Failure Mechanisms of Ceramic Total Hip Arthroplasty

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