Artificial joint material analysis: Medical implantable Metal? Polymers? Ceramics?

As a surgical procedure for the treatment of end-stage osteoarthritis and other joint diseases, artificial joint replacement has been widely used in clinical practice with good results, relieving the pain and improving the quality of life for many patients with severe osteoarthrosis. Where did the history of artificial joint replacement begin?

In 1890, Gluck first applied ivory to manufacture the mandibular joint; in 1938, Wiles used Stainless Steel for the acetabulum and femoral head; then Moor carried out artificial femoral joint replacement; in 1940, the Wder brothers used synthetic resin to manufacture artificial joints; in 1951, total hip artificial joint replacement began. 1952, Habowsh used acrylic to fix teeth to fix artificial In 1958, Charnhey made a low-friction artificial joint with a polytetrafluoroethylene acetabulum and a metal femoral head based on the theory of slippery TDRTEFDHFYUHH in a heavy-body environment, and then in 1962, Charnley made a total hip artificial joint with a high-density polyethylene acetabulum and a 22-mm diameter femoral head. In 1962, Charnley formed a total hip artificial joint with a high-density polyethylene acetabulum and a 22-mm diameter femoral head and fixed it with bone cement (methacrylate), with more satisfactory results. Since then, artificial joint replacement has entered a new stage of practical application.

So, what are the artificial joint materials used to replace our human joints?

An artificial joint, as a human implant, must have the following characteristics:

①Compatible with human tissue, no toxic side effects on the human body and no rejection reactions;

②Be able to combine well with the biological interface and be stable;

③Stable performance, resistant to human microenvironment, not easy to be degraded, electrolyzed and corroded;

④Easy to synthesize and manufacture, and can be mass produced.

⑤ Suitable biomechanical properties, which can be better adapted to human tissue at the implantation site;

There are no prosthetic materials available that absolutely meet all of the above conditions, and given this situation, combining materials with different advantages can make up for the lack of a single material. It has become the primary choice of physicians today, but in the process of selecting materials, we need to ensure that the requirements of the physiological environment and joint biomechanics are met as much as possible. There are three main types of artificial joint prosthesis materials in common use today: metallic, polymeric and ceramic materials.


1. Polymer materials

1.1 Polymer materials mainly include: polymethyl methacrylate, ultra-high molecular weight polyethylene and highly cross-linked polyethylene.

Polymethyl methacrylate, also known as "bone cement", is mainly used for the fixation of bone cement prosthesis, while UHMWPE and high cross-linked polyethylene are mainly used for the lining of the acetabulum and the spacer of the tibial prosthesis. Joint prosthesis is an expensive implant to be implanted in the human body, but also to be used for many years without damage, many people are considering polyethylene so "low-end" material will not be able to do it? In fact, material scientists and orthopedic surgeons have tried more advanced materials, such as PTFE, but the results were not satisfactory, after continuous screening, polyethylene with excellent resistance to wear and impact has become the best choice.

1.2 However, the polyethylene used for joint prosthesis is still different from the polyethylene used for basins and plastic bags. Artificial joints are implantable prostheses to replace diseased or damaged joints, which must have adequate wear resistance, mechanical properties and oxidation resistance, in addition to biocompatibility requirements. "Since the 90's, high cross-linked polyethylene has been formed by chemical reactions and even high energy rays, supplemented by fine heat treatment, to further increase the wear resistance.

1.3 UHMWPE is widely used as a material for artificial joint replacement because of its own excellent physical and chemical properties.

To be continued...