Many people with advanced knee osteoarthritis are familiar with the problem: the knee hurts, swells, feels stiff, and makes every movement a torment. When conservative measures such as physiotherapy, weight reduction, or pain medication no longer provide sufficient relief, doctors often resort to so-called infiltrations – i.e., injections directly into the joint. Cortisone injections are particularly popular because they work quickly and often significantly reduce inflammation in the joint.

However, many patients are not aware that those who are scheduled to receive a knee replacement or endoprosthesis in the near future should be cautious with cortisone infiltrations. The timing between injection and surgery plays a crucial role. Operating too soon after an injection can increase the risk of infections after joint replacement – a complication that should be avoided at all costs.

What is an infiltration?

An infiltration refers to the targeted injection of a medication – usually a cortisone preparation – into or around the knee joint. The goal is to slow down inflammation in the joint and alleviate pain. The treatment is often performed on an outpatient basis and can be helpful in cases of osteoarthritis, bursitis, or irritation in the area of the knee joint.

Cortisone has a strong anti-inflammatory effect and often provides noticeable relief shortly after administration. Many affected individuals report significantly less pain and improved mobility – often for several weeks or even months.

However, cortisone also has side effects: it can temporarily weaken the body's own defenses, affect sugar metabolism, and damage cartilage with repeated use. Therefore, it should always be used targeted and time-limited – especially when a major surgery like a knee replacement is pending.

Why cortisone injections are critical before knee replacement

The most important finding in recent years is: A cortisone infiltration shortly before a planned knee replacement can increase the risk of infection.

The background is the immunosuppressive effect of the cortisone injection. The medication suppresses inflammation – which is helpful in everyday life but can become a problem during surgery. If residues of the active ingredient are still present in the joint, the local defense against pathogens can be weakened. Even with strict hygiene, there is then an increased risk that bacteria will settle in the area of the freshly implanted endoprosthesis.

Infections around a knee prosthesis are among the most serious complications in endoprosthetics. They can lead to lengthy treatments, revision surgeries, or in the worst case, even the removal of the prosthesis. Therefore, it is crucial to identify and avoid potential risk factors - such as too short a time between cortisone injection and surgery - early on.

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

In recent years, several studies have shown that the risk of infection may be increased if the interval between cortisone injection and surgery is less than three months.

Many professional societies therefore recommend maintaining at least a three-month interval between the last injection and the planned implantation 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 orthopedic surgeon must make an individual decision in consultation with the surgical team. 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 given very recently (e.g., within the last four to six weeks), the surgery is usually postponed. If the cortisone injection was given longer ago and there are no additional risks, surgery can still be performed under strict hygiene measures.

The decision should always be made individually and in close consultation with the treating physician.

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

A periprosthetic infection – that is, 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 form so-called biofilms there. These make the pathogens resistant to antibiotics and the immune system. If an infection is not detected in time or cannot be controlled, it may be necessary to remove the entire prosthesis again – 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 like cortisone infiltration shortly before surgery.

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. Medicinal pain therapy: Anti-inflammatory medications (e.g., Ibuprofen, Diclofenac) can provide temporary relief, provided there are no contraindications.
4. Hyaluronic acid injections: This form of infiltration is considered gentler because it does not have an immunosuppressive effect.
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 a pain-relieving effect.

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 significantly overweight, for example, your individual risk for complications after knee replacement surgery is generally higher. In this context, the question of an injection before surgery becomes even more important. In such cases, a particularly careful assessment should be made.

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 education: Always inform the treating physician when and which injections were given into the joint.
• Optimize health status: Adjust blood sugar levels, reduce weight, avoid skin infections.
• Stop Smoking: Smoking significantly worsens wound healing and increases the risk of infection.
• Exercise and physiotherapy: A trained body recovers faster.
• Stabilize chronic conditions: Diabetes, high blood pressure, or cardiovascular diseases should be well-managed.

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 not only consider the condition of the joint, but also the entire patient. This includes the question of when which therapies were performed, what the general state of health is, and when the optimal time for surgery has arrived.

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

Prof. Kutzner is considered one of the leading specialists for knee endoprosthetics in the Rhine-Main region. 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

Cortisone infiltrations can provide short-term relief for knee osteoarthritis – however, those planning a knee replacement should use them with caution. The key point: Maintain at least a three-month interval between cortisone 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 replacement will find that the ENDOPROTHETICUM Rhein-Main in Mainz under the direction of Prof. Dr. med. Karl Philipp Kutzner is one of the top addresses for modern endoprosthetics in the Rhine-Main region.

Here, all questions regarding infiltrations, cortisone, operation timing, implant selection, and rehabilitation are discussed individually. The goal is to enable each patient the best possible, safe, and long-term successful joint replacement – without unnecessary risks.

Tip:
Those who want to inform themselves about the optimal preparation for a knee prosthesis can directly book a consultation appointment via the website www.endoprotheticum.de or by phone. The team takes the time to clarify all open questions in detail.