If buttock is injected with moderate amount of fat graft in subcutaneous pocket, one would expect that firmness and structure would remain the same. If significant overgrafting is performed, it is possible that buttock firmness may decrease. There are many individual variations in this regard and because of that it is very difficult to answer this question with certainty. I hope this much helps.
Dear jxdddy,generally speaking, transferred fat should be the same as other fat in your buttocks, and it should not be hard. If you are considering a surgery, I would suggest you to consult a board-certified plastic surgeon. Only after a thorough examination you will get more information and recommendations.Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery