Can you also use scupltra if you already have butt implants (under the muscle)?

Sculptra is a
dermal filler composed of poly-l-lactic acid microspheres. It is
injected deeply into the dermis, but would not reach or affect your
butt implants. The PLLA microspheres stimulate the skin to produce
new collagen, which gradually replaces the microspheres as they are
absorbed by the body. The new strands of collagen create a stronger
support for the skin, leading to increased volume, strength and
resilience. I have used Sculptra to add volume and lift to the
buttocks with very nice effects. Please find a board-certified
dermatologist who is an expert with Sculptra to help you achieve the
shape you want on your buttocks.

Thank you for sharing your question.  As most butt implants are placed beneath your gluteal muscles you can use Sculptra closer to the skin surface to increase size.  Hope this helps.

Certainly Sculptra can be used in patients who have implants. It needs to be done superficial to the implants or in an area free of implants. I think what you describe is suitable for the Sculptra.