The fourth-year pro is the team's third-leading tackler and an impactful run defender, posting a Patriots-high eight tackles for loss this season.
Though Spikes has been dealing with a knee injury for several weeks, often riding a stationary bike during the media accessible portion of practice, the move was a surprise as he played in all 16 games this season, the first time he has done so in his NFL career.
The move leaves the Patriots' defense down yet another starter, as a season laced with injuries to impact players continues. The Patriots have Dont'a Hightower as one starter at linebacker, with second-round pick Jamie Collins and veteran Dane Fletcher among those players who are likely to play more prominent roles going forward.
Though Spikes is a starter, he had been used less regularly in sub packages because of his coverage limitations. That's an area where the athleticism and instincts of Collins have shown up as his own role has grown this season.
Spikes is the second starting linebacker to hit injured reserve for the Patriots, as stalwart Jerod Mayo missed much of the season after suffering a pectoral injury.
Spikes is due to become a free agent this offseason, though it is unclear if he and the team have had discussions on a possible contract extension.
The Patriots host the Indianapolis Colts on Saturday in the divisional round of the playoffs.