Abstract
Polyethylene damage, including normal wear, may occur for a variety of reasons. The opposing view would have one believe that all of those reasons are malignant and lead to unavoidable, reasonably short term failure.
The logical question is first whether simple spacer change has any clinical advantage, e.g. being a smaller operation, easier to rehab, recoup from, and sparing the unavoidable bone loss associated with the removal of ostensibly firmly fixed components. It is clear that all of these 3 or 4 points are true. That is, spacer change is a small procedure, characterised by all the points mentioned.
The only relevant questions are whether main component removal is necessary all the time because there is a more basic problem that portends rapid failure or because failure to take advantage of one-staging to a more extensive revision early, makes that more extensive revision impractical or more difficult for the patient when delayed any given number of years.
The answers to these last two considerations or questions are clearly no.
A bad batch of poly can lead to osteolysis or wear independent of malalignment or ligament imbalance. It should be treated by poly change and where appropriate bone grafting.
Poly wear in the presence of malalignment of some degree can be more controversial. Factors to consider should be (i) the availability of presumably improved poly from the given manufacturer, (ii) the amount of malalignment, (iii) the age of the patient, and (iv) any prospects for changing the alignment short of main component revision. The latter can be done with asymmetric poly, or for femoral malalignment, correction of that alignment with osteotomy, in selected instances.
The patient age factor relates to both ends of the spectrum. In the younger patient one wants not to waste current main components, i.e. prematurely move to the patient's next prosthesis. And, the very elderly patient may have a clinical situation well suited to the smaller operation and a life expectancy that would exceed the albeit imperfect durability of a residually malaligned spacer change.
So, even if most spacer changes do not last as long as ordinary primary components, that does not mean that none will. Nor does it mean that they will not last long enough in an extremely elderly patient.
