Knee osteoarthritis and other advanced knee problems often lead to severe pain and functional limitations. When conservative measures (physiotherapy, medication, injections, etc.) are no longer sufficient, a knee prosthesis often comes into play. There are various forms of this – from total joint replacement to partial joint replacement (e.g., sled prosthesis ), in which only part of the knee joint is replaced.

For people with a nickel allergy , the important question is: How safe and compatible are the implant materials? Many standard implants contain nickel, and allergic reactions are possible. This is where the idea of ​​nickel-free or low-nickel implants or surface coatings comes into play.

In this article, you will learn how a knee prosthesis can work for people with nickel allergies, what materials are available, and how a specialist like Prof. Kutzner at the Endoprotheticum Rhein-Main in Mainz can help.

What is a knee prosthesis?

A knee prosthesis replaces damaged or worn joint surfaces in the knee. Depending on the extent of osteoarthritis or damage, there are:

• Total knee arthroplasty (total joint replacement): The entire joint (all compartments) is replaced.
• Partial joint replacement : Only part of the knee joint is replaced, e.g., an inner or outer area.
• Sled prosthesis (unicondylar replacement, inner or outer sled): Variant of partial joint replacement in which only one side (inner or outer compartment) is replaced.

Important are:

• Preservation of as many natural structures as possible, such as ligaments (e.g. cruciate ligaments), healthy cartilage areas, etc.
• Optimal fit and alignment of the implant.
• Biocompatible materials, good sliding surface (metal-plastic, etc.).

Partial joint replacement and sled prosthesis – definitions & differences

Partial joint replacement generally refers to the replacement of only individual compartments in the knee. The most common types:

• Unicompartmental (internal or external) partial joint replacement / sled prosthesis : only part of the knee joint surface (internal or external) is replaced.
• Patellofemoral partial joint replacement : replacement of the gliding surface between the kneecap and thigh.

A sled prosthesis is a special type of partial joint replacement that uses a component called a "sled" that slides between the thigh and lower leg on one side of the joint. Advantages:

• Less bone removal
• Preservation of cruciate ligaments and other stabilizing structures
• Faster rehabilitation
• More natural knee kinematics

Nickel allergy: causes, frequency, relevance for knee prostheses

What is nickel allergy?

• Contact allergy to nickel (frequent skin contact, jewelry, watches, etc.).
• Recognizable by redness, eczema, itching on skin contact.
• Immunological reaction: Sensitization of the immune system to nickel ions.

Frequency of nickel allergy

• Relatively common in the general population.
• Studies often show higher sensitization rates in women, especially before the age of 40–50.
• For patients with knee prostheses: In Germany, surveys have shown that allergy implants are often used in cases of known allergies to nickel or cobalt (e.g., 84% of orthopedic surgeons surveyed in cases of known allergies).

How relevant is nickel allergy in knee prostheses?

• There are case reports in which patients with sled prostheses (unicondylar partial prosthesis) or knee prostheses had persistent complaints, demonstrably caused by nickel allergy.
• Symptoms may include: pain, swelling, joint effusion, dermatitis, delayed wound healing, and possible implant loosening.
• However, not everyone with a skin nickel allergy reacts to an implant – the system is complex, as bone tissue and the surrounding area react differently than skin.

Research & Surveys on Nickel Allergy

• As mentioned, a survey in Germany shows that in cases of known allergies, many orthopedic surgeons use special allergy implants.
• Studies and case reports show that implant revision with low-nickel or titanium-based (nickel-free) endoprostheses has led to improvement in some cases.

Controversy and findings: How relevant is the problem of nickel allergy?

What is secured, what is still open

What is secured:

• Nickel allergy exists and is common in a certain proportion of the population.
• There are case reports of complaints following knee replacement surgery that were attributed to allergies.
• In certain patients, the use of low-nickel or coated/covered implants may lead to symptom relief.

What is not yet fully secured:

• How often a knee prosthesis needs to be revised due to a nickel allergy.
• Whether skin allergy reliably predicts how strongly the immune system reacts in deep tissue and bone.
• Long-term data on the durability and function of allergy implants vs. standard implants are limited.

Data & Surveys

• Survey among members of the Working Group on Endoprosthetics (Germany): For planned prostheses with a known allergy to nickel or cobalt, approximately 84% of surgeons use a so-called “allergy implant.”
• However, according to this survey, the proportion of patients with knee prostheses who experience complaints due to a metal allergy is significantly lower (e.g. 1.1% of knee endoprostheses in 2009).

Materials & implant variants: Nickel-free or low-nickel solutions

If someone has a nickel allergy or wants to rule it out, there are several strategies and materials:

Titanium-based and titanium-coated implants

• Titanium is generally very biocompatible, has low allergenic potential, and can be used in pure form or as a coating.
• Example: Case reports in which a prosthesis was replaced titanium-based
• Important to check: Titanium-based implants can also contain traces of other metals, depending on the manufacturer and alloy.

Oxinium / Zirconium alloys

• Some clinics use prostheses made of, for example, an oxinium alloy (zirconium/niobium) or with surface technologies that have extremely low nickel content. For example, the Freiburg Clinic uses materials with very low nickel and chromium content for its mono- and double-slide prostheses: nickel < 0.0035%, chromium < 0.02%.

Surface coatings / sealants / coatings

• Coatings with titanium or titanium oxide, ceramic, gold plating, etc., which can form a barrier between the fabric and the base metal.
• Some “allergy prostheses,” for example, use titanium coatings to avoid contact with nickel.

Low-nickel stainless steels & special alloys

• Stainless steels in prostheses often contain nickel, but there are special alloys with very low nickel content or special treatments that greatly reduce the release of nickel.

Availability and limitations

• Not every hospital/manufacturer offers nickel-free implants as standard.
• The costs can be higher, and permits and documentation are more complex.
• Long-term data are sometimes not as comprehensive as for standard implants.

Diagnosis: How can you detect a nickel allergy before and after implantation?

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• Questions like: Have you ever had eczema after contact with jewelry? Do you react to contact with metals?

Allergological testing procedures

• Epicutaneous test (patch test) for skin contact allergy.
• Lymphocyte transformation test (LTT) – tests the response of immune cells to metal ions.
• Histological examination (e.g. in revision surgery), tissue samples.

Imaging & laboratory diagnostics

• Exclusion of infections (CRP, ESR, if necessary joint aspirate).
• X-ray, scintigraphy, if necessary CT or MRI to localize loosening or metal abrasion.
• Monitor for signs of hypersensitivity reactions: swelling, persistent pain, irritation.

Time of diagnosis

• Ideally before surgery if allergy is known or suspected.
• If symptoms occur after implantation, act quickly: rule out mechanical problems, inflammation, infections and then consider allergies.

Treatment options & surgical planning for nickel allergy

Before the operation

• Allergy testing : patch test, LTT, detailed medical history.
• Material selection : Discuss with your surgeon which prostheses are available and which manufacturers offer nickel-free or very low-nickel implants. Ask about alloy data and coatings.
• Advice on partial joint replacement vs. total joint replacement : If possible, choose partial joint replacement / sled prosthesis.

Intraoperative

• Careful selection and documentation of the implant type and material.
• Minimal trauma, shortest possible operation time, good soft tissue management.

After the operation

• Pain therapy, physiotherapy, mobilization.
• Observe for complications: swelling, redness, increased irritability.
• If symptoms occur, recheck for allergies and, if necessary, revision.

Why a knee specialist like Prof. Kutzner / Endoprotheticum Rhein-Main in Mainz

Prof. Dr. Karl Philipp Kutzner is a specialist in orthopedics and trauma surgery, specializing in hip and knee arthroplasty. The Endoprotheticum Rhein-Main in Mainz is a specialized facility focusing particularly on joint replacement and joint surgery , with extensive experience in sled prostheses, partial joint replacements, and customized and minimally invasive treatment. endoprotheticum.de

Advantages:

• Specialized practice with high case volume → good routine.
• Expertise in sled prostheses/partial joint replacements. (e.g., "sled prostheses and partial joint replacements" are part of Prof. Kutzner's surgical spectrum.) endoprotheticum.de
• Possible advice on allergy implants/special alloys, material selection, etc.
• Good selection of implants and high-quality technical equipment.

Frequently Asked Questions (FAQ)

Question: Can I even get a knee replacement if I have a nickel allergy?
Answer: Yes – many patients with nickel allergies get knee replacements, and with the appropriate choice of material (low-nickel, titanium-coated, etc.), allergic reactions can be minimized.

Question: Is a sled prosthesis always possible?
Answer: Not always – it only makes sense if only one compartment is affected, the ligament structures are intact, and there are no severe deformities.

Question: How "nickel-free" are nickel-free implants really?
Answer: There are low-nickel alloys and implants with very low nickel content (e.g., < 0.0035%), titanium coatings, or titanium-based complete solutions. It is important to obtain manufacturer information. Completely "100% nickel-free" is often difficult, as traces can be present, but modern solutions come very close.

Question: Do I have to choose a total joint replacement instead of a partial joint replacement because of my allergy?
Answer: No, quite the opposite – partial joint replacement is often a better choice because of the lower metal exposure, provided the conditions are met.

Conclusion: Nickel allergy is usually not a catastrophe

• Nickel allergy is an important issue with knee prostheses, especially with standard implants containing alloys containing nickel.
• Partial joint replacements and sled prostheses are particularly attractive options for people with nickel allergies – less metal, faster recovery, more natural knee feel.
• Modern implant materials such as titanium-based or titanium-coated oxinium/zirconium alloys and specially coated allergy prostheses offer sensible ways to minimize the risks.
• Careful diagnostics before and after surgery are essential: allergy testing, imaging, medical history.
• An experienced knee specialist specializing in knee arthroplasty, such as Prof. Kutzner at the Endoprotheticum Rhein-Main in Mainz, offers ideal conditions for selecting the right implant and performing the operation safely.