Choosing the right bearing surface in hip arthroplasty is crucial for the longevity and functionality of a hip prosthesis. While ceramic-on-ceramic (CoC) pairings were long considered state-of-the-art, CoXPE (ceramic on ultra-high-crosslinked polyethylene) is increasingly establishing itself as the gold standard. The reason: CoXPE combines low wear with high stability and flexibility, whereas CoC suffers from some specific disadvantages that limit its acceptance.

Ceramic on ultra-high cross-linked polyethylene: Minimal abrasion and maximum reliability

CoXPE bearing surfaces offer an outstanding combination of wear resistance and protection of surrounding tissues. The highly cross-linked polyethylene plastic reduces abrasion to a minimum, which significantly lowers the risk of osteolysis (bone loss caused by particles). This is a crucial advantage over older bearing surfaces such as metal-on-metal or metal-on-soft polyethylene, which have become notorious for their high particle generation.

The problems of ceramic on ceramic

Although CoC boasts an extremely hard and durable surface, it has disadvantages that limit its use:

ceramic fragments

Despite modern manufacturing methods, the risk of fracture remains under heavy stress or with misalignment. This aspect is particularly problematic for younger and athletically active patients.

Squeaking phenomenon

The occurrence of unpleasant squeaking noises in coccygeal bearing surfaces can significantly impair quality of life. Although rare, it is perceived as bothersome by patients.

Costs and complexity

CoC prostheses are more expensive and require a more precise implantation technique to achieve optimal results.

Why CoXPE is displacing CoC

The superior properties of ceramic on highly cross-linked polyethylene – especially its high load-bearing capacity and flexibility – make this bearing surface the preferred choice in modern hip arthroplasty. While CoC remains an option in specific cases, it is increasingly being replaced by CoXPE, as the latter minimizes the risk of undesirable complications.

Vitamin E makes the highly cross-linked polyethylene even more resistant

Adding vitamin E to highly cross-linked polyethylene (XPE) in hip prostheses is an important measure to improve the long-term durability and stability of the material. Vitamin E is added because of its antioxidant properties, which protect the polyethylene from oxidation.

Reasons for adding vitamin E to polyethylene:

Prevention of oxidation : Polyethylene can oxidize over time, which can weaken the material structure and lead to increased abrasion. This abrasion is one of the main causes of hip prosthesis failure, as it promotes the formation of wear particles that can attack the bone and lead to aseptic loosening. Vitamin E helps to slow down this oxidation process and thus extend the lifespan of the implant.

Increased abrasion resistance : By preventing oxidation, the polyethylene remains more robust and less susceptible to material fatigue. This means that the ceramic-XPE bearing pairing, frequently used in modern hip prostheses, generates less wear and thus offers a longer service life.

Improved long-term performance : Studies have shown that XPE with vitamin E exhibits significantly higher long-term stability, making it a preferred choice for patients requiring a durable and resilient hip prosthesis. Vitamin E not only protects against oxidation but also helps the material remain more resistant to wear and tear, especially in young and active patients.

Vitamin E is therefore an important component of modern highly cross-linked polyethylene materials in hip prosthetics, as it improves the chemical stability of the material and thus contributes to better long-term results.

Conclusion: The future belongs to the sliding pairing of ceramic on highly cross-linked polyethylene

Modern bearing surfaces like CoXPE exemplify the progress in endoprosthetics. By combining durability, safety, and comfort, they set new standards, while other bearing surfaces like CoC are increasingly becoming less relevant. Adding vitamin E to the polyethylene further enhances these properties considerably.