They say if you did not have a tentus sht with in ten years you could need one. I personally would not get one for a knife cut in my house. If it was a rusty nail in the foot I would think about the shot.
Do I Need A Tetnus Shot If I Cut My Finger At Home With A Knife?
A knife kept in the house would have a very low probability of carrying the organism that causes tetanus, so I wouldn't get a tetanus shot UNLESS it has been over ten years since my last tetanus booster.