Tierney missed Saturday’s 2-0 win over Leicester and has not played for the Gunners since their 2-2 draw with Crystal Palace on October 18.
In his absence, Nuno Tavares has been filling in and the youngster has excelled for Arsenal after being given a chance to impress.
Arsenal are next in action against Watford on November 7, with the international break to follow after, and Arteta has revealed he is unsure when Tierney will be back.
“Well he didn’t train with the team yesterday. He still wasn’t feeling good,” said Arteta.
“He is still in pain. He is not comfortable when he is running, so he was struggling.
“We are trying to help him as much as possible. We need him back and I don’t know when that will be.”