EAGAN, Minn. -- Denver Broncos running back Mike Boone's thigh injury isn't as serious as the team initially feared when he left the practice field on a cart Thursday, but it could still impact the Broncos' decisions when rosters are cut to 53 players on Aug. 31.
A magnetic resonance imaging (MRI) exam revealed Boone, according to team sources, will miss a minimum of 4-to-6 weeks with the injury. He pulled up during a drill late in a joint practice Thursday with the Minnesota Vikings and was eventually taken to the locker room on a cart.
The Broncos believed Friday that Boone would not need surgery to repair the injury.
Before Thursday's practice began Broncos general manager George Paton had praised the quality of Boone's training camp to this point and the impact he could have in the Broncos' offense. Paton was the Vikings' assistant general manager during Boone's three seasons in Minnesota.
"Mike is an explosive runner and he's different from what we have -- a little bit more of a change of pace," Paton had said Thursday. "He can take it to the house. He has the most speed of any of our backs. I think he'll help us in the pass game. I mentioned before, he's a four-phase teamer, which is vital for your backup running backs."
The Broncos have a crowded running back depth chart with Melvin Gordon, rookie Javonte Williams, Boone and Royce Freeman all having taken at least some snaps with the starters thus far in camp. In each of the past three seasons, when John Elway was the Broncos' chief football decision-maker before Paton was hired this past January, the Broncos kept three running backs on the Week 1 roster. In 2018 and '19 they also kept fullback Andy Janovich at the cutdown to 53 in addition to the three running backs.
Having Boone miss so much time could force the Broncos to keep an additional running back.
If Boone misses just four weeks, including the time it takes to get his conditioning back to the level he could play in a game, he would be slated to return for the opening week of the regular season. If he misses six weeks, including the ramp-up of his conditioning, that would put him at a Week 3 return.
If he misses as much as six weeks recovering from the injury and then needs additional time to work through conditioning that could push his return into October for at least Week 4 of the regular season.