but unlike the other countries, it never issued a warning about the specific biomet device.da, now is the director for health research. he is critical how many medical devices, including the biomet m2a, are cleared by the fda. >> a patient, if they think the fda puts the seal on the device, that it's safe under all circumstances. that's not true. >> reporter: nbc analysis found five devices where other countries issued safety warnings but the fda never did the same. including a knee implant and a pregnancy test that gives false results. a see difference, how countries monitor device safety. the fda has what is called an adverse event database, where many doctors and patients can report injuries. but critics say the system is too slow. >> it sometimes takes them months, if not years, to discern that there is a major problem that requires action. >> reporter: but other countries are more proactive, like australia, which keeps special registries to track the outcome of 100% of joint implants, including hips. experts say that kind of system allows regulators to spot problems mor