With an increasing demand for joint replacements, metallic materials are widely used in the making of structures and implants. Cobalt-based alloys are an essential engineering material that is used in millions of implants and medical surgeries due to their excellent thermal conductivity and mechanical properties. 

The first medical use of cobalt-based alloys was made for dental implants. Various tests have proved that alloys are biocompatible and are an appropriate option for surgical implants. Today, the use of Co alloys for surgical applications is mainly related to orthopedic prostheses for the knee, shoulder, and hip as well as to fracture fixation devices. The experts at https://www.elgiloy.com/wire-inconel-alloy-718/ suggest that one should opt for the materials that ensure biocompatibility and success of the joint replacements. Therefore, the implant materials must meet extremely high requirements concerning biocompatibility with the surrounding body tissue material and corrosion resistance to body fluids. 

Let’s know more about the properties of the cobalt-based alloys that arise from the crystallographic nature of cobalt, hence making it a superior choice for medical applications. 

Biocompatibility 

On the exposure of implants to human tissues and fluids, several reactions take place between the host and the implant material. These reactions command the permissibility of these materials by our system. The presence of good biocompatibility in cobalt-based alloys produces the best artificial joints.

Mechanical Properties  

The mechanical properties present in a particular type of material decide if the material is worth selection for a specific application. Properties such as hardness, tensile strength, modulus, and elongation are of prime importance. The fatigue strength of the material ensures the long term success of the implant. And, the material’s reaction to the repeated cyclic loads or strains is determined by the fatigue strength of the material. Biomechanical incompatibility can occur, if an implant fracture due to inadequate strength or mismatch in mechanical property between the bone and implant. This biomechanical incompatibility can even lead to the death of bone cells known as the ‘stress shielding effect”. Therefore, a material such as cobalt-based alloy containing an excellent combination of high strength and low modulus closer to bone should be used for implantation. Using material with these properties avoids the loosening of implants and ensures a higher service period to avoid revision surgery.

High corrosion and wear resistance

Development of implants with high corrosion and wear resistance is very important for the longevity of the material in the human body. The presence of high corrosion and wear resistance in cobalt alloys makes them the best choice for implants. Having these properties ensure the release of non-compatible metal ions into the body. The service period of the material is mainly established by its abrasion and wear resistance. The low wear resistance can result in implant loosening and wear debris can cause multiple reactions in the tissue in which they are deposited. To avoid such situations, it is very important to use high corroded materials. This high corrosion is found in cobalt alloys making it the best alternative for implants. 

Osseointegration

The implant surface is not capable of integrating with the adjacent bone and other tissues. This happens due to micro-motion which finally results in implant failure or loosening. On inappropriate integration of the implant with bone, fibrous tissue is formed between the implant and the bone. Therefore, to have a proper implant, materials with adequate surfaces are required. These substances integrate well with the adjacent bone. Factors such as surface chemistry, surface roughness, and surface topography all play a vital role in the development of good osseointegration. 

Observing these properties, you have an idea about the behavior of cobalt-based alloys. The presence of these qualities makes them best to meet the medical demands. Thus, there should be no scope to make errors during the selection process of the material. Let us have a look at simple tricks to obstruct joint diseases. 

Preventing failure in implants

Before selecting material to prepare bio-protheses, it is very essential to consider the mechanical and material issues. While the usage of certain conditions can lead to the failure of the implants. The loosening of an implant is generally caused by wear debris, unstable implant, and adverse reaction of a prosthesis with host tissue. Some metals are susceptible to degradation by corrosion. A process that can release by-products may cause adverse biological responses. In such situations, using cobalt-based alloys comes to the rescue. It is one of the only alloys with good corrosion resistance and good mechanical strength in chloride environments. These metals own such properties due to alloying additions and the formation of the chromium oxide Cr2O3 passive layer. 

Realizing the importance of material selection for implanting, choose an approach that can improve the biocompatibility that occurs instantly after implantation. The novel behavior found in cobalt-based alloys makes it best for clinical use, making the implant successful. 

Cite this article as:
Editorial Staff, "Cobalt based alloys : A superior choice for medical applications," in Medicalopedia, December 15, 2020, [Permalink: https://www.medicalopedia.org/9456/cobalt-based-alloys-a-superior-choice-for-medical-applications/].