How Long Can Artificial Joints Last? A Real Must-read for You!

Navigation

Metal on Polyethylene (MoP)
Metal on Meta (MoM)
Ceramic on Polyethylene (CoP)
Ceramic on Ceramic (CoC)
Conclusion
Read More

The service life of artificial joints has long been a concern for patients, their families, and medical professionals alike. However, advancements in the design and processing technology of artificial materials, coupled with continuous surgical innovations, have significantly extended the lifespan of artificial total hip joints.

There are many factors that can affect the service life of a total hip prosthesis, such as the patient’s health status, weight, activity level, bone quality, the surface treatment process of the acetabular cup and femoral stem, wear-resistant properties of the friction interface, and surgical techniques. Although vitro experiments can predict the wear resistance of a certain prosthesis, the complex physiological and chemical environment and the complex mechanical environment of the materials implanted in the human body will affect the wear rate of the prosthesis.

Therefore, it is difficult to accurately judge the service life of the artificial joint in a specific patient.

Friction interface is one of the most important factors affecting the life of artificial joints.

Acetabular cups can be combined with polyethylene, metal, ceramics, and other materials.

(a) MoP bearing (b) Large head MoM bearing (c) Small head MoM bearing (d) CoC articulation (e) CoP articulation

Metal on Polyethylene (MoP)

Advantages: low friction coefficient, chemical corrosion resistance, stress crack resistance, and better energy absorption under repeated stress, etc., have been used in clinical practice for many years.

Disadvantages: Polyethylene wear debris particles can produce different degrees of macrophage reactions in the body, leading to bone destruction and osteolysis, which in turn cause aseptic loosening and failure of the prosthesis.

Metal on Meta (MoM)

Advantages: Metal materials have high strength, high toughness, and strong corrosion resistance, which meet the characteristics of hip replacement prostheses.

Disadvantages: Metal friction releases metal ions, which are distributed in various tissues and organs throughout the body with the circulation of body fluids. Among them, the brain, lungs, liver, and spleen are considered to be the most concentrated parts of metal ions, and their potential harm to the human body cannot be ignored.

Ceramic on Polyethylene (CoP)

Compared with the metal-to-polyethylene interface combination, the ceramic-to-polyethylene interface combination has the obvious advantages of hard texture and low friction coefficient, which reduces the chance of scratches and surface damage, and can theoretically reduce polyethylene wear. However, whether the ceramic head can really reduce the wear rate of polyethylene remains to be further studied and observed in the laboratory and clinical practice.

Ceramic on Ceramic (CoC)

The excellent mechanical properties, biological stability, and liquid film lubrication mechanism of ceramics make it an excellent material for improving the service life of hip prostheses.

The third-generation alumina ceramic artificial joint significantly improved hardness and mechanical strength compared with the previous two generations, and the incidence of prosthetic fracture has also been reduced to 0.004%.

The fourth generation of ceramics is a new type of alumina-based composite material, which combines alumina, zirconia, and chromium oxide. It has better biocompatibility and wear resistance, and its material strength and toughness are better than other materials.

Now, ceramic materials have been developed to the fourth generation, which, in addition to having higher biocompatibility, has brought revolutionary breakthroughs in hardness, lubrication, toughness, and wear resistance. It not only has strong anti-fragmentation properties but also has extremely high fracture toughness. In the third generation and before the ceramic lining, due to the limitation of the strength of the ceramic itself, it must ensure sufficient thickness, which limits the size of the ceramic ball head. A ball head that is too small not only increases wear but also has the risk of dislocation and breakage.

The incidence of stripe wear in the fourth-generation ceramic articular prosthesis was significantly lower than that in the third-generation ceramic articular prosthesis. And because of its high strength, the lining can be made thinner so that 32mm or 36mm large-diameter ball heads can be used, thereby reducing impact and wear on the articular surface, reducing the incidence of joint dislocation after replacement, and improving hip replacement, Joint stability and joint range of motion.

Conclusion

After more than 40 years of development, both the characteristics of ceramics and the fixation methods of components have been significantly improved. Ceramic-on-ceramic has become one of the main joint interface options in the field of total hip replacement.