What happens to the muscle after subpectoral implant removal technique?

Muscles are released to create a space into which the implant is placed.  How and how much of the muscle is release is very variable.  However, regardless of the situation, once the implant is removed from submuscular space (if it was placed under the muscle), there is no change in the way the muscle functions and feels.  If you were able to function with implants in, you will be able to continue after the implants come out.  The muscle will simply heal in it's place.

In my experience patients never complained about any muscle related issue after the implants were removed.

The edge of the muscle that was cut to allow for sub muscular placement does not need to be repaired.  The functional origin of the pec major is still intact.

We routinely remove sub-pectoral implants and replace them over the muscle to fix the JUMPING BREAST DEFORMITY, or unsightly wide cleavage with or without armpit breasts.  The muscle is simply relocated and sutured down to the chest wall.  The same can be performed when simply removing implants. If the muscle is pulling and deforming the breast outward, it can be dissected  from its attachments to the breast tissue, stretched back to its normal anatomical position and sutured back to the chest wall.

Hi! There are 2 options for explantation, implant removal while leaving the capsule or capsulectomy. The former lets microscopic amounts of gel to remain in the capsule and the latter will enable the surgeon to remove as much silicone as reasonable without creating significant deformity. However, this operation may require a larger incision and both surgery and recovery time will be longer. Muscles can repair themselves but it is best to consult your surgeon regarding this concern. 
#RealSelf100

In experienced hands, it is entirely possible to do most cases of explantation with the en bloc procedure and muscle repair. Please see the video. Your skin could stretch back under several conditions: (1) if your breast tissue did not decrease over the period from your original breasts; (2) if your pectorals major muscle maintained its bulk; (3) if your pectorals major was not cut during insertion; (4) or if it was cut during insertion, it was repaired successfully after explantation; (5) if your rib contour was not altered by the implants. In other words, your skin has to be supported by adequate volume in the breast. In general, breasts with sub pectoral implants tend to do better than sub glandular implants after explantation, because the breast tissue is less stretched by the implants. Breasts that had no contracture tend to do better.

Once the breast implant is removed, the pectoralis muscle will simply heal back in place without any problems. Nothing else needs to be done. Most implants can be removed under local anesthesia.

                  The
vast majority of breast augmentations are performed with the implants placed
beneath the muscle.  Occasionally,
patients request removal of these implants for a variety of medical, surgical
and aesthetic issues.  The
technique utilized to remove subpectoral implants varies from patient to
patient and is dependent on a multitude of variables.

                  In
the majority of cases the procedure is a relatively simple operation.  A small incision is made and the
implant is removed.  In other cases
more aggressive procedures may be necessary.

                  When
the surgical procedure requires aggressive pocket dissection along the sternum
and infra-mammary fold to accommodate larger breast implants, more aggressive
procedures may be necessary at the time of explantation.  This may involve efforts to reconstruct
the chest wall by reattaching the pectoralis muscle.  In other cases where severe capsular contractures are
present removal of the capsule may be necessary as well. 

                  If
you’re considering removal of your sub-muscular breast implants it’s important
that you consult a board certified plastic surgeon.  This surgeon should be able to help determine the best
approach to this problem. 

If the implants were placed in the sub pectoral space, removal of the implants should not result in any significant problem.  This does depend to some degree on what work was done to the muscle at the time of the original surgery, such as extensive detachment of the muscle from the sternum.  However, for the most part the muscle will function normally with minimal if any distortion.

Once the implant is removed, the implant pocket collapses on itself.  Gradually scar tissue is formed within the pocket sticking the muscle back over the ribs.  You do not have to do anything with the released muscle.  It stays in place as it heals.

After sub-muscular breast augmentation the part of the muscle which is separated or cut in order to allow for placement of the implant heals above the scar capsule.  After removal of the implant the muscle continues to be in the tissue above the scar capsule and has already healed and therefore doesn't cause a problem.

You should be aware that in some cases removal of the implant may cause some drooping of the tissue.  There are some great Q&A on this forum about that very subject.