Parallel wear tests to evaluate wear in joint reconstruction - TRL6

WHY

The failure of the hip replacement is often a combination of tribocorrosion of the hip joint materials and inflammations due to wear particles in the body. A new methodology needs to be developed so as to allow for a fast prescreening of the reliability of new biomaterials, in conditions that simulate the actual conditions (e.g. environment, motion, contact pressure, countermaterial). 

HOW

Based on the pioneering work of Dr. Vesa Saikko, using a circular translation pin-on-disk (CTPOD) we applied the method with our multistation machine (Phoenix Tribology). To simulate the actual contact, ultra high molecular weight polyethylene (UHMWPE) pins were used as counter materials, the materials under investigation are nano-composite coatings.  The tribosystem is immersed in a 10% bovine calf serum (simulating body fluids). This test setup allows to run for up to 50 tests in parallel. After testing the weight loss of the UHMWPE and biomaterials was measured, whereas the surface morphology was evaluated by confocal microscopy.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESULT

Efficient screening of joint materials showed 

• Spread on wear values confirms the need for statistical (parallel) testing.
• Repeatability of the wear resistance could be evaluated with a high confidence level.
• The weight loss of the polyethylene counter material strongly depends on surface finishing (roughness) of the coating.
• This methodology allows for a fast prescreening and ranking, in conditions that closely correlate to actual conditions. It is an essential tool for development and evaluation of new biomaterials.