Breast Reconstruction: Implants - Under vs. Over the Muscle

Laura Frese PA-C: Laura Frese PA-C is a Physician Assistant at Cedars-Sinai Medical Center in the department of Plastic and Reconstructive Surgery. She received her Masters in the Physician Assistant program at St. Louis University followed by a surgical residency at Johns Hopkins. For the past 15 years, her practice as a PA has had a strong focus in breast reconstruction.

Holly is a writer, performer, and health advocate, sharing her personal experience as a breast cancer survivor and carrier of the BRCA1 gene mutation to raise awareness, and support women as they navigate their own cancer journey - practically, spiritually, and emotionally. With training and background in Reiki, spirituality, and holistic health/wellness, her writing runs the gamut from being a regular contributor at The Huffington Post, to produced playwright, to Senior Writer for a global non-profit.

As I mentioned in the first article in this series, I had no idea what I was in for when I opted for breast reconstruction with implants. I basically thought I was going to get a boob job. Simple, right? If only.  I didn’t know about the many steps, considerations or decisions to be made. 

One such decision is where the implant will be placed. In a mastectomy, since all the breast tissue is removed, the implant is placed directly under the skin and above the pec muscle (prepectoral) or under the pec muscle (submuscular). Each offers its own set of pros and cons. 

In order to make the best decision for yourself, and to better understand what to bring up when talking with your cosmetic surgeon, it’s always good to be armed with info. So, here you go!

Under the muscle

With this option, the cosmetic surgeon places the implant directly below the chest muscle.


  • Looks and feels more natural- An under-the-muscle implant yields results that tend to look and feel natural because they have both the skin and muscle to cover it; it is less obvious that there is an implant there.
  • Less likely to sag over time- As a result of the support provided by the pectoralis muscle, there is less likelihood for the implant to sag over time. Breasts with over-the-muscle implants, by contrast, are more often victims of gravity.
  • Lower rates of infection and capsular contracture- Generally, not only do under-the-muscle implants tend to have lower rates of infections than over-the-muscle implants, but there is also a reduced rate of the buildup of scar tissue around the implants (called capsular contracture), which can cause the breast to become hard or misshaped.


  • Longer recovery time and more long-term pain/weakness- Because muscle is cut into during this surgery, recovery time is longer and can be more painful than with over muscle implants. There is also the small risk that cutting into the muscle will cause muscle function loss or weakness in the chest and arms. Additionally, since the pectoralis muscle ordinarily lays flat against the chest wall, placing the breast implant under it may cause a constant feeling of chest tightness.
  • Animation Deformity or Dynamic Distortion (Translation: Looks weird when flexed or used)- Since breast tissue was removed during the mastectomy, the skin is now directly in contact with the underlying muscle, which means that with any movement of the pectoralis major muscle, there is a visible contraction and displacement of the breast, wrinkling the skin and pushing the implant up, down, and/or out. This problem is called “dynamic distortion” or “animation deformity.” 
  • Will shift over time- The pec muscles push the implants towards the armpits when used; as such, under the muscle implants are much more likely to shift and move wider apart over time (True story: Mine already have.)

Above the muscle

Over the last 20 years or so, with the introduction of acellular dermal matrix (ADM), over-the-muscle implant placement has become more popular, because ADM provides an additional barrier between the implant and skin. Harvested from the dermal layer of human skin, but stripped of all reactive cell components, ADM is essentially a biological mesh that is made of a thin layer of collagen and has the strength and flexibility of the skin. The prepectoral implant is held in place by and wrapped in, ADM, which eventually integrates into the surrounding tissues. 


  • Less pain and recovery time, and more mobility- In essence, putting in over-the-muscle implants allows for a totally muscle-sparing and muscle-preserving reconstruction, so there is improved longer-term comfort and muscle strength than with under-the-muscle. Also, because the muscle is not cut, it is a less invasive surgery, which results in a quicker recovery time and comparatively less pain; there is a noted decreased need for post-op opioid painkillers with this type of surgery.
  • They stay put, with no movement deformity- Chest muscle use doesn’t affect the implant that is over the muscle, decreasing the likelihood of animation deformity or of its shifting over time. In other words, it looks way less weird when you flex it or contract it, and you can rest assured that as long as you don’t do too much too soon, they won’t travel.


  • Rippling- Because there is no muscle to cover it, the rippling and wrinkling of the implant are likely to be visible through the skin. This is hard to camouflage, especially since it tends to be more prevalent in the cleavage area and upper part of the breasts and chest. Fat grafting is a way many cosmetic surgeons address this. It is a process through which fat tissue is harvested from one area of the body, liquified, and then injected into the breast area. This requires liposuction from a donor site such as the thighs or belly, is usually performed during the implant placement surgery, and may then need to be done up to four times for the best effect.
  • Looks less natural- With just the skin covering the implant, less coverage can make the outlines of the implant noticeable through the skin, especially in thinner women. There may be a very clear “step-off” between implant and the chest wall. Like with rippling, fat-grafting may be able to address this issue.

A quick word about fat-grafting

Fat-grafting has its own recovery protocol and period that may extend longer than implant recovery, including wearing compression garments for six weeks. Many women have said this recovery was more painful than recovery from the implant placement, and that they continue to experience pain and intermittent swelling in the fat donation site for a year or more. Also, the results may not stick: Sources I found had wildly different statistics, like anywhere between a 20%-75% chance the fat will be reabsorbed in the body, and additional fat-grafting procedures may be needed. 

This is definitely something to discuss with your surgeon because that is a huge range. I was told there was a 40-60% chance the fat would be reabsorbed by my body, and to me, that wasn’t a good enough odds to go through extra surgery and recovery time.  But when it does work, it is incredibly successful. 

The decision

I felt rather tormented over the “under vs over” decision and wasn’t sure which way to go, but after talking with my surgeon about my priorities, I ended up going with under the muscle. First and foremost, I wanted my breasts to look as natural as possible, and I was also told that because I’m thin, the rippling caused by over-the-muscle implants would be prominent and noticeable, especially in the cleavage area, and that the likelihood of fat-grafting fixing it was slim. 

I had to understand, however, that choosing under the muscle also meant the possibility of the implants shifting over time – which they have. Wearing a supportive bra that pushes them together helps mitigate this, so in clothes, you’d have no idea. 

There are some cosmetic surgeons who now exclusively do over-the-muscle surgery because of the reduction in healing time and the results they are able to achieve. If you are not sure that is right for you, seek out a second opinion from a surgeon who does both so you can be confident in your decision based on your specific anatomy. Cosmetic surgeons should describe your options and discuss the advantages and disadvantages of both, and show you photos of women who have had different types of breast reconstruction. 

Speaking to your surgeon about what your priorities are and understanding the pros and cons of each type of implant will help you come to the best decision for you. Also, ask to see recent photos of that surgeon’s results and ask for a patient reference. Seeing photos of their work, and speaking to a patient who is happy with the outcome, can give you more confidence when making such a major decision. 

For more information on breast reconstruction, visit the other articles in this series:

Breast Reconstruction After Mastectomy: Implants and Tissue Expanders

Keeping Your Nipples with a Mastectomy

Nipple Reconstruction After Mastectomy Yes, it’s a thing!

“I had no idea what I was in for when I opted for reconstruction with implants after my mastectomy; I basically thought I was going to get a boob job – simple! (if only, right!?) I didn’t know about the many steps, different considerations to be taken into account, or decisions to be made; one such decision is where the implant will be placed - under or over the muscle. Each has its own set of pros and cons.”

- Holly Sidell

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