HelloThank you for the consultation. Migration of fillers over time after 5 years is unlikely to happen if you are using FDA approved dermal fillers there are nonapproved fillers out there and silicone that can potentially cause migration years later. It important also to get treatment from...
This shouldn't be an issue however, I recommend consulting with a board certified physician in order to determine your treatment options. Best, Dr. Emer.
You may want to consider Sculptra Butt Lift. This treatment will not be permanent and will take a few sessions to complete, but it will be non surgical. It is performed in the office with virtually no down time or restrictions. See an experienced injector near you to learn more.