The 49ers placed Bethune (groin) on injured reserve Wednesday.
Bethune suffered a groin injury late into the 49ers' Week 18 loss to the Seahawks. The injury has proven to be season-ending, and the team will now grow even thinner at linebacker as they enter the playoffs. The recent signing of Eric Kendricks to the active roster will hopefully be enough to sustain the team until it can potentially regain the help of All-Pro linebacker Fred Warner (ankle).