Bone anchors, in particular bone screws, in particular pedicle screws

Abstract

The invention relates to a bone anchor (2), wherein the bone anchor (2) comprises a shaft (4) that can be inserted into a bone and a fork head (6) that can be oriented polyaxially relative to the shaft and has two legs (7) for receiving a correction rod, wherein the fork head (6) with its legs (7) defines a core opening (32), wherein an orientation of the fork head (6) relative to the shaft (4) desired by the surgeon can be temporarily determined.According to the invention, it is proposed that, for temporarily fixing the orientation of the clevis head (6) relative to the shaft (4), a clamping piece (26) can be supplied to the clevis head (6) through the access opening (10) and clamped there against the shaft (4) by exerting a temporary actuating force in the axial longitudinal direction (16) on the clamping piece (26), and that the temporary actuating force in the axial longitudinal direction (16) can be generated by supporting an actuating means (34) against an extension device (8) and can be introduced into the clamping piece (26), and that the clamping piece (26) extends outwards between the legs (7) of the clevis head (6) in the specified radial direction (22) via the core opening (32) and is thus supported against the legs (7) of the clevis head (6) and is non-rotatable in the circumferential direction (20).