It's obvious why:
Sept. 14, 2007: Undergoes microfracture surgery on his right knee, forcing him to miss the entirety of what was to be his rookie season.
Oct. 28, 2008: Sprains his right foot in NBA debut versus Lakers in Los Angeles, going scoreless on 0-for-4 shooting with five rebounds. Blazers lose 96-76 and Oden misses two weeks as a result of the injury.
Feb. 12, 2009: Chips his left patella after bumping knees with Warriors' Corey Maggette during game against Golden State. Finishes with eight points and 11 rebounds after spending much of the night in foul trouble. Blazers lose 105-98.
Dec. 5, 2009: Fractures his left patella against Houston, crumpling to the Rose Garden floor in pain in the first quarter. The Blazers win 90-89, but lose their center for a season for a second time.
Nov. 3, 2010: Oden has an examination with team doctor Donald Roberts. Although things seem normal, Oden reports discomfort in his left knee.
Nov. 7, 2010: Oden works out in Los Angeles before the Blazers play the Lakers. Head trainer Jay Jensen says Oden looked "strong" and the workout was "strenuous."
Nov. 8, 2010: Oden tells Jensen at the memorial service for Maurice Lucas that he has swelling in the knee.
Nov. 9, 2010: Oden sees Roberts and has a "moderate amount of fluid" drained from the knee.
Nov. 10, 2010: Oden flies to Los Angeles and sees noted orthopedic surgeon Neal ElAttrache, who sees little swelling in the knee, possibly because it was drained the previous day.
Nov. 11, 2010: In the lobby of their Los Angeles hotel, Oden shows Jensen his knee, which had swollen significantly from the day before.
Nov. 13, 2010: Oden gets an MRI back in Portland that shows a hole in his articular cartilage. As Jensen, Oden and Roberts study the results, "It was like we got kicked the stomach," Jensen says.
Nov. 17, 2010: Team announces Oden will have a second microfracture surgery, this time on his right knee, ending a season prematurely -- or before he played a game -- for the third time in four seasons.