Would a tummy tuck with muscle repair help improve posture and lumber lordosis?

In general abdominal muscle strength can help with spine issues. Therefore repairing the abdominal rectal diastasis can help abdominal strength and help with back support. I am not aware of any studies showing a specific effect on lordosis.

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  There are no large series studies looking into this.  In theory, muscle repair can help with lordosis, but it really depends on your individual anatomy.   Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most
important aspect is to find a surgeon you are comfortable with. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon

The origin of lumbar lordosis can be complex. The possibility that this condition could be improved with a tummy tuck should be discussed with your plastic surgeon.

Thank you for your question regarding possible
improvement in posture after a tummy tuck.  I advise my Melbourne,
Florida, tummy tuck patients that the abdominoplasty or tummy tuck can be
expected to improve the appearance of the abdomen.  Some people do note
that they have improvement in posture; however, this is not the distinct
purpose of the operation and therefore, cannot be promised or guaranteed. 
Definitely discuss with your board-certified plastic surgeon.  Hope this
information is helpful to you.  Best of luck!

Thank you for the question.
   As you know, part of the tummy tuck operation involves plication (re approximation) of the abdominal wall muscles that have spread with pregnancy. This reconstruction likely strengthens the core and MAY help with issues such as lower back discomfort (assuming there are no other  anatomic causes of the lower back pain).  I would caution you however NOT to assume that any lower back pain or postural concerns will be resolved after tummy tuck surgery.
Best wishes.

I wouldn't count on it, but a tummy tuck can improve the appearance of the abdomen by removing excuses skin and tightening the central abdomen to hopefully make it flatter.

The lordosis can be a great strain on the back muscles. Theoretically the diastasis repair could help but this would be on a case by case basis.All the best,Talmage Raine MD

There are many factors which can cause  lumbar lordosis. In my opinion obesity and lax abdominal muscles certainly contribute to lordosis.  I am unaware of any study has signed typically proves that abdominoplasty with muscle repair reduces lumbar lordosis.   However, anecdotally, if the abdominal wall is tightened  by a tummy tuck with muscle repair it is conceivable that it would help.