The arthroscopic surgery was performed Monday in Southern California, and the team said he is expected to miss 8-to-10 weeks. The Trail Blazers open their season Oct. 28.
The 6-foot-11 Frye averaged 6.8 points in 78 games last season. He's expected to again be a key reserve, backing up power forward LaMarcus Aldridge.
The Knicks selected Frye with the eighth pick of the 2005 draft. He was sent to the Trail Blazers two years later as part of the Zach Randolph deal.
Forward Ike Diogu, the ninth pick of the 2005 draft, was acquired by the Trail Blazers this summer, and could see additional time in Frye's absence.