Knee Replacement | Specialists and Information

Physicians who hold this seal are affiliated with medical facilities that are certified by endocert as an Endoprosthetics Center (EPZ) or as a Maximum Care Endoprosthetics Center (EPZmax) and have thus demonstrated compliance with the established requirements during an audit. Recertification is required every three years.

You can find the criteria, requirements, and differences between EPZ and EPZmax here.

Knee arthroplasty refers to the implantation of an artificial knee joint (knee prosthesis). Depending on how much of the joint is replaced, the procedure is referred to as either a total knee replacement (also known as TKR), meaning the entire joint surface is replaced with an artificial implant, or a partial knee replacement, when only part of the joint is removed and replaced with prosthetic materials.

The human knee joint consists of the femur, tibia, and patella. These bones are connected to one another by tendons and ligaments (cruciate ligaments, lateral and medial collateral ligaments, quadriceps tendon, patellar ligament), thereby providing the knee joint with the necessary stability. The surfaces of the femur and tibia that form the knee joint are located within the joint capsule, which is filled with synovial fluid. The synovial fluid serves to nourish the layers of cartilage covering the bones; these layers not only prevent direct bone-to-bone contact but also, together with the two menisci, act as a kind of shock absorber during impact.

Due to the complex structure of the human knee joint and the specific mechanical demands placed on an artificial knee joint, the implantation of an artificial joint into the knee is a highly challenging procedure.

As a result of rheumatic diseases (for example, joint inflammation, known as rheumatoid arthritis), severe obesity, misalignments (bowlegs, bow legs), deformities, or injuries (post-traumatic arthritis), the cartilage and menisci may be destroyed first, followed by the bone surfaces involved in the joint. This process is called osteoarthritis, which refers to joint wear and tear beyond normal levels. Unlike localized cartilage damage, this condition affects more or less the entire joint.

When osteoarthritis occurs in the knee, it is referred to as knee osteoarthritis. Whenever joint wear has progressed to the point where conservative treatments or joint-preserving surgeries are no longer effective, joint replacement may be considered.

If, on the other hand, there is no radiologically confirmed knee osteoarthritis, or if the existing osteoarthritis causes little pain that limits daily activities, knee replacement surgery should be postponed for the time being.

Injuries to the ligamentous apparatus can compromise the stability of the knee joint to such an extent that it leads to increased joint wear and tear—that is, the development of osteoarthritis—which also necessitates a knee replacement. Bone tumors or comminuted fractures (broken bones) may also necessitate the implantation of a knee prosthesis.

If osteoarthritis or other changes or diseases of the knee joint are suspected based on the patient’s symptoms and medical history (patient interview), an X-ray examination is very effective for assessing the bony structure and the leg axis. In addition, magnetic resonance imaging (MRI) can be used to visualize the articular cartilage, the menisci, and the ligaments.

Ultrasound (sonography) allows for the visualization of soft tissues and fluid-filled spaces (joint capsule). Bone scintigraphy is now used only in rare cases to examine the bone area beneath the cartilage in greater detail. Depending on where and in what quantity an administered substance accumulates, conclusions can be drawn about the degree of cartilage destruction and any bone damage that may already be beginning.

In order to implant custom-made prostheses, the exact anatomical measurements of the affected leg are determined using computed tomography prior to knee replacement surgery. The computer then generates a three-dimensional image of the knee joint, which serves as a model for the actual knee prosthesis—custom-made for each individual patient. 

In general, surgeons aim to replace only as much of the knee joint surface as the condition requires. They therefore implant a knee replacement that is either smaller or larger depending on the extent of cartilage and bone damage (stage-appropriate knee replacement).

In addition to selecting the right type of prosthesis, the range of services offered by a specialist in knee replacement includes, among other things, the following methods:

• Implantation of resurfacing prostheses (mini-prostheses) as interim prostheses in cases of limited cartilage damage
• Implantation of sled prostheses, i.e., replacement of the medial or lateral half of the knee joint
• Replacement of the femoropatellar joint (the joint between the thighbone and the kneecap, with or without replacement of the outer or inner portion of the knee joint).
• Implantation of total knee replacements (TKR), in which the entire surface of the damaged knee joint is replaced.
• Implantation of axis-guided knee prostheses for advanced knee osteoarthritis and to treat severe joint instability (wobbly knee or overly loose ligaments), as well as for very severe misalignments of the knee joint (severe bowlegs or knock-knees). 
• Fabrication of custom prostheses for specific patient groups (e.g., patients with allergies)
• Performing revision arthroplasty (replacement surgery for endoprostheses, knee prosthesis replacement)

Custom prosthesis solutions, precisely tailored to the individual patient and manufactured using 3D printing technology, are considered particularly innovative and promising. These custom prostheses are available as partial and total knee replacements.

The modern prosthesis design, adapted to the patient’s individual anatomy, has been shown to more closely match the individual biomechanics of the knee joint being replaced than conventional knee prostheses and offers an uncompromisingly precise fit.

Experts in knee arthroplasty are typically specialists in orthopedics and trauma surgery with many years of surgical experience in knee surgery and arthroplasty. They can reliably diagnose osteoarthritis of the knee and other conditions and then select the most appropriate treatment approach (conservative or surgical) for the patient. Through certifications (specific to each state), they ensure a high standard of surgical care.