DEVICE AND METHOD TO ACCESS THE ANTERIOR COLUMN OF THE SPINE
Methods and devices are configured to permit a surgeon to access the anterior column of the spine without significant manipulation of intervening nerve elements.
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This application is a divisional of and claims priority to co-pending U.S. patent application Ser. No. 12/573,813 filed on Oct. 5, 2009 of the same title, and published as U.S. Patent Application Publication No. 2010/0087878 also of the same title, which is hereby incorporated by reference in its entirety, and which claims priority of co-pending U.S. Provisional Patent Application Ser. No. 61/195,191 filed Oct. 4, 2008. Priority of the aforementioned filing date is hereby claimed and the disclosure of the Provisional Patent Application is hereby incorporated by reference it its entirety.
BACKGROUNDThe surgical reconstruction of the bony skeleton is a common procedure in current medical practice. Regardless of the anatomical region or the specifics of the reconstructive procedure, many surgeons employ an implantable device that can adjust, align and maintain the spatial relationship(s) between adjacent bones. An extensive array of surgical techniques and implantable devices have been formulated to accomplish this goal.
Symptomatic degeneration of the lumbar spine occurs most commonly at the L4/5 and L5/S 1 levels and fusion of one or both of these segments has emerged as a common surgical procedure. Currently, these vertebral bodies may be fused using an anterior, lateral or posterior approach and each has particular advantages and draw backs. Frequently, circumferential fusion of the unstable level with fixation of both the anterior and posterior aspect of the spine is desired. This requires that patients undergo a combination of the aforementioned approaches. The anterior or lateral approaches are used to insert the bone graft into the disc space between the adjacent vertebras while the posterior approach is used to place bone screws or similar fasteners that are used to immobilize the vertebral bodies.
Access to the disc space for bone graft placement requires dissection through the vital tissues that lie anterior or lateral to the spine. U.S. Pat. No. 7,309,338 and others disclose a method for the access of the anterior column of the lumbar spine using a pre-sacral approach. (U.S. Pat. No. 7,309,338 is hereby incorporated by reference in its entirety.) The procedure has been popularized by the corporation TranS1, Inc of Wilmington, N.C. as the “AXLIF” procedure. The technology for both the L5 to S1 fusion procedure and the L4 to S1 fusion procedure are described on the web site “www.trans1.com”. All contents and disclosures of the web site are hereby incorporated by reference in their entirety. The procedure is further described in the article: A novel minimally invasive pre-sacral approach and instrumentation technique for anterior L5/S1 intervertebral discectomy and fusion. By Marotta et al., Neurosurg. Focus 20 (1): E9, 2006. The article is hereby incorporated by reference in its entirety.
With experience, an important shortcoming of the “AXLIF” procedure has been discovered. The procedure, which entails placement of a threaded screw or a threaded rod through an anterior segment of the sacrum and into the superior vertebral bones, fails to provide adequate segmental fixation in rotation and other planes of spinal motion. Thus, the “AXLIF” procedure must be supplemented with additional screw and orthopedic device stabilization in order to adequately immobilize the operative segment. Most commonly, posterior screw/rod fixation into the pedicle portion of the vertebral bones is used to supplement the “AXLIF” procedure. Unfortunately, the need to provide supplement fixation through alternative surgical corridors, such as the posterior approach to the spine, greatly limits the usefulness of the “AXLIF” procedure and obviates the advantages that the procedure provides over other current art.
SUMMARYIt is a goal of the present disclosure to supplement the “AXLIF” procedure with additional fixation placed onto the sacrum and vertebral bodies of superior bones through a pre-sacral surgical corridor. The pre-sacral surgical corridor designates a soft tissue corridor developed onto the anterior surface of the sacrum and extending from a skin incision at about the level of the coccyx and extending cephalad to at least the level of the 83 vertebral bone. In this way, the need for additional fixation onto the posterior aspect of the lumbar spine is minimized.
In one aspect, a method for fixation of a sacral bone is disclosed. In one embodiment, the fixation is with at least an immediately superior vertebral bone, and the method includes: (i) creating a first borehole into an anterior surface of the sacral bone, (ii) advancing a first fixation post through the first borehole, the sacral bone, and a disc space immediately superior to the sacral bone, and into a superior vertebral bone, the superior vertebral bone being immediately superior to the disc space, (iii) positioning a fixation element (e.g., plate in one variant) onto the anterior surface of the sacral bone, the fixation element configured to abut the anterior surface of the sacral bone and to remain separated from the disc space and the superior vertebral bone, and (iv) advancing at least a second fixation post through the sacral bone, the disc space, and into the superior vertebral bone, the second fixation post being further positioned within an aperture of the fixation element.
In another aspect, an apparatus for fixation of a sacral bone is disclosed. In one embodiment, the fixation is with at least an immediately superior vertebral bone, and the apparatus includes: a first fixation post configured to be advanced through a first borehole created in an anterior surface of the sacral bone, and a disc space immediately superior to the sacral bone, and into a vertebral bone immediately superior to the disc space, a fixation element configured to abut the anterior surface of the sacral bone and to remain separated from the disc space and the vertebral bone, the fixation element comprising at least an aperture, and a second fixation post configured to be advanced through the sacral bone, the disc space, and into the vertebral bone, at least a portion of the second fixation post being positioned within the aperture of the fixation element.
Other features and advantages should be apparent from the following description of various embodiments, which illustrate, by way of example, the principles of the disclosed devices and methods.
In order to promote an understanding of the principals of the disclosure, reference is made to the drawings and the embodiments illustrated therein. Nevertheless, it will be understood that the drawings are illustrative and no limitation of the scope of the invention is thereby intended. Any such alterations and further modifications in the illustrated embodiments, and any such further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one of ordinary skill in the art.
Vertebral bone 802 contains an anteriorly-placed vertebral body 804, a centrally placed spinal canal and 806 and posteriorly-placed lamina 808. The pedicle (810) segments of vertebral bone 802 form the lateral aspect of the spinal canal and connect the laminas 808 to the vertebral body 804. The spinal canal contains neural structures such as the spinal cord and/or nerves. A midline protrusion termed the spinous process (SP) extends posteriorly from the medial aspect of laminas 808. A protrusion extends laterally from each side of the posterior aspect of the vertebral bone and is termed the transverse process (TP). A right transverse process (RTP) extends to the right and a left transverse process (L TP) extends to the left. A superior protrusion extends superiorly above the lamina on each side of the vertebral midline and is termed the superior articulating process (SAP). An inferior protrusion extends inferiorly below the lamina on each side of the vertebral midline and is termed the inferior articulating process (IAP). Note that the posterior aspect of the pedicle can be accessed at an indentation 811 in the vertebral bone between the lateral aspect of the SAP and the medial aspect of the transverse process (TP). In surgery, it is common practice to anchor a bone fastener into the pedicle portion of a vertebral bone by inserting the fastener through indentation 811 and into the underlying pedicle.
The preceding illustrations and definitions of anatomical structures are known to those of ordinary skill in the art. They are described in more detail in Atlas of Human Anatomy, by Frank Netter, third edition, Icon Learning Systems, Teterboro, N.J. The text is hereby incorporated by reference in its entirety.
Disclosed are methods and devices that permit a surgeon to access the anterior column of the spine without significant manipulation of the intervening nerve elements. (The “anterior column” is used here to designate that portion of the vertebral body and/or FSU that is situated anterior to the posterior longitudinal ligament. Thus, its use in this application encompasses both the anterior and middle column of Denis. See The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. By Denis, F. Spine 1983 November-December; 8(8):817-31. The article is incorporated by reference in its entirety.)
The “AXLIF” procedure is more fully described within the previously listed and incorporated article and web site. An abbreviated description of the procedure follows and those of ordinary skill in the art will understand that the description does not fully recite all of the features and operative steps of the “AXLIF” procedure.
A skin incision is placed lateral to and at the approximate level of the coccyx. The surgeon's finger is used to bluntly dissect the colon and other soft tissues away from the anterior surface of the sacrum. Blunt dissection is continued with finger and instrument dissection until the anterior aspect of the S1 and S2 bones are reached. The anterior bony surface of the sacrum is entered at approximately the level of the intersection of the lower aspect of S1 and the superior aspect of S2. A hole is drilled through the S1 body portion of the sacrum and advanced into the L5/S1 disc space. An L5/S1 discectomy is performed through the formed sacral bore hole and the disc space is packed with bone graft or bone graft substitute. Preferably, the totality of the procedure is performed in a percutaneous manner, under X-ray guidance and through specifically designed hollow tubes. The bore hole is extended into the L5 vertebral body and a threaded screw is placed into the S1 body, across the L5/S1 disc space and into the L5 vertebral body. (See the previously listed referenced and incorporated web site and article for a full description of the “AXLIF” procedure).
An embodiment of the threaded screw is shown in a perspective view in
An internal bore 102 rests within screw 100 and contains threaded segment 103. Hex drive segment 107 is located on an end of internal bore 102 of screw 1 00. Segment 107 is used to engage a hex-ended screw driver (not shown), wherein the driver is adapted to rotate and drive screw 100 into bone.
Plate 120 is shown in
In use, the bottom surface 1204 of the plate is adapted to rest against the anterior bony surface of the sacrum. Protrusions 128 are adapted to anchor into the anterior sacral surface and provide additional contact and fixation with the sacral bone. A threaded screw 131 is adapted to traverse the upper bore hole Y1 and engage threads 103 of bore 102 of screw 100 (see
Since the internal aspect of the vertebral body contains bone that is less dense and less resistant to screw pull-out than an exterior wall of the vertebral body, the distal tips of screws 133 are preferably driven into the more dense surfaces of the exterior walls of the L5 vertebral body. For example, while not shown in the
As an additional mechanism to strengthen the bony fixation provided by the plate and screw set, a locking mechanism is contemplated that would lock the head of screws 131 and 133 onto plate 120. This may be accomplished in a number of ways. In an embodiment, plate cover 1222 is used to forcibly capture and frictionally lock the head of screws 131 and 133 onto plate 120. Locking cover 1222 is shown in
It is a goal of the present disclosure to supplement the “AXLIF” procedure with additional fixation placed onto the sacrum and vertebral bodies of superior bones through a pre-sacral surgical corridor. In the preceding embodiments, a plate and bone screw assembly which has been implanted onto the anterior aspect of the sacrum using a pre-sacral surgical corridor is used to supplement the fixation of the “AXLIF” procedure. The pre-sacral surgical corridor designates a soft tissue corridor developed onto the anterior surface of the sacrum and extending from a skin incision at about the level of the coccyx and extending cephalad to at least the level of the S3 vertebral bone. The plate preferably attaches to the threaded screw 100 of the “AXLIF” procedure. The bone screws 133 are preferably anchored distally onto a rigid aspect/wall of the L5 vertebral body and attached proximally onto the plate using a plate/screw locking mechanism. While the invention has been illustrated for use in L5 to sacrum fixation, it is understood that the procedure can be similarly applied in L4 to sacrum fixation. In the latter, the bone screws 133 extend from the plate to the L4 vertebral body. As before, they preferably anchor distally onto a rigid aspect/wall of the L4 vertebral body (side walls, posterior body wall, superior body wall, inferior body wall and/or the internal aspect of the pedicle/vertebral body interface an the like) and attached proximally onto the plate using a plate/screw locking mechanism.
In an additional embodiment, fixation of a screw 133 onto a vertebral bone cephalad to the sacrum (such as L5, L4 or above) can be further enhanced by advancing an additional bone anchor into the superior bone and joining screw 133 to that anchor. Since the trajectory of the additional bone anchor may be different than that of a screw 133, the overall trajectory of the joined screw 133/additional anchor assembly will differ than that of screw 133 alone. This property can be advantageously used to place a screw 133 though a pre-sacral approach and have the distal aspect of the joined screw 133/additional anchor assembly screw rest at a point that is posterior to the center of rotation (IAR) of the function spinal unit that is being fixated. This concept and method of use will be more fully discussed below.
Anchor 330 is shown in
In use for L5 to sacrum fixation, anchor 330 is advanced into the pedicle portion of the L5 vertebral bone using a posterior surgical corridor so that the shank 334 enters the vertebral bone at approximately location 811 (
Screw 133 has central bore 1330 adapted to accept wire 365. Screw 133 is rotated and advanced over wire 365 until the distal end resides within bore 344 of anchor 330. The placed screw 133 is shown in
With reference to
While the preceding embodiment has be illustrated for L5 to sacral fusion, it is understood that the same devices and method can be used at fixate the L4 vertebral bone to the sacrum. In that embodiment, an additional anchor 330 is advanced into each of the two pedicle portions of the L4 vertebral bone. A screw 133 is placed through each of bores X and guided to bore 344 of the corresponding anchor 330 using a surgical guide and wire 365 as previously described. The set screw 372 of each anchor 330 is tightened after placement of screw 133. The proximal aspect of each screw 133 is also locked to plate 120 (which is in turn affixed to screw 100 via screw 131 and bore Y) by a screw to plate locking mechanism.
The preceding disclosure teaches multiple embodiments to supplement the bone fixation strength of the “AXLIF” procedure by placing a plate and screw assembly that has been placed through a pre-sacral surgical corridor. While describe as separate embodiments, the various mechanisms may be used in combinations to produce additional assemblies that have not been specifically described herein, but, nevertheless, would fall within the scopeof this invention.
The disclosed devices or any of their components can be made of any biologically adaptable or compatible materials. Materials considered acceptable for biological implantation are well known and include, but are not limited to, stainless steel, titanium, tantalum, combination metallic alloys, various plastics, resins, ceramics, biologically absorbable materials and the like. Any components may be also coated/made with nanotube materials to further impart unique mechanical or biological properties. In addition, any components may be also coated/made with osteo-conductive (such as deminerized bone matrix, hydroxyapatite, and the like) and/or osteo-inductive (such as Transforming Growth Factor “TGF-B,” Platelet-Derived Growth Factor “PDGF,” Bone-Morphogenic Protein “BMP,” and the like) bio-active materials that promote bone formation. Further, any surface may be made with a porous ingrowth surface (such as titanium wire mesh, plasma-sprayed titanium, tantalum, porous Coer, and the like), provided with a bioactive coating, made using tantalum, and/or helical rosette carbon nanotubes (or other carbon nanotube-based coating) in order to promote bone in-growth or establish a mineralized connection between the bone and the implant, and reduce the likelihood of implant loosening. Lastly, the system or any of its components can also be entirely or partially made of a shape memory material or other deformable material.
Although embodiments of various methods and devices are described herein in detail with reference to certain versions, it should be appreciated that other versions, embodiments, methods of use, and combinations thereof are also possible. Therefore the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
Although embodiments of various methods and devices are described herein in detail with reference to certain versions, it should be appreciated that other versions, embodiments, methods of use, and combinations thereof are also possible. Therefore the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
Claims
1. (canceled)
2. A method for fixation of a sacral bone with at least an immediately superior vertebral bone, comprising:
- creating a first borehole into an anterior surface of said sacral bone;
- advancing a first fixation post through said first borehole, said sacral bone, and a disc space immediately superior to said sacral bone, and into a superior vertebral bone, said superior vertebral bone being immediately superior to said disc space;
- positioning a fixation element onto said anterior surface of said sacral bone, said fixation element configured to abut said anterior surface of said sacral bone and to remain separated from said disc space and said superior vertebral bone; and
- advancing at least a second fixation post through said sacral bone, said disc space, and into said superior vertebral bone, said second fixation post being further positioned within an aperture of said fixation element.
3. The method of claim 2, further comprising causing at least a portion of said fixation element to at least partially cover said first borehole.
4. The method of claim 2, further comprising enhancing fixation of said fixation element onto said anterior surface of said superior vertebral bone via providing at least one protrusion on a surface of said fixation element configured to abut said anterior surface of said sacral bone.
5. The method of claim 2, wherein said acts of advancing said first and second fixation posts comprises advancement such that a trajectory thereof diverges within said sacral bone.
6. The method of claim 2, wherein said act of advancing said first fixation post into said superior vertebral bone comprises advancing said first fixation post into an L5 vertebral bone.
7. The method of claim 6, further comprising at least partially engaging a cortical surface of a side wall of said L5 vertebral bone via said second fixation post.
8. The method of claim 6, further comprising causing said second fixation post to at least partially extend into an L4 vertebral bone.
9. The method of claim 6, further comprising advancing a third fixation post through said sacral bone, said disc space, and into said L5 vertebral bone.
10. The method of claim 9, further comprising positioning said third fixation post within a second aperture of said fixation element.
11. The method of claim 9, wherein said acts of advancing said second and third fixation posts comprises advancement such that a trajectory thereof diverges within said sacral bone.
12. The method of claim 9, further comprising at least partially engaging a cortical surface of a side wall of said L5 vertebral bone via said third fixation post.
13. The method of claim 9, wherein said act of advancing said third fixation post further comprises causing said third fixation post to at least partially extend into an L4 vertebral bone.
14. The method of claim 2, further comprising inserting said first fixation post into a third aperture of said fixation element.
15. The method of claim 2, further comprising rigidly affixing said second fixation post onto said fixation element via a locking feature of said fixation element.
16. The method of claim 15, further comprising substantially immobilizing said second fixation post with respect to said first fixation post via said locking feature.
17. An apparatus for fixation of a sacral bone with at least an immediately superior vertebral bone, said apparatus comprising:
- a first fixation post configured to be advanced through a first borehole created in an anterior surface of said sacral bone, and a disc space immediately superior to said sacral bone, and into a vertebral bone immediately superior to said disc space;
- a fixation element configured to abut said anterior surface of said sacral bone and to remain separated from said disc space and said vertebral bone, said fixation element comprising at least an aperture; and
- a second fixation post configured to be advanced through said sacral bone, said disc space, and into said vertebral bone, at least a portion of said second fixation post being configured to be positioned within said aperture of said fixation element.
18. The apparatus of claim 17, wherein said fixation element comprises a substantially plate-like structure which is further configured to at least partially cover said first borehole.
19. The apparatus of claim 18, wherein a surface of said fixation element configured to abut said anterior surface of said sacral bone comprises at least one protrusion configured to enhance plate fixation onto said sacral bone.
20. The apparatus of claim 17, wherein a trajectory of said first and said second fixation posts diverges within said sacral bone.
21. The apparatus of claim 17, wherein said immediately superior vertebral bone comprises an L5 vertebral bone.
22. The apparatus of claim 21, wherein said second fixation post is configured to at least partially engage a cortical surface of a side wall of said L5 vertebral bone.
23. The apparatus of claim 21, wherein said second fixation post is configured to at least partially extend into an L4 vertebral bone.)
24. The apparatus of claim 21, wherein a third fixation post is configured to advance through said sacral bone, said disc space, and into said L5 vertebral bone.
25. The apparatus of claim 24, wherein said third fixation post is further positioned within a second aperture of said fixation element.
26. The apparatus of claim 24, wherein a trajectory of said second and said third fixation posts diverge within said sacral bone.
27. The apparatus of claim 24, wherein said third fixation post is configured to at least partially engage a cortical surface of a side wall of said L5 vertebral bone.
28. The apparatus of claim 24, wherein said third fixation post is configured to at least partially extend into an L4 vertebral bone.
29. The apparatus of claim 17, wherein said first fixation post is inserted to a third aperture of said fixation element.
30. The apparatus of claim 17, wherein said fixation element comprises a locking feature configured to rigidly affix said second fixation post onto said fixation element, the locking feature configured to substantially immobilize said second fixation post with respect to said first fixation post.
31. An apparatus for fixation of a sacral bone, comprising:
- a first fixation element configured to be advanced through a first hole created in a first surface of said sacral bone, and a disc space superior to said sacral bone, and into a vertebral bone superior to said disc space;
- a fixation apparatus configured to abut said first surface of said sacral bone and to remain separated from said disc space and said vertebral bone, said fixation apparatus comprising at least an aperture; and
- a second fixation element configured to be advanced through said sacral bone, said disc space, and into said vertebral bone, at least a portion of said second fixation element being configured to be positioned within said aperture of said fixation apparatus.
Type: Application
Filed: Jan 16, 2013
Publication Date: Aug 1, 2013
Applicant: (San Diego, CA)
Inventor: SAMY ABDOU (San Diego, CA)
Application Number: 13/743,240
International Classification: A61B 17/86 (20060101); A61B 17/84 (20060101);