According to Keith Pompey of the Philadelphia Inquirer, the procedure involved Simmons having bone marrow injected into his right foot. Simmons is recovering from a Jones fracture of the fifth metatarsal suffered in September.
Simmons will resume training by the end of the week, per the Sixers.
The procedure comes just a few days after a CT scan revealed Simmons' foot hadn't fully healed.
"He's heartbroken," Sixers general manager Bryan Colangelo said at the time, per Brian Seltzer of Sixers.com. "He wants to play, be out there. It's eating him alive, I'm sure."
"It's not the way you want to start your career, but it happens," Colangelo added, per Tom Moore of Calkins Media.
While the Sixers didn't release a timetable for Simmons' return when he was initially injured, similar injuries often require a six- to eight-week recovery period. A scan in late January was believed to have shown his foot had healed and he'd suffered no setbacks, but reports later in February indicated the foot perhaps had not fully recovered.
Simmons' latest scan indicated as much, forcing him to miss his entire rookie season.
It's been a major disappointment for the Sixers, who on Monday also announced that center Joel Embiid was out indefinitely with swelling in his left knee, per ESPN. Simmons—the No. 1 pick of the 2016 NBA draft—and Embiid are believed to be the cornerstones of Philadelphia's future.
The pair unfortunately don't represent the present, as Simmons has yet to play a game and Embiid—who missed his first two seasons due to injuries—has only appeared in 31 games this season. The Sixers have a lot to be excited about, with Dario Saric having an excellent rookie season and a slew of first-round picks owed to the team in the coming years.
But this season has taken a disappointing turn given the latest news on Simmons and Embiid.