Judge Anderson also gets knocked out in a previous chapter of this story (Judge Dredd the Megazine #380.)
What makes this scene unusual and why I really like it is that the bad guys are forced to employ two different knockout methods because Anderson is such a bada** and continues to fight and wipe the floor with these guys while trying to stay conscious.
Also love the "what do we do with her?" moment after she's unconscious.
Source: http://readcomicbooksonline.net/reader/Judge_Dredd_The_Megazine/Judge_Dredd_The_Megazine_382