Reddick was sent to a nearby hospital for an MRI exam, the results not yet known as of early Wednesday evening. Those will determine whether the A's once again have to place Reddick on the disabled list, having already done so because of the same injury earlier in the season.
Reddick's injury surfaced just one day after catcher Derek Norris broke a toe, with the A's already playing without John Jaso, who is still dealing with concussion symptoms.
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.