Extract
To The Editor: What appears most evident in the paper
"Ceramic Failure After Total Hip Arthroplasty with an Alumina-on-Alumina
Bearing" (2006;88:780-7), by Park et al., is the high percentage of
fractures of ceramic components (four liners and two heads out of a total of
357 implants, or 1.7%). The same figures were presented in a poster by Park et
al. at the 2006 AAOS annual meeting in Chicago1. Also, on the same
occasion, other Korean surgeons presented a similar poster2, in
which five of 157 sandwich ceramic liners were reported to have fractured,
giving a 3.2% fracture rate. Summing up the experiences of the two groups of
surgeons, we calculated a percentage of fractures of 2.1%. The sandwich type
of acetabular liner considered in these works has been in use since 1994, and
to date more than 20,000 liners have been implanted in Europe, Asia, and
Oceania. Excluding those in Korea, twenty-eight fractures of these implants
have occurred (a rate of about 0.14%), to our knowledge. In all of the cases
examined, the cause of the failure was a subluxation of the head, which often
can be traced back to malpositioning of the acetabular cup.