Real Money Rummy studies for the current hip implants showed that the friction and wear at the tribo-pair interface are the most significant clinical problems. Besides that, other implant failure involves fretting and tribo-corrosion which increases revision rate. Also, the metal debris and toxic ions release results in the adverse local tissue response (ALTR), pseudotumor formation. Currently, CoCrMo alloy material is widely used as bearing surface for hip implants. However, there are major cytotoxicity problems associated with this CoCrMo material in hip implant. Thus, despite having sound tribo-performance, it is not aptly suitable for long-term implant application, particularly, to improve the longevity of hip implant without revision surgery. In contrast, Ti6Al4V avails excellent biocompatibility, better specific strength, and superior corrosion resistance with inferior tribo-performance. Once the poor wear performance of Ti6Al4V is conquered, it has the potential to become the best alternative for CoCrMo in orthopedic application.
Surface texturing technology is the latest approach to improve the tribological performance between articulating surfaces. It decreases real area of contact, produce an extra hydrodynamic pressure build-up and traps the on-site wear debris. Incorporation of these micro-textures over Ti6Al4V surface can significantly improve the longevity of hip implant.
Thus, this study investigates the feasibility of micro-groove cross hatched textures on Ti6Al4V articulating with Ultra High Molecular Weight Polyethylene (UHMWPE) for a Metal-on-Polymer (MoP) hip implant to improve biotribological performance. Micro-groove crosshatch textures with various width ranging from 50 µm to 250 µm are fabricated by Laser Surface Texturing (LST) technique over polished Ti6Al4V samples. Tribological performance against various texture width is analysed for the different loading conditions under biological environment using linear reciprocating tribometer. Considering the best texture width, the other geometrical parameters such as depth and area density, are analysed under the same testing condition to obtain an optimised texture geometry. The results show that the selection of micro-groove geometry is critical for obtaining the maximum tribological benefits. Texture width equal or more than the Hertzian contact is reducing friction and wear up to 50% and 15 times respectively, at the tribo-pair. Also, the shallow texture depth of 5 µm depth at 25% area density was found to be the best geometry for crosshatch textures in Ti6Al4V/UHMWPE tribo-pair under implant articulating condition.