Knee replacement due to osteoarthritis
Advanced osteoarthritis of the knee often requires a partial or total knee replacement if symptoms have not been successfully alleviated by conservative treatment or by arthroscopy.
A thorough examination will determine if a knee replacement is appropriate and necessary in your case. The objective of a knee replacement is freedom from pain as well as restoration of the ability to move and walk. However, an artificial joint can never completely replace the perfection of a natural joint. One must always be aware that this is an artificial joint with mechanics that can sometimes be heard, and that it is subject to wear in proportion to the load placed on it.
There are various methods available at the present time, but soft tissue-oriented knee joint resurfacing has proved particularly successful in knee replacement surgery. In this method, the collateral ligaments of the affected knee are given special attention. In contrast to other methods, in which computers or individual templates are used to ensure that the upper and lower leg axes are properly aligned (axis-oriented method), in the soft tissue-oriented method, the forces of the medial and lateral collateral ligaments in flexed and extended positions are determined during surgery using a special soft-tissue pressure sensor. Scarred collateral ligaments are released until the affected knee, under the same amount of pressure on the medial and lateral collateral ligament, is straight again. Thus, it is possible to adapt the artificial knee joint resurfacing individually to the various illness-related changes in the knee joint. Only after the collateral ligaments are balanced and the leg is straight is the surface replacement inserted to form the “new cartilage”. This ensures that the new artificial knee surface replacement is evenly loaded.
The soft tissue-oriented method is used for the following procedures:
- Partial resurfacing (unicompartmental prosthesis, patellofemoral replacement): only one half of the joint surface needs replacing, thereby preserving the cruciate ligaments.
- Total resurfacing (knee replacement): the entire joint must be replaced.
- Revision knee replacement (interlocking/constrained knee prosthesis, total knee replacement): when the collateral ligaments no longer function or bone quality is poor (osteoporosis); in cases of significant malpositioning or as a replacement for an existing prosthesis.
Partial resurfacing (sledge prosthesis)
Partial resurfacing (patellofemoral replacement)
Total resurfacing (knee replacement)
Revision knee replacement (interlocking/constrained knee prosthesis, total knee replacement)
the material of prothesis
Normal knee replacements are made of stainless steel, an alloy containing a mixture of cobalt, chromium, molybdenum and nickel. Some people have a known allergy to these components, or can develop one over time. To prevent this, we use biocompatible, hypoallergenic prostheses whenever possible. These are sprayed with titanium, which makes the surface of the artificial joint even smoother. This results in less wear and smoother motion of the artificial joint. The titanium coating also prevents potential allergens such as nickel from dissolving out of the components. Consequently, we have less irritation of the tissue, less pain and a longer lifespan of the artificial joint. The components of the meniscus replacement (inlay) and the replacement of the posterior surface of the patella are made of a kind of plastic (ultra-high-molecular-weight polyethylene).
The procedure varies depending on whether it is a partial or total replacement or a revision knee replacement. However, the processes during surgery are similar. In the initial step, diseased bone and tissue are removed. The remaining bone is then shaped so that the components of the knee replacement fit exactly and can be fixed in place. For most of the procedure, a tourniquet is not needed. The form of tourniquet used for a small part of the operation is an inflatable cuff which is placed around the thigh and interrupts the blood flow to the leg. By doing without it, bleeding can be better controlled and the tissue protected. This improves wound healing and reduces the risk of infection. The tourniquet is only used when cementing the artificial joint, to ensure the best possible contact between the bone, cement and artificial joint.
After the operation and subsequent rehabilitation, you should not only be free of symptoms, but also be more or less able to live your life and pursue your favourite activities as before. This includes social and sporting activities. If you have adjusted well to the new joint, increased your training moderately and not taken too many risks, all types of sport should be possible again. Of course, some sports such as skiing, snowboarding, football, tennis (stop/start, contact sports, etc.) are more dangerous and less suitable than gentler sports such as swimming, cycling and hiking.
Lifespan of a knee replacement
Although you might hope that the new knee will last a lifetime, it is important to be aware that an artificial knee joint is always a temporary solution: not because of the prosthesis itself, but because the ageing process can have a major influence on the stability of the artificial joint. These days, the average lifespan of a prosthesis is at least ten to fifteen years. This means that patients who have a knee joint replacement at a young age can expect to need another replacement or revision procedure later in life. However, given the remarkable progress in surgical techniques and the development of new artificial joints, this need not be seen as a problem. The lifespan of an artificial knee joint can be negatively affected by many factors. Ultimately, this leads to a loosening of the artificial knee joint with an associated increase in pain upon weight bearing and gait insecurity. At an advanced stage, this requires a revision knee replacement.
Contact us for a consultation
Our doctors have many years of experience and are highly skilled in sports and joint surgery. Dr Andreas L. Oberholzer is a well-known expert in knee surgery and has extensive experience in knee replacements. He trains international doctors in this area and promotes the further development of soft tissue-oriented techniques for implantation of artificial knee joints.