Many people with advanced knee osteoarthritis know the problem: the knee hurts, swells, fühlt stiff and makes every movement a torment. When conservative Maßnahmen such as physiotherapy, weight reduction or pain medication no longer provide sufficient relief, Ärztinnen und Ärzte often resort to so‑called infiltrations – also injections directly into the joint. Particularly popular are cortisone injections, as they act quickly and often significantly reduce the inflammation in the joint.

But what many patients do not know: Whoever is expected to receive a knee prosthesis or endoprosthesis should receive, should be cautious with corticosteroid infiltrations. Because between injection and surgery the timing plays a decisive role. If operated too early after an injection, the risk for infections after joint replacement increases – a complication that must absolutely be avoided.

What is an infiltration?

Under a Infiltration refers to the targeted injection of a medication – usually a corticosteroid preparation – into or around the knee joint. The aim is to curb inflammation in the joint and relieve pain. The treatment is often performed on an outpatient basis and can be helpful for osteoarthritis, bursitis or irritations in the knee joint area.

Cortisone works strongly anti-inflammatory and often provides noticeable relief quickly. Many affected report significantly less pain and better mobility – often for several weeks or even months.

However, cortisone also side effects: It can temporarily weaken the body's own defense, affect sugar metabolism and with repeated use further damage cartilage. Therefore it should always be used targeted and time‑limited – especially when a larger operation such as a knee endoprosthesis is upcoming.

Why cortisone injections are critical before knee replacement

The probably most important finding of recent years is: A corticosteroid injection shortly before a planned knee prosthesis can increase the infection risk.

The background is the immunosuppressive effect of the corticosteroid injection. The medication suppresses inflammation – which is helpful in everyday life, but can become a problem during surgery. If residues of the active ingredient remain in the joint, the local defense against germs can be weakened. Even with the strictest hygiene, there is then an increased risk that bacteria settle in the area of the newly implanted prosthesis.

Infections around a knee prosthesis belong to the most severe complications in endoprosthetics. They can lead to prolonged treatments, revision surgeries, or in the worst case even necessitate removal of the prosthesis. Therefore it is important to identify and avoid possible risk factors – such as a too short‑term cortisone injection – early.

How long should one wait after a cortisone injection for a total knee arthroplasty (TKA)?

In recent years several studies have shown that the infection risk may be increased if less than three months elapse between the cortisone injection and the operation.

Many professional societies therefore recommend, at least a three-month interval between the last injection and the planned placement of a knee endoprosthesis.

This period is considered a conservative safety margin – usually the body breaks down the cortisone largely during this time, and the immune system can fully recover. If the surgery is performed only after these three months, the risk drops to the normal baseline level.

What could happen if surgery is performed too early?

Sometimes the situation is clear: the knee is barely stable, the pain does not allow for a longer waiting period – and yet a cortisone injection was only a few weeks ago.

In such cases, the treating orthopaedist together with the surgical team an individual decision must be made. Several factors are taken into account:

• How long ago was the last injection?
• What amount and which preparation were used?
• How severe are the symptoms, and how urgent is the surgery?
• Are there additional risk factors (e.g., diabetes, overweight, skin problems)?

If the injection was administered very recently (e.g., within the last four to six weeks), the operation is usually postponed. If the cortisone injection was given longer ago and no additional risks are present, surgery can still be performed under strict adherence to hygiene measures.

The decision should always individual and be made in close coordination with the treating physician.

Why is the risk of infection in the context of a knee prosthesis so dangerous?

A periprosthetic infection – also an infection around the artificial joint ‗ is one of the most feared complications in endoprosthetics. It can occur even with the best surgical technique and modern materials.

The problem: Bacteria can settle on the surface of the prosthesis and there form so‑called Biofilms form. These make the germs resistant to antibiotics and the immune system. If an infection is not detected in time or cannot be controlled, it may become necessary to remove the entire prosthesis – a severe setback for those affected.

Therefore, experienced surgeons place great emphasis on perfect hygienic conditions, a stable immune system of the patient and careful preparation before the procedure. This also includes avoiding risky measures such as an injection with cortisone shortly before the operation.

Are there alternatives to cortisone infiltration in the knee?

Yes. Those waiting for a knee replacement and still experiencing severe pain do not necessarily have to resort to a cortisone injection. There are a number of conservative options available to alleviate pain without increasing the risk of infection:

1. Physiotherapy: Exercise therapy can help maintain joint function and reduce pain.
2. Targeted strength training: Strong thigh muscles relieve the knee joint.
3. Pharmacological pain therapy: Anti-inflammatory medications (e.g., Ibuprofen, Diclofenac) can help temporarily, provided there are no contraindications.
4. Hyaluronic acid injections: This form of infiltration is considered gentle, as it does not act immunosuppressively.
5. PRP treatments (autologous blood therapy): In certain cases, autologous plasma can help reduce inflammation.
6. Cold and heat applications: Depending on the symptoms, both can have pain‑relieving effects.

These methods can bridge the waiting time until surgery – always in consultation with an experienced orthopedist.

Special aspects: If additional risk factors are present

Diabetes, obesity, smoking

If you have diabetes, smoke, or are severely overweight, then: your individual risk for complications after a knee endoprosthesis is overall higher. Consequently, the question of an injection before surgery becomes even more important. more important. In such cases, careful weighing is especially necessary.

Skin or soft tissue problems

Open areas, eczema, or skin inflammation around the knee or in its vicinity (e.g., lower leg) increase the risk of infection. Before an injection or surgery is performed, a skin examination should be conducted – and if necessary, skin treatment should be initiated.

Previous joint fracture or infection in the medical history

If you have previously received a joint injection, have a joint inflammation (arthritis), or a bone or joint condition (e.g., fracture) in the knee area, all this information must be communicated to the surgeon — it influences the planning and risk assessment.

Immunosuppression

If you are taking medications that weaken your immune system (e.g., long-term cortisone, immunosuppressants), this must be taken into account when deciding on the injection and surgery timing.

How should patients prepare themselves?

Anyone planning a knee replacement should start preparing optimally for the procedure in a timely manner. This includes:

• Active counseling: Always inform the treating physician when and which injections were administered into the joint.
• Optimize health status: Adjust blood sugar levels, reduce weight, avoid skin infections.
• Smoking cessation: Smoking impairs wound healing and significantly increases the risk of infection.
• Exercise and physiotherapy: A trained body recovers more quickly.
• Stabilize chronic conditions: Diabetes, hypertension, or cardiovascular diseases should be well controlled.

An experienced surgical team considers all these factors in the surgical planning and discusses the best possible approach with the patients.

Frequently Asked Questions (FAQ)

How dangerous is a cortisone infiltration shortly before surgery?

In short: It can be dangerous. If cortisone is injected into the joint within the last three months before a knee replacement, the risk of infection increases. This does not mean that every patient will experience complications, but the risk is measurably higher. Therefore, if possible, cortisone injections should be avoided during this period.

How long should I wait after a cortisone infiltration?

At least three months are considered a safe interval. Afterwards, the operation can usually be performed without additional risk.

Can I still get cortisone if I have severe pain?

Yes, but only if no surgery is planned in the coming weeks or months. If the surgery date is already fixed, it is better to opt for alternative pain therapies.

What if I have already received the cortisone injection?

It is important to inform the surgeon immediately. Together, it can be decided whether the operation should be postponed or whether special measures need to be taken.

Are there safe alternatives to cortisone injections?

Yes. Physiotherapy, pain medication, exercise, and sometimes hyaluronic acid or PRP treatments can be good interim solutions.

What does an experienced knee specialist do differently?

An experienced knee specialist will never only consider the condition of the joint, but the whole person. This includes the question of when which therapies were performed, how the general health condition is, and when the optimal timing for the operation has arrived.

In ENDOPROTHETICUM Rhein-Main under the leadership of Prof. Dr. med. Karl Philipp Kutzner this holistic approach is pursued consistently. Here patients receive not only excellent surgical care, but also a personalized consultation on all questions regarding infiltrations, conservative treatments and the safe timing of an endoprosthesis.

Prof. Kutzner is considered in the Rhine-Main area as one of the leading specialists for knee endoprosthetics. His team ensures that every decision – whether injection, surgery or conservative treatment – is medically sensible, safe and long‑term successful .

Conclusion: Caution is better than negligence

Corticosteroid infiltrations with Kortison können provide short‑term relief in knee osteoarthritis – but anyone planning a knee prosthesis should use them cautiously. The most important point: At least three months interval maintain between corticosteroid injection and surgery.

During this time, the body can recover, the immune system becomes stable again, and the risk of infection decreases significantly.

Anyone unsure or who has recently received an injection should consult an experienced specialist. This helps avoid unnecessary complications and ensures the surgery is performed under optimal conditions.

Recommendation: Consultation at ENDOPROTHETICUM Rhein-Main

Patients preparing for a knee endoprosthesis will find at the ENDOPROTHETICUM Rhein-Main in Mainz under Prof. Dr. med. Karl Philipp Kutzner one of the first addresses für modern endoprosthetics in the Rhine‑Main region.

Here all questions concerning Infiltrations, cortisone, operation timing, implant selection and rehabilitation are discussed individually. The goal is to provide every patient the bestmöglichen, safe and long‑term successful joint replacement – without unnötige risks.

Tip:
If you want to learn about the optimal preparation for a knee prosthesis, you can directly über the website www.endoprotheticum.de or by phone arrange a consultation appointment. The team takes time to answer all open questions ausführlich.