The 23-year-old, who commanded an undisclosed fee when joining the Millers from Bury in the summer, has been dogged by injuries this campaign and has not featured since the end of August.
And with the Millers going for promotion in League One, boss Steve Evans is reluctant to use him having been out of action for so long, though has kept the door open for a potential return.
"We brought David in here among good competition when there were several clubs in for him," Evans told the club's official website.
"Just as we got him fit he came off the bench and got the goal against Crawley and a week afterwards he pulled a groin and then needed a double hernia operation.
"He's been working his way back to fitness but we've had to look at our immediate options and what he needs is a run of games, which looking at the games and the weather in January and February it's going to be difficult for him.
"Oldham made it very easy, we didn't put him available, they asked the question and it's a good move for him.
"Let me make it very clear though, this is not the last time you'll have seen David Worrall."
Meanwhile, centre-half Pablo Mills, who was on a short-term contract until the end of January, has been released early and joined League Two side Bury.
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- Steve Evans