USA Today—June 27, 2012
About 285,000 hip replacements are performed annually. An estimated 500,000 Americans have all-metal devices, which were believed to last longer than those made from other materials. In about the past 10 years, metal-on-metal implants and less invasive resurfacings often were chosen for younger, more active patients. From 2005 to 2006, the last year for which information is available, 32% of hip replacement surgeries were metal-on-metal devices.
But in the past few years, doctors have been seeing problems. Metal debris can break off when the joint's ball-and-socket pieces move against each other. The debris can cause pain and tissue damage, which can lead to complicated revision surgeries. Though the majority of people notice no problems, some studies show the all-metal devices require revisions at rates three to four times higher than those made from other materials and cause more problems in women.
Among current FDA recommendations: Doctors "may consider" blood tests, joint aspiration and imaging, and if patients have health changes, they should tell their physician they have a metal-on-metal implant or resurfacing.
The agency also will scrutinize actions taken by other countries that have more stringent follow-up recommendations. In the United Kingdom, for instance, the Medicines and Healthcare products and Regulatory Agency declared in February that patients with symptoms should have annual follow-up care for the rest of their lives rather than for five years. Also recommended were blood tests for metal levels and imaging tests of the joint and surrounding tissues. Acceptable levels of metals also are outlined with timetables for follow-up tests. The agency also advises when doctors should consider revision surgeries.
A problem with requiring more frequent follow-ups only for patients experiencing problems is that the symptoms are not always noticed until the damage is done, Wright says.