Jason Terry, as it turns out, was not running on two healthy legs by the end of the season.

The Celtics guard, who tweeted a picture of himself running on a treadmill in the Celtics’ Waltham practice facility yesterday, had an arthoscopic procedure to remove the plica from his left knee.

The plica is described as an extension of the protective synovial capsule of the knee, and can become irritated, enlarged or inflamed if caught between the patella and the femur.

“I saw him today, and he looked great,” said Celtics president of basketball operations Danny Ainge. “He’s doing really well.”

In addition, Celtics guard Terrence Williams recently had an injection to relieve a painful case of tendinitis in one of his knees.