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.
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This invention is directed to implants used in spinal fixation surgery and more particularly is directed to means for anchoring artificial ligament tape in a construct for tethering an uppermost fused vertebra to higher vertebrae.
The prior art discloses a variety of structures and methods for treating one or more degenerated, deformed or damaged vertebral stages of a patient's spinal column by means of internal spinal fixation. Typically, this involves the attachment of a spinal implant system to provide a construct that is attached to two or more adjacent vertebrae to support and stabilize the vertebrae in order to allow them to fuse together in a stationary relationship relative to each other. Spinal fusion constructs typically include pedicle screws and longitudinal support members or rods that are attached to the pedicle screws and together they fix the position of the adjacent vertebrae to which they are attached.
However, a problem that develops after surgery in many patients as a result of patient activity or stature is that the vertebra that is immediately above the highest fused vertebra breaks away from the highest fused vertebra and falls forward. Surgeons sometimes attempt to prevent that problem by securing vertebrae that are immediately above the uppermost instrumented vertebra to the uppermost instrumented vertebra by means of artificial ligament tape. (An instrumented vertebra is a vertebra to which a device is implanted or connected.)
One way of doing this is to first drill a hole through the spinous process of the uppermost instrumented vertebra and also the contiguous vertebrae that are immediately above the uppermost instrumented vertebra and are to be secured by the ligament tape. The ligament tape is then threaded through the drilled holes upward from the uppermost instrumented vertebra to the higher vertebrae and then threaded back down again through the holes to the uppermost instrumented vertebra. In one procedure the ligament tape is then pulled in tension and tied to itself or to one or two of the rods that are a part of the construct. Unfortunately, this procedure often results in a loosening of the ligament tape because much of the tension is lost during the manipulation of the ligament tape into a knot and also because the tape can loosen further after surgery from slippage of the knot.
In order to reduce this loosening problem, the prior art has provided specialized anchoring devices that are attached to the construct and allow the surgeon to fasten the ligament tape to the construct. These specialized anchoring devices avoid the use of a knot and also allow a greater tension to be maintained while the tape is being secured to the anchors and thereby reduce or eliminate later slippage at the anchor. However, these specialized anchoring devices result in a construct that adds them as one or more additional devices that must be included in the construct. The additional devices increase the space occupied by the construct, require additional manipulation by the surgeon, must be taken into account when closing the wound and increase cost.
It is therefore an object and feature of the invention to provide a structure for anchoring the artificial ligament tape without requiring the surgeon to mount any additional specialized anchoring devices on the support rods or any other part of the construct.
The term “artificial ligament tape” is used in a generic sense to refer to a type of cordage that is available for surgeons to perform the procedures that are described above. Some prior art refers to equivalent structures as tape, cable, rope, tether, wire, braid, band or strand. They are an elongated structure that is flexible so that they bend easily (with the application of relatively little force) but also have a strong resistance to being stretched longitudinally by a substantial pulling force. Other equivalent terms include artificial ligament reconstruction tape, Mersilene tape and TLS® strips.
BRIEF SUMMARY OF THE INVENTIONThe basic concept of the invention is to provide a structure which can be included as an integral part of a pedicle screw and to which an artificial ligament tape can be anchored. As a result, a construct that uses a pedicle screw will not require an additional, dedicated, special purpose anchor. Instead pedicle screws can be installed in their usual manner but will serve both their conventional purpose, as widely described in the prior art, and also serve as anchors for an artificial ligament tape.
A ligament tape-receiving passageway is formed through the tulip assembly of a 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 at one end to the passageway and at its opposite end 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.
In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
DETAILED DESCRIPTION OF THE INVENTIONReferring to the drawings,
The tulip assembly 14 also includes a primary set screw 20 that threadedly engages the interior wall of the saddle 18 and has a tool slot 21. The primary set screw 20 moves axially when rotated for clamping a rod 19 against the bottom of the saddle 18. An alternative tulip assembly (illustrated in
The term “primary set screw” is used in this description as the broad generic term for the part of the tulip assembly 14 that moves axially when rotated to move further into the saddle in order to clamp a support rod against the bottom of the saddle. The term includes structures that use other than conventional threads, such as inclined grooves on opposite sides of the saddle and an internal screw with outward extending tabs that extend into the grooves for moving into the saddle when rotated. Such structures may be referred to as a twist lock. The term also includes tulip assemblies that use a surrounding nut that is threadedly engaged to the exterior of the tulip assembly and an interior disk with diametrically opposite arms that extend outwardly through the open ends of the saddle so the arms are contacted by the nut and the disk is driven against the rod when the nut is rotated.
As illustrated in
The foregoing description describes conventional prior art pedicle screws and their components. The structural features of the invention are next described.
Referring still to
An opening 30 in the tulip assembly 14 transversely, and preferably perpendicularly, intersects and opens into the passageway 26 and also opens at its opposite end to the exterior of the tulip assembly 14. A clamping member 32 is configured to be movable along the opening 30 into clamping engagement against a segment of an artificial ligament tape that is threaded through the passageway 26. Preferably, the clamping member 32 is a secondary set screw that is threadedly engaged within the opening 30 so that it can be rotated by a tool to be advanced along the opening into engagement against the ligament tape to secure the tape in position where it is tightly anchored to the pedicle screw 10.
There are various preferred and alternative structural variations of the embodiment illustrated in
An opening 54 for receiving a clamping member 56 is a threaded hole 54 into an outwardly facing end of the primary set screw 52. The clamping member 56 is formed by a secondary set screw 56 that is threadedly engaged in the threaded opening 54. The secondary set screw 56 is configured to advance into the opening 54 and against the artificial ligament tape 46 in the passageway 50 by rotation of the secondary set screw 56.
Still another embodiment of the invention is illustrated in
The push bar 70 must be sufficiently longer than the opening 68 so that it will be held against the artificial ligament tape 72 with sufficient force to securely anchor the tape 72 in the tulip assembly 58. Preferably the push bar 70 is formed either from a sufficiently stiff but elastic, resiliently compressible material or a malleable material such as commercially pure titanium. With this embodiment, after the artificial ligament tape 72 is threaded through the tape-receiving passageway 66 and pulled tight, the primary set screw 60 is rotated to tighten it down into the saddle 64 and against the rod 62. The rod 62 clamps down onto the push bar 70 and forces it into the tape-receiving passageway 66 and against the artificial ligament tape 72. If the push bar 70 is elastic or malleable, it becomes deformed from the force applied as a result of rotating the primary set screw.
With all the embodiments of the invention, the surgeon installs the pedicle screws and assembles the construct in the usual manner. Ordinarily, each vertebral body will have two pedicle screws, one in each of its pedicles. The artificial ligament tape is then threaded from an uppermost vertebra or vertebra above the construct and back down again in the customary manner as previously described to tether the upper portion of the spine to the construct. The two ends of the tapes are then threaded through the tape-receiving passageways in the tulip assembly of the chosen pedicle screws.
From the above it can be appreciated that the invention provides two new advantages. First, when an embodiment of the invention is used, there are no additional devices to be installed in the construct. Therefore a construct is provided that does not occupy additional space or additional volume. Although there are no additional devices, the disadvantage of tying the artificial ligament tape to itself by a knot are avoided. The advantages of anchoring the artificial ligament tape to the construct is attained by allowing the artificial ligament tape to be pulled and held taught while the clamping member is rotated and tightened against the artificial ligament tape to anchor it to the construct.
REFERENCE NUMBER KEY
-
- 10 pedicle screw (
FIGS. 1-3 ) - 12 screw shank of pedicle screw (
FIGS. 1-3 ) - 14 tulip assembly (
FIGS. 1-3 ) - 16 tulip head (
FIGS. 1-3 ) - 18 saddle of tulip head (
FIGS. 1-3 ) - 19 rod (
FIGS. 1-3 ) - 20 primary set screw (
FIGS. 1-3 ) - 21 tool slot (
FIGS. 1-3 ) - 22 longitudinal support rod (
FIGS. 1-3 ) - 24 longitudinal axis of tulip assembly (
FIGS. 1-3 ) - 26 ligament tape-receiving passageway (
FIGS. 1-3 ) - 28 open ends of passageway (
FIGS. 1-3 ) - 30 opening (
FIGS. 1-3 ) - 32 clamping member (
FIGS. 1-3 ) - 34 skirt (
FIG. 5 ) - 35 tulip assembly (
FIGS. 6-11 ) - 36 ligament tape-receiving passageway (
FIGS. 6-11 ) - 38 primary set screw (
FIGS. 6-11 ) - 39 support rod (
FIGS. 6-11 ) - 40 opening/channel (
FIGS. 6-11 ) - 41 saddle (
FIGS. 6-11 ) - 42 clamping member/secondary set screw (
FIGS. 6-11 ) - 44 artificial ligament tape (
FIGS. 6-11 ) - 46 artificial ligament tape (
FIGS. 12-15 ) - 48 tulip assembly (
FIGS. 12-15 ) - 50 ligament tape-receiving passageway (
FIGS. 12-15 ) - 52 primary set screw (
FIGS. 12-15 ) - 53 support rod (
FIGS. 12-15 ) - 54 opening for receiving clamping member/set screw (
FIGS. 12-15 ) - 55 saddle (
FIGS. 12-15 ) - 56 clamping member/secondary set screw (
FIGS. 12-15 ) - 58 tulip assembly (
FIGS. 16-18 ) - 60 primary set screw (
FIGS. 16-18 ) - 62 support rod (
FIGS. 16-18 ) - 64 saddle (
FIGS. 16-18 ) - 66 ligament tape-receiving passageway (
FIGS. 16-18 ) - 68 opening for receiving clamping member/bore (
FIGS. 16-18 ) - 70 clamping member/push bar (
FIGS. 16-18 ) - 72 artificial ligament tape (
FIGS. 16-18 )
- 10 pedicle screw (
This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.
Claims
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 at a cylindrically contoured peripheral side 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 and enclosed by 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.
7. A pedicle screw in accordance with claim 1, wherein the pedicle screw is a polyaxial pedicle screw.
8. A pedicle screw in accordance with claim 1, wherein the pedicle screw is a monoaxial pedicle screw.
9. A spinal support system, comprising:
- a pedicle screw;
- a tulip head connector having cylindrically contoured peripheral sides and extending in a longitudinal direction from an upper surface to a lower surface and extending in a lateral direction perpendicular to the longitudinal direction, the tulip head connector comprising a U-shaped slot for retaining a spinal support rod therein, the U-shaped slot including cylindrically contoured interior surfaces having threads and peripheral side surfaces, the cylindrically contoured interior surfaces define a longitudinal axis extending in the longitudinal direction;
- a first set screw having a thread pattern on a side surface thereof for engaging the cylindrically contoured interior surfaces of the U-shaped slot;
- at least one passageway extending through the tulip head connector, the at least one passageway being configured to receive at least one ligature for passing therethrough and enclose the at least one ligature within the passageway, the passageway spaced on a side from the slot, extending parallel to the slot between opposite peripheral sides of the tulip head and terminating at opposite ends located at an outer peripheral surface of the tulip head no further outward than the cylindrically contoured peripheral sides of the tulip head;
- at least one opening extending through the tulip head connector, from a cylindrically contoured peripheral side of the tulip head, and intersecting with the at least one passageway, the at least one opening having interior surfaces having threads thereon; and
- a second set screw, the second set screw having a thread pattern on a side surface thereof for engaging the interior surfaces of the at least one opening.
10. The spinal support system of claim 9, wherein the first set screw is configured to:
- move axially when disposed in the U-shaped slot and rotated; and
- secure the rod within the U-shaped slot when moved axially towards a bottom surface of the U-shaped slot.
11. The spinal support system of claim 9, wherein the at least one passageway is:
- formed in the tulip head.
12. The spinal support system of claim 9, wherein the at least one passageway does not intersect with the U-shaped slot and is configured to receive the at least one ligature such that the at least one ligature extends through the at least one passageway in a lateral direction that is parallel to an extension direction of the spinal support rod.
13. The spinal support system of claim 9, further comprising:
- the spinal support rod and the at least one ligature,
- wherein the U-shaped slot comprises a bottom surface shaped like a saddle and the first set screw is configured to move axially along the longitudinal axis when rotated, the first set screw being configured for clamping the spinal support rod against the bottom surface of the U-shaped slot when moved axially forward along the longitudinal axis toward the bottom surface.
14. The spinal support system of claim 9, wherein the at least one passageway extends through a first peripheral side and a second peripheral side of the peripheral sides of the tulip head connector in a direction that is substantially parallel to the U-shaped slot.
15. The spinal support system of claim 9, wherein the at least one passageway extends in a direction that is substantially perpendicular to the longitudinal axis of the tulip head connector.
16. The spinal support system of claim 9, wherein the pedicle screw is a polyaxial pedicle screw or a monoaxial pedicle screw.
17. A spinal implant system, comprising:
- a polyaxial pedicle screw;
- a tulip head connector coupled to the polyaxial pedicle screw, the tulip head connector having cylindrically contoured peripheral sides and extending in a longitudinal direction from an uppermost surface to a lowermost surface and extending in a lateral direction perpendicular to the longitudinal direction, the tulip head connector comprising a U-shaped slot with a bottom surface shaped like a saddle for retaining a spinal support rod therein, the U-shaped slot including at least one cylindrically contoured interior surface having a thread pattern thereon, the tulip head connector including a plurality of outside peripheral side surfaces,
- a first set screw having a thread pattern on a side surface thereof for engaging the at least one cylindrically contoured interior surface of the U-shaped slot;
- at least one passageway extending through the tulip head connector and configured to receive and enclose a ligature within the passageway, the passageway spaced on a side from the slot, extending parallel to the slot between opposite peripheral sides of the tulip head and terminating at opposite ends located at an outer peripheral surface of the tulip head no further outward than the cylindrically contoured peripheral sides of the tulip head;
- at least one ligature for passing through the at least one passageway;
- at least one opening extending through the tulip head connector, from a cylindrically contoured peripheral side of the tulip head, and intersecting with the at least one passageway, the at least one opening including interior surfaces having threads thereon; and
- a second set screw, the second set screw having a thread pattern on a side surface thereof for engaging the interior surfaces of the at least one opening.
18. The spinal support system of claim 17, wherein
- the at least one opening is inclined at an acute angle to the longitudinal direction; and
- the second set screw comprises threads configured to engage with the at least one opening.
19. The improved pedicle screw of claim 2, wherein
- the opening in the tulip head is inclined at an acute angle to the longitudinal axis; and
- the clamping member comprises a secondary set screw having threads configured to engage with the opening.
20. The spinal support system of claim 9, wherein
- the at least one opening is inclined at an acute angle to the longitudinal direction; and
- the second set screw comprises threads configured to engage with the at least one opening.
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Type: Grant
Filed: Feb 15, 2022
Date of Patent: Jul 15, 2025
Assignee: WARSAW ORTHOPEDIC, INC. (Warsaw, IN)
Inventor: Paul H. Eichenseer (New Albany, OH)
Primary Examiner: Matthew J Kasztejna
Application Number: 17/672,001
International Classification: A61B 17/86 (20060101); A61B 17/68 (20060101); A61B 17/70 (20060101);