I recall reading an article where it said there isnt really anything u can do about it just be happy u have abs. Not sure how scientic the article was bc it was a while back.
I've been in 2 major car accidents myself and I foam roll and stretch a lot but I have to do it everyday because my body always goes back to being jacked up very quickly.
Most people however do not have symmetry. You will find minor compensations even in a person that seems to have perfect posture. Most of the time we only notice our imperfections and they are far exaggerating. Often others will never see them. If your competing in a bodybuilding contest it may be noticable if it's extreme. If you don't plan to do a competition then I wouldn't worry about it.
“Lord, whom shall we go away to? You have sayings of everlasting life"- John 6:68
WHAT has science offered?
Most people don't have symmetrical abs. Go check out some pictures of professional bodybuilders. Most of them have asymmetrical abs. Pretty common. But visable abs are better looking than nonvisable ones, don't get caught up in worrying if they're symmetrical or not. Just concentrate on developing what you have. Cause that's about all you can do anyway.