It's unclear when the procedure took place, but Terry's daughter posted a photo on Instagram late last month showing her father in a wheelchair, holding crutches. Terry tweeted a photo of himself on an anti-gravity treadmill at the Celtics' practice facility in Waltham, Mass., on Tuesday.
"I saw him today, and he looked great," Ainge told the Herald. "He's doing really well."
Removing the plica, folds of tissue in the joint which are generally unobtrusive but can become irritated, is most commonly done to reduce pain or inflammation in the knee joint.
The 35-year-old Terry, who is signed through next season, averaged 12 points per game in the playoffs, but scored no points on 0-for-5 shooting in the season-ending Game 6 loss against the New York Knicks.