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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.

 

 

 

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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).

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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.