A tibia cutting block for performing precise cuts into a tibia comprises an approximately cuboid body with a tibia attachment side and opposing thereto a front side. The body has a cutting guide slot extending from a top side into the body, a blade holding slot extending from a right side or a left side into the body, a first anchoring pin hole which is close to the intersection of a first plane defined by the blade holding slot and a second plane defined by the a cutting guide slot, a second anchoring pin hole distant from the first anchoring pin hole and a reference pin guide. All are penetrating the body from the front side to the tibia attachment side.
