Previous umbilical hernia repair and muscle tightening, why are the muscles still separated? Could it happen after TT? (Photo)

You are an excellent candidate for
Abdominoplasty with Mesh Reinforcement.This technique will eliminate your umbilical hernia and provide the
benefits of the abdominoplasty.The mesh
increases the mechanical strength of the abdominal wall resulting in early
satiety, weight loss and maintains the reduced weight.The use of wide mesh has been shown to be
effective in decreasing the forces that cause the recurrence of hernias.Best Wishes,Gary Horndeski, M.D.

Thank you for the picture. Abdominoplasty does not repair a hernia. A hernia possibly can be repaired during an abdominoplasty. You need to seek general surgery consultation as to why your hernia continues to recur.

It is hard to say what is currently going on without an examination and not knowing exactly what procedure was performed initially.  In my experience, my patients do not have recurrence of the diastasis after a full abdominoplasty.  Good Luck, Gaurav Bharti

Yes to all your questions but over the internet with a poorly posted photo very hard to advise. Best to seek ONLY IN PERSON opinions.... 

It is very difficult to give you good advice based on the limited photograph and based on the limited information of what was previously done. Generally speaking, with tummy tuck surgery, the entire length of the abdominal wall musculature/fashion is exposed allowing for accurate plication of the abdominal wall fashion from the xiphoid down to the pubic bone; this complete plication was likely not performed during the limited exposure procedure you have  had done previously.  The risk of separation of abdominal wall fascia plication after tummy tuck surgery should be very small.You will do well achieving your long-term stable weight  (if you are not there already) prior to proceeding with tummy tuck surgery. You may find the attached link, dedicated to tummy tuck concerns, helpful to you as you learn more. Best wishes.

It is difficult to see anything in that photo. In your abdominoplasty, the muscles are probably much better exposed nad a good repair can be done. Also, sometimes a dermal matrix is placed to reinforce this repair.
Best Wishes,
Pablo Prichartd, MD