Only Stephen Colbert could turn an ordinary wrist injury into a media crusade, perhaps revealing contrasts among television’s three evening news anchors along the way.

The Comedy Central host broke his wrist before a taping of “The Colbert Report” in June. He has since made “wrist violence” a source of comedy for his character, a self-absorbed television pundit, embarking on a celebrity cast-signing tour and promoting bright red “WristStrong” bracelets. His cast is up for auction on eBay, with proceeds going to a charity for injured service members.

Brian Williams, the “NBC Nightly News” anchor, and Katie Couric, the “CBS Evening News” anchor, both played along. But Charles Gibson, anchor of ABC’s “World News,” did not, and some media observers interpreted his recalcitrance as a statement that real news shows are not to be conflated with parodies.

Unlike Mr. Williams or Ms. Couric, Mr. Gibson has never appeared on either Mr. Colbert’s show or on “The Daily Show with Jon Stewart.”