Tribology of Titanium implants

Introduction

It has been estimated that 15 percent of the human population suffers from osteoarthritis. The increase in risk factors such as genetics, aging, and obesity are some of the reasons for this increase. Human life expectancy has increased in the past decade due to the invention of various medical solutions for existing diseases. These solutions have made life run swiftly over the period by increasing research methodologies to provide better results. Orthopedic implants are being used for many decades and there are various materials that are being researched and have been implemented in these implants.

Fig-1 Titanium implants [1]

Why Titanium

Titanium has been studied as the most used material for bio-implants because of its biocompatible nature. The surface characterization of the titanium is suitable for cell growth which makes it more favorable to be used in implants. It has the property of resistance to corrosion from various body fluids and has high fatigue strength. The oxide layer formed on the titanium surface in the presence of oxygen helps in preventing the chemical reaction between the metal and the surrounding environment [2].

Factors for Biomaterials

There are also various other factors such as topography, surface charge, elastic modulus, wettability, cytotoxicity, free surface energy, etc which make it more suitable to be used in bio-implants. The surface charge of any biomaterials is important and determines its osseointegration with the body cells. The cytotoxicity in the biomaterial is another factor that determines the contamination in the body environment. The biomaterial used for implants should not release any toxic debris into the body. Further surface topography is another important factor that determines the surface stress distribution, corrosion, wear, etc. similarly the wettability of the surface should be considered for the biomaterial which defines if the material is suitable for bodily fluid environments [3].

Fig-2 Biocompatible properties [4]

Tribology of Titanium

Being the most desirable material for biological implants, titanium possesses very poor tribological properties it has high and unstable frictional properties, low resistance to abrasion, and severe adhesive wear. These properties make it more unsuitable in most interfacial applications where sliding or continuous movement is observed. However, there are various surface modification techniques such as surface coating, surface texturing, etc that can be applied to improve its tribological properties [5].

Future of Titanium implants

Additive manufacturing techniques have increased their effectiveness in producing various components for desired applications. In recent days titanium powder is used to produce the desired components by 3D printing. The precise components can be printed using the Ti powder which can allow the reduction in waste material and reduce the weight of the components. This innovation can provide life-changing solutions to patients [6].

Fig-4 3D printed titanium implants [7]

Reference

[1] https://all3dp.com/1/3d-printing-orthopedics-knee-hip-spine-implants/

[2] Sidambe, A.T., 2014. Biocompatibility of advanced manufactured titanium implants—A review. Materials, 7(12), pp.8168-8188.

[3] Quinn, J., McFadden, R., Chan, C.W. and Carson, L., 2020. Titanium for orthopedic applications: an overview of surface modification to improve biocompatibility and prevent bacterial biofilm formation. IScience, 23(11), p.101745.

[4] Naahidi, S., Jafari, M., Edalat, F., Raymond, K., Khademhosseini, A. and Chen, P., 2013. Biocompatibility of engineered nanoparticles for drug delivery. Journal of controlled release, 166(2), pp.182-194.

[5] Dong, H., 2010. Tribological properties of titanium-based alloys. In Surface engineering of light alloys (pp. 58-80). Woodhead Publishing.

[6] https://www.med-technews.com/medtech-insights/latest-medtech-insights/titanium-and-3d-printing-the-future-of-medical-implants/

[8] https://www.mtaa.org.au/news/3d-printing-implantable-medical-devices