Simmons went up and grabbed a rebound midway through the third quarter, then slowly dribbled down the court and flipped an inlet pass to Al Horford. As a whistle blew to stop play, he turned toward Philadelphia's bench, flexed his left leg, touched the back of it and then walked off the court.
He then slowly walked back to the locker room, where he was soon joined by Sixers general manager Elton Brand.
Sources told ESPN's Adrian Wojnarowski that early indications on Simmons' condition are encouraging, with no pain or swelling in his left knee.
Simmons was shown leaving the arena shortly before the final buzzer sounded, dressed in street clothes and walking very gingerly.
"We don't know," Sixers coach Brett Brown said after the game, when asked for a further update on Simmons' status. "I'm sure the club will make some statement about his departure from the floor soon.
"More than that I don't know. But I'm very curious to hear what that news is."
Philadelphia was happy to have Simmons back for the resumption of the NBA season inside the league's bubble at Walt Disney World Resort, after a back injury he suffered in the first quarter of a game in Milwaukee on Feb. 22 kept him out through the suspension of the season on March 11, and at least left open the possibility of him missing the playoffs had the season gone on as scheduled.
Instead, Simmons has not only returned to Philadelphia's lineup in the bubble, but he has done so at a new position -- power forward -- as Brown has replaced Horford in the starting lineup with second-year point guard Shake Milton.
Simmons played 23 minutes Wednesday, finishing with eight points, six rebounds and four assists. The playoffs are scheduled to begin on Aug. 17.