| abstract |
An implant (10) for use in fixing one segment of a spinal column to another segment thereof by means of at least one rod member, comprises a screw member (11) for insertion in the pedicle of a segment of a spinal column and having an enlarged diameter head (13) with an open ended transverse slot (16) to receive a fixing rod member (20), and clamp means having a screw threaded connection with the head (13) of the screw member (11) and having a clamping portion fitting around the outside of the head (13) of the screw member (11) for engaging a fixing rod member (20) inserted in the transverse slot (16) of the screw member (11) and clamping it therein. The clamp means comprises a collar (14) around a reduced diameter portion (19) of the head (13) and a clamping screw (15) having a threaded shank (18) inserted in a threaded counterbore (17) in the head (13) and having a flanged head (22) for engagement with the collar (14). The axial length of the shank (18) is less than the axial length of the collar (14) whereby a rod member (20) can be clamped by the collar (14) without being engaged by the shank (18). Ancillary instruments for use with the implant system include a center punch (40) for locating a hole to be drilled in a pedicle for insertion of a screw member (11), and a screw driver (50) for holding and inserting a screw member (11) into a drilled hole in a pedicle. |