Risk of High-profile Saline Breast Implants Pushing out over Time?

It is very important to decide on the look you are going for. In my opinion, high profile implants do not look very natural. They are very projecting and in my opinion are a bit "torpedo-ish".
So, think if you are looking for a very natural look or a more implanted look. Once you have decided on this then you can decide on the volume and profile. I would not go the opposite route of trying to get the volume into you so that you have to do high profile. Any implant in the body will take its toll over time. Obviously the larger the implant, the more stretching it will do over time. You just have to be aware of that. Good luck. Hope that helps.

If you use an implant that is wider than you breast base diameter then there is definitely a higher risk of lateral displacement and malposition.  You should be very careful when selecting an implant that is too large for your frame.  Vectra 3D imaging is a great system to help determine the right implant size for your body and anatomic features.  

High profile implants have more projection than the other shaped implants of the same volume. I am not a big fan of tear drop shaped implants, because they can shift in position and look like footballs.

Hi Jenna. A high profile saline implant on your frame would certainly give you a more rounded appearance and more filling in the upper portion of the breast. In my experience, a round, smooth, saline implant is preferable to tear-drop shaped implants. All implants (saline or silicone) are affected by gravity and will descend with time. Many patients who have implants come back for a breast lift at a later time. If at the time of surgery the "pocket" (the place where the implant is placed) is created correctly, then it is unlikely to move out to the side. Hope this helps you make your decision.

It sounds as if you would like a big size implant for your frame. With your narrow chest, a high profile implant may be your best choice. I have become less enthusiastic about the tear drop implants. I used them for many years and have seen rippling and deflations at a much higher rate than the smooth wall saline implants.
The only way an implant can migrate laterally, or to the outside part of your chest, is if your surgeon over dissects the pocket. The implants do have a tendency to drop or droop over time, but this is normal. I would discuss your final size wishes with your doctor, not just the size of the implant. When done properly, high profile implants have a very natural look.

Gravity affects objects of equal mass equally. This is a law of physics. So, it's not really the shape of the implant - high profile saline vs. anatomic implant - that leads to the implant moving lower. It's just gravity.
Over time, any and all breast implants will descend on the chest wall. This is true of natural breast tissue as well. Over time, natural breast tissue and breast skin will stretch, settle, and become ptotic. Gravity sucks.
An anatomic implant may move less in that these are often textured. The textured implants tend to "stick" in the position where they are placed. The textured surface that helps keep the anatomic implant from turning sideways - (just picture that teardrop shape sideways on your chest) - may help to keep it stuck to the chest wall so that it doesn't descend as much. This is just a theory though and I don't think there is any scientific evidence to support it.
So, what I'm trying to say is that either implant will provide you with a good result provided that you have a good surgeon. I prefer the round implants over the "shaped implants" except in select situations because of the fact that they can move and rotate.

Of course, i haven't examined you. But it sounds from your description of your chest, that you would be overstuffing your breasts with 425cc implants. The problem is not that they will be pushed out to the side. It's that so much tension and weight in your tissues over time causes atrophy and deformities.
You want your breasts to look good for a long time. So consider a somewhat smaller size.
But there is nothing wrong with high profile implants. You actually see less rippling with them. And avoid tear drop shaped implants. They have a higher incidence of problems.

It is more important to discuss the "look" you want with your plastic surgeon rather than to get fixated on a volume amount. If you want significant upper pole fullness far beyond what is "natural," then go with the high profile implant. Based on your width, the moderate profile implant would be in the 275-300 range and wouldn't create upper pole buldging at all. This is what "natural" would look like. The moderate plus profile would create some excess fullness but not excessively. So decide on the implant based on the "look" you desire and using the right base width, the volume just follows. Don't lock in on a volume number.
The implant shouldn't move laterally if the submuscular pocket is created properly and if you don't do excessive pectoralis muscle exercises for 8-12 weeks after surgery which could cause the muscle to pull the implant laterally and superiorly before the pocket is fully lined with a capsule.