What can I do to prevent lateral movement, and support my submuscular, 300cc smooth, round implants? I'm 3 weeks post op.

At this point there is not much you can do to change the position of the device itself, meaning it is where it is at this point.  As the tissues relax over time ( three months), that will be the real indicator of whether they want to go to he sides more or not.  This is often one of the consequences of the transaxillary approach - it limits your direct ability to control the pocket.  I would just follow your sugeon's post-op instructions and be patient.  I hope this helps.

Hello,Thank you for your question. When the implants are under pressure from tight, swollen tissue post op, they will sometimes be displaced a little up/outward as this is the path of least resistance until breast tissue relaxes and expands. Wearing a soft, wire-free support bra post operatively is great. I also advise my patients not to engage in upper body workouts or lifting over ten pounds for 6 weeks. Talk to your Plastic Surgeon as they know your situation the best.Take care

First step is to let your breast heal and recover for several weeks. Lateral displacement can be the result of pocket shape at the time of augmentation, though is more often seen as the result of poor tissue support over several years. Most will not have the issue. 

Thank you for your question.  The best thing to do would be to contact your doctor to discuss the issue.  They may want you to stop the massaging or place tape on the side of the breast if the implant actually is moving laterally.Best,Dr. Dan KrochmalMAE Plastic SurgeryNorthbrook, IL

The pocket may change to some extent in time. To minimize lateral movement I recommend massage , but not pushing laterally. It is also good for awhile to wear a sports bra to bed to hold them in place and not shift laterally if you lie on them.Just a suggestion.All the best,Talmage Raine MD