Roberson was taken off the court on a stretcher after his left leg appeared to give out on the receiving end of an alley-oop attempt.
Roberson, 26, underwent surgery to repair the injury and will miss the remainder of the season, the team announced Sunday. He missed eight games earlier this season with patellar tendinitis in his left knee.
"He's certainly a huge loss," Thunder coach Billy Donovan said after Saturday's game. "Everyone's been able to see that since he's kinda come back to us and what he's been able to do defensively. And he's found a way to be, offensively, a really effective player for us."
The injury happened with 4:33 remaining in the third quarter of the Thunder's 121-108 victory. Roberson, who was in the right corner, broke to the basket as Russell Westbrook lobbed the ball to him. However, Roberson crumpled to the court after his leg bent in an awkward direction. He appeared to land on his buttocks and then slid off to the side of the court.
Roberson was examined by trainers for several minutes before being put on a stretcher -- sitting -- and taken off the court. His leg was placed in an air cast.
While some teammates were huddled around Roberson, forward Carmelo Anthony took a knee at midcourt.
"It's a hard situation, to kind of be up close and personal with that like that," Anthony said. "The only thing I did was kind of take a knee and pray a little bit and hope things go for the best at that point."
Anthony said it was "1,000 percent" difficult to return "to a competitive mindset after seeing one of your guys go down like that."
Oklahoma City led by 25 points (91-66) when it happened. The Pistons then cut the lead to nine points.
Forward Paul George said he'll be there to assist Roberson in dealing with the injury. George understands better than most, having come back after breaking his right leg in an exhibition game with USA Basketball in 2014.
"I'll be there for him along the way, try to help as much as possible, putting him in a good place with the injury," George said. "Because I know how it is. I've been down that road before. So real unfortunate. But one thing about Dre, man, he's tough, and he's a strong person, so he'll definitely persevere through it."
"It's s---, it's real s---," center Steven Adams said. "He's a huge part of our team and why we win. It's a huge blow to us, but we're just going to have to rely on some of the players to step up."
Anthony said the Thunder will sometimes rely on Roberson to guard some of the opponent's top offensive threats and that he's a "smart defender" whom they could rely on nightly defensively. Roberson, who made his 39th start Saturday and was averaging 5.0 points and 4.7 rebounds entering the game, is a player whose value doesn't always show up statistically for Oklahoma City.
How much will the Thunder miss Roberson's defense? According to ESPN Stats & Info, in 539 minutes with Roberson joining Westbrook, George, Anthony and Adams on the floor, the Thunder allow 95.9 points per 100 possessions; in 402 minutes for the Thunder's Big Four without Roberson, they allow 114.5 points per 100.
"A lot changes," Westbrook said. "A lot of things that's not seen on the court, a lot of things not seen in the stat sheet -- and that's a huge part. Like I've always said, he's a huge part of our team's success. And obviously, with him going down, we've got to be able to figure out and make up for the things he brings to the game defensively and offensively."
Stay strong @boogiecousins and Andre Roberson! Prayers your way for a strong recovery 🙏🏽— Stephen Curry (@StephenCurry30) January 28, 2018
Donovan indicated that rookie Terrance Ferguson and second-year pro Alex Abrines could replace Roberson in the lineup. Ferguson played 23 minutes Saturday, with six points and three rebounds. Abrines played six minutes with three points.
ESPN's Adrian Wojnarowski and Royce Young contributed to this report.