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Endoprosthesis: description, surgical procedure, risks

by Josephine Andrews
Published: Last Updated on 216 views

An endoprosthesis is an artificial joint replacement. It is usually made of metal, plastic and ceramic and is implanted in place of a damaged joint. The endoprosthesis either replaces only parts of the joint or the entire joint. Read everything you need to know about the surgical procedure, how the endoprosthesis works and what the risks are.

What is an endoprosthesis?

In endoprosthetics, damaged joints are replaced with endoprostheses. Depending on whether you want to replace an entire joint or just parts of it, you use a total endoprosthesis (TEP) or a partial endoprosthesis ( hemia endoprosthesis, HEP) .

An endoprosthesis should last as long as possible, but at the same time be tolerated by the body. It is usually made of metal, ceramic and plastic. Special metal alloys made of titanium, cobalt or chrome are usually used for modern endoprostheses. The inlay of the endoprosthesis, which replaces the articular cartilage, consists of the plastic polyethylene.

The connection between endoprosthesis and bone is called anchorage. A distinction is made between:

  • Cemented endoprosthesis : It is the most common variant. The endoprosthesis is connected to the bone with the help of a special plastic cement.
  • cementless endoprosthesis : It is first pressed into the bone and anchored by ingrowth. This variant is more suitable for younger patients, since their bone substance is stronger and more stable than that of older patients.
  • hybrid endoprosthesis : It combines both types – one part of the endoprosthesis is cemented, the other cementless attached.

When do you need an endoprosthesis?

Joints in the hip, knee, shoulder, ankle, elbow and spine can be replaced with an endoprosthesis if they no longer fulfill their function or are only able to move to a limited extent. Possible causes for this are:

  • Osteoarthritis (wear and tear of the articular cartilage)
  • rheumatoid arthritis (chronic joint inflammation that can destroy the affected joint)
  • Tissue death (necrosis) in the joint area
  • Breaks (fractures) in the joint area
  • joint stiffening

Sometimes an already implanted endoprosthesis has to be exchanged for a new one.

What do you do with an endoprosthesis?

Beforehand, the doctor will ask you about previous illnesses, injuries, medication and allergies. He will examine the affected joint for mobility, stability and pain and will explain the operation to you. Preparation for the procedure also includes blood tests and imaging – X -rays , computed tomography (CT), magnetic resonance imaging (magnetic resonance imaging, MRI).

course of the operation

The operation is performed under general anesthesia. The surgeon gains access to the affected joint via a large skin incision (classic surgical method) or several small incisions through which the necessary instruments are inserted (minimally invasive variant). He pushes the muscles in the joint area as gently as possible to the side – if necessary, he also cuts them.

Then the surgeon opens the joint capsule that surrounds the actual joint. In this way, he can remove damaged or worn joint surfaces and articular cartilage. The remaining bone surfaces are prepared for the endoprosthesis with special rasps, milling machines and saws.

A trial implant is now used to check the size, mobility and stability required for the artificial joint replacement. The finally selected suitable endoprosthesis is then – if it is a cemented variant – connected to the bone with the help of so-called bone cement. A cementless endoprosthesis with its cone-shaped anchorage, on the other hand, is hammered into the bone and thus secured (press-fit fixation). A screw connection between the endoprosthesis and the bone is also possible.

Finally, the surgeon checks the correct fit and mobility of the artificial joint. An X-ray may be taken to check before the wound is sewn up. A bandage protects the wound from infection.

Further information: Knee TEP

If you want to know how to perform a total knee arthroplasty, read the article  TKA .

Further information: Hip TEP

If you need more detailed information on total hip arthroplasty, read the article on total hip  replacement .

What are the risks of an endoprosthesis?

Various complications can occur during or after the operation. These include:

  • bleeding
  • thrombosis
  • infections
  • Injury to skin , muscles or bones
  • loosening of the endoprosthesis
  • allergic reactions to components of the endoprosthesis

What do I have to consider after an endoprosthesis?

After the implantation of an endoprosthesis, you usually stay in the hospital for one to two weeks. Physiotherapeutic follow-up treatment begins on the first day after the operation:

Based on a structured plan, the muscles are built up and the mobility of the joint is restored. In passive physiotherapy, a physiotherapist moves and mobilizes the joint without your active participation. In addition, you will carry out exercises independently under the guidance and supervision of the physiotherapist.

The subsequent three to four week (sometimes longer) rehabilitation can take place either on an outpatient basis or in a special rehabilitation clinic. The function of the operated joint is restored. You will also learn how to move around in everyday life in a way that is gentle on your joints and what types of sports and activities you can do. Swimming , cycling and Nordic walking are considered to be particularly easy on the joints . In order to avoid consequential damage, weight control is also recommended.

Your doctor will carry out radiological checks and examinations at regular intervals in order to be able to detect possible loosening of the endoprosthesis or late complications as early as possible. If you experience pain or other discomfort in the area of ​​the operated joint, you should consult your doctor immediately.

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