Langley limped out of Saturday's game against Barnsley complaining of a "strange" feeling in his knee.
His condition is still being assessed, but tests have confirmed that he has sustained no new damage to the cruciate area.
Langley is suspended for this Saturday's game against Plymouth but should be available for the home match against Tranmere the following weekend.
Meanwhile, Watford have formally agreed to extend Lee Cook's spell at Loftus Road, although the winger will be on 24-hour callback.
Cook's initial month on loan was due to expire after the Plymouth game.
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