Material of a knee prosthesis

Types of knee prostheses

Types of knee replacement:

There are different types of Knee endoprostheses.
It is not always necessary all of it Knee joint to replace. Accordingly, a distinction is made between the complete Knee prosthesis and the partially Joint replacement.

With both types of knee arthroplasty, a distinction is also made as to the extent to which the connection between the femur and tibia components (thigh and lower leg components) is guaranteed.

One further distinguishes between different Degree of coupling of the Knee prosthesis:

• uncoupled knee prostheses
• partially coupled knee prostheses / partially coupled knee prostheses
• fully coupled knee prostheses, also called hinge prostheses

In the early days of endoprosthetics, the fully coupled types of prostheses were predominantly used (Hinge prostheses). However, since it was found in the course of scientific studies that the partially coupled knee prostheses or the uncoupled prostheses had a longer shelf life, the fully coupled prosthesis models faded into the background. These prosthesis models still have to be installed in unstable capsule-ligament relationships.

Appointment with a knee specialist?

I would be happy to advise you!

Who am I?
My name is dr. Nicolas Gumpert. I am a specialist in orthopedics and the founder of .
Various television programs and print media report regularly about my work. On HR television you can see me every 6 weeks live on "Hallo Hessen".
But now enough is indicated ;-)

The knee joint is one of the joints with the greatest stress.

Therefore, the treatment of the knee joint (e.g. meniscus tear, cartilage damage, cruciate ligament damage, runner's knee, etc.) requires a lot of experience.
I treat a wide variety of knee diseases in a conservative way.
The aim of any treatment is treatment without surgery.

Which therapy achieves the best results in the long term can only be determined after looking at all of the information (Examination, X-ray, ultrasound, MRI, etc.) be assessed.

You can find me in:

• Lumedis - your orthopedic surgeon
  Kaiserstrasse 14
  60311 Frankfurt am Main

Directly to the online appointment arrangement
Unfortunately, it is currently only possible to make an appointment with private health insurers. I hope for your understanding!
Further information about myself can be found at Dr. Nicolas Gumpert

The following results from the above-mentioned structure of the prosthesis models Classification:

1. Complete knee replacement (= Full denture):
   With this knee prosthesis, the entire articular surface of the thigh and tibia head is replaced. A replacement of the back of the kneecap may also be necessary. In the context of complete knee replacement, one differentiates between:
• Unlinked total endoprosthesis
• Partially coupled total endoprosthesis
• Fully coupled total endoprosthesis

2. To 1.) The uncoupled total endoprosthesis (Joint surface replacement)
   This subgroup of different types of knee prostheses is most similar to normal knee mobility.

   This is the case because both the thigh and the lower leg part of the prosthesis type are not connected to one another - like a hinge - just like in the normal human knee joint.
   To be able to install this type of prosthesis, you have to anterior cruciate ligament not preserved, it will even be surgically removed - if still present - before the prosthesis is implanted. This has to be done because the cruciate ligament, as the name suggests, crosses the knee joint. The function of the cruciate ligament is taken over by the artificial knee joint.
   In order to be able to assign maximum stability to this type of prosthesis, posterior cruciate ligamentas well as the side ligaments must be fully functional.

   To 2.) The partially coupled knee endoprosthesis
   This form of total endoprosthesis is mainly used in patients with weak ligaments, thus usually in patients whose posterior cruciate ligament and / or whose side ligament is torn and / or damaged. Especially at rheumatism -Patients the use of this knee prosthesis is often necessary.
   During the operation, an upward, round, metallic handle is placed in the patient's thigh from the shin part. Care is taken that both Elongation, as well as diffraction, as well as rotation (= rotation) is enabled.

   To 3.) The fully coupled total endoprosthesis
   They represent the first generation of all knee joint prostheses. In contrast to the other types of knee joint prostheses described above, this form has the highest degree of coupling between the thigh and
   Tibial component. One of the reasons for this is that these two components are connected to one another by a rigid axle. This rigid axis acts like a kind of hinge joint and enables flexion and extension, but rotation is above this Knee prosthesis not possible.
   Another disadvantage is their size and, among other things, the associated weight. Due to the massive nature of these prosthetic models, an excessive amount must be used Bone substance To be “sacrificed”.
   Fully coupled total endoprostheses are usually used for replacement operations, unstable joints, massive ones X legs - and Bow-legged built-in.

   At one Change of prosthesis (Prosthesis replacement operation) often has to refer to a so-called "Revision model“The hinge prostheses mentioned above are often used here.

3. Partial joint replacement (= sled prosthesis):
   If only the inner or outer section is affected by the destruction of the knee joint, then not the entire Knee joint be replaced. Depending on the individual state of the disease, today only the affected area is replaced with a so-called Sled prosthesis, the
   
   • From a metal runner for the thigh and
   • Consists of a metal disc with a plastic covering for the tibia head.

   The anchoring of this type of prosthesis can either

   • cemented or
   • uncemented respectively.

   The bone cement is usually a fast-hardening plastic. It is mixed during the knee prosthesis operation and hardens completely within a few minutes. In the event that you have to prevent a prosthesis infection, the mixture can be a antibiotic be added.

Operation of a knee prosthesis

The aim of the implantation of a knee prosthesis is to replace the worn out cartilaginous part of the knee joint with an operation that removes as little of the existing bone tissue as possible. The Extent of the operation therefore depends on the Extent of damage of the knee joint. If possible, the patient's own Knee ligaments preserved become.

Depending on the wear and tear on the joint three different prostheses to disposal. Of the unilateral resurfacing, also called unicondylar sledge prosthesis, in which the surface of one of the two thigh rollers (Condyles) is replaced. Or the complete resurfacing, in medical terminology also as a total knee endoprosthesis (Knee replacement) designated. A third technique is that Complete resurfacing with an axially guided pedicled knee prosthesis.

The more the patient's ligamentous apparatus is affected by the operation, the more of the stresses that arise in daily life must later be taken over by the prosthesis. The prosthesis is therefore classified according to the so-called Degree of coupling. The higher the degree of coupling, the more immobile the knee joint is after the operation. In the unicondylar sledge prosthesis it is usually a uncoupled, in the Knee replacement around a uncoupled or partially coupled and at the axle-guided Knee prosthesis by one fully coupled Prosthesis.
The type of prosthesis used in the patient is determined by age, mobility and state of health as well as the degree of wear of the joint and the condition of the bones and ligaments.

In the unicondylar sledge prosthesis only one of the two thigh rollers is provided with a surface replacement. This is the smallest and easiest intervention. This technique is only possible if only one of the two thigh rollers is worn, the rest of the knee joint is working properly and the ligamentous apparatus is intact.

At the most common is therefore the Total knee replacement (Knee TEP) used. The knee joint is completely removed and its components are replaced by artificial elements. The knee TEP is an artificial hinge joint, as such it can fulfill all the tasks of the original joint and enables stability and a secure stance with the leg extended.

The replacement of the diseased knee joint is under general anesthetic carried out. Of the Surgeon opens the affected knee while maintaining healthy structures such as muscles and ligaments and gaining an overview of the extent of joint damage. Depending on this, he decides which type of knee prosthesis should be used. In the case of surface replacement, the worn joint surfaces are completely replaced by artificial surfaces made of a robust and smooth metal alloy. These newly introduced elements are held in place by wedges, which are anchored in the thighbones and shins.

With the axis-guided knee TEP, the original joint surfaces are also replaced by artificial materials. With axis-guided knee replacement surgery, the anchoring in the bone is deeper than with pure surface replacement. In addition, the components used in the thigh and shin are coupled at the level of the kneecap in order to prevent them from slipping sideways. This form of the prosthesis is used when the originally existing one Tape apparatus already badly damaged and could not provide support for an uncoupled resurfacing.