Oden was hurt in a collision during a game at Golden State last Thursday. He was unable to play in the All-Star Weekend's rookie challenge.
The 7-foot center is listed as day-to-day. Team doctors are expected to evaluate his knee later Wednesday.
Oden, the top pick in the 2007 draft, sat out all of last season after microfracture surgery on his right knee. He missed six games at the start of this season with a foot injury.
Oden has averaged nine points and just over seven rebounds in 39 games this season. Joel Przybilla will start in Oden's place against the Grizzlies.
Blazers starting point guard Steve Blake was described as probable against Memphis, after missing 13 of the last 14 games because of a separated right shoulder.
Blake was averaging 11.3 points a game before he was injured.