Bradley sat out Sunday's 7-5 win and will fly back to Boston prior to Monday's series finale for some further testing from the Red Sox's medical staff.
The Red Sox will wait until after that exam before determining if Bradley needs to go on the disabled list.
"The MRI shows he's got some inflammation and a little bit of, I guess you'd call it a sprain to the outside of the knee," said Red Sox manager John Farrell. "We're going to send him back to Boston to get a full workup, a complete exam with Dr. Asnis back there, so right now there's no determination or decision about his roster status, but [it's] precautionary. We want to be sure we take every measure available to us."
Bradley sustained the injury when the ground gave out on him as he rounded first base after a flyout in the ninth inning of Saturday's 4-1 loss to the Tigers. At first, Bradley's left foot got stuck in the ground, and then he fell on his right knee.
If Bradley needed a DL stint, the Red Sox would probably move Andrew Benintendi to center field, and Young and Brock Holt could share duties in left field.
Before and after Sunday's game, Bradley was in good spirits and optimistic there is nothing seriously wrong with him.
"I feel a lot better," said Bradley. [Both from the] initial diagnosis and I've already kind of been getting treatment on it and [I feel like] we're going in the right direction."
It is clear Bradley wouldn't be ready to play by Monday, which is why the Red Sox are sending him home early.
"I think it's just to have extra eyes on it and have our doctors take a look at it and kind of go from there," said Bradley.
The ailment -- even if minor -- added to a stressful weekend for the Red Sox, who have been beset by a rampant illness that has spread around the team and two players (shortstop Xander Bogaerts and setup man Matt Barnes) out on the bereavement list.
Here is the latest on the medical/roster front:
• Mookie Betts was over his sickness enough to be in the lineup for the first time since Opening Day. He started in right field and went 0-for-3 with two walks and a run scored.
• Barnes returned to the roster for Sunday's game as right-hander Noe Ramirez was optioned to Triple-A and fired two scoreless innings for the win.
• Bogaerts is expected to be back at shortstop for Monday's finale of this four-game series. A corresponding roster move will have to be made, which will likely result in Deven Marrero being optioned.
• Hanley Ramirez remained back in Boston after testing positive for influenza, and is all but certain to miss the remainder of the series in Detroit.
"I spoke to him twice [Saturday]," said Farrell. "He was able to get up and start moving around. Right now, it's unlikely he'd come to Detroit. If we can get him to the ballpark [Monday], in Fenway, and start getting some activity, that would be probably the best-case scenario."
• Righty setup man Joe Kelly was back at the ballpark Sunday after retreating to the team hotel with sickness before Saturday's game. He might be available to pitch Monday.
• NESN was also back to a full booth Sunday. Play-by-play man Dave O'Brien was hit hard with flu-like symptoms that led to him leaving in the middle of Saturday's game. O'Brien was back to work a day later alongside analyst Jerry Remy.
• Red Sox prospect Brian Johnson had a scary incident Saturday when he was hit in the face by a line drive while pitching for Triple-A Pawtucket. Johnson was also hit in the head in 2012 while pitching in a Minor League doubleheader at Fenway Park.
"Traded some messages with him this morning," said Farrell. "He's upbeat. He's looking forward to getting back on the mound, taking his regular turn. The CT scan he went through was clean. There were no fractures of any kind after getting hit with a line drive."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.