Can my butt indentation be fixed?

Hello dear!!
Thanks for the question and provided information as well.
Unfortunately, without pictures, it is very difficult to give you a proper answer. l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

Indentations in fat can occur anywhere after trauma. The one on your buttock doesn't have any connection with the arm injury except that it happened at the same time. Fat injection is generally the most effective and permanent solution to restore contour.

Thanks for your question about Butt Augmentation.It is not uncommon for patients to have areas of small dents in their buttock.  This can at times result from prior injury.  Filling in the area to improve the look and smoothness of the buttock can be done quite nicely with fat grafting to the area.  Visit with a Board Certified Plastic Surgeon to receive an evaluation and treatment plan.Best Wishes