Bearing surfaces are scanned using an advanced
coordinate measuring machine (CMM).
Our Legex 322 CMM from Mitutoyo has a measurement accuracy of greater than one micron (one thousandth of a millimetre). A ruby probe glides over the surface, continuously collecting data points.
Automated programmes allow the CMM to distinguish between the unworn parts of the bearing surfaces and determine the geometry of the parts when they left the factory.
From this unworn area, the original geometry of the component can be reverse engineered.
From this original geometry, the amount of material that has been worn away during the life of the prosthesis can be estimated.
The distribution of material loss can be plotted in the form of three dimensional wear maps. Green areas represent the as manufactured surface, with red indicating areas of material loss (wear).
CMMs are capable of scanning most surfaces, including more the complicated geometries such as knee and ankle replacements.
The accuracy of wear anlysis is limited however by the ease with which the original geometry can be reverse engineered.