Are Breast Implants Better Over or Under the Muscle for Breast Reconstruction?

The Smart Patient Questions

OK, I admit it. I’m a convert. A convert to over the muscle. After years and years of doing breast reconstruction under the muscle… hell, I invented under the muscle One Stage Breast Reconstruction… I now do almost every case over the muscle. Why is it so much better? Mostly, the recovery. And the muscle motion. People say it doesn’t look as natural, but I even have some tips and tricks to make over just as aesthetically great as under the muscle.

The recovery of regular breast reconstruction under the muscle can hurt. The pectoral muscle is actually detached from the fifth and sixth ribs, but left attached to the sternum. This allows the pectoral muscle to cover the top of the implant. In the old direct-to implant submuscular reconstruction, acellular dermal matrix (ADM) covers the bottom of the implant, and holds it in place. Looks great, but the muscle surgery, in addition to the mastectomy, hurts more. The muscle also moves when you move your arms, especially lifting something heavy or doing a push-up. This actually happens in regular breast augmentation too, but in breast augmentation, there is a breast in front of the pectoral muscle. In reconstruction, it’s right up front, under the skin, and people can sometimes see it. This is called pec flex deformity. 

Despite these negatives, under the muscle remained the standard for years. The muscle made the implant look more real, as it covered the top edge. Implants under the muscle also had a lower rate of capsular contracture, especially when we use ADM too. Some patients hated the flex deformity though, and some patients had chronic pain. In these patients we fixed the pec muscle, and used ADM for the entire internal bra. And you know what? They looked and felt great.

As the over the muscle movement started to sweep the plastic surgery field, most surgeons realized that you can actually wrap the implant in ADM while the mastectomy is happening. Then, when it is the plastic surgeon’s turn to do the reconstruction, just throw the whole thing in there. Tack it in place. That, unfortunately, looks bad. It pulls the ADM around the implant, creating even more of a fake, implanted look. Can’t we do better?

So, what’s the right way to use the ADM? First, let’s look back at why the submuscular reconstruction looked better. The pectoral muscle bridged the implant to the chest wall and softened it. The ADM can be used in the same way, bridging the gap between the implant and the ADM. The ADM can also be used as a full implant support, letting the loose skin lift up and the implant sit in a high yet natural position. The implant should never get its support from the skin, it should get the support from the ADM sutured correctly in position. This also makes the reconstruction safer, as it takes any tension or implant weight off the skin.

A final issue to consider is radiation. Well, it turns out that over the muscle ADM reconstruction is LESS likely to contract that under the muscle. Why? Because muscle contracts with radiation. Acellular matrix does not. If you know you need radiation, then place the implant over the muscle. And use direct to implant, so the final implant will be in place and you won’t need the expander swapped to an implant after radiation. Why use an expander at all? But that’s a whole new blog!

Lisa Cassileth MD, FACS