Joints can be damaged or show instability due to various diseases or an accident. In such cases, joint replacement with an endoprosthesis is often necessary. This can restore mobility to the joint and prevent pain.
What is endoprosthesis?
Endoprostheses are artificial joints that replace a damaged joint and remain in the body permanently as an implant. Such as an artificial hip joint. Endoprostheses are artificial joints that replace a damaged joint and remain permanently in the body as an implant. For this purpose, the worn joint is removed under anesthesia and replaced by an artificial joint. Endoprostheses are often used for hip and knee joints, less frequently for ankle, elbow or finger joints. When the entire joint is replaced, it is referred to as a total endoprosthesis, or TEP for short. Depending on the extent of the damage, only certain parts of the joint can be replaced. Partial joint replacement of the hip, in which only the joint head is replaced, for example, is called hemiendoprosthesis or HEP for short; in the case of the knee, partial endoprosthesis is also referred to as sled prosthesis.
Function, effect and goals
Osteoarthritis, gout or rheumatic diseases can lead to joint damage. Other causes include an accident or bone fracture, malposition of the joint, or, in rare cases, bacterial infection. Tumors that occur near joints can also lead to damage. Depending on the degree of destruction or limitation of function, and if no other treatment options are available, joint replacement with an endoprosthesis may be necessary. Likewise, with age, natural wear and tear may necessitate the use of an endoprosthesis. Under general or partial anesthesia, damaged parts of the joint are removed and the remaining bone is milled for the fitting of the endoprosthesis. The implant is then inserted and fixed in place. The endoprosthesis is made of metal, plastic or ceramic or, in the case of a TEP, a combination of these materials. A distinction is made between cemented and cementless prostheses, and there are also so-called hybrid prostheses in which parts are cemented and other areas are cementless. Cementing, for which a fast-hardening plastic is used, makes it easier to insert and fix the artificial joint. In the cementless prosthesis, the joint is precisely fitted and fixed in place by the formation of new bone substance by the body. After the operation, wound pain occurs in the first few days, which is treated with medication. Physiotherapeutic exercises for the mobility of the joint can be performed already on the first day after the operation. Only in the case of a cementless endoprosthesis, no or only partial weight-bearing is allowed during the first week after the operation until the implant is sufficiently fixed by the newly formed bone substance. In the case of hip and knee endoprostheses, forearm crutches are required during the first weeks after the operation. These prevent overloading of the operated joint and improve safety when taking the first steps. The inpatient stay usually lasts about a week before rehabilitation measures with physiotherapeutic exercises improve mobility and train the muscles that stabilize the joint. Regular follow-up examinations by an orthopedist or in the clinic are necessary to detect possible complications early on and to ensure the long-term function of the artificial joint. The endoprosthesis takes over the function of the replaced joint, mobility is restored and pain is eliminated. As a result, the quality of life is improved and patients can return to work, hobbies and sports. Since endoprostheses do not have an unlimited lifespan, the artificial joint is mainly chosen for older patients. However, depending on the clinical picture, the implantation of an endoprosthesis can be useful even at a younger age. The service life of an artificial hip or knee joint is now 15 to 20 years, although heavy loads can significantly shorten the service life.
Risks, side effects and dangers
Due to the surgical procedure, endoprosthesis poses comparable risks to other surgeries: Thrombosis can occur during or after surgery, infections can lead to disturbances in wound healing, a bruise can form after surgery, or postoperative bleeding can occur. In addition, nerves or blood vessels may be injured, and occasionally blood loss occurs during surgery, requiring a blood transfusion. Specific risks for joint arthroplasty include bone tissue avulsions in rare cases. These necessitate additional stabilization, for which wires or screws are used. If an allergic reaction to one of the components of the endoprosthesis occurs, the joint must be replaced again. During the first ten years after implantation, loosening of the artificial joint may occur. This change, which is associated with pain and instability and is sometimes inflammatory, requires a new operation. In addition, friction of the prosthesis on the joint surface can cause prosthesis wear, which can trigger inflammatory reactions. In so-called heterotropic ossification, the body converts soft tissue into bony tissue and, without countermeasures, there is a loss of joint mobility obtained through surgery. When exercising, sports that are easy on the joints, such as cycling, walking or swimming, should be preferred. Sports with sudden stop and rotational movements, as in squash, should rather be avoided. However, the practice of sports also depends on the type of endoprosthesis and in what form a sport is performed. For example, breaststroke is not suitable for a hip endoprosthesis, but crawl or backstroke are safe.
Typical and common joint disorders
- Osteoarthritis
- Joint inflammation
- Joint pain
- Joint swelling
- Rheumatoid arthritis
