Characteristics of metals used in implants

Area of Science:

• Biomaterials Science
• Medical Device Engineering
• Materials Science

Background:

• Implantable device performance hinges on biofunctionality and biocompatibility.
• Material selection for medical applications increasingly relies on biocompatibility considerations.
• Corrosion susceptibility and tissue effects are central to metal alloy biocompatibility.

Purpose of the Study:

• To review the functionality of current metals and alloys for stenting applications.
• To describe the unique properties of Nitinol for potential use in urologic stents.

Main Methods:

• Review of existing literature on metallic biomaterials.
• Analysis of corrosion resistance and tissue encapsulation data for implant alloys.
• Description of Nitinol's shape memory and pseudo-elasticity.

Main Results:

• 316L stainless steel, cobalt-chromium, and titanium alloys rely on oxide passivation for corrosion resistance.
• Stainless steel exhibits lower corrosion resistance, suitable only for temporary implants.
• Titanium and Co-Cr alloys show minimal corrosion, but ion diffusion into tissues occurs, influencing fibrous tissue encapsulation.

Conclusions:

• Nitinol's shape memory and pseudo-elasticity offer potential advantages for urologic stent applications.
• Understanding material-tissue interactions is crucial for optimizing implant performance and longevity.
• Continued research into advanced biomaterials is essential for improving medical device efficacy.