Harrington is expected to be back on the court in time for summer workouts.
A key reserve, Harrington hurt his knee in a win over the Orlando Magic on April 1, but played through the persistent pain down the stretch. He averaged 14 points and six rebounds during the regular season.
He averaged nearly 10 points during a first-round playoff series against the Los Angeles Lakers, scoring 24 points in a Game 7 loss that ended Denver's season.
Harrington also broke his nose in the series after catching an inadvertent elbow from Andrew Bynum as they battled for a rebound.