Hackworth, a £150,000 signing from Leeds last summer, picked up the injury 30 minutes into the 4-0 reserve win over Lincoln City last week.
The former Leeds man will see a specialist today, and will find out if he needs an operation to cure the problem.
Billy Dearden told the clubs website;"Tony's seeing a specialist today, and then we'll decide whether it's best to just rest it or for Tony to have an operation"
Hackworth signed a 4 year deal with Notts last summer, but failed to make a real impact as he struggled to stay injury free as he kept picking up niggling injuries. He made 14 starts and 27 sub appearances for Notts last season, hitting just 3 goals. He however did hit 6 goals for the reserve team last season, but when he was fit to play the late season form of Danny Allsopp and Paul Heffernan was so good he did not get a look in.
This season he has made 2 brief sub appearances for Notts, coming on against Cardiff in the League and against Oldham in the Worthington Cup.