Celtics' Walker gets knee injection, out until early January

BOSTON (AP) -- Celtics point guard Kemba Walker will be sidelined until at least the first week of January after receiving a stem cell injection in his left knee.

Boston president of basketball operations Danny Ainge said Tuesday the decision was made after Walker consulted with multiple specialists in early October. Walker was then put on a 12-week strengthening program for the upcoming season. He is expected to resume on-court activities in early December.

Walker nearly had his first playoff run with Boston derailed in July when he tweaked the knee during workouts leading up to the resumption of the season in the Florida bubble. It left him limited during the seeding games portion of the…