A league source told ESPN's Ed Werder that Dr. Bob Anderson will view Lacy's scans and determine whether the running back will travel to Charlotte, North Carolina, for a visit.
McCarthy wouldn't rule Lacy out when he talked to reporters Wednesday and said the Packers were still "going through all the information."
"He's made a little bit of progress, is the feedback that I've been given. Frankly, he's going to have to have a wonderful, great 24 hours to play in the game," McCarthy said. "We'll see what tomorrow brings. But he will be in the large rehab group today."
With James Starks undergoing knee surgery, Lacy had been the Packers' only active running back against Dallas on Sunday, when he rushed for 65 yards on 17 carries in a 30-16 loss.
With both Lacy and Starks now expected to miss time, the Packers made a move Tuesday to address their thinning running back corps by acquiring Knile Davis in a trade with the Kansas City Chiefs.
The Packers gave up a conditional draft pick for Davis, who already has started practicing with his new team. A source told Schefter that the pick is a conditional seventh-rounder in 2018.
Starks is expected to be out a couple of weeks, and the same could be true of Lacy, with a source telling Werder, "I don't see [Lacy] playing anytime soon."
The Packers will have to get Davis up to speed on the playbook quickly if he is to be ready when the Bears visit Lambeau Field on Thursday night.
"It's obviously a big challenge when you're on a short week, but he's definitely a talented young player," McCarthy said Tuesday. "So just looking forward to getting him into the mix and get going."
It won't be the first time the Packers have used Anderson as a consultant. Last year, he performed ankle surgery on receiverTy Montgomery, and he helped in the diagnosis of tight end Jared Cook's sprained ankle earlier this season.
To make room for Davis on the active roster, Green Bay placed top cornerback Sam Shields, who has been out since the season opener with a concussion, on injured reserve.
The Packers have been struggling in the passing game, and the injuries to Lacy and Starks have added to their issues on offense. McCarthy got a look at Davis in Green Bay's last preseason game, when he ran for 58 yards and one touchdown on 14 carries in the Chiefs' 17-7 win on Sept. 1.
Davis had been passed over by Spencer Ware and Charcandrick West on the Chiefs' depth chart, and the return of Jamaal Charles from his knee injury made him expendable.
"I feel like I'm off the reins," Davis said after practice Tuesday. "I'm just excited to be a part of Green Bay and do what I can here. Hopefully my role is bigger."
Davis, a former Arkansas standout, was the Chiefs' third-round pick in 2013. He was expected to team with Charles in a power-and-lightning backfield. But issues with fumbles that plagued him in college continued in the NFL, and he gradually lost playing time to other running backs.
His best season was in 2014, when he ran for 463 yards and six touchdowns. But he has carried only 29 times for 70 yards and one touchdown the past two seasons combined.
Davis was a long shot to make Kansas City's roster out of training camp, but his special-teams ability might have made the difference. He has averaged 27.2 yards on kickoff returns during his four-year career, and he has returned three kicks for touchdowns.
The fact that the Chiefs and Packers were trade partners is hardly surprising. Chiefs general manager John Dorsey played for the Packers in the 1980s, spent most of his career in their front office and rose to director of football operations before joining the Chiefs prior to the 2013 season.
Davis was the third player he drafted in Kansas City.
ESPN's Adam Schefter and Ed Werder, and The Associated Press contributed to this report.
Knile Davis trade proves Packers were desperate for RB
Ed Werder says desperation was the motive for Packers GM Ted Thompson to acquire Knile Davis from the Chiefs.