A hip prosthesis is the partial or complete artificial replacement of the natural hip joint. It is usually used when wear and tear of the hip joint and the resulting pain can no longer be adequately treated with conventional methods. Nowadays, an artificial hip joint can quickly and gently help to restore joint mobility and regain freedom from pain.
The hip prosthesis is a so-called endoprosthesis. This type of prosthesis is implanted and is therefore invisible from the outside inside the body. In Germany, well over 350,000 endoprostheses are implanted every year.
The best result that can be achieved with a hip prosthesis is freedom from pain for the patient. With a hip prosthesis, patients can return to normal everyday life and regain their quality of life.
Artificial joint replacement of both hip joints © psdesign1 / Fotolia
A hip prosthesis is used when the natural joint is restricted in its function.
This is the case, for example, with advanced hip arthrosis, when the joint head can no longer glide smoothly in the socket. This results in pain during everyday movement, which is initially treated conservatively, i.e. without surgery. Watch the video to see how joint wear and tear is caused by cartilage damage:
However, if this pain can no longer be alleviated by conventional therapies, the only remaining option is artificial joint replacement of the diseased hip with a hip prosthesis.
You can use the following questions to determine whether a hip joint implant is a sensible therapy for you. If you can answer "yes" to 4 to 5 of these questions, you should talk to your orthopaedic surgeon about a joint replacement:
Modern hip endoprostheses are modeled on nature and imitate all the natural components of a real joint. These are the spherical joint head on the elongated shaft and the joint socket.
The body's own stabilizing ligament structures (tendons), which provide a holding function for the joint, are ideally preserved during the operation.
In principle, two different types of prosthesis can be used to replace the hip joint:
The stem can be anchored in the femoral neck bone. An artificial joint socket usually consists of a shell in which the artificial joint head can slide. This interaction is called a bearing couple.
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From Science Museum London / Science and Society Picture Library - Stainless steel and ultra high molecular weight polythene hip replacement Uploaded by Mrjohncummings, CC BY-SA 2.0, Link
In the hip area, surface replacement in the form of the McMinn cap prosthesis (Fig. 1) is preferred, especially in young patients.
Here, with excellent restoration of joint function, there is only minimal bone loss , which facilitates subsequent revision operations(hip prosthesis replacement). When using a normal cementless cup prosthesis, the femoral head is merely crowned. This results in an almost anatomical reconstruction of the joint architecture. The original joint head size is retained. This results in excellent joint mobility.
The most commonly used type of prosthesis in the hip joint area is a femoral stem prosthesis. This artificial hip joint is a combination of
This artificial joint head can have different individual diameters.
Depending on the choice of hip prosthesis, there are different sliding pairings of the joint components. The material of a prosthesis consists of, for example
The use of the different materials depends on the individual requirements in each case (e.g. age, allergy to certain metals, mechanical stress, body weight).
In addition to the McMinn cap prosthesis and the femoral stem prosthesis (Fig. 3), the improvement of the long-established short stem prosthesis (Fig. 2) has become increasingly popular in recent years with rising implantation figures.
Cap prosthesis - Short stem prosthesis - Femoral stem prosthesis
Another difference in hip prostheses is the anchoring method.
In the past, the first artificial joints were generally inserted onto or into the cut bone using a special plastic mixture (also known colloquially as "bone cement"). Today, it is also possible to insert the hip prosthesis without cement (cementless fixation).
This has been made possible by a special surface treatment of the implants. The surface of the titanium material is modified with laser beams, for example, to give it a porous fine structure. This allows the implant to anchor itself very firmly in the bone and grow into the healthy bone. This makes subsequent loosening of the prosthesis less likely.
Cemented prostheses are more difficult to remove than uncemented ones. As the average lifespan of a hip TEP is up to 15 years, removability is an important criterion when selecting the type of anchoring. After all, if the artificial joint needs to be replaced, this replacement operation should be easy to perform.
A combination of both types of anchoring is also possible. This is referred to as a "hybrid joint". The implanting doctor selects the appropriate anchoring form based on the patient's joint condition, age and bone quality.
The following applies:
- Young, active patients under the age of 60 should receive cementless anchoring if possible. The reason for this is that a replacement operation is to be expected when the durability of the prosthesis is exhausted.
- For patients up to the age of 75, a so-called hybrid restoration, i.e. a cementless cup and a cemented stem, is preferred.
- Older patients over the age of 75 usually benefit from a fully cemented version, as their bone is often no longer very strong and requires additional cement stabilization.
The clinic team will select the appropriate type of prosthesis, the best tolerated prosthesis material and the best-fitting prosthesis shape for the individual patient based on the information obtained during the preliminary consultation and the special features visible on the X-ray.
Themost important criterion for the type of prosthesis anchorage is the bone quality: cemented, cementless or hybrid.
Fully cemented, cementless and partially cemented hip prosthesis.
In most cases, the operation to insert a hip prosthesis is an invasive procedure and must be performed under general anesthesia . It is a major operation in which both the natural joint, including the head and possibly the femoral neck, must be removed.
The artificial hip joint can then be inserted. An open operating field is therefore required during the operation to insert a hip prosthesis in order to be able to place and attach all structures correctly. The surgeon therefore needs a clear view of the joint.
When inserting an artificial hip joint, the patient lies in the lateral position on the side not to be operated on. The pelvis is supported by anterior and posterior pelvic supports and the leg to be operated on lies in a leg support shell.
The procedure of a hip prosthesis operation in detail:
The surgeon now has a clear view of the diseased joint. The actual operation on the hip joint begins and the insertion of the hip prosthesis is prepared - these surgical steps can be seen in the video :
The implant is securely anchored and, if necessary, fixed with bone cement. The correct fit of the hip prosthesis within the leg is then checked using X-ray images.
As these parts fit together precisely like balls in a ball bearing, friction-free movement of the bony joint partners is possible again after the operation. Once the prosthesis has been inserted anatomically correctly, the opened surgical area can be sutured or stapled shut again.
The media is increasingly using terms such as "keyhole surgery", arthroscopy or minimally invasive surgery. The significant success of this surgical procedure lies in the fact that the accompanying injuries to the surrounding tissue can be kept to a minimum.
On the way to the damaged joint, the skin and surrounding tissue (e.g. muscles) must be opened in order to access the surgical site. This accompanying tissue damage is often responsible for the fact that post-operative healing (i.e. after the operation) takes significantly longer than would be necessary from a pure joint procedure.
With minimally invasive surgery, the skin incision can be significantly shorter than 10 cm and is not 20 cm long as it used to be. Depending on the individual characteristics of the patient's anatomy (height, weight, required implant size), the length of the incision can vary considerably. However, it is kept as short as possible.
Minimally invasive arthroscopy of the hip joint: hip arthroscopy © bilderzwerg / Fotolia
However, the purely cosmetic aspect of a shorter scar is not the reason for a minimally invasive procedure. In fact, minimally invasive surgery is much more gentle on the muscles. Access routes are chosen that utilize natural, anatomically existing tissue gaps, for example between individual muscles. Muscles are no longer detached or severed, but only gently pushed apart along the fibers.
In addition, special miniaturized instruments are used that require less space in the operating area itself.
For the patient, this means a procedure that is gentler on the tissue and results in less blood loss. This also means that less blood is needed and the overall hospital stay is shorter. By preserving the muscles supporting the joint, patients are already more mobile the day after the operation and are able to perform and train important joint functions independently.
Minimally invasive therefore means more than just a shortened incision. The decisive factor is the preservation of tissue under the skin.
The insertion of an artificial hip joint is a permanent operation that cannot be reversed. The entire natural joint must be removed for the hip TEP.
To prepare for this operation, at least one specialist in orthopaedics and an expert in endoprosthetics must be consulted before the operation can actually be carried out. This is the only way to ensure that the artificial replacement is actually necessary and will lead to the best possible result for the patient.
As usual, the patient undergoes a number of preliminary examinations before the operation. These ensure a safe and smooth procedure during the implantation. These preliminary examinations include
- A blood sample to check the blood values,
- an ECG to check the cardiovascular system,
- a preliminary consultation with the anesthesiologist (anesthetist).
The best way to prepare for hip replacement surgery is to obtain thorough information and talk to the doctor and clinic team.
© RFBSIP / Fotolia
However, patients themselves can also play an active role in ensuring that the artificial joint replacement is an optimal treatment success.
Even if the pain significantly affects the patient: The artificial hip joint is not an emergency operation, but a carefully planned procedure. Nevertheless, in addition to all the surgical improvements, new medications and modern anesthetic procedures, there is always a small risk.
On the other hand, the patient's quality of life and enjoyment of life are significantly reduced by the discomfort caused by his illness. The pros and cons must therefore be carefully weighed up, and your doctor will help you with this.
A healthy diet should already play an important role in everyday life. However, it is all the more important in the run-up to an operation. Sometimes patients have "put on a few pounds" due to the recent restriction of movement.
They should now consciously, but not forcibly, reduce these. The family doctor or internist will help them to work out a gentle diet, but they should not lose more than 1 kg per week.
The following rule of thumb is recommended for a good constitution at the time of the operation and for good wound healing: In principle, all food components should be included - carbohydrates in the form of whole grain products, plenty of fruit and vegetables, lean meat, protein-enriched foods and calcium-rich dairy products.
Due to the joint disease, the muscles surrounding the joint are weakened, shortened and in some cases already atrophied(muscle atrophy).
Before the operation, however, the patient should begin to train these muscles on their own. If the movements cause him too much pain, he should avoid these movements and perform more tensing exercises (isometric training).
Doing these exercises several times a day on your own will improve the future healing process.
In addition to the joint disease, most patients also have one or more concomitant diseases such as high blood pressure or diabetes. They are therefore often forced to take medication on a regular basis. Unfortunately, some relatively common medications (such as ASA) must be viewed critically in connection with an operation, as they can increase the risk of surgery or cause completely new risks - especially in combination with anesthetics.
For this reason, patients are usually given a list of critical medications when their artificial hip joint is scheduled for implantation. Patients should discuss this with their family doctor, review their personal medication and, if necessary, discontinue or change it in good time before the procedure.
Aftercare following a partial prosthesis or hip replacement is complex and takes time. The artificial hip joint must be slowly acclimatized and adapted to its new tasks. Professional orthopaedic rehabilitation is advisable.
Exercise is very important after the insertion of a hip prosthesis in order to maintain the functionality of the prosthesis itself and to rebuild the muscles in which it is embedded after the operation.
At the same time, a strengthened musculature protects all joints from overloading and thus also from signs of wear and tear. After an operation and the insertion of a hip prosthesis, physiotherapy is the most effective way to start building up the muscles. The therapy concept is tailored precisely to the patient and their needs.
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