How can you correct an "animation deformity" after breast reconstruction?

The implant pocket can be changes to above the muscle.  This is called a prefectoral technique.  This requires a material be wrapped around the implant.

If the animation deformity is causing more of a cosmetic than a functional issue (ie the pain is not your main complaint), then some fat grafting can be used to help add a layer between the muscle and skin to lessen the appearance of the wrinkling with flexion of your chest muscles. This will never completely eliminate the movement. The only way to do that is convert your implants from under the muscle to over the muscle, which can be done at the time you switch out your expanders to implants. Depending on how thick your mastectomy flaps are, you may have some visible rippling of your implant. This can be made better by using a more overfilled implant or an anatomic implant, as well as some fat grafting to thicken the upper breast tissue and hide the implant better. Some patients have such severe pain and muscle spasms with subpectoral implants/expanders and feel great relief after conversion to above the muscle implants, so if this is your main issue, then I would advise discussing this with your surgeon. 

You can certainly improve and sometimes eliminate the animation deformity following reconstruction.  You will always have a bit of muscle movement when placing implants under the pectoralis major muscle. This is true with augmentation patients as well.  If you have developed a deformity that is severe, I would recommend tethering the muscle with dermal matrix as a first step.  In my experience, this almost always solves the problem when done properly.  If this does not work, you can transition the implant over the muscle after repairing the muscle to the chest wall.  This will certainly improve/eliminate the problem, but usually leads to a less natural looking reconstruction and will require more additional surgeries to fat graft and give you the result you deserve.  Good luck!