A system for anchoring a pedicle screw in a patient's vertebra uses a pedicle screw having a threaded portion sinkable in the vertebral arch. The space between the threaded portion and cortical edge layer of the pedicle is at least partially filled by a spacer that enables an all-round support of the threaded portion at the cortical edge layer. A kit includes a pedicle screw and a spacer which at least partially fills the space between the threaded portion and cortical edge layer of the pedicle. A spacer has an essentially oval cross-section for form-locking fit in a corresponding axial recess sunk in the pedicle and having an axial through-hole to accommodate the threaded portion of a pedicle screw, as well as a spacer in the form of an essentially cylindrical pedicle augmentation in the form of a bone screw or a bone bracket.