The 25-year-old was subjected to a horrendous challenge by Birmingham's Martin Taylor during a Premier League game last season, and then was stretched off with a severely-broken leg and a dislocated ankle.
"There is no reason why he can't be as good as before," Frenchman told Arsenal's official website ahead of Sunday's trip to West Ham.
The Naturalized Croatian's injury is perceived one of the most horrific injuries of all times, and Wenger believes it could've ended his career prematurely if he had been older than 25.
"He is a very young boy and when you have that kind of injury before the age of 25 you recover and progress normally. That is what the statistics say.
"[If you are older] when you have that kind of injury, it is bye bye to your career. The luck we have is that he's very young."
The Brazilian-born is well ahead of his rehabilitation schedule, and will most probably make his comeback before the Premiership reverse Fixtures.