Williams dislocated his shoulder during practice March 8. The Blazers say he will have surgery March 30 in Los Angeles.
Averaging 3.7 points in his 24 appearances, the 6-foot-5 Williams had shown promise this season. He's scored 88 points in just 149 total minutes.
Williams' career got off to a rocky start, when his rookie season last year was postponed by surgery on both knees.
Acquired by Portland with the 22nd overall pick in the 2010 draft, Williams played at Memphis after transferring from Duke for personal reasons.