Can paraplegics have a tummy tuck (abdominoplasty surgery) to improve the atrophy of stomach muscles?

You raise two important issues here. 
Being paraplegic is not a contraindication to an abdominoplasty. However, the risks versus benefits needs to be considered and you would need a full medical work-up for this. 
Regarding the muscle atrophy, surgery will not improve the 'atrophy' but may tighted the gapping between the rectus muscles. The atrophy would need assessment to see there is any other pathology and whether this requires repair with a sutures only, mesh or another technique. 
I hope this has been helpful. Good luck. Nakul Patel

A tummy tuck can help tighten the muscles which may have become weak or thin over time, however it does not reverse the atrophy of the muscle itself. For patients with a bulge due to severe thinning of the abdominal wall and muscles, they may be better served with mesh reinforcement if the bulge is becoming uncomfortable or a medical problem. Hope this helps!Johnson C. Lee, MD
Board-Certified Plastic Surgeon