Kemba Walker is set to miss the start of the NBA season after the Boston Celtics guard received a stem cell injection in his knee. 

The procedure was administered following consultation with specialists in October, the Celtics revealed in a statement on Tuesday.

He was subsequently put on a 12-week strengthening program to prepare for the 2020-21 campaign, which is tentatively scheduled to begin on December 22. 

Four-time NBA All-Star Walker is expected to return to on-court activities this month, though a further update on his status will not be provided until the first week of January. 

The Celtics acquired former Charlotte Hornets star Walker in a sign-and-trade deal last offseason, inking him to a six-year, $141million contract.

Walker averaged 20.4 points per game, his lowest average since he put up 20.9 in the 2015-16 season with the Hornets. His last season in Charlotte saw him manage 25.6 points per game. 

That dip is likely partially down to his drop in minutes. Walker played 31.1 minutes per game in 2019-20, his lowest average since his rookie season (27.2). 

Jayson Tatum, Jaylen Brown, Gordon Hayward and Marcus Smart all played more minutes than Walker, who scored 19.6 points per game in the playoffs as the Celtics reached the Eastern Conference Finals in the NBA bubble in Orlando, eventually losing to the Miami Heat in six games.

However, with Hayward signing a max contract with the Hornets, Walker's time on the court could increase when he recovers. 

The Celtics also announced that forward Tristan Thompson will have his availability for the first week of training camp limited because of a minor hamstring strain suffered in an offseason workout.