Artificial knee joint | Knee endoprosthesis

The unicondylar endoprosthesis - also known as a sled prosthesis or partial prosthesis - is used if only one half of the joint surface is diseased and the knee joint does not have a pronounced malalignment (bow leg, knock-knee). The healthy parts of the joint remain intact.

A special form of this is the patellofemoral endoprosthesis (patellofemoral bearing replacement). This implant is used when only the sliding bearing between the thigh bone and kneecap needs to be replaced. If the osteoarthritis on the back surface of the kneecap is advanced, it must be replaced with a corresponding plastic replacement. This is referred to as a posterior patella replacement.

A total surface replacement is implanted if the entire joint needs to be replaced, i.e. if the entire joint surface on the lower and upper leg bone is destroyed. The collateral ligaments, which serve to maintain the natural range of motion, remain in place.

The coupled knee prosthesis (revision prosthesis, total knee replacement) is used if the collateral ligaments no longer function, the bone quality (osteoporosis) is insufficient or in the case of significant deformities of the knee joint (bow leg, knock-knee). Coupled means that the thigh component is firmly connected to the lower leg component. This system therefore no longer requires the collateral ligaments.

Normal knee prostheses are made of stainless steel, an alloy consisting of a mixture of cobalt, chromium, molybdenum and nickel. Some people have a known allergy to these components or may develop one over time. To prevent this, we use body-compatible implants, so-called allergy prostheses, wherever possible. These are sprayed with titanium, among other things, which makes the surface of the artificial joint even smoother. This results in less wear and tear and better gliding of the artificial joint. In addition, the titanium coating prevents possible allergens, such as nickel, from being released from the metal. As a result, there is less irritation of the tissue, less pain and the artificial joint lasts longer. The components of the meniscus replacement (inlay) and the replacement of the back surface of the kneecap are made of plastic (ultra-high molecular weight polyethylene).

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Mechanical causes that have a negative impact on the service life of an artificial joint are increased stress on the joint and deterioration of the original anchoring of the joint in the bone. The joint's own activity plays a decisive role in overloading the joint. The more active and, above all, the more joint-straining sports you do, the more strain is placed on the anchoring of the lower leg component of the artificial joint. Overloading can also occur if the artificial joint is not optimally positioned. Furthermore, the original anchoring of the artificial knee joint in the bone can slowly deteriorate due to an increase in osteoporosis or quickly deteriorate due to a bone fracture caused by a fall. Both lead to loosening of the artificial knee joint.

Infections

These lead to activation of the immune system with inflammation and weakening of the anchorage. Infections can threaten the artificial knee joint throughout its life. Bacteria can enter the bloodstream via wounds to the skin or mucous membrane, lung or bladder infections, etc. and settle on the artificial knee joint. There they multiply and lead to an infection. The insidious thing about this is that such an infection is often only noticed after a long period of time. It manifests itself primarily through severe pain and swelling.

Allergies

An allergy can develop over the course of a lifetime: The immune system defends itself against the foreign material, which consists of stainless steel (nickel, chromium, cobalt and molybdenum), or its bone glue (cement). This leads to a non-infectious inflammation of the artificial joint, resulting in loosening of the joint.

Newly occurring stress and movement pain in the artificial knee joint that does not subside after a short time should definitely be clarified by an experienced knee specialist.

We can offer knee surgery under general anaesthesia (general anaesthesia), regional or conduction anaesthesia (spinal or local anaesthesia) or a combination of these. You will discuss which anaesthesia is most suitable for you with the anaesthetist before the operation.

Orthopaedic surgery has made great progress in recent decades. When performed by an experienced orthopaedic surgeon with years of training, knee operations are now routine procedures. The patient therefore has nothing to fear from an operation. Anaesthesia has also developed further and now enables very well-tolerated and safe anaesthesia, even for long operations.

Every operation harbours risks. These include general complications such as: Infections, wound healing disorders, haematoma and post-operative bleeding, thrombosis, injury to nerves, vessels or other anatomical structures, adhesions, excessive formation of scar tissue with reduced mobility and function of the knee joint and residual pain. Special complications such as bone fractures, allergies, increased osteoarthritis behind the kneecap, non-optimal positioning of the artificial components, incorrect guidance of the kneecaps, etc. will be discussed with you during a detailed consultation.

The risks are low for an initial operation, but then increase with each subsequent knee operation. A complication may mean that you have to have another operation. In a good clinic, you will be closely monitored so that a rapid response can be made in the event of complications.

The cost of knee surgery depends on various factors, mainly the duration and complexity of the procedure and the amount of material to be implanted. As a rule, your health insurance will cover the full costs, provided you have the appropriate insurance. Additional insurance (private or semi-private) is required for treatment at our specialist centre.

Whether a subsequent rehabilitation stay is also covered by the health insurance company must ideally be clarified with the insurance company before the operation.

If you wish to finance the operation yourself, we will be happy to put together a cost estimate on request and after a thorough examination. This also applies in particular to foreign patients.