View Full Version : Standards for metal on metal prostheses

Barker, Dan (dhs_rgh)
11-21-1999, 02:34 PM
Dear BIOMCH_L subscribers

As part of a new two piece prosthesis design we are favouring the use of
cobalt-chrome on cobalt-chrome articulation. Is anyone aware of any
standards, formal or informal, which govern tribological factors such as
surface roughness, sphericity, and diametral clearance.

I am aware of the extensive literature re metal-metal articulation, but I
cannot find any specific design guidelines such as " for a particular
diameter head subjected to a load level X, the surface roughness should be
........, the sphericity should be ............., and the diametral
clearance should be .............. . I am aware of the ASTM standards which
don't seem to cover this and that it is desirable to minimise surface
roughness, sphericity and diametral clearance but what are the maximum
allowable numbers?

If anyone has references explaining modern manufacturing techniques for
Co-Chrome (ie producing highly accurate spheres and incredibly low surface
roughness 5nm) it would be greatly appreciated

Looking forward to any replies

Dan Barker
Research Engineer

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