A tibia cutting block (10) for performing precise cuts into a tibia comprises an approximately cuboid body with a tibia attachment side (16) and opposing thereto a front side (17). The body has a cutting guide slot (12) extending from a top side into the body, a blade holding slot (11) extending from a right side (18) or a left side (19) into the body, a first anchoring pin hole (14) 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 (15) distant from the first anchoring pin hole and a reference pin guide (13). All are penetrating the body from the front side to the tibia attachment side.
