This Opinion Page Editorial in the New York Times reports the "substantial equivalent” standard of the 510(k) process doesn't work because some devices reach back 35 years and were never assessed for safety or efficacy.
The article, dated August 4, 2011 can be found here. (may require Log In and subscription)
"The committee found no reason to believe that any devices on the market are unsafe or ineffective, it said their use in clinical practice provides at least some level of confidence. But it threw up its hands and said it had no way to determine which, if any, devices might be risky because there is virtually no data to rely on."
*Editors Note* The Opinion piece makes one factual error when it says " only the highest-risk devices, such as implantable defibrillators and replacement heart valves, undergo clinical trials in patients to show that they are safe and effective. Devices deemed only a "moderate risk" are cleared if the manufacturer can show that they are "substantially equivalent" to devices previously cleared."
*There are a number of high-risk devices or Class III that do not undergo clinical trials and are grandfathered in under the 510(k) approval to market, claiming substantially similar. Many of these are implanted permanently in the body.