BOSTON — Boston Celtics center Kendrick Perkins underwent surgery on his left shoulder today to repair an injury that nagged him during the NBA finals and forced him to miss Game 5.

The Celtics said Perkins, 23, had arthroscopic surgery at New England Baptist Hospital, as did rookie Bill Walker, who had damage to his right knee repaired today.

The NBA champions said both procedures, led by team physician Dr. Brian McKeon, were successful. No timetable has been set for Perkins' and Walker's off-season returns to the Celtics.

In 2006, Perkins dislocated his left shoulder, missed three games and needed surgery after the season to repair it.

The shoulder nagged him again late last season, and he aggravated the injury in the finals against the Lakers, causing him to miss Game 5. Asked before that game whether he was always in pain or just when he moved it, Perkins replied, "Any moment, it's painful."

In Game 4, the 6-foot-10-inch, 264-pound center left the game clutching the shoulder after slamming into Lakers forward Lamar Odom. When the Celtics returned to practice two days later, Perkins seemed unable to move his left arm, dribbling and shooting with his right hand only.

The Celtics obtained rights to the 6-6 Walker, out of Kansas State, in exchange for cash after he was chosen with the 47th pick by Washington in last week's NBA draft.

He injured his right knee in a pre-draft workout last month and missed the Celtics' rookie camp. He had surgery on the same knee as a high school freshman.

Walker also underwent surgery on his left knee as a college freshman after he suffered a torn ligament.