Pedicle screws with integrated anchor for retaining artificial ligament tape used for posterior ligament reconstruction
A pedicle screw of the type used in spinal fixation surgery has integral structure for anchoring artificial ligament tape. A tape-receiving passageway is formed through the tulip assembly of the pedicle screw. The passageway has open ends and is configured to receive an artificial ligament tape threaded through the passageway. An opening is formed in the tulip assembly, transversely intersecting the passageway and opening to the exterior of the tulip assembly. A clamping member is movable along the opening into clamping engagement against a segment of the artificial ligament tape that is threaded through the passageway.
1. An improved pedicle screw including a threaded screw shank mounted to a tulip assembly, the tulip assembly including a tulip head having cylindrically contoured peripheral sides and including a U-shaped slot forming a saddle for receipt of a spinal support rod and the tulip assembly also including a primary set screw that engages an interior wall of the saddle or a primary nut that engages an exterior wall of the tulip assembly, the primary set screw or nut moving axially when rotated for clamping the rod against a bottom surface of the U-shaped slot of the saddle, wherein the tulip head additionally comprises:
(a) a ligament tape-receiving passageway formed through the tulip head, spaced on a side from the slot, extending parallel to the slot between opposite peripheral sides of the tulip head and terminating at opposite open ends located at an outer peripheral surface of the tulip head no further outward than the cylindrically contoured peripheral sides of the tulip head, the passageway not intersecting the slot and configured to receive an artificial ligament tape threaded through the passageway parallel to the support rod;
(b) an opening in the tulip head, transversely intersecting the passageway, not intersecting the slot and opening to the exterior of the tulip head; and
(c) a clamping member that is movable within the tulip head along the opening into clamping engagement against a segment of the artificial ligament tape threaded through the passageway.
2. A pedicle screw in accordance with claim 1 wherein the tulip head has a longitudinal axis and the passageway is aligned across the tulip head transversely with respect to the longitudinal axis.
3. A pedicle screw in accordance with claim 2 wherein the passageway is a hole through the tulip head, the opening is a threaded hole and the clamping member is a secondary set screw threadedly engaged in the opening and configured to advance along the opening and against the artificial ligament tape by rotation of the secondary set screw.
4. A pedicle screw in accordance with claim 3 wherein the passageway has a rectangular cross section.
5. A pedicle screw in accordance with claim 4 wherein the passageway is aligned at a right angle to the longitudinal axis.
6. A pedicle screw in accordance with claim 4 wherein the rectangular cross-section has a major axis and a minor axis, and the major and minor axes are inclined at an acute angle to the longitudinal axis.