Knee endoprosthesis / Top clinic in Germany, Friedrichshafen

Knee endoprosthesis

The implantation of a knee endoprosthesis is one of the routine surgeries at German orthopedic centers. The board certified endoprosthesis center in Friedrichshafen is designed for 45 beds, including 6 intensive care beds. In the period from 2003 to 2009 about 3 000 implantations of knee endoprosthesis have been performed here.

The aim of knee arthroplasty is to reduce pain, restore joint function and improve the quality of life. The specialists of Friedrichshafen are devoted to the most secure and efficient techniques of knee replacement. The knee joint arthroplasty is performed in a sparing minimally invasive way. Great importance is given to the postoperative period and the patient's rehabilitation.

The following models of endoprosthesis are used for knee replacement at the Clinic of Friedrichshafen:

  • Oxford knee prosthesis
  • LINK
  • Smith-Nephew
  • Wright
  • Zimmer
  • NexGen mobile bearing

The experienced specialist selects the knee endoprosthesis model individually, taking into consideration the condition of the bone tissue and anatomical features of the knee.

Special attention is paid tot he materials of knee prosthesis. The partial or complete-knee prosthesis, which we use at our clinic, consists of a special cobalt-chromium-molybdenum alloy. The plastic parts are made of ultra-high-molecular-weight polyethylene. Due to the excellent biocompatibility of these materials, allergies and side effects can be ruled out.

Types of knee replacement implants

Endoprosthesis (or: knee replacement) as part of the treatment of the damaged knee joints implies replacement of one or both of the articular surfaces. The specialists distinguish between the following main types of knee replacement implants:

  • Unilateral arthroplasty (Sled prosthesis - replacement of the sliding surface of the joint)
  • Total joint replacement (Replacement of the whole joint)

The types of prostheses differ according to the scale of joint damage and are defined individually after the thorough examination. Our doctors comprehensively consult the patients about the various implant systems, their benefits and risks.

Before the surgery, the medical team at the hospital plans the procedure in detail and discusses the anesthesia. The operational planning is based on X-ray recordings or other imaging techniques. It helps to define the exact parameters of the knee replacement implants.

The mobile and fixed knee implants

Knee endoprosthesis

Generally, there are two classic designs of the knee replacement implants: mobile and fixed knee systems. The technical difference is in this case in the mobility of the upper and lower leg component sliding surface. The mobile bearings can rotate on the metal plate of the tibial component. The knee implants with fixed bearings are more stable. They click firmly into the metal component and are thus well fixed. Which kind of the implant to choose, is decided during the preliminary diagnostics and consultation. Both variants are absolutely safe, reliable and functional. They offer good mobility, flexion and sufficient stability.

The knee endoprosthesis is usually fixed by the so-called bone cement, which establishes a fixed connection between the bone and prosthesis. But there is also the possibility that the endoprosthesis is fixed without cement. The combination of both methods is common in practice - in this case we speak of a hybrid supply.

The modern knee replacement systems. Types of knee replacement implants.

The entire knee joint needs replacement only in rare cases. More frequently only the part of the joint is worn or damaged. The LINK® sled prosthesis, used at our clinic, replaces only one side of the damaged cartilage surface and spares the massive surgical intervention.

If only one side / part of the joint is damaged and all the knee ligaments are safe, a partial slide end prosthesis or unicondylar endoprosthesis is implanted only on the inner or outer side of the knee joint. The advantage: the healthy areas of the knee as well as the cruciate ligaments remain intact.

If the entire knee joint is damaged, a surface prosthesis is implemented: The surgeons replace the entire surface of the thigh and lower leg bone.

Modular prosthesis. Hybride knee replacement systems

In case of instability of the lateral and cruciate ligaments the special modular prostheses with different variants of the coupling are implemented. With different lengths and arbitrary stem extensions the stability of the knee can be restored even with bone defects. These modular endoprostheses allow individual adaptation of the prosthesis to the patient's needs: The individual components can be combined depending on the requirements. These prostheses are used in severe joint destruction or exchange interventions as part of the surgical revision.

The rotation knee prosthesis. Knee replacement system for better axial alignment

This kind of knee replacement implant allows axial rotation and reduces the stress on the prosthesis anchorage. This model of knee replacement implant is available in two versions and four implant sizes (right and left):

  • the model without patella flange (best variant for primary implantation). Its advantage is that it helps to preserve the bony femoropatellar joint
  • the model with patella flange for femoropatellar joint replacement

We treat the patients with various diseases of the knee joint, mainly with degenerative diseases (osteoarthritis), inflammatory rheumatic knee disorders (rheumatoid arthritis), cartilage and the bone damages.Annually we perform more than 3 000 successful knee replacement surgeries. If you consider the possibility of knee replacement, we would be glad to consult you on the modern implant systems, applied at the orthopedic department of the Clinic of Friedrichshafen.

Indications for knee endoprosthesis

During the endoprosthesis surgery, the affected joint components are replaced with knee prosthesis („artificial joint“), repeating the form of healthy joint. The modern design of the knee joint prosthesis includes a femoral and tibial components. The newest technology involves the use of special stabilizers which play the role of the natural ligaments. The surgeon also inserts plastic liners that perform the function of cartilage and reduce friction and minimize the risk of the endoprosthesis fracture.

The knee endoprosthesis may be necessary in following cases:

  • Degenerative arthritis with the damage to the articular cartilage
  • Medial knee osteoarthritis (varus gonarthrosis)
  • Lateral knee osteoarthritis (valgus)
  • Osteoarthritis in the outer chamber of the knee
  • Osteoarthritis behind the kneecap (retropatellar osteoarthritis)
  • Osteoarthritis in the joint between the patella and femur

Depending on the disease and its severity, the specialist will select the best possible solution and treatment for the patient. Whether conservative treatment or surgery followed by rehabilitation – we offer our patients personalized attention.

Individual knee endoprosthesis at the Clinic of Friedrichshafen

Each knee is unique. It implies that each knee endoprosthesis should be performed individually. The Clinical Center of Friedrichshafen has the special system of computer planning. On the basis of the CT data, a virtual 3D model of the patient's knee is created and a so-called digital mold is produced, by means of which the implant is made.

Individual fitting is achieved due to the system of computer navigation, which is implemented during the surgery. Correct positioning and orientation help to reduce the bone preparation, prolong the service of the prosthesis and shorten the rehabilitation period. The following endoprosthesis types are implemented at Friedrichshafen Clinic:

  • Unicompartmental knee endoprosthesis - used to replace a part of the knee joint (internal or external condyle); This type of knee implant has a metal inlay in the thigh component with a polyethylene sliding on the opposite side of the tibia.
  • Total (bicondylar) knee endoprosthesis - used in considerable damage to the bone and ligament apparatus;
  • Hemicap knee endoprosthesis - small prosthesis in the form of a screw with a cap-component, used to replace the articular cartilage;

All these endoprosthesis modells imply minimally invasive surgery with maximum preservation of bone. The team of the orthopedic department closely cooperate with the specialists of the leading university clinics, which means that in each particular case only the safest techniques are implemented.

Oxford knee endoprosthesis: Unicompartmental knee replacement

The Oxford knee prosthesis from Biomet is known worldwide for over 30 years as a partial knee replacement technique with very good clinical results. The partial knee endoprosthesis replaces only one side of the natural knee joint and thus allows better preservation of healthy bone. The prosthesis consists of a femoral component, a mobile meniscus insert and a tibial component. The upper and lower leg component are made of a metal alloy, the meniscus application consists of a specially molded plastic.

The femoral component is designed as a spherical segment. The force generated when moving over a large area is gently spread over the meniscus. The movable meniscus insert slides on the tibial component, imitating the natural movement. The wear of the joint components is significantly reduced by this construction method.

New knee: The most important information for patients

In Germany alone, around five million people suffer from osteoarthritis - a widespread disease that robs people of their quality of life more and more. Once the creeping wear process in the joints has reached an advanced stage, patients are in pain almost 24 hours a day, even at rest and especially at night. In many cases, the symptoms become so severe that it is unthinkable to have a restful sleep.

The big problem with it: Until today, osteoarthritis is considered incurable, drugs and certain therapies can slow down the course of the disease and alleviate their symptoms. As a last resort out of the pain hell only one prosthesis remains. Arthrosis patients can often be treated with artificial hip and knee joints. But although surgery is now considered a routine procedure in the hands of an experienced surgeon, many patients are still unsure: When was the right time for a prosthesis? What should you consider before you go under the knife, and what comes in one's everyday life? Answers to all important questions is provided by our great joint replacement guide. Here's what you need to know about a new knee.

The reasons for the knee joint surgery

1. What are the most common reasons for using an artificial knee joint?

"In most cases, patients suffer from osteoarthritis. The technical term is gonarthrosis", explains Professor Dr. med. Eugen Winter. In the process, the cartilage increasingly wears off, and the joint space is reduced more and more - until bone rubs on bone. In the advanced stage bony attachments or tufts, so-called osteophytes, form. The joint creates a permanent state of irritation. This mechnical inflammation process causes more and more pain. Frequently, the onset of gonarthrosis is fueled by previous damage, such as cruciate ligament tears, major meniscal injuries or overloading by misalignment of the leg axis (strong O or X legs).

2. What special features should be considered for gonarthrosis?

In case of gonarthrosis, the doctors divide the knee into three joint or damage zones. They are called in technical language compartments: behind the kneecap (retropatellar) and on the inside and outside, each between the femur and tibial bone. If only the inside or the outside is affected, the doctor speaks of a unicondylar gonarthrosis, with bilateral damage to bicondylar gonarthrosis. The name derives from the term condyle (in German: Knorren). These are bony prominences, each at the end of thigh and lower leg bones. "You can imagine them as a kind of hump or roller," explains Dr. Winter.

The diagnosis

3. Why do doctors talk about knee endoprostheses?

Endoprostheses are implants (artificial spare parts) that remain permanently in the body, the ending "endo" comes from the Greek and means something like "inside".

4. What do knee TEP and resurfacing prosthesis mean?

Sometimes there is talk of a knee TEP. The abbreviation TEP stands for total endoprosthesis. The entire knee joint is replaced - more precisely, the bone surfaces. This is what derives from the term resurfacing prosthesis, which is also widely used (more on this topic under points 7 to 9).

5. What tests are needed to determine the extent of osteoarthritis?

The doctor interviews the patient in detail about his complaints, then examines them with his hands - the technical term for this is clinical examination. He examines, among other things, how flexible and stable the knee joint is, and which movement patterns cause pain. Basically, an x-ray is made, sometimes a magnetic resonance or computed tomography can be useful.

The right time of knee surgery

6. How does the patient notice that the time has come for a new knee?

The later you can use an artificial joint, the better - unless the bones are already taking massive damage. "In addition, the axes and the stability of the ligaments play a crucial role in an artificial knee joint," says Winter. "In particular, a strong X-leg and pronounced ligament instability can make it impossible to use small joints anymore. However, the rule applies to the artificial knee joint: the smaller the joint can be selected, the better its function. The best results are achieved with the so-called half-slide. Therefore, the correct timing of surgery is more difficult to diagnose than with hip replacement. "But the most important decision-making feature - doctors speak of a major indication - is pain. "If the patient needs longer amounts of pain medication to endure the symptoms, then he should think about a final prosthesis," says Winter. In severe advanced gonarthrosis, the pain also occurs at rest, such as in bed at night. The people living with it are barely able to walk, the walking distances are getting shorter and shorter.

Preparation for knee surgery

7. How is an artificial knee built?

As the name dermal replacement prosthesis suggests, the defective parts of the joint are removed and the underlying bones practically crowned - with metal parts. Each so-called prosthetic component is anchored in the thigh and lower leg bones. In between there is an inlay made of a plastic called polyethylene.

8. Which different model types are available?

Essentially, the operators use three different types. In about 80 percent of cases, classic surface replacement prostheses are used. About 15 percent of the patients are treated with a so-called unicondylar sled prosthesis, shortened also called hemislides or half slides. Only one side of the joint is replaced - either inside or outside. Comparatively rarely do doctors use (partially) coupled knee prostheses. "The thigh and lower leg portions are anchored with much longer shafts in the enucleated bone and connected together at the height of the kneecap. This practically creates a guided artificial knee joint ", explains Prof. Dr. med. Winter.

9. Which model is suitable for which patients?

If the gonarthrosis is limited to a joint portion, a unicondylar sled prosthesis is considered. However, it is also a prerequisite that the cruciate ligaments are still preserved and the sidebands are stable. "In addition, the patient must not have an extreme X or O leg," explains Jansson. In most cases, the sled prosthesis is minimally invasively installed - this means that the surgeon needs an approx. Eight centimeter long skin incision as access. Ligaments and muscles remain unchanged, the rehab is shorter than with a complete resurfacing. However, the so-called revision rate with about five percent (not including relaxed prostheses) is higher than with the TEP. Revision in this context means that the carriage is removed and replaced again - then usually with a complete resurfacing. Complete resurfacing, also called bicondylar sled or double sled, is still standard on most knee joint replacement surgeries. In these cases, osteoarthritis has already damaged the entire knee joint. As with hemisliding, the metal parts can either be clamped in the bone (term: press-fit procedure) or fastened with bone cement. The anterior cruciate ligament is removed, in some cases the posterior cruciate ligament. The sidebands are adapted to the artificial knee joint. In patients with very loose ligaments or after prosthetic loosening, a (partially) coupled prosthesis can offer new stability.

10. How far have the know-how of doctors and technology in knee TEP advanced?

The knee is by nature, unfortunately, not a simple hinged hinge, act on the many-layered loads. "The movement pattern when bending the knee joint is complex, the knee rotates about several axes, at the same time pushes the lower leg on the outer side a little forward," explains the knee expert. Despite these challenges, joint replacement on the knee has long since become a success story. "However, there is still a lot to do," notes Winter. "From surveys and studies, we know that only 80 percent of patients are really satisfied with their knee TEP, 10 percent rate their situation unchanged, and another 10 percent cope worse than before surgery," says Prof. Dr. med. Winter. "The better results are still provided by the cemented knee TEP."

If you think of the knee replacement surgery in Germany, please, contact our international office at the Clinical Center of Friedrichshafen for more information.

Knee endoprosthesis

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Medical Staff

Prof MD Eugene Winter

Prof MD Eugene Winter
Head of the Orthopedic Department of Clinical center of Friedrichshafen

MD Norbert Heuer

MD Norbert Heuer
Head physician assistant

MD Christoph Kaiser

MD Christoph Kaiser
Senior physician

MD Rainer Schnell

MD Rainer Schnell
Senior physician

Ingrid Glauss

Ingrid Glauss
Medical secretary








Facts and Figures

  • 12000 outpatient
  • 2523 inpatients
  • 2500 surgeries
  • 735 arthroplasty of the joints of the hip, knee and shoulder
  • 1500 hand surgeries

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