The injury was discovered during a more intense physical.
The newly-acquired center sustained the injury in last year's preseason, but he played through the injury. The Stars' medical staff consulted with the front office before deciding to have the surgery.
“He played through it before and he could have played through it again, but we want the best Derek Roy we can get,” Stars general manager Joe Nieuwendyk said. “It was a group decision, and we felt this was the best decision."
Roy's injury is complicated by a number of concerns, including a potential NHL work stoppage. The current collective bargaining agreement expires on Sept. 15.
Options to replace Roy in the lineup include Cody Eakin and Tom Wandell. The Stars also drafted center Radek Faksa with the 13th overall pick, but the Stars were looking to avoid using those three players that high in the lineup.
Faksa is also a concern because of his entry-level contract and game limitations.
This could put the Stars back on the market for a top-six forward. With Rick Nash, Alex Semin and others still out there, can the Stars bring in another big gun?
Roy is 29 years old, and he spent his first eight years in the NHL with the Sabres. He has 427 career points in 549 games.
The Ottawa native could have a number of productive seasons in Dallas when he recovers from the surgery.