Artificial joints and artificial bone replacement materials should have the following basic properties: lightweight and high-strength materials, biocompatibility and corrosion resistance, tissue reaction of implants in the body does not cause material deterioration, fatigue and less damage caused by repeated stress and other properties. The most important properties of metal implants are formability, additive properties, and polishing properties. They must maintain their function over the expected life span without deterioration under fatigue, abrasion, corrosion, and impact loads.
Titanium and titanium alloys meet all the above requirements. The first kinds of artificial joint materials, such as denture powder, polypropylene and plexiglass, have low strength, easy folding and poor biocompatibility. Later use stainless steel, but the proportion of stainless steel is larger, about 2 times of the proportion of human skeleton, and in the body by humoral action will appear corrosion and fracture. Co-Cr alloy is also an excellent artificial joint material, but unfortunately, cobalt, chromium elements are toxic to the human body. Titanium and titanium alloy have small specific gravity (similar to that of human bone), high strength, good mechanical processing and excellent corrosion resistance, so it is an ideal artificial joint material.
The titanium materials specified for surgical transplantation are mainly pure titanium and ti-6al-4veli alloy. Recently, ti-6al-7nb and ti-13nb1-13zr, which have good human affinity, have also been approved by ASTM standards. Titanium is used as artificial bone, on which cells can regenerate and bones can grow. Titanium has a good affinity with human bones, epithelium and building tissues. In order to improve the surface quality of the implant material connected with human bone, the bioceramic layer on the roughened surface is also an effective method. At present, titanium and titanium alloys have been widely used in artificial joints, artificial bones, joint baseboards, broken bone fixers, internal bone marrow nails, artificial heart valves, cranium and so on. According to statistics, the annual demand for titanium alloy artificial joints in China exceeds 5,000 sets, and the clinical application effect is good.
