What are possible long term complications of butt implants if placed on fascia vs placed deep in muscle?

Firstly, buttock implants should never be put on top of the fascia or subfacial. They should only be placed intra- muscular within the gluteus maximus muscle. If they are placed in any other position (other than intramuscular) they will be very visible, palpable, and will drop down like a "dirty diaper" effect over time.  So please take note and do your research very carefully because very few surgeons place the implants correctly intramuscular. If performed by a buttock implant specialist, buttock implant are no more dangerous than fat transfer or breast implants:
Risks and potential complications of buttock implants are very similar to breast implants - ~1% risk of infection, ~2% risk of wound healing complications, ~2% risk of bleeding and/or fluid collections. One main difference is while breast implants have a nearly 20% risk of hardening from excessive scar tissue formation surrounding the implant (aka capsular contracture), in my experience buttock implants have ~2% risk of this.  Also, because buttock implants are made of soft semi-solid silicone rubber and do not have a silicone shell that contains a liquid on the inside, like breast implants do, they cannot rupture or leak. They therefore are considered a permanent implant that never has to be changed at a certain interval,  unlike breast implants are generally recommended to be changed every 10 years to replace them with a fresh durable pair  Glad to be of help.   

Dear fdbashar,   Any surgery carries with it the possibility of  complication that you have to be knowledgeable about. The goal, obviously, is to have a smooth recovery and preserving  the long term nice result. However, different factors like tissue elasticity, pregnancy, aging may have negative impact on the long term outcome. Also, quality of surgery is critical for the long term result.   The 2 most common technique for butt implants are sub fascia (on top of the muscle) and intra muscular (inside the muscle) . Sub cutaneous (on top of the fascia) and sub muscular (under the muscle) are not popular , because the skin and fat alone, without the fascia,  are not strong enough to stabilize the pocket with the implant and the sub muscular technique allows for a small implant, placed only up high on the butt to avoid damage to the Sciatic nerve.    My preferred technique is sub fascia, because it is a natural plane that is strong and allows for the placement of large implants in an  attractive and  natural looking way. It creates nice 'S' curve, nice projection, round hips and I use single incision between the cheeks. The intra muscular technique does not have these features and recovery is more painful and longer.    I have performed butt implants surgery on about 600 patients, and the overwhelming majority of them are happy with the outcome, even years after surgery. As long as the patients follow up my recommendation for post operative instruction and behavior, recovery is free of complication and the result is beautiful.   Always, consult with experienced board certified plastic surgeons who operate in accredited surgery center for your safety. Most importantly, check the before and after pictures in the photo gallery, to make sure that they are numerous, consistent and attractive with the above mentioned features.                         Best of luck,                                               Dr Widder   

The ideal is to put the retromuscular implant, that is, behind the muscle by the movement (when the person sits) to have a good coverage of the muscle, if it can be put behind the fascia, but the result is not the same when it is Behind the muscle, over time the fascia is atrophying and the implant can form folds.