Coach Dave Rose made the announcement on the school's website.
Collinsworth started the first four games of the season for the Cougars. He was averaging 5.9 points and 5.6 rebounds a game.
The procedure Friday revealed cartilage damage that required additional microfracture surgery. Rehabilitation will take four to five months but Collinsworth is expected back for the 2011-12 season.
Collinsworth's younger brother, freshman Kyle Collinsworth, has started 14 of 18 games at small forward for the ninth-ranked Cougars and is averaging 6.7 points and 3.6 rebounds a game.