A artificial knee joint (knee prosthesis / knee TEP) is recommended when conservative measures (physiotherapy, medication, injections, weight reduction, aids) no longer provide lasting pain relief and functional improvement and quality of life is severely limited. The operation aims to eliminate pain, correct malalignments and restore mobility. This applies to both the total knee arthroplasty (TEP) and partial prostheses (e.g. unicompartmental knee arthroplasty) — the selection depends on the extent and location of joint wear as well as patient factors.

Why correct indication for a knee prosthesis is so important

The indication — i.e., the decision on who benefits from what — is the most important factor for a good outcome. Not every person with knee osteoarthritis automatically needs a TKA; in early or unilateral cases, a unicompartmental knee arthroplasty (UKA) or surface replacement may be more appropriate. Similarly, a thorough clarification of concomitant diseases, leg axis, ligament instabilities, and the condition of the patellofemoral joint surface is important because incorrect selection leads to dissatisfied patients, premature revisions, or persistent complaints. Surgeon experience, precise diagnostics (X-ray, possibly MRI, clinical examination), and individualized patient counseling are therefore crucial.

Types of Knee Prostheses — Briefly Explained

1. Total knee arthroplasty, complete artificial knee joint (knee TEP)

The TEP replaces the joint surfaces of the thigh (femur), shinbone (tibia), and usually the back surface of the kneecap (patella) with metal-plastic components. It is the standard treatment for advanced, multi-compartmental osteoarthritis, deformities, or when multiple joint parts are affected. Modern implants can be very durable and reliably eliminate pain. OrthoInfo+1

2. Unicompartmental prosthesis / partial joint replacement

The sledge prosthesis replaces only one previously isolated affected compartment (medial or lateral). Advantages: bone-sparing, usually faster recovery, more natural knee kinematics with suitable selection. Disadvantages: not suitable for extensive multi-compartment osteoarthritis, advanced ligament or axis problems, or inflammatory arthritis. Good long-term results are documented with careful patient selection.

3. Patellofemoral Prosthesis (PFJ / PFA)

The patellofemoral arthroplasty replaces only the joint between the kneecap and thigh bone. It is an option for isolated patellofemoral osteoarthritis (PFJ osteoarthritis), offers less invasive replacement, and can largely preserve native kinematics. The results are variable — but often very good with careful indication.

Pre-examinations: how is it decided which implant is suitable?

Before the operation, the following occur:

• detailed medical history (pain profile, functional limitations, expectations),
• Clinical examination (stability, range of motion, leg axis),
• X-rays in defined planes (weight-bearing AP, lateral, oblique views), often supplemented by full-leg X-rays to determine the axis,
• Possibly MRI to assess menisci, cartilage, and soft tissues, especially in young patients or unclear findings.

Together with the patient, the best form of therapy (conservative vs. UKA vs. TEP vs. PFJ) is then decided. This phase is crucial for success.

Knee replacement surgery: Brief overview

1. Anesthesia: Regional (spinal/epidural) and/or general.
2. Access and preparation: Bone and cartilage parts are removed according to the chosen implant.
3. Component fitting: Metal components on the femur and tibia, with a polyethylene gliding surface in between. If the patella is replaced, a patellar component is used.
4. Checking the leg axis, soft tissue balance, and range of motion.
5. Closure and wound care.

The operation typically lasts between 60 and 120 minutes, depending on complexity and prosthesis type. Modern concepts (minimally invasive, computer-navigated positioning, robotic-assisted) can improve accuracy.

What complications can occur?

Even with optimal technique, there are general and knee-specific risks:

• Wound healing disorders, infection (early/late),
• Thrombosis / pulmonary embolism (reduced by prophylaxis),
• Blood loss / post-operative bleeding,
• Persistent pain or limited mobility (e.g., due to scarring, soft tissue problems, malalignment),
• Loosening or implant failure (with long-term follow-up),
• Instability or patellar problems.

Important point: professional perioperative care (anticoagulation according to risk, wound management, early mobilization) and good rehabilitation significantly reduce the risk of complications.

Expected Outcome & Durability

Modern knee prostheses last for several decades in many cases; studies show that a high proportion of TEPs remain functional for 15–25 years. Unicompartmental prostheses also have very good long-term data with careful selection; the survival rates are encouraging in current reviews and registers. Important influencing factors on the outcome are patient age, activity level, surgical technique, implant choice, and follow-up treatment.

Special notes on unicondylar prosthesis (sled prosthesis)

• Advantages: less bone removal, faster recovery, often shorter hospital stay.
• Disadvantages: Risk that osteoarthritis in other compartments will progress later and revision surgery will be necessary.
• Key: perfect patient selection (isolated, predominantly medial/lateral pain and wear, intact ligament stability, suitable leg axis).
  Modern studies and analyses confirm very good results in selected patients; however, the experience and case number of the surgeon are crucial for success.

Patellofemoral arthroplasty (PFA) — when is it useful?

The PFJ arthroplasty replaces only the joint partners between the patella and trochlea and is an option for isolated patellofemoral osteoarthritis, especially when conservative measures fail. It is bone-sparing, can be less restrictive, and can provide very good functional results with correct indication. However, long-term durability and selection criteria are more difficult compared to TEP; therefore, specialized assessment is important.

Preparing for an artificial knee joint - what you can do yourself

A good preparation for the implantation of an artificial knee joint not only improves the healing process, but also the long-term result. Patients benefit if they strengthen their muscles, reduce their weight and learn exercise routines before the operation. Training with walking aids or simple everyday movements (e.g. getting up from a chair, climbing stairs) is also useful. The fitter you are going into the operation, the easier the rehabilitation will be afterwards.

Living with a knee prosthesis – what is allowed, what is not?

Many patients wonder which activities are possible again after a total knee replacement or knee prosthesis . Generally, low-impact sports such as swimming, cycling, or hiking are recommended and promote mobility. High-intensity sports with many rotational movements or jumps (e.g., soccer, handball, squash) should be avoided or only performed after consulting with the surgeon. It is crucial to avoid overloading the artificial knee joint unnecessarily while remaining active.

Second opinion with a knee specialist - why it's important

Deciding on a knee replacement is a significant step. Therefore, it is worthwhile to seek a second opinion from an experienced knee specialist. Specialists like Prof. Dr. Karl Philipp Kutzner at ENDOPROTHETICUM Rhein-Main in Mainz take the time for comprehensive counseling, carefully review your findings, and explain the pros and cons of the various prosthesis models. This ensures that the indication is correct and you receive the best solution for you.

Rehabilitation: this is what the aftercare for an artificial knee joint looks like

Early mobilization (ideally on the day of surgery) is standard. A structured rehabilitation plan includes:

• Mobilization and gait training (including stairs),
• Muscle building (quadriceps, hamstrings),
• Mobility exercises,
• Training in everyday life (sitting, stairs, driving a car),
• if necessary, pain and thrombosis prophylaxis, wound checks.

Enhanced Recovery Programs (ERAS) accelerate recovery and can shorten hospital stay without compromising safety. Inpatient or outpatient rehabilitation, follow-up physiotherapy, and individual aftercare are part of ensuring success.

Quality of life after knee replacement

Most patients report significant pain relief and improved ability for daily mobility — many can resume walking, cycling, and moderate recreational activities. Sports with high joint stress (e.g., soccer, skiing with high risk) should be discussed; joint-friendly activities (cycling, swimming, hiking) are usually possible. Realistic expectations management before surgery increases satisfaction afterwards.

When is a revision necessary?

Reasons for revisions include infectious complications, aseptic loosening, instability, periprosthetic fractures, or progressive wear and tear in UKA. Revision surgeries are technically more demanding, making avoidance through careful planning and operation, as well as early treatment of risks (infections, poor wound healing), crucial.

Frequently Asked Questions (FAQ) about the artificial knee joint

1. When do I need an artificial knee joint?

An artificial knee joint is useful when pain and movement restrictions persist despite physiotherapy, medication, and other conservative measures, and the quality of life is significantly limited.

2. What is the difference between knee replacement and knee TEP?

Both terms usually mean the same thing: a knee prosthesis replaces worn-out joint surfaces with implants. The term knee TEP stands for 'total endoprosthesis' - here, all joint components are replaced.

3. Are there different types of knee prostheses?

Yes, depending on the findings, there are unicompartmental knee arthroplasty (UKA) for a partial area, the surface replacement, the total knee endoprosthesis (TEP) as well as special patellofemoral prostheses (PFJ), which only replace the sliding bearing between the kneecap and thigh.

4. How long does knee replacement surgery take?

Typically between 60 and 120 minutes - depending on the type of prosthesis, findings, and technique used.

5. Is the operation painful?

Not during the operation, as anesthesia is administered. In the first few days afterwards, normal wound and movement pain occurs, which can be well treated with pain therapy. The goal is significant pain relief in the long term.

6. How long does an artificial knee joint last?

Modern implants often last 15–25 years or longer. Durability depends on age, activity level, and the right implant choice.

7. Can I do sports again after a knee replacement?

Yes! Especially joint-friendly sports such as swimming, cycling, or hiking are possible. Sports with jumps and abrupt changes of direction should be avoided.

8. How long does rehabilitation last?

Rehabilitation typically lasts 3–6 weeks on an inpatient or outpatient basis. This is followed by outpatient physiotherapy. Many patients experience initial improvements within a few weeks, with the final outcome developing over several months.

9. How long am I on sick leave after the operation?

For sedentary activities, approximately 6–12 weeks. For physically demanding work, the inability to work can last longer. Here, the individual healing process decides.

10. Does the kneecap always need to be replaced?

No, not always. Whether a patellar component is implanted depends on the cartilage condition and the type of prosthesis.

11. What are the most common risks?

As with any surgery: infections, thromboses, bleeding, or wound healing disorders. Specific to the knee: loosening, instability, or limited mobility. With modern techniques and experienced surgeons, complications are rare.

12. What can I do myself to contribute to my recovery?

Regular physiotherapy, movement in everyday life, muscle strengthening, and adherence to medical recommendations. A healthy diet and nicotine abstinence also promote healing.

13. Can I drive a car with an artificial knee joint?

Yes, usually after 6–8 weeks – as soon as you can safely move your leg and brake without pain. Your doctor will give you the individual "go-ahead".

14. Can I get a second artificial joint after a knee prosthesis?

Yes, if later the other knee or a hip joint is affected, other joints can also be treated with prostheses. Many patients have multiple endoprostheses.

15. Should I get a second opinion?

Absolutely! A second opinion from a specialized knee specialist like Prof. Dr. Karl Philipp Kutzner at ENDOPROTHETICUM Rhein-Main, Mainz gives you certainty in deciding on the right implant.

How to choose the right clinic / surgeon for an artificial knee joint

• Specialization and case volume: Centers and surgeons with high case volumes in knee arthroplasty typically have better outcome data.
• Transparent education: benefits, risks, alternatives - everything should be explained understandably.
• Multidisciplinary concept: Surgical team, anesthesia, physiotherapy, and rehabilitation structure (short pathways to ENDO rehabilitation) are advantageous.

Conclusion: consultation with a knee specialist recommended

For a technically sound, individual consultation regarding an artificial knee joint, we recommend a consultation with a specialized knee specialist like Prof. Dr. med. Karl Philipp Kutzner at ENDOPROTHETICUM Rhein-Main. The overall concept at the curaparc Campus in Mainz with direct connection to the curaparc-clinic and its own ENDO-Reha represents an integrated care structure that combines operative excellence with close follow-up care — a rarity in today's healthcare system.