Why do permanent sutures keep coming out of my belly button 4 yrs after Tummy Tuck & 1 yr after a 2nd Removal surgery? (photos)

I had a tummy tuck 4 years ago. 3 years later I had an additional surgery by the same plastic surgeon to remove permanent sutures that were coming out of my belly button. The explanation being that I had lost so much weight after the tummy tuck, that the sutures were too close to the skin. Now, 1 year after the additional surgery, sutures are beginning to break through my belly button again. Can this be fixed? Why didn't the additional surgery take care of this?