Coates, 24, had his knee scoped two weeks before the start of training camp and the Steelers placed him on the PUP list. He is expected to practice with the team Wednesday.
Coates, the Steelers' 2015 third-round pick, said he injured the knee while training this summer. It was his second offseason knee surgery, and he also had surgery to repair a sports hernia after the season.
The 6-foot-1, 212-pound Coates is coming off a 2016 season that opened with an opportunity to make a mark thanks to Martavis Bryant's suspension. A finger injury slowed Coates, who saw action in 14 games but was limited to 21 catches for 435 yards and two touchdowns. But he caught an NFL-best six passes of 40 yards or longer, including a 72-yard touchdown against the New York Jets.
"You always got to prove yourself, I don't care how good a season you had or how bad a season you had," Coates told the Pittsburgh Post-Gazette. "You always got to prove to them and show them you're capable of doing the same things you did before. You always want to show them you worked on this or I got better at that. There's always something to prove, no matter who you are.
"It's just a fact -- I missed a lot, with injuries, with the offense. That catches up with people. You don't get them reps, you can't get them back. You missed them. You fall behind all through the season."