Background: It has been stated that care must
be taken not to scratch the metal components during total knee arthroscopy;
however, this concern has not been studied. Clinical observation
during arthroscopy of total knee replacements suggested the possibility
of damage to the femoral component by the arthroscopic cannula;
therefore, a bench test was performed to study this potential risk.
Methods: Cobalt-chromium femoral components were
tested to determine the surface damage that resulted from moving
a stainless-steel arthroscopic cannula and a plastic arthroscopic
cannula across the components under a variety of applied loads.
Scanning electron microscopy and surface-roughness measurements of
the prosthetic surface were used to evaluate the damage.
Results: The stainless-steel cannula produced observable alterations
to the surface of the femoral component at loads as small as 8 N.
The majority of these alterations were deposits of stainless steel
from the cannula onto the component. The plastic cannula did not
appear to produce alterations on the component surface. Surface
roughness increased with increasing loading of the stainless-steel
cannula, but there was no noticeable change with increasing loading of
the plastic cannula. These forces did, however, severely damage
some parts of the plastic cannula.
Conclusions: Alterations to the surface of cobalt-chromium
femoral components can occur during arthroscopy with stainless-steel
cannulae but not with plastic cannulae. The results of this study
support a recommendation to use plastic cannulae during arthroscopy
of total knee replacements.
Clinical Relevance: Arthroscopy of total knee replacements
is increasing in the clinical setting, and damage to the prosthesis
should be avoided whenever possible. This study provides evidence
that damage to the femoral component is possible with a stainless-steel
cannula and that use of a plastic cannula may reduce this risk.