INDIANAPOLIS -- The question of whether or not Todd Gurley is healthy has been one of the biggest mysteries in the NFL over the past few months and although the team won't come out and say it, there's definitely some concern inside the organization about his left knee.

The Rams currently have Gurley on an offseason regimen in hopes of getting him completely healthy for the 2019 season, but if that doesn't work or if his knee regresses, the team may consider stem cell treatment for their star running back, according to a team source.

Although stem cell procedures haven't quite gone mainstream in the NFL, multiple former running backs have undergone the treatment, including Jamaal Charles and Knowshon Moreno. Both Charles and Moreno had the procedure done after tearing an ACL earlier in their football career. Gurley tore his ACL during his junior year at the University of Georgia in 2014.

Rams coach Sean McVay was asked about the possibility of a stem cell procedure during a one-on-one interview with CBSSports.com at the NFL combine on Thursday and denied it, but he did say that the team is looking at "new methods" to help Gurley with his ailing knee.

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"As far as the stem cells, that's not something that's been communicated to me, but there is a program," McVay said. "We've got these doctors and there's always new methods of staying as up-to-date as you can, and number one, the player has to feel good about it. Todd does such a good job of doing his own research and knowing what are the things [he] can do."

McVay also added that the team is open to using new advancements in medicine as long as Gurley is comfortable with it.

"I think every year provides a new opportunity based on the research and some of the medical advances to attack it in the right way," McVay said. "As long as Todd is feeling good about that, that's what we'll do."

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One option that's not on the table right now is surgery. McVay told a horde of media members at the combine that surgery definitely won't be happening this offseason.

Gurley's troublesome left knee became such an issue this year that it caused him to miss the final two games of the regular season. At the time, the Rams attributed Gurley's absence to soreness and inflammation. According to McVay, the team is hoping that they can get Gurley back at full strength this offseason.

"We're going to implement a plan to have him attack it to get that knee back to feeling full strength, feeling good based on just the amount of work that he's gotten," McVay said. "That would be no different whether he missed any games or not, though."

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The 33-year-old Rams coach also said that the team has been closely watching Gurley's knee since the day he was drafted in 2015.

"We've always had the approach with him even going back to when we drafted him before I was here, and that's really where we're at," McVay said. "There's been a plan in place specific to monitoring that knee every single offseason for him and having a plan to make sure that we're putting him in a position to sustain that workload. This season will be no different."

A team source also said that the team is concerned about the amount of hits that Gurley is taking. The Rams running back has carried the ball 1,042 times since his rookie year. To put that in perspective, no other running back in the NFL has even carried the ball 950 times over that time span. Gurley leads the NFL in carries over the past four seasons even though he's missed six regular-season games in that time span.

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Rams general manager Les Snead didn't deny that the team is worried about the amount of wear and tear on Gurley. As a matter of fact, during an appearance at the combine Thursday, Snead said that the Rams may consider bringing in a running back to help take some of the load off of Gurley in 2019.

"There's an element of wear and tear and I think we have to determine in probably two stages: are we going to give him the amount of load that he's had in the past or are we going to lessen that load to let's say keep him fresher for the season and for the seasons beyond," Snead said, via the NFL's official website. "If you go that route, you have to have a good, let's call it Batman and Robin combination or add another superhero figure into that and figure how you're going to do it. We're in the process of figuring that out and I do think with Todd and his career -- it happens to a lot of young guys, all of a sudden they wake up ... and you're a little sorer than you were the day before."

The problem for the Rams is that Gurley's soreness has been lingering, which is why the team may eventually consider the stem cell option.

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Due in large part to Gurley's injury, the Rams brought in C.J. Anderson to help him carry the load at the end of the regular season. It was Anderson who first publicly admitted just how bad Gurley's knee was back in December.

"He was more hurt than what we thought," Anderson said on Feb. 19. "The injury was a little bit more than what everybody in the building thought, including himself."

The health of Gurley is now a $45 million mystery for the Rams. Gurley became the highest-paid running back in NFL history back in July when he signed a four-year, $60 million extension that included $45 million in guaranteed money. When the Rams signed Gurley to the record-setting deal, they clearly weren't expecting their offense to turn into a running back by committee, but as Snead said, that's something that could happen if the 24-year-old's injury lingers into 2019.