@pdemling Welcome to Mayo Connect. Kudos to you for helping your brother. I went through a similar issue a number of years ago.
You need to contact the original orthopedic surgeon (if still practicing) for records of his implant. He needs the specific model name and serial number for each implanted component. Yes, they exist, and the doctor, the hospital and Zimmer should have the records.
Next he needs to see an orthopedic surgeon skilled in doing revisions, particularly in cases of heavy metal poisoning. In addition to the cognitive issued he is suffering, there is often tissue deterioration where the metal ions are deposited, and a lot of cleaning out may be required.
He may also have elevated levels of chromium in his body. Do not let anyone convince him that he should have chelation therapy to remove the metal from his body - the only effective treatment is removal of the offending parts. Then the body will excrete the metal over a number of months. He should also have his heart and thyroid checked, as these may be affected by the buildup of cobalt, so a cardiologist and endocrinologist may need to be added to his "team." With cognitive issues, maybe a neurologist as well.
He may also want to consider contacting a lawyer, as Zimmer and the doctor should have notified him, and should cover all costs related to the revision.
Yikes! I have learned only recently that people are still living with these implants - mine were removed (both hips) nearly 12 years ago, only 5 years after implanting, and I was very ill by that time.
What steps has he (or you) taken so far? Who identified the problem?
Sue