Shoulder joints, hip sockets, dental implants or hearing aids: the medical industry has been using titanium in all manner of medical applications since the 1950s. The natural properties of this strong and corrosion-resistant element make it reliable and completely biocompatible.
What is even more fascinating about titanium is that it promotes osseointegration by physically bonding with the bone around which it is placed, without the need for an extra adhesive.
Titanium implants resist high energy forces without breakage, don’t react to bodily environments and last longer than many other materials.
Metals in orthopedic implants through the ages
Humans have been using metallic materials to replace body parts and to treat fractures for over a century. Earlier applications with lead, aluminum, silver and gold have since been abandoned as the materials proved too weak for long-lasting uses.
Steel, iron, nickel, copper and zinc implants used between 1920 and 1950 led to adverse bodily reactions. Titanium first gained popularity in the dental industry in the 1940s and quickly found its way into orthopedics in the 1950s.
Today, it is the go-to material for internal fixation, inner-body devices, prosthetics and medical instruments.
Properties of titanium alloys used in medicine
In its pure form, titanium
- low density,
- high strength
- high level of corrosion resistance
- It is also non-magnetic and non-toxic, two properties that are particularly advantageous for application in biomedical materials
. Itscoefficient of thermal expansion and modulus of elasticity both resemble that of human bone.
- Pure titanium is the most corrosive-resistant form of titanium on the medical market and is frequently used when ductility and malleability
Alloys come into play when strength to weight ratio is vital to the success of the implant. Most interestingly, titanium connects very well to human tissue and bone.
The most common alloys used in medical and dental implants are Titanium 6AL4V / Titanium 6Al4V ELI – alpha-beta alloys containing approximately 90% titanium, 6% aluminum and 6% vanadium. They facilitate a high level of fracture resistance and work in harmony with the body to promote osseointegration.
Osseointegration: titanium is adhesive and non-corrosive
Any implant inserted into the body is treated as an assault, and the tissue surrounding the implantation site is highly sensitive. Titanium is completely inert, thanks to its protective oxide film formed naturally upon exposure to oxygen. It is also completely resistant to fluid and tissue corrosion; therefore it won’t be rejected by the body. Titanium bonds well with human bone because it has a high dielectric constant.
Other types of biomaterials may require adhesives to connect with bone and tissue, but titanium facilitates this process naturally, a benefit not found in any other metal. Once the bond is formed, only a very high force can succeed in breaking it.
Heads and shoulders, knees and toes
Surgical instruments such as forceps, dental drills and laser electrodes often contain titanium because it is resistant to bacteria, compatible with radiation, durable yet lightweight and non-corrosive. Neurosurgical applications include cranial plates, acrylic and mesh. Children’s titanium rib cages facilitate expansion as the body grows.
Finally, titanium is the biomaterial of choice around the world for hip and knee replacements, as well as elbow and shoulder joint replacements. Bone screws, plates, staples, mesh and cables made of titanium support broken bones and facilitate fixation.
Want to know more about titanium? Try searching for titanium on Matmatch and find about more about its properties.