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Strategy: which implant for which patient? Specific considerations about TKA…
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factor for achieving good results with
cementless implants. Whiteside showed that
outcomes with cementless tibial components
could be superimposed to those of the best
studies involving cemented fixation. However,
the tibial component was not highly loaded
because a PCL-retaining TKA implant had
been used [19].
The stresses placed on the tibial component
must be taken into consideration. As such, the
HLS system with a 3
rd
condyle appears to be a
promising posterior-stabilised implant because
the relatively low contact point generates lower
stresses. But to be on the safe side, it is
preferable to use a longer stem than the one in
the initial system. The few studies that have
looked specifically at the tibial component
found no significant complications [2].
So what do we recommend to those wanting to
use a cementless implant?
Indeed, any proven coating must be included
hydroxyapatite (> 20μm). Press-fit is preferred
to screw fixation to achieve primary stability.
Coating the implant in the cancellous bone area
is to be avoided, in case it needs to be extracted
later on. Tibial components, especially ones
within posterior-stabilised systems, should
have a longer keel.
The implant choice is important, as is the need
for instrumentation specific to cementless
implantation. The guides must optimise the
precision of the cuts (fig. 6). The degree of
press-fit required must be quantifiable with
accurate jigs (fig. 7).
Fig. 5
Fig. 6
Fig. 7