This is a fairly common concern; I get asked this question almost weekly, but my partner and I do lots of breast surgery.Dr. Schlesinger has given a nice discussion of the muscular components of back pain after augmentation. But there is one other cause that helps to explain both upper and lower back pain after breast augmentation.Swelling occurs after surgery of the breasts, and chest and ribcage swelling is always evident after this surgery, to one degree or another, in every patient. Swelling is both due to (hopefully minor) surgical trauma, and also to "third-spacing," which is generalized tissue swelling secondary to adrenocortical hormone ("stress hormones") release with surgery and anesthetic medications. This third-spacing causes ALL of your tissues to swell a bit, reaching its peak 3-4 days after surgery. Add this to the actual surgical site swelling, and you have a few pounds of "extra" fluid in your tissues. (This is confirmed by standing on a scale right before surgery and again a day or two after surgery when the weight goes up by 4-8 pounds, and only 1 pound per implant (454g or cc) accounts for that increase of weight.)In the days that follow surgery, when you are standing the fluid gradually is pulled by gravity to your ribcage, abdomen, and eventually hips. You may already notice this in your pants fit. When you are sleeping, the swelling is pulled by gravity towards your back, and this is another cause of your back discomfort.Heating pads are NOT a good idea, since I have seen blisters and open wounds from falling asleep (and not moving because of pain medication blunting your normal roll and adjust responses). Same thing goes for ice--I have seen blistered frostbite from ice bags directly on skin.Take your muscle relaxants. If this does not settle fairly promptly over the next few days, you may wish to consider purchase of a TENS unit (Transcutaneous Electrical Nerve Stimulator) unit that can help diminish painful nerve impulses. But I doubt this will be necessary in a few more days. Your body will clear the excess fluid via your kidneys. Best wishes! Dr. Tholen