It turns out that Hightower suffered a minor injury:
Per source, Patriots LB Dont'a Hightower is believed to have suffered an MCL sprain last night in Denver.— Albert Breer (@AlbertBreer) November 30, 2015
If this injury sounds familiar, it's what the initial reports were for running back Dion Lewis. Depending on the severity of the injury, Hightower could be sidelined for two to eight weeks. Since the linebacker returned to the field, it's likely that the sprain in towards the minor side of the spectrum and Hightower will only miss a couple weeks.
Fortunately for the Patriots, linebacker Jamie Collins should return to the rotation to prevent the duo of Jonathan Freeny and Jerod Mayo from being every-snap linebackers. Hopefully Hightower can rest and return at 100% in time for the playoffs, alongside every other important member of the Patriots.