The Importance of Metal Alloys in Medicine for Implants and Devices

January 22, 2024

The Importance of Metal Materials in Medical Implants and Devices

Metals and metal alloys play an important role in the development of medical implants and devices. Different metals have properties that make them suited for different purposes, like strength, thermal conductivity, and biocompatibility. Choosing the right material for the device in question ensures that it will be both functional and safe for the patient.

What Are Biocompatible Materials?

Biocompatible materials are materials that can come into contact with the inside of the human body without causing harm. A biocompatible material is nontoxic and does not trigger an immune response, making it safe to use for medical devices.

Which Metals Are Most Commonly Used for Medical Devices?

Stainless Steel

Stainless steel is one of the most common metals used in medical devices. This metal is nontoxic and durable, and it does not corrode. Stainless steel is often used for medical implants as well as body piercings, most commonly in the form of 316 and 316L stainless steel, which are exceptionally resistant to corrosion. It's also used to make surgical tools; these implements are made with 440 stainless steel, which can be honed to create very sharp blades.

Copper

Copper is a not commonly used on its own in the medical field, as it's fairly soft and can be toxic inside the body. However, because copper is antimicrobial, copper alloys are sometimes used to make dental implants and employed on surfaces in medical facilities that are often touched, like doorknobs and bed rails.

Titanium

Titanium is used in the medical field due to its biocompatibility, strength, and resistance to corrosion. It's a lightweight metal that's a great alternative to stainless steel in medical implants. It can even be 3D-printed to make custom devices. However, it's more expensive than stainless steel, and it does not hold up well over time when used in replacement joints.

Cobalt Chrome

Cobalt chrome is a very hard metal used in medical and dental implants. It stands up well to wear over time, making it suitable for joint replacements.

Aluminum

Aluminum is most commonly used to make medical devices used outside of the body, like IV stands, bed frames, and walkers. It's a lightweight metal that's easy to shape and mold. However, since aluminum oxidizes readily, it must be either anodized or painted.

Magnesium

Magnesium alloys are lightweight and strong and have a similar density to bone, so they're commonly used for bone grafts. Magnesium is biocompatible, but it dissolves inside the body, so it's best used for devices that don't need to be permanent. One great use for magnesium alloys is in pins and screws used to repair bone fractures; as the bone heals itself, the metal dissolves, meaning that it won't need to be surgically removed later on.

Gold

Gold is biocompatible and highly resistant to corrosion, but it's also quite soft on its own, so it's most commonly used as part of an alloy. Gold has a long history of being used for dental repairs because it's easy to mold, though this has become increasingly uncommon, in part because of its cost; gold is very expensive. It's also highly conductive, so it's well-suited for use in the electrical components of powered medical implants.

Platinum

Platinum, like gold, is a good conductor and biocompatible. It's used in a lot of the same applications, especially in the circuitry of devices like hearing aids and pacemakers.

Silver

Silver has antimicrobial properties that make it highly useful for medical applications. It's used to coat medical implements, and it's also sometimes included in medical implants to help prevent infection.

Iridium

Iridium is a hard metal that resists corrosion. Its durability makes it a good choice for things like the electrodes on pacemakers, which need to stand up to constant use.

Tantalum

Tantalum is a ductile and corrosion-resistant metal that's biocompatible and highly heat-resistant. It's increasingly being used in orthopedic and dental implants.