US 20050119753 A1
Instrument and implants are disclosed which provide for insertion of an implant into an intervertebral disc space from multiple approaches to the spine. Specifically, as a preferred aspect of the invention the implant includes a tapered portion and the implant may be inserted from multiple approaches to the spine with the orientation and taper properly oriented in the disc space regardless of the approach.
1. A spinal implant for implanting into a disc space of a spine, comprising:
an implant body having three pairs of substantially parallel sidewalls constructed and arranged to permit insertion of said implant body into the disc space at least from a direct anterior approach to the spine and an oblique angle to the spine; and
wherein said implant body is tapered.
2. The implant of
3. The implant of
said implant body is formed of bone; and
a portion of said implant body includes unmachined donor implant bone portion.
4. The implant of
5. The implant of
said implant body further includes an angled driving wall in which said second insertion tool bore is defined; and
said angled driving wall defines a recess surface that extends substantially perpendicular with respect to one of said pairs of sidewalls.
6. The implant of
7. The implant of
8. The implant of
9. The implant of
10. A spinal implant for implanting into a disc space of a spine, comprising:
an implant body having three pairs of substantially parallel sidewalls; and
wherein two of said three pairs of sidewalls are disposed at an oblique angle with respect to one another to permit insertion of said implant body into the disc space at least from a direct anterior approach to the spine and an oblique angle to the spine.
11. The implant of
12. The implant of
13. The implant of
said implant body is formed of bone; and
a portion of said implant body includes an unmachined donor implant bone portion.
14. The implant of
15. The implant of
16. A spinal implant for implanting into a disc space of a spine, comprising:
an implant body having means for permitting insertion of said implant body into the disc space at least from a direct anterior approach to the spine and an oblique angle to the spine.
17. The implant of
said means for permitting insertion of said implant body includes three pairs of substantially parallel sidewalls; and
wherein two of said three pairs of sidewalls are disposed at an oblique angle with respect to one another.
18. The implant of
19. The implant of
20. The implant of
said implant body is formed of bone; and
a portion of said implant body includes unmachined donor implant bone portion.
The present application is a divisional of U.S. patent application Ser. No. 10/213,328 filed Aug. 6, 2002 entitled “Anterior Impacted Bone Graft and Driver Instruments”, which is a continuation of PCT patent application Ser. No. PCT/US01/05638 filed Feb. 22, 2001 entitled “Anterior Impacted Bone Graft and Driver Instruments” which was published in English under Article 21(2) and which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/183,930 filed Feb. 22, 2000 entitled “Instruments and Implants for Multi-Directional Insertion of a Vertebral Spacer” which are hereby incorporated by reference in their entirety.
The present invention relates generally to instruments and implants for intervertebral spacing. More specifically, the present invention provides instruments and implants that may be utilized to provide multi-directional insertion techniques to establish and maintain intervertebral spacing. Still more preferably, the present invention provides implants made of bone adapted to be inserted from more than one direction while maintaining proper orientation in the disc space.
The removal of damaged or diseased discs and restoration of disc space height to treat chronic back pain and other ailments, is well-known. Spacers are often utilized to maintain or reestablish disc space height after removal of all or a portion of the disc. Such spacing implants may include those promoting fusion between adjacent vertebral bodies, inert implants, and artificial disc implants. Such implants are typically designed to be inserted from an anterior, posterior or lateral approach. However, such implants are often designed for insertion only from one of the particular approaches to the spine. This is particularly true where implants are intended to maintain non-parallel angulation between adjacent vertebrae. Therefore, multiple implants each designed for insertion from one of the various approaches to the spine must be maintained in inventory to accommodate the various surgical demands of each procedure. Maintaining multiple implant designs may create inventory problems for both manufacturers and their customers. Moreover, the complications of creating multiple implants to accomplish the same desired spacing is compounded when implants are made of a scarce resources, such as allograft bone.
Therefore, there remains a need for instruments, techniques, and implants that reduce implant inventory without sacrificing desired implant configurations.
The present invention provides for instruments to implant a single implant design from multiple approaches to the disc space. In a preferred aspect of the present invention, instruments are provided for inserting an implant from a direct anterior approach to the spine and from an oblique-anterior approach to the spine.
In a further aspect of the present invention, an implant is provided that includes features permitting insertion into the disc space from multiple directions. In a preferred aspect of the present invention, the implant may be configured for insertion from a direct anterior approach as well as an anterior-lateral approach to the spine. Still more preferably, the anterior-lateral approach to the spine is from an oblique angle with respect to the sagittal plane.
In still a further aspect of the present invention, a multi-faceted implant is provided comprising an implant body having a first pair of substantially parallel side walls and a second pair of substantially parallel side walls. The second pair of substantially parallel side walls are disposed at an oblique angle with respect to the first pair of substantially parallel side walls. The angulation between the first and second set of parallel side walls permits insertion of the implant into the disc space from multiple directions. Further in one preferred embodiment the distance between the first pair of side walls is substantially identical to the distance between the second pair of side walls. One choice is to dispose the second pair of side walls at an angle of approximately 30 degrees with respect to the first pair of side walls. In a more preferred aspect of the present invention, the implant body has upper and lower bone engaging surfaces that are tapered to maintain angulation between adjacent vertebrae. In still further preferred aspects of the invention, one of each of the first and second pair of side walls includes an insertion tool bore.
In yet a further aspect of the present invention, a method of making an implant of boney material is provided. The method comprises forming a first pair of substantially parallel side walls on the boney material. A second pair of substantially parallel side walls is formed at an oblique angle with respect to the first pair of side walls. In one aspect the method further includes forming a plurality of driving surfaces on the donor bone. Still more preferably, the upper and lower bone engaging surfaces are disposed at an angle with respect to each other.
In still a further aspect of the invention an implant inserter is provided. Preferably, the implant inserter includes anti-rotation components to limit rotation of the implant about the longitudinal axis of the inserter and rotation about the axis of the implant itself. In one preferred embodiment, the anti-rotation components comprise a pair of angled side walls on the inserter adapted to engage a pair of corresponding surfaces on the implant. In still a further preferred aspect, a threaded post engages a corresponding opening on the implant and the angled surfaces are spaced from the opening to limit stress placed on the implant adjacent the opening.
These and other objects of the present invention will become apparent from the following description of the preferred embodiments.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
The present invention provides implants and instruments for multi-directional implantation of an intervertebral spacer. Additional instrumentation and techniques for disc space preparation are disclosed in Provisional Application entitled “Instruments and techniques for Disc Space Preparation,” filed Feb. 22, 2000. The disclosure of the referenced Provisional Application is incorporated herein by reference in its entirety. Referring now to
Implant 10 includes a pair of opposing side walls 24 and 26 formed in substantial parallel alignment with longitudinal axis 64. A further pair of oblique angled side walls 20 and opposing side wall 28 are formed at an angle A5 with respect to side walls 26 and 24. In a preferred embodiment, angle A5 is approximately 30 degrees. In a preferred aspect, from driving wall 18 extends substantially perpendicular to longitudinal axis 64 and at an angle of A4 with respect to angled surface 20. In a preferred embodiment, angle A4 is substantially 60 degrees. Implant 10 includes a front face 18 and an opposing end face 30. While not required, front face 18 and face 30 are planar surfaces in substantially parallel alignment. Further, front face 18 is substantially parallel to end face 30. A first opening 40 is formed in implant 10 and is internally threaded to received an externally threaded post. Internally threaded opening 40 extends substantially along longitudinal axis 64 and in substantial alignment with side walls 24 and 26. A second bore 42 has an axis 66 extending substantially parallel to axis 64 and spaced at a distance D9 therefrom. Bore 42 is adapted to receive a substantially smooth pin. It will be understood that a pin extending in bore 42 will limit the tendency of implant 10 to rotate as an externally threaded rod is inserted into threaded opening 40. In a preferred aspect, distance D9 is approximately 5 mm.
Referring now to
Referring still further to
As shown most clearly in
Dimensions of donor bone vary depending on the source of the bone, as well as the specific location of the source of an allograft ring taken along a bone, such as the femur. In one aspect of the invention, intended for use in the lumbar spine, it is preferred that the implant have certain minimal dimensions for the safety and efficacy of the device. While such dimensions are disclosed herein, it is contemplated that dimensions may be altered for various implants in the lumbar, thorasic, and cervical spine without deviating from the present invention provided that the implant provides the desired strength and stability. Specifically, minimum dimensions are given from the surface of the outer side walls to central channel 16. As previously indicated, central channel 16 is preferably defined by the naturally occurring medullary canal. However, it may be altered or increased by additional machining to form a channel having desired dimensions or shapes. Side wall 19 has a dimension D5. Side wall 25 has a dimension D7. Side wall 31 has a dimension D4. Side wall 27 has a dimension D8. In a preferred aspect, dimensions D5, D7, and D8 are limited to a minimum thickness of 4 mm. Dimension D4 may have an even smaller minimum thickness of approximately 3 mm.
Referring now to
In a preferred embodiment, upper surface 12 includes buttressed ridges 13 providing an anti-migration surface to engage adjacent vertebral bone upon insertion and limit movement out of the disc space. In a similar fashion, lower bone engaging surface 14 includes a plurality of buttressed bone engaging ridges 15. Bone engaging ridges 15 are shown in greater detail in
The present invention further includes an implant inserter, such as that shown in
Distal guide 88 includes upper and lower tapered guiding surfaces 89 and 95, respectively. Guide 88 also includes substantially parallel opposed side walls 91 and 93. Guide 88 has a width W1 extending between side walls 91 and 93. Further, with reference to
Referring now to
In still another aspect of the invention, an oblique inserter is shown in
Referring now to
Referring now to FIGS. 15(a) and 15(b), implant inserter 110 is shown here connected with implant 10. Implant 10 is coupled to implant inserter 110 by engagement of externally threaded portion 120 of the inner shaft with internally threaded opening 44. Driving surfaces 126, 128, and 130 of distal guide 118 substantially engage surfaces 26, 22, and 18, respectively, of implant 10. It will be understood that driving surfaces of distal guide 118 are configured to substantially mate with the external surfaces of implant 10 such that force transmitted on the implant inserter tending to urge the implant into the disc space is substantially transmitted to implant 10. Additionally, angled side walls 126 and 130 inhibit rotation of implant 10. Further, in a preferred aspect, substantially parallel side walls 20 and 28 of implant 10 are in substantial parallel alignment with opposing parallel side walls 122 and 124 of distal guide 118. Width W2 of distal portion 118 is substantially equal to or greater than the width D6 between opposing side walls 20 and 28 of implant 10.
Referring now to FIGS. 16-19(b), a further embodiment of an implant according to the present invention is shown. Implant 200 includes an upper bearing surface 228 and opposing lower bearing surface 230. Each of the upper and lower bearing surfaces include anti-migration members. In a preferred aspect of the invention, the anti-migration members are comprised of buttressed ridges extending substantially perpendicular to side walls 212 and 220. Still more preferably, upper and lower bearing surfaces 228 and 230 extend at an angle A25 with respect to one another forming a tapered implant. It is contemplated that angle A25 may have a variety of angles, but in a preferred embodiment specifically adapted for establishing and maintaining lumbar lordosis, angle A25 is approximately 8 degrees. Further, the implant has a maximum height of H20, which in a preferred aspect is approximately 21 mm.
As with the implant according to the first embodiment shown in
The driving walls of implant 200 have been modified in comparison to the implant of
Referring now to FIGS. 20(a)-21(c), a straight implant inserter according to another aspect of the present invention is illustrated. Implant inserter 250 is substantially identical to the implant inserter of
Referring now to drawing FIGS. 22(a) and 22(b), implant inserter 250 is shown selectively coupled to implant 200. Distal guide 252 abuttingly engages implant 200. More specifically, angled drive surfaces 256 and 258 abuttingly engage angled drive surfaces 210 and 208, respectively. It will be understood that angled surfaces act to inhibit rotation of implant 200. Angled surfaces 256 and 258 limit rotation of the implant about the longitudinal axis of the inserter as the threaded post is engaged to implant 200 and rotation of the implant about itself as force is applied to urge the implant into the disc space. Thus, the angled drive surfaces provide secure engagement with the implant without the need for additional openings that may weaken the implant walls. Concave surface 260 is intended to be spaced from naturally occurring surface 206 such that machining of surface 206 is not required to provide the requisite clearance. Further, by spacing the driving walls from the wall having the threaded opening, force applied to the implant during insertion is concentrated away from the implant opening thereby having less tendency to cause fracture. This may be particularly beneficial where somewhat brittle materials, such as bone or ceramics, are used to form the implant. As shown in FIGS. 22(a)-(b), with implant 200 securely engaged with driver 250, opposing implant side walls 200 and 220 are in substantial alignment with implant driver side walls 257 and 259. It will be understood that by providing angled driving surfaces rather than a single planar drive surface, more of the natural architecture of the bone may be maintained, thereby increasing the strength of the implant. While angled drive surfaces are shown as substantially planar surfaces it will be understood that they may also be arcuate, concave, convex, or complex surfaces.
Implant 200 may be inserted into a vertebral disc space properly prepared for receipt from a direct anterior approach. As shown in
Referring now to FIGS. 24(a)-24(c), implant 200 is shown disposed in a prepared end plate of vertebral V1. It will be understood that an opposed vertebra is disposed above the implant creating a disc space, but the upper opposed vertebra has been removed from the illustration for the purpose of clarity. Implant 200 is shown disposed in channel C1 defined in the end plate of vertebra V1. One method of forming channel C1 is disclosed in Provisional Application entitled “Instruments and Techniques for Disc Space Preparation,” filed on Feb. 22, 2000, which is incorporated herein by reference. Channel C1 extends in a direction extending from the anterior to the posterior portion of the vertebra and is configured for direct anterior insertion of an implant. End surface 216 is shown in substantial alignment with posterior portion 274 of channel C1. Thus, end surface 216 is disposed substantially adjacent the posterior portion 275 of vertebra V1. Side walls 212 and 220 are disposed laterally with respect to vertebra V1. Thus, implant 200 is disposed in the disc space between vertebra V1 and the upper opposed vertebra (not shown) such that the taper between opposed bone engaging surfaces 228 and 230 is in proper alignment and orientation to maintain the appropriate angular relationship between the opposing vertebral bodies.
Referring now to FIGS. 25(a)-28, there is shown an implant inserter 300 adapted for insertion of implant 200 from an anterior-oblique approach to the spine. Inserter 300 includes features also found in implant inserter 250 with the exception that distal guide 302 has been configured to permit engagement with an implant for oblique insertion. Distal guide 302 includes a first angled drive surface 310 disposed at an angle A33 with respect to side wall 306. In a preferred embodiment, A33 is approximately 42 degrees. A second angled drive surface 314 is disposed at an angle A32 with respect to side wall 308. In the preferred aspect, A32 is approximately 30 degrees. A third angled surface 312 is disposed at an angle A30 with respect to angled drive surface 310 and an angle A31 with respect to angled drive surface 314. In a preferred embodiment, angle A30 is approximately 144 degrees and angle A31 is approximately 108 degrees. Additionally, an internal bore 316 is formed through distal guide 302. Bore 316 is formed a distance D30 from side wall 308 and a distance D31 from side wall 306. In a preferred aspect of the invention, D31 is greater than the distance D30 such that bore 316 is offset with respect to the longitudinal axis of guide 302. More specifically, distance D30 is approximately 12 mm and distance D31 is approximately 15 mm.
Referring to FIGS. 29(a) and 29(b), implant inserter 300 is shown selectively coupled to implant 200. Angled driving surfaces 310 and 314 are in abutting engagement with driving surfaces 212 and 208. It will be noted that angled surface 312 and 310 have sufficient length such that side wall 206 is not intended to be in substantial contact with the implant driver. Further, it is contemplated that surface 312 may be spaced slightly from wall 210 to limit stress on the implant adjacent opening 226. Implant 200 is aligned with distal guide 302 such that opposing side walls 214 and 222 are in substantial alignment with side walls 308 and 306, respectively, of distal guide 302. Moreover, angled driving surfaces 310 and 314 cooperate to limit implant rotation.
Referring now to FIGS. 30(a)-31(c), a distraction window 342 is disposed in a disc space created by vertebra V2 and an opposing upper vertebra (not shown) with distraction extensions 344 and 346 extending into the disc space. Distraction window 342 is positioned in the disc space from an anterior-oblique angle approach to the spine. Specifically, reference line 348 represents a direct anterior approach to the spine, in substantial alignment with the sagittal plane. In the anterior-oblique approach, distraction window 342 is positioned into the disc space from an angled approach shown by angle A35. In a preferred embodiment, with opposing angled side walls disposed at an approximately 30 degree angle, angle A35 is approximately 30 degrees. A guide tube 340 is selectively coupled to distraction window 342, thereby forming a substantially rectangular working channel into the disc space. Inserter 300 with interconnected implant 200 is then inserted through guide sleeve 340 until implant 200 is disposed in the disc space in preformed channel C2. The guide sleeve has dimensions substantially corresponding to the implant dimensions, thereby limiting the amount of tissue, vessels and other structures that must be removed or retracted for placement of the implant. The inner shaft is then rotated to release implant inserter from implant 200. The implant inserter, guide tube, and distraction window may then be removed. The orientation of implant 200 in comparison to vertebra V2 is substantially identical to the orientation of implant 200 with respect to vertebra V1 shown in FIGS. 24(a)-24(c). End wall 216 is in substantial alignment with posterior portion 274 of channel C2. End wall 216 is disposed substantially adjacent posterior portion 275 of vertebra V2. Further, opposed side walls 212 and 250 are in substantial lateral alignment with the lateral portions of vertebra V2. Thus, it will be understood that implant 200 is positioned in the disc space with the tapering surfaces 228 and 230 extending in the proper orientation to provide maintenance of angulation between vertebra V2 and the opposing upper vertebra (not shown).
While not shown by illustration, it will be understood that the implants described herein may be inserted from a direct lateral approach to the spine. The same orientation in the disc space may be achieved regardless of the direction of insertion and the guiding instruments used.
Thus, the present invention provides an implant having multiple facets or substantially parallel side walls allowing uniform orientation of the implant in the disc space although it is inserted by multiple, often guided, approaches to the spine. Specifically, the embodiments of the implants according to the present invention permit insertion from a direct anterior, oblique-anterior and a direct lateral approach to the spine. While preferred embodiments of the invention has disclosed three pair of substantially parallel side walls disposed at a various angles, it is contemplated that more than three pair of substantially parallel side walls could be utilized to provide for implant insertion from a plurality of angles. Further, while a particular angle of 30 degrees has been utilized for the purposes of illustration in a preferred embodiment, it will be understood that any oblique angle might be utilized to provide for insertion from multiple approaches from the spine.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.