http://fdanews.com/newsletter/article?issueId=14568&articleId=135224

Quality problems with metal-on-metal (MoM) hip replacement systems, like
Johnson & Johnson (J&J)’s ASR devices, may not be as widespread as UK data
indicates, the U.S. Food and Drug Administration (FDA) says. National Joint
Registry of England and Wales data, which last year showed high revision rates
for two ASR hip resurfacing systems, led to a UK medical device alert and
recommended blood tests, as well as a worldwide J&J recall in August. But the
FDA argues the adverse event rate for these devices remains unclear, and the
agency is in the process of gathering additional information about adverse
events in people with MoM hip implants.