The reason you can’t spot reduce fat is that the process that mobilizes fat from fat cells to the blood to be carried to the working muscles is hormonally controlled. Therefore when you are running and your legs need more fuel your body will release a hormone into the bloodstream which allows fat to be transported from fat cells all over your body to the working muslces.
which doesn´t change anything about my statement. I totally agree with you with regard to exercise and fatmetabolism, but there is enough evidence to proof that at least alcohol and stress triggers abdomimal fat accumulation through increased cortisoleproduction. Some studies at the John Hopkins University even suggest saturated fat to increase abdominal fat.
Regards
Martin
What if you use alcohol to avoid stress 
.
good question 
.
An earlier suggestion to work on the underlying muscles may be a good direction to go. Unfortunately, when a muscle or joint has been injured or impacted by surgical intervention a component of the nervous system is impacted called proprioception. It’s almost like the dimmer switch has been turned down to that area and the brain can’t find the pathway to get to that muscle to turn it on efficiently. The problem is you can’t just do more abdominal work, first you have to reestablish the “connection” of the brain to the muscles - kinesthetic awareness - awareness of the muscles movement. You’ll need to first learn how to find and use the transverse abdominal muscle (the often forgotten one) to establish functional core stability then reintroduce appropriate abdominal exercises. If you want more info I can get you a reference for a good book to guide you through this.