LATERAL APPROACH EXPANDABLE SPINAL IMPLANT AND METHOD
An expandable interbody fusion device configured for placement into the intradiscal space between vertebral bodies in a lumbar spine from a lateral approach. The device is expanded by the insertion of a plurality of wafers into the device in situ. The length of the device is configured to extend on the vertebral body endplate from pedicle to pedicle and to reside interiorly of the ring apophysis with at least a portion of the device resting on the area of increased bone density at the posterior portion of the endplate between the pedicles.
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This application is a National Stage Application under 35 U.S.C. §371 of PCT International Application No. PCT/US2012/054055, filed Sep. 7, 2012, which claims priority to U.S. Provisional Patent Application No. 61/532,673, filed on Sep. 9, 2011, the entire contents of which are incorporated by reference herein.
FIELD OF THE INVENTIONThe subject invention relates generally to the field of spinal implants and more particularly to expandable interbody fusion devices and methods for implanting such devices in a lateral approach.
BACKGROUNDSpinal implants such as interbody fusion devices are used to treat degenerative disc disease and other damages or defects in the spinal disc between adjacent vertebrae. The disc may be herniated or suffering from a variety of degenerative conditions, such that the anatomical function of the spinal disc is disrupted. Most prevalent surgical treatment for these conditions is to fuse the two vertebrae surrounding the affected disc. In most cases, the entire disc will be removed, except for a portion of the annulus, by way of a discectomy procedure. A spinal fusion device is then introduced into the intradiscal space and suitable bone or bone substitute material is placed substantially in and/or adjacent the device in order to promote fusion between two adjacent vertebrae.
Spinal fusion devices may be inserted during a spinal surgical procedure using an anterior, posterior, posterior lateral or extrapedicular approach. Certain spinal devices for achieving fusion using such approaches are also expandable so as to correct disc height between the adjacent vertebrae. Examples of expandable interbody fusion devices are described in U.S. Pat. No. 6,595, 998 entitled “Tissue Distraction Device”, which issued on Jul. 22, 2003 (the '998 Patent) and U.S. Pat. No. 7,967,867 entitled “Expandable Interbody Fusion Device”, which issued on Jun. 28, 2011(the '867 Patent). The '998 Patent and the '867 Patent each discloses sequentially introducing in situ a series of elongate inserts referred to as wafers in a percutaneous approach to incrementally distract opposing vertebrae to stabilize the spine and correct spinal height, the wafers including features that allow adjacent wafers to interlock in multiple degrees of freedom. The '998 Patent and the '867 Patent are both assigned to the same assignee as the present invention, the disclosures of both patents being incorporated herein by reference in their entirety.
Other spinal fusion devices may be inserted into the disc space using a lateral approach, as shown for example, in U.S. Pat. No.7, 749,269 which issued on Jul. 6, 2010 and is assigned on its face to Warsaw Orthopedic, Inc. (the '269 Patent) and U.S. Pat. No. 7,918,891 which issued Apr. 5, 2011 and is assigned on its face to NuVasive Inc.(the '891 Patent). The fusion devices described in both the '269 Patent and the '891 Patent are monolithic implants of fixed dimensions with neither having capability of expansion or tissue distraction once introduced into the intradiscal space. As such, the height of the implant upon insertion determines the final height of the corrected disc space. In addition, for implantation using a lateral approach, these implants are configured to be of length to be positioned in the disc space from one lateral side to the other such that the implant rests on the cortical rims of both opposing lateral sides of a vertebral body.
Consequently, there remains a need for an expandable interbody fusion device for insertion into the intradiscal space between opposing vertebrae using a lateral approach.
SUMMARY OF THE INVENTIONThe present invention contemplates an expandable interbody fusion device configured for placement into the intradiscal space between vertebral bodies in a spine from a lateral approach to increase the disc height between vertebral bodies upon expansion and to stabilize the spine.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the drawing figures and the following written description. It is understood that no limitation to the scope of the invention is thereby intend. It is further understood that the present invention includes any alterations and modifications to the illustrated arrangements and further includes applications of principles of the invention as would normally occur one skilled in the art to which this invention pertains.
Referring now to
Turning to
At the posterior portion of each vertebral body 14, 16 there are two short, thick processes known as pedicles 24 and 26, which project dorsally, one on either side, from the superior part of the vertebral body at the junction of its posterior and lateral surfaces as shown in
With continued reference to
Accordingly, considering the vertebral body dimensions set forth in Table 1 a device 10 having a length L ranging from about 31 mm to 46 mm would extend approximately from pedicle-to-pedicle consistent with the dimension, Pd for the lumbar vertebrae L1 to L5. A device 10 having such a range of lengths would also preferably be less than the interior dimension, Vi. Further, the length L may be as great as approximately 48 mm and still satisfy these conditions.
Referring now to
As shown in
Turning now to
As also described in the '867 patent, each wafer 44 includes features to interlock adjacent wafers in multiple degrees of freedom. One particular feature includes a series of resiliently flexible prongs 65 that project outwardly above the upper surface 54 of the wafer 44 as shown in
Referring now to
Having satisfactorily achieved a direct lateral access surgical corridor through the tissue down to the disc space, a discectomy is performed to provide appropriate space for introduction of the expandable device 10. In some instances, pre-distraction of the disc space may be required to facilitate the introduction of the device 10, it being understood that such pre-distraction is not the final distraction desired to achieve corrected disc height and spinal correction. The device 10 is inserted by an insertion instrument as described in the '867 Patent which supports the device 10 upon and during insertion and releases the device 10 once expanded. Where a retractor is used with, for example, a plurality of blades to create a relatively large access corridor for enhanced visual observation, the device 10 may be inserted through the retractor which holds tissue apart adjacent the surgical site. Because of the relatively small profile of the unexpanded device 10, the retractor may not be necessary and instead the device 10 may be introduced percutaneously through a cannula of fixed dimension which would be placed over the last and largest tissue dilators with less tissue disruption.
As depicted in
Having expanded the device 10, suitable bone filler or bone graft 68 may be inserted into the intradiscal space 12. As depicted in
By reference to
Having described the particular arrangements of the device 10 and method of placement, it should be understood that other variations may be contemplated. For example, as shown in
Claims
1. An expandable interbody fusion device for insertion into the intradiscal space of a lumbar spine to reside at least in part on the area of increased bone density at the posterior portion of the endplate of the vertebral body between a lateral spacing defined as the pedicle-to-pedicle dimension and laterally within the interior of the ring apophysis extending peripherally around the endplate, comprising an elongate device having an upper surface for engaging the endplate of a vertebral body and a lower surface for engaging the endplate of an opposing vertebral body, the upper surface and a lower surface being separable increasingly upon expansion of the device, the device having a length configured to be less than the lateral spacing within the ring apophysis and not less than the pedicle-to-pedicle dimension.
2. The expandable interbody fusion device of claim 1, wherein said device comprises a superior endplate including said upper surface, an inferior endplate including said lower surface and an expansion structure therebetween.
3. The expandable interbody fusion device of claim 2, wherein said expansion structure comprises a plurality of elements stacked between said superior endplate and said inferior endplate.
4. The expandable interbody fusion device of claim 3, wherein said elements each comprise a generally planar wafer.
5. The expandable interbody fusion device of claim 4, wherein said wafers are each configured to be introduced between said superior endplate and said inferior endplate individually consecutively.
6. The expandable interbody fusion device of claim 5, wherein each of said wafers comprises a leading end defining a lifting surface for engaging a trailing end of an earlier introduced wafer so as to displace and lift said earlier introduced wafer in said stack of wafers.
7. The expandable interbody fusion device of claim 5, wherein each of said wafers comprises structure for interlocking said wafers to each other.
8. The expandable interbody fusion device of claim 1, wherein said device comprises a radiopaque marker at least on said upper surface and said lower surface.
9. The expandable interbody fusion device of claim 1, wherein said upper surface and said lower surface each comprises a convex surface along a length of said device.
10. The expandable interbody fusion device of claim 9, wherein said upper surface and said lower surface each comprises a convex surface along a width of said device.
11. The expandable interbody fusion device of claim 1, wherein said upper surface and said lower surface defined a lordotic angle therebetween.
12. The expandable interbody fusion device of claim 1, wherein said device has an unexpanded height between said upper surface and said lower surface and an expanded height therebetween, the expanded height being at least 50% greater than said unexpanded height.
13. The expandable interbody fusion device of claim 12, wherein said device has an unexpanded height of about 8 mm ranging to an expanded height of about 17 mm.
14. The expandable interbody fusion device of claim 1, wherein said device has a length for use in the L1 to L5 region of the lumbar spine ranging from about 31 mm to 48 mm.
15. The expandable interbody fusion device of claim 1, wherein said device has a width ranging from about 14 mm to 20 mm.
16. The expandable interbody fusion device of claim 1, wherein said device has a length of about 37 mm, a width of about 16 mm and unexpanded height of about 8 mm.
17. A method of inserting an expandable interbody fusion device from the lateral approach into the intradiscal space of the lumbar spine, comprising the steps of:
- providing an access corridor to the spine from the lateral approach;
- providing an elongate expandable device having a length less than the lateral width of the vertebral endplate between the peripheral ring apophysis and not less than the pedicle-to pedicle spacing of the vertebral body;
- inserting said device into the intradiscal space between opposing vertebral bodies and within the ring apophysis of said endplate with at least a portion of said device residing on the area of endplate increased bone density at the posterior portion of the endplates between the pedicles; and then
- expanding the expandable device in situ to increase the height of the intradiscal space and stabilize the spine.
18. The method of claim 17, wherein said elongate expandable device comprises a superior endplate, an inferior endplate and an expansion structure therebetween, and wherein said expansion structure is expanded to increase the height of said device.
19. The method of claim 18, wherein said expansion structure comprises a plurality of elements that are introduced into said device individually consecutively to form a stack of elements between said superior endplate and said inferior endplate.
20. The method of claim 18, wherein the height of said device is increased from an unexpanded height to an expanded height, said expanded height being at least 50% greater than said unexpanded height.
21. The method of claim 17, wherein said device is inserted generally along a transverse center line extending across the lateral width of a vertebral endplate of the lumbar spine.
22. The method of claim 21, wherein said device is positioned to reside within said intradiscal space more posterior than anterior.
23. The method of claim 17, wherein said access corridor is created with the use of intraoperative nerve monitoring instruments.
24. The method of claim 23, wherein said access corridor is created with the use of tissue dilators.
25. The method of claim 24, wherein a retractor having a plurality of blades is used to enlarge the access corridor, and wherein said device is inserted through said retractor.
26. The method of claim 24, wherein a cannula of fixed dimension is placed over a last and largest dilator, and wherein said device is inserted through said cannula.
27. The method of claim 17, wherein a bone filler is inserted into said intradiscal space adjacent said expanded device.
28. The method of claim 27, wherein said bone filler is injected with a graft insertion instrument to inject said filler under pressure to stress load the filler against the vertebral endplates of opposing vertebral bodies communicating with said intradiscal space.
Type: Application
Filed: Sep 7, 2012
Publication Date: Jul 24, 2014
Applicant: SPINE WAVE, INC. (Shelton, CT)
Inventor: Peter Barreiro (West Haven, CT)
Application Number: 14/342,563
International Classification: A61F 2/44 (20060101);