"The tests (Monday) were encouraging," Lions coach Jim Schwartz said. "He's going to be sore, but he doesn't have anything that's long term."
That's good news for a team that needs the speedy running back in its offence to add to receiver Calvin Johnson and quarterback Matthew Stafford.
When Bush has been healthy for nearly six quarters, Detroit has beaten the Minnesota Vikings 34-21 and led Arizona 14-10 at halftime.
Without him playing much of the third quarter Sunday, the Lions were held scoreless offensively in the second half of a 25-21 loss to the Cardinals.
"Our offence was moving very well in the first half, we were converting third downs," Schwartz said. "In the second half, I don't think we converted one. He meant a lot. Calvin was making a lot more plays in the first half because of the dynamic of Reggie.
"When he went out of the game, we weren't really able to maintain that."
The Lions (1-1) don't know — or aren't saying —if they expect Bush to play Sunday at Washington (0-2) or if he'll need at least a game off to heal.
"I guess it could be medium term," Schwartz said. "It's too hard to speculate on injuries, and that's why I usually don't. I don't like putting any kind tag on things because you never know how people are going to react to anything."
Bush took a helmet to his left knee in the second quarter on a short pass he turned into a 26-yard reception. He entered the game later in the first half and played sparingly in the third quarter before going to the sideline for the rest of the game.
"I was cleared to come back," Bush told reporters on Sunday in Arizona. "I felt like I could run. I just wasn't myself. It was best for me not go in."
Bush accounted for 69 yards of offence in two-plus quarters against the Cardinals. He had 191 yards from scrimmage in an opening-week win over Minnesota in his Detroit debut.
The Lions signed the free agent to a $16 million, four-year deal in the offence, banking on him being the run- and pass-receiving threat that Jahvid Best was before concussions ended his career with the franchise.
"If we're going to be without him, we're going to need to find other ways to move the ball and other ways to score because we didn't get that done in the second half," Schwartz said. "He's a good fit in our offence, and we're going to work to get him back as soon as we can."
If Detroit doesn't have Bush in the lineup, it will likely start Joique Bell and make 2011 second-round pick Mikel Leshoure active for the first time this season.
Whomever the Lions have on the field, they will be trying to break the franchise's winless ways in Washington.
Detroit has lost 18 straight in the regular season on the road against the Redskins, a skid that trails only its 21-game streak against the Packers on the road in NFL history.
If the Lions lose at Washington again, they will have 22 straight defeats — including playoff games — to match the league-record, road-losing streak they currently own against Green Bay, according to STATS LLC.
The Lions, whose last game in Washington was in 2007, haven't beaten the Redskins franchise on the road since 1935 when they were based in Boston.
Schwartz, though, doesn't want anyone on the team to be saddled with those sad facts.
"It's hard to put that on the resume of a particular player," he said.
NOTES: Schwartz said DT Nick Fairley (shoulder) is day to day after being inactive at Arizona and said WR Patrick Edwards, who didn't finish Sunday's game because an ankle ailment, was being evaluated on Monday.
AP NFL website: www.pro32.ap.org
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