Sagging After Breast Implants - Normal?

Over
time, gravity will continue to have an effect and the breast skin will tend to
stretch. The degree of stretching and #sagging varies between women: generally,
women with smaller breasts experience less recurring sagging. If sagging does
occur, further excision of the skin on an outpatient basis can be used to
correct the problem. Heavy and large breasts, with or without implants, may lead to recurrent sagging and
may require the removal of a small amount of breast tissue to achieve an
optimal shape and size. An implant #revision or exchange intends to replace the damaged implants with new silicone or saline filled implants with newer technology. For example, silicone gel implants are more “cohesive” meaning “gummy bear like” which prevents migration of the gel if there is a break in the outer shell. This will reduce future risk of complications.Secondary breast surgery can be complex and needs to be done by an experienced plastic surgeon.

As you age it is natural for your breasts to start to sag. This is because of the pull of gravity and weakening of tissues that provide support. However with the added weight of implants the rate of sagging can be faster. That's why it's important to wear a good support bra. Sagging is inevitable for every woman and is not unique for women with implants. Unfortunately it is difficult to say when a woman's breasts will actually start to sag, with implants or not. 

Every patient is unique and the quality of their tissues are unique. There is no set amount of time that a woman will develop sagging breasts (ptosis) with implants or that she ever will. If you are concerned about your breasts visit the surgeon that placed your implants or other board certified plastic surgeons to develop a plan to improve the shape of your breasts with or without your implants.
Good Luck.

This tends to depend on whether the implants are placed under or over the muscle. When placed under and the breast tissue ages or sags over the implant, patients may develop the so called "Snoopy deformity". However, implants placed over the muscle tend to sag with the breast tissue and may form the so called"Rock in the Sock" deformity.

Yes, it is normal for breasts to sag over time.  Eleven years sounds like a good run, but maybe you need a lift or revision?

Sagging of breast tissue, 11 years after augmentation can be due to two factors.
First, your skin may have stretched or lost its elasticity due to age, pregnancy, weight gain or loss.
Secondly, the capsule formed naturally around your implants (your body will always form a capsule around the implant) may have become tight, thus displacing the implant upward. This is called capsular contracture.
I recommend you see your original surgeon (if he/she is still practicing) for an evaluation.

Without a photograph it is impossible to relate to what you refer to as "sagging" since the term may mean different things to different people.. As such, my comments can only be viewed in general in nature.
Philosophically speaking leaving political correctness and social platitudes aside, we are all but partially renewable protein and water based structures which begin to age, deteriorate and die shortly after we are born. Unlike some good red wines, we do NOT get better with age. Convince yourself by looking at photographs some "Where are they now?" features of athletes and movie stars of the 70's and 80's. For an added dose of reality, look at pictures of yourself 10 years ago. VERY depressing.
The breast, like all tissues in our bodies, looks better in a 22 year old than in a 42, 62 or 82 year old. Placing an added weight (IE Breast implant) into an unstable stretchable, poorly suspended and variable supported structure (IE the female breast) and in the process further weakening the breasts' natural suspension by dividing some of cooper's ligaments FURTHER hastens the inevitable future sagging of the breasts. (One of the reasons why BIGGER is definitely not always better when it comes to augmentation...)
As to "HOW LONG" before breasts sag, that would depend on you, your age, the size/ weight of the implants and how much support (time wearing bra) you are willing to put up with. The answer is not uniform and would depend on you. The only real answer is - it WILL happen and happen quicker with larger implants and failure to wear a bra.
To read much more about BREAST AUGMENTATION, inclusive breast sagging, follow the informative link below -
Dr. P. Aldea

A photo would be worth a thousand of our words. My guess the sagging could be due to weight changes, aging, poor result etc. Please post photos.
From MIAMI

It would not be unusual to have some degree of sagging 11 years following your augmentation.  There are several factors which contribute including size of implants, placement of implants, support, and weight gain/loss.  Remember that gravity is a constant and a larger, augmented breast needs some degree of support.

After 11 years, what you are most likely seeing is the aging of your own tissues rather than any "sagging" of the implants.  If the implants are soft and in good position, you could have a lift done to elevate the tissue, re-shape it and tighten up the laxity.