Extract
"Zirconia Ceramics or `By Night, All Cats Are
Grey.'"1 This
was the curious title given four years ago to a French study regarding the
controversy over zirconia in total hip replacement. The authors of that study
commented: "In the absence of rigorous scientific clarification,
information on biomaterials is frequently a source of confusion and misleading
generalisations worrying to orthopaedic surgeons."Indeed, from their inception eighteen years ago, the performance of
zirconia ceramic balls (Fig. 1)
has been both confusing and controversial. Given the diversity of clinical
results, it may well be true that not all zirconia balls were created equal.
Thus, the above quotation appears as salient today as it was in 1999. A more
recent French study reinforced this opinion: Hamadouche et al. noted that they
could find only two studies that demonstrated favorable clinical results with
the use of zirconia
balls2. The
literature published by major ceramic companies has also noted that certain
clinical groups found higher rates of osteolysis with the zirconia-ultra-high
molecular weight polyethylene
couple3,4.
How was this possible after an eighteen-year history of use of zirconia
implants, with more than 400,000 zirconia implants reportedly sold
worldwide5,6?