5'6, 118lbs - can muscle repair in a TT over-loosen over a period of time? (Photos)

Hi. It is certainly possible for a muscle repair to loosen or weaken over time, but it is something that I rarely see. Really hard to comment accurately in your case, though, not knowing the specific techniques that your surgeon used or what your physical exam is like. Sometimes the muscle repair is intact but the muscles just need to have dynamic strengthening with core exercises etc. I would recommend getting back in to see your surgeon for an examination and let your surgeon give you an assessment and options. Depending on how that goes you can always consider a second opinion if needed.
Good luck and take care, Dr. Howell

It is unusual for the diastasis repair to be altered like this without other influences such as weight gain or pregnancy. An examination is needed to determine if the nature of the contour that concerns you is from abdominal wall laxity or something else.