Celtics guard Kemba Walker will miss start of season after knee injection

Celtics guard Kemba Walker won’t be ready for the start of next season in early December after receiving a stem cell injection in his knee and being placed on a 12-week strengthening program, the team said.

Walker met with numerous specialists in early October before getting the injection in his left knee. He is expected to return to on-court activities in early December and see how he’s progressing with an update in early January.

Celtics guard Romeo Langford had successful surgery in late September to repair a torn scapholunate ligament in his right wrist. Forward Tristan Thompson -- who just arrived to Boston from the Cleveland Cavaliers -- suffered a minor hamstring strain in the offseason prior to arriving to Boston.

The Celtics open their 2020-21 preseason schedule on Dec. 15 against the Philadelphia 76ers. The season will begin on Dec. 22.