated on. In the context of the hip prosthesis this access can be opened anterolateral (from the front), lateral (from the side) or posterior (from the back).
The size and therefore the length of the access is individually different and varies between 10 and 30 cm. At first the area to be operated is prepared by the operation team, the surgeon finally severs fabric and muscle layers to make a free way to the hip joint possible.
When this has happened the femoral head gets dislocated from the area of the socket of the hip.
Preparation ion of the femoral head
The femoral head becomes completely removed after the opening of the operation and dislocating the femoral head from the socket of the hip. Decisive is in which height the femoral head is divided off. This has a big effect on the course of the operation, above all also on the leg length and therefore on the situation after the surgery.
Preparation of the socket of the hip
The socket of the hip also must be prepared. For this a bowl is put into the hip socket after the hip socket has been shaped circular. There are different models of such bowls how already mentioned above. While so-called “press- fit”-sockets are "merely" hit into the socket, there are sockets, which must be installed by means of antibiotic- containing cement. Sop that a undisturbed movement can be possible as a rule the diametre of the bowl has to be about 2mm lafger than the diameter of the head. So that the placement of the bowl will not be wrong, it is being controlled in the context of the operation with the help of an aiming machine and, if needed, even corrected.
If one states in the context of such control firm, that the new components are only insufficiently fixed, this problem can be counteracted in exceptions by means of additional screwing. This can lead to further problems under circumstances particularly at necessary change operations.
Preparation of the marks zone
For this, at first the tube bone gets drilled with the help of a drill into the marks zone. The use of so-called "rasps" makes the preparing of an area possible into which the shaft fits exactly. Whether there is an exact fit gets proven before the implant is installed with or else without cement into the bone.
Choice of the head
A femoral head fitting the hip socket is now put on the shaft. All artificial joint parts have therefore been implanted. Of course a checking of the functioning of the new hip joint is necessary before you sew up the wound.
Here the possibility of a further luxation (= dislocation) of the hip joint should be excluded. It can happen that an artificial hip joint tends to luxation. To counteract such cases "inlays" which can in addition be brought in into the pan were developed. Therefore you make a better roofing of the femoral head possible and can prevent that at extreme movements the hip joint dislocates.
Sore seal
After "passing" the function test the operation area is sewed up again. One understands by it that the hip joint capsule is (partly) at first locked again and perhaps cut off muscle parts established in the area of their origin again. The individual skin layers finally must be sewed up. Different seam techniques or even the possibility of the "tacker together" is at the surgeon's disposal for it.
Narcosis and duration
You must assume that a hip prosthesis operation can a last on an average - between 45 minutes and 2 hours in which deviations can be conceivable up and below.
The operation can be carried out in both general but also in partial narcosis.
In this place you still shall point out that following to the prosthetic operation rehabilitation treatments as a rule should be attached. Which form can be taken into consideration for this in the individual case, should be discussed with the attending / operating doctor. The motto is valid: Help of one's own is usefully but too much help, too much ambition can slow the healing process down or limit it considerably.
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