Hassan had picked up the injury while playing for the ICC Combined Associate and Affiliate XI in Dubai against England, in January. He had opened the bowling in the first innings of that game, claiming the wickets Andrew Strauss and Jonahtan Trott, before having to withdraw from the match.
He has since undergone surgery on his knee, and while not fully recovered yet, should be fit in time for the World T20 - the tournament starts on September 18 - according to Afghanistan Cricket Board chief Hamid Shinwari. "We have selected Hasan with confidence, [believing] that he will attain full fitness before the tournament starts and can get match fitness on our tour to the West Indies early next month," Shinwari told AFP.
Left-arm spinner Mohammad Nasim Baras, and batsmen Najibullah Zadran and Shafiqullah, who were not part of Afghanistan's squad for the World T20 qualifiers, have also been brought in.
The qualifiers were Afghanistan's last international T20 assignment. Four players miss out from the squad that played that tournament: fast bowler Aftab Alam, batsman Shabir Noori (both of whom played in the ongoing Under-19 World Cup for Afghanistan), allrounder Mirwais Ashraf and left-arm spinner Zamir Khan.
This will be the second consecutive World T20 that Afghanistan play in, having made it to the tournament in the Caribbean in 2010. They are one of the two non-Test playing nations in this edition, after having finished second at the qualifiers. They finished only behind Ireland, losing the final of the qualifying tournament to them in Dubai, in March.
Afghanistan are placed in Group A, with India and England.