German scientists are developing a small implant and screw made of magnesium, with sufficient mechanical stability, and the degree of degradation in the human body can be controlled without causing damage to human tissue.
Where bones break, doctors usually use implants to fix bone fragments, and the choice of implants requires careful consideration. Titanium or steel screws and fixing plates are very stable in mechanical and chemical properties, but if they are to be disassembled, they must be operated again; organic material implants may slowly dissolve, and there is also insufficient strength, and the dissolved substances are harmful to the human body. Disadvantages.
In response to this problem, the German Federal Institute for Material Testing used magnesium to develop alloy plates and orthopedic screws with the best functional surfaces. This magnesium implant is especially suitable for children with rapidly growing bones. The biodegradable screws will not affect the children's bone growth, can eliminate secondary surgery, reduce the risk of infection and save costs.
Researcher Eli Brunick said: "Magnesium alloy implants are not only biocompatible, but also have similar mechanical properties to bones at the initial stage of fragile healing, so they are more suitable than titanium."
In some cases, the magnesium alloy may generate hydrogen during the degradation process, and even form bubbles under the patient's skin. If more hydrogen is formed than can be removed immediately by the body, the healing process of fragile bones will be disrupted.
To develop new implants, human tissue fluid is essential. But the acidity of interstitial fluid is much more complicated than that of blood. Depending on body parts and tissue conditions, different parts and tissues will affect the inserted screws.
In order to make realistic predictions on the progress of human biological corrosion, Brunic has developed an experimental analyzer and flow cell that simulate human PH adjustment. In a battery pack consisting of 10 flow cells, the magnesium alloy sample was immersed in artificial tissue fluid and caused the tissue fluid to flow at the same speed as the human body.
The researchers simulated the biological corrosion of the human body under real conditions to obtain the best alloy ratio of magnesium and other biocompatible elements, as well as the new surface function of the absorbable magnesium screw, which makes the implant slow in the human body. , Controlled degradation, will not form bubbles. Brunick explained that depending on the acidity of the organization, the response will be different. In a weakly acidic environment, a large amount of hydrogen will be formed during magnesium corrosion; while in an alkaline environment, carbonate-containing products will be formed to prevent degradation.
Bruneck said: "The flow cell is a small laboratory that can simulate the reality of biological corrosion in real life." The next step is to put the alloy sample and live cells in the micro laboratory together to simulate the human body in more detail. Corrosion process.