Metal on Metal Total Hip Arthroplasty
First used in the 1950s by Peter Ring and McKee and Farrar in the
United Kingdom these all-metal prostheses did remarkably well. However
the metallurgy and tribological design was primitive by present day
standards. There were frequent early failures but many of these joints
remained functional for many years often to the end of the patients
life (in those days total hip arthroplasty was performed exclusively
in patients over 65).
The spectacular success of the cemented metal on high density polyethylene
design of Charnley in the 1960s brought about the demise of all metal
total hips. However as the decades progressed the serious problems
arising from polyethylene wear became ever more apparent. As a result,
interest in all metal couplings revived.
The chrome cobalt metal couplings benefited from modern tribological
design which succeeded in creating metal joints with an extremely
low wear rate. These were pioneered clinically by Weber (Switzerland)
with cementing and by Wagner (Germany) without cementing: at over
10 years follow up these joints are producing excellent results.
This technology is an option for the biologically young active patient.
Metal on metal is at this time more versatile in application than
ceramic on ceramic but there is a biological/philosophical disadvantage
in that the metal debris, although small in quantity, is biologically
active whereas the ceramic is not. No ill affects have been proven
to occur from the long term presence of the chrome cobalt alloy wear
particles in the tissues although they may be found in distant organs.
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