WO2013074419A1

WO2013074419A1 - Spinal therapy implants

Info

Publication number: WO2013074419A1
Application number: PCT/US2012/064465
Authority: WO
Inventors: Thomas Matthew Womble; Leighton J. Lapierre
Original assignee: Trans1 Inc.
Priority date: 2011-11-15
Filing date: 2012-11-09
Publication date: 2013-05-23

Abstract

An array of different spinal implants that may be used in the process of providing therapy to achieve spinal fusion. Some implants have a leading edge portion having a leading vertical face which is a small end of a quadrilateral pyramidal frusta with rounded edges that extends a set of four sloped faces from the leading vertical face to the first connecting wall, second connecting wall, first vertebral side, and second vertebral side. Some implants have a cross bar marker that may be used to center the implant with respect to a spinous process as the cross bar marker is half way between a leading edge of the implant and a trailing edge of the implant.

Description

Spinal Therapy Implants

[0001] This application claims the benefit of United States Patent Application No. 13/658,426 filed October 23, 2012 for Spinal Therapy Lateral Approach Access Instruments and Implants and incorporates the '426 application by reference in its entirety. Through the '426 application, this application claims the benefit of US Provisional Application No 61/629,228, filed November 15, 2011 for Spinal Interbody System Apparatus and Method and incorporates the '228 application by reference in its entirety.

[0002] While the '228 applications has been incorporated by reference to provide additional detail it should be noted that this provisional was written at an earlier time and had a different focus from the present application. Thus, to the extent that the teachings or use of terminology differ in any of these incorporated applications from the present application, the present application controls. BACKGROUND

[0003] Field of the Disclosure.

[0004] This disclosure relates generally to minimally invasive surgical techniques including techniques and implants for provision of therapy to a spine from a lateral approach. Implants that may be used with other approaches to the spine are disclosed.

[0005] General Comments and Terminology.

[0006] As used herein, the term "biocompatible" refers to an absence of chronic inflammation response or cytotoxicity when or if physiological tissues are in contact with, or exposed to (e.g., wear debris) the materials and devices of the present disclosure. In addition to biocompatibility, in another aspect of the present disclosure it is preferred that the materials comprising the instrument systems are sterilizable.

[0007] In one aspect of the present disclosure, certain components of the device assemblies and systems of the present disclosure are configured to comprise biocompatible materials and are able to withstand, without wear, multiple cycles / procedures without failing. It will be further understood that the length and dimensions of instruments and components described herein will depend in part on the target site selection of the treatment procedure and the physical characteristics of the patient, as well as the construction materials and intended functionality, as will be apparent to those of skill in the art

[0008] In order to make it easier for a reader to find certain sections of this document that are of particular interest to the reader, a series of headings have been used. These headings are solely for the purpose of helping readers navigate the document and do not serve to limit the relevance of any particular section to exclusively the topic listed in the heading.

[0009] In the context of this discussion: anterior refers to in front of the spinal column; (ventral) and posterior refers to behind the column (dorsal); cephalad means towards the patient's head (sometimes "superior"); caudal (sometimes "inferior") refers to the direction or location that is closer to the feet. Proximal is closer to the beginning of the channel and thus the surgeon; distal is further from the beginning of the channel and in use more distant from the surgeon. When referencing tools including cutters or other tools distal would be the end intended for insertion into the access channel and proximal refers to the other end, generally the end closer to the handle for the tool.

SUMMARY

[0010] One aspect of the present disclosure may be summarized as teaching:

[0011] An implant for positioning in a motion segment between a cephalad vertebra and caudal vertebra, the implant comprising:

• a trailing edge portion that may be engaged by an implant movement tool;

• a leading edge portion on an opposite side of the implant from the trailing edge portion;

· a first connecting wall connecting the leading edge portion to the trailing edge portion;

• a second connecting wall connecting the leading edge portion to the trailing edge portion, the leading edge portion, trailing edge portion, and first and second connecting walls forming a perimeter frame around a fusion cavity;

· a first vertebral side;

• a second vertebral side; and • the leading edge portion having a leading vertical face which is a small end of a quadrilateral pyramidal frusta with rounded edges that extends a set of four sloped faces from the leading vertical face to the first connecting wall, second connecting wall, first vertebral side, and second vertebral side.

[0012] Another aspect of the present disclosure may be summarized as:

[0013] An implant for positioning in a motion segment between a cephalad vertebra and caudal vertebra, the implant comprising:

• a trailing edge portion that may be engaged by an implant movement tool;

• a first connecting wall connecting the leading edge portion to the trailing edge portion;

• the first connecting wall is connected to the second connecting wall through the trailing edge portion, the leading edge portion, and at least one cross bar;

• the implant having a set of four markers located in each of a set of four intersections of the trailing edge portion with the first connecting wall and the second connecting wall, and the leading edge portion and the first connecting wall and the second connecting wall such that a failure of two of the markers to line up at either corner connecting the leading edge portion indicates a lack of alignment with a fluoroscopic view; and

• a cross bar marker may be used to center the implant with respect to a spinous process as the cross bar marker is half way between a leading edge of the implant and a trailing edge of the implant.

[0014] There are many aspects of the teachings contained within this disclosure are addressed in the claims submitted with this application upon filing. Rather than adding redundant restatements of the contents of the entire set of claims, these claims should be considered incorporated by reference into this summary. [0015] This summary is meant to provide an introduction to the concepts that are disclosed within the specification without being an exhaustive list of the many teachings and variations upon those teachings that are provided in the extended discussion within this disclosure. Thus, the contents of this summary should not be used to limit the scope of the claims that follow.

[0016] Inventive concepts are illustrated in a series of examples, some examples showing more than one inventive concept. Individual inventive concepts can be implemented without implementing all details provided in a particular example. It is not necessary to provide examples of every possible combination of the inventive concepts provide below as one of skill in the art will recognize that inventive concepts illustrated in various examples can be combined together in order to address a specific application.

[0017] Other systems, methods, features and advantages of the disclosed teachings will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within the scope of and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE FIGURES

[0018] The disclosure can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

[0019] FIG. 1 is a front perspective view of an implant.

[0020] FIG. 2 is a rear perspective view of an implant.

[0021] FIG. 3 is a side view of an implant.

[0022] FIG. 4 is a top view of an implant.

[0023] FIG. 5 is a front view of an implant.

[0024] FIG. 6 shows a cross section of the implant from FIG. 1 taken through the midline of the cross bar.

[0025] FIG. 7 shows a view of the trailing end portion of the implant from FIG. 1.

[0026] FIG. 8 shows a front plan view of an implant with a six degree lordotic angle. [0027] FIG. 9 shows a rear plan view of the implant from FIG. 8.

[0028] FIG.51 is a side view of the implant from FIG. 8.

[0029] FIG. 11 is a front perspective view of an oblique lordotic implant.

[0030] FIG. 12 is a front view of the oblique lordotic implant of FIG. 11.

[0031] FIG. 13 is a side front view of the oblique lordotic implant of FIG. 11.

[0032] FIG. 14 shows a cross section of an implant that has a threaded bore and two lateral engagement features.

[0033] FIG. 15 shows a cross section of an implant that has a no-threaded bore and two lateral engagement features.

[0034] FIG. 16 is a front perspective view of an implant.

[0035] FIG. 17 is a rear view of the implant in FIG. 16.

[0036] FIG. 18 is a side view of the implant in FIG. 16.

[0037] FIG. 19 is a top view of the implant in FIG. 16.

[0038] FIG. 20 is a front perspective view of an implant.

[0039] FIG. 21 is a rear view of the implant in FIG. 20.

[0040] FIG. 22 is a side view of the implant in FIG. 20.

[0041] FIG. 23 is a top view of the implant in FIG. 20.

[0042] FIG. 24 is a front perspective view of an implant.

[0043] FIG. 25 is a rear view of the implant in FIG. 24.

[0044] FIG. 26 is a side view of the implant in FIG. 24.

[0045] FIG. 27 is a top view of the implant in FIG. 24.

[0046] FIG. 28 is a front perspective view of an implant.

[0047] FIG. 29is a top view of the implant of FIG. 28.

[0048] FIG. 30 is a side view of the implant of FIG. 28.

[0049] FIG. 31 is a rear view of the implant of FIG. 28.

[0050] FIG. 32 is a front perspective view of an implant.

[0051] FIG. 33 is a rear view of the implant from FIG. 32.

[0052] FIG. 34 is a top view of the implant from FIG. 32. DETAILED DESCRIPTION

[0053] Provision of Therapy After Creating an Access Channel.

[0054] There are a number of methods for accessing the disc space from an approach other than a trans-sacral access route. After such an access route to the disc space is established, therapy may be provided. One form of therapy is to fuse two adjacent vertebrae together. Some surgeons provide the therapy of spinal fusion without using an implant. Other surgeons use a spinal implant in the process of providing therapy to achieve spinal fusion. Spinal fusion typically involves the use of osteogenic, osteoconductive, or osteoinductive material (bone graft). Bone graft is the material that is used to promote bone growth and forms the scaffold that bridges the adjacent vertebral bodies comprising a motion segment in the spine. Two fused vertebrae do not move with respect to one another.

[0055] It is useful to have one name for the variety of materials used to promote fusion. Thus, fusion promoting materials include osteogenic, osteoconductive, and/or osteoinductive material including bone graft material whether the material is autograft or allograft and various bone graft substitutes or bone graft extenders. Various techniques for promoting effective fusion of adjacent vertebrae are well known to those of skill in the art so a minimal summary is sufficient for this document.

[0056] Preparation of Disc Space

[0057] One process to promote fusion is to conduct a discectomy to remove nucleus pulposus of the disc and to abrade the vertebral endplates adjacent to the disc space as bleeding from the endplates promoted bone growth and fusion. An interbody implant (sometimes called a fusion cage) may be introduced into the disc space along with quantities of one or more fusion promoting materials. Frequently, the nature of the access channel used to access the disc space will impact the dimensions of the cage that may be delivered to the disc space.

[0058] Frequently, tools are inserted that serve as trial implants. These tools provide guidance to the surgeon on the most appropriate size of implant to use for a particular patient's anatomy for a particular access route. The position of the trial implant may be assessed via fluoroscopy. One dimension that may be ascertained by trial devices is the appropriate choice of height for the implant. In some instance it may be that assertive insertion of a series of progressively larger trial devices will serve to increase the distance between adjacent vertebrae (vertebral distraction) which may be a desired outcome of the surgical intervention.

[0059] IMPLANTS.

[0060] FIG. 1, FIG. 2 and FIG. 3 show a front perspective view, a rear perspective view, and a side plan view of an implant 2000 that may be delivered through the psoas muscle and into a disc space as part of surgery to create fusion of two adjacent vertebrae from a motion segment.

[0061] More specifically, these three figures show an implant 2000 for positioning in a motion segment between a cephalad vertebra and an adjacent caudal vertebra. The implant 2000 having a trailing edge or end portion 2004 that may be engaged by an implant movement tool. The term implant movement tool includes: a tool designed to place an implant into a disc space; any tool used to reposition the implant within the disc space, and a tool designed to remove a previously placed implant from a disc space. These tools may be one in the same, but often the tools for removing an implant that has been in place since an earlier surgical procedure may be different as bone ingrowth may make movement more difficult.

[0062] The figures show a leading edge or end portion 2008 on the opposite side of the implant from the trailing end portion 2004. The leading end portion 2008 and the trailing end portion 2004 are connected by a first connecting wall 2012 and a second connecting wall 2016. The combination of the leading end portion 2008, first connecting wall 2012, trailing end portion 2004, and second connecting wall 2016 form a perimeter frame that partially encloses a space that may be called the fusion cavity 2024. The fusion cavity 2024 may be filled or partially filled with fusion promoting materials. The fusion cavity 2024 may be filled with fusion promoting materials before delivery to the disc space. Additional fusion promoting materials may be provided to the fusion cavity 2024 and to the disc space after the delivery of the implant 2000 to the disc space.

[0063] A cephalad side 2028 of the implant 2000 is adapted to make contact with an endplate of the more cephalad of the two adjacent vertebrae. The opposite side of the implant is the caudal side 2032 intended to make contact with an endplate of the more caudal of the two adjacent vertebrae. In some implants, the two vertebral sides, the cephalad side 2028 and the caudal side 2032 of the implant 2000 are mirror images. These implants 2000 are sometimes called parallel implants even if the curved sides are not parallel to one another. Given an appropriate tool to deliver the implant 2000, it is possible that either side of a parallel implant could become the cephalad side.

[0064] Other implants seek to impose a correction to the curvature of the spine by having a wedge shape. In order to provide the wider part of the wedge where it is needed the orientation of the implant for a particular delivery route is limited.

[0065] One of skill in the art will recognized that part of the sloped faces of the leading and trailing ends (discussed below) will not make contact with the vertebral endplates.

[0066] The cephalad side 2028 will contact the cephalad side of the first connecting wall 2012 and the cephalad side of the second connecting wall 2016. The caudal side 2032 will have the corresponding parts.

[0067] Notice that in both the leading edge portion 2008 and the trailing end portion 2004 there are a front quadrilateral pyramidal frusta 2036 and a back quadrilateral pyramidal frusta 2044 with rounded edges. Thus, a leading face 2048 and a trailing face 2050 are vertical faces.

[0068] A cross bar 2052 may be included in the implant 2000 to augment the structure. The cross bar 2052 may be sized so that the cross bar 2052 is not part of the cephalad side 2028 that makes contact with the vertebra or the caudal side 2032 that makes contact with the vertebra as the thickness of the cross bar 2052 in the cephalad caudal direction is less than the thickness of the first connecting wall 2012 and the second connecting wall 2016. By having almost the entire cross bar 2052 thinner than the connecting walls 2012, 2016, fusion promoting material may be placed on all four sides of the cross bar 2052 to facilitate bone growth to fuse the two vertebrae.

[0069] The fusion cavity 2024 allows bone growth through the fusion promoting material to connect the cephalad vertebral endplate to the caudal vertebral endplate. Optionally, a series of one or more passages (not shown) connect the fusion cavity 2024 from the inner side of a connecting wall to an outer side of the connecting wall. These passages may have bone ingrowth, particularly if packed with fusion promoting material. Likewise a non-circular bore 2064 in the trailing end portion 2004 may provide another connecting passageway for the bone ingrowth into the fusion cavity 2024.

[0070] FIG. 4 is a top view of implant 2000. FIG. 5 is a front view of implant 2000. The implant 2000 may include a set of markers 2068 that are more radio-opaque than the material used for creating the implant 2000. The use of relatively opaque markers 2068 allows the markers 2068 to show up clearly on the fluoroscopic view to allow the placement of the implant 2000 to be judged as the implant 2000 is intended for delivery with a specific orientation with respect to the patient's anatomy.

[0071] One radio-opaque material that may be used for markers 2000 is tantalum, although other materials may be used. The markers used in the implant 2000 are a set of four corner markers 2072 which are rods oriented vertically (will become the cephalad/caudal direction) and a cross bar marker 2076 located in the center of the cross bar 2052. Other marker sets may be used. For example, a three rod marker set could be used with a pair or vertical (cephalad/caudal) rods near the intersection of each of the connecting walls 2012, 2016 near the start of the trailing end portion 2004 and a third rod running across the leading end portion 2008 (perpendicular to the two vertical rods). (See FIG 55 and FIG. 15 discussed below.)

[0072] As described in more detail below, the implant 2000 may be provided with a set of anti-migration features 2084 that engage the vertebral endplates to resist movement of the implant 2000 towards the place where the implant was introduced. Thus the anti-migration features 2084 provide more resistance to movement towards the trailing edge 2004 of the implant 2000 than resistance towards the leading edge 2008 of the implant 2000.

[0073] FIG. 6 shows a cross section of implant 2000 through the midline of the cross bar 2052 (taken along the cephalad/caudal and anterior/posterior plane). The cross bar 2052 connects the first connecting wall 2012 to the second connecting wall 2016. The cross bar 2052 may have a cross bar flare 2088 at either end to flare into the connecting walls 2012, 2016. As the cephalad/caudal thickness of the cross bar 2052 is less than the cephalad/caudal thickness of the connecting walls 2012, 2016 adjacent to the cross bar 2052, there is space for fusion promoting material above and below the cross bar 2052. The cross bar marker 2076 may be a rod or some other shape such as an implanted sphere. The cross bar marker 2076 rod could be shorter than the rods used for the corner markers 2072. While the orientation of the cross bar marker 2076 may be vertical as shown, cross bar markers could be placed in the anterior/posterior direction or the distal/proximal direction. Placement of the cross bar marker 2076 approximately halfway along the distal/proximal axis of the implant 2000 allows the cross bar marker 2076 to be used via an anterior/posterior fluoroscopic image to align the implant 2000 with the spinous process and check the implant orientation. Note that when the implant 2000 is properly aligned, the closest corner markers 2072 will be aligned with a corresponding pair of corner markers 2072 in an anterior/posterior fluoroscopic image.

[0074] FIG. 7 shows a view of the trailing end portion 2004 of implant 2000 with the four sloped faces 2092 of the quadrilateral pyramid frusta 2044 surrounding the trailing face 2050. The edges 2080 between the four sloped faces 2092 are rounded. While the edges between the four sloped faces 2092 and the trailing face 2050 are not rounded, these edges could be rounded analogous to the rounded edges between a leading face 2048 and the four sloped faces 2096 on the leading end portion 2008 shown in front plan view in FIG. 5.

[0075] FIG. 7 shows the non-circular bore 2064 and the lateral engagement feature 2096 that may be used with an implant movement tool. One of skill in the art will recognized that additional lateral engagement features may be added to the trailing edge portion 2004. It is preferred that the lateral engagement feature 2096 be sufficiently deep that the implant movement tool may engage with the lateral engagement feature 2096 so that an implant 2000 engaged with an implant movement tool is not wider than the maximum width of the implant 2000 so that the difference between the maximum width of the implant 2000 and the delivery channel width may be minimized.

[0076] Lordotic Implants.

[0077] In some instances the implant is not a parallel implant but may have a difference in average cephalad/caudal height along the first connecting wall compared with the average height of the second connecting wall. When inserted laterally, this difference in height from anterior to posterior helps maintain a lordotic angle in the spine. The implant may be designed to have a greater height on the anterior portion of the disc space than on the posterior portion of the disc space. Thus instead of a zero degree slope between the outer edge of the first connecting wall to the second connecting wall, there may be a slope in the range of something more than zero to about twelve degrees. A six degree lordotic angle may be suitable for many patients requiring this correction.

[0078] A variation of the implant discussed above is an implant 2200 with a six degree lordotic angle. FIG. 8, FIG. 9 and FIG. 10 illustrate the lordotic aspect of such as implant. FIG. 8 shows a front plan view of an implant 2200 with a six degree lordotic angle. The average height of the anterior connecting wall 2204 is greater than the average height of the posterior connecting wall 2208. FIG. 9 which is a rear plan view of the implant 2200 which shows that the anterior connecting wall 2204 has a greater height than the posterior connecting wall 2208. FIG. 10 shows a side view of the posterior wall 2208 with the larger anterior wall 2204 visible in the background. Other features for implant 2200 may be similar to implant 2000. If a cross bar is used, then the height may be constant or may vary from anterior to posterior.

[0079] Size Ranges.

[0080] The dimensions of the implants will be a function of the location of within the spine that receives the implant as the disc spaces get larger towards the lower portion of the spine. An implant intended for the L4/L5 disc space will tend to be larger for a given patient than an implant for the L1/L2 disc space. The dimensions of the implants will also be a function of the size of the patient as some patients have larger bones than other patients. Thus, the anterior to posterior dimension and the lateral dimension will vary based on the size of the relevant vertebral endplates. The height of the implant will be selected to match the surgeon's preference for the spacing of the two vertebrae after the surgical intervention. As noted above, there may be a lordotic angle of up to approximately twelve degrees. A summary of the range of typical dimensions for a lateral implant for the L1/L2, L2/L3, L3/L4 and L4/L5 disc spaces are summarized in the table below.

[0081] Coronal Wedge Implants.

[0082] Sometimes an implant varies in height in two ways. Thus rather than a simple lordotic implant, that varies from the anterior side of the disc to the posterior side of the disc, the implant may vary from the one lateral side of the disc to the other lateral side of the disc. [0083] FIG. 11, FIG. 12, and FIG. 13 show the two aspects of variation for an oblique lordotic implant 2300. FIG. 11 is a front perspective view of an oblique lordotic implant 2300 shown without optional passages 2056 or the implant movement tool features (such as 2064 or 2096 discussed above). As shown in FIG. 12, the oblique lordotic implant 2300 grows from posterior side 2296 to anterior side 2292 and from the distal end 2088 to the proximal end 2082. The difference from posterior side 2296 to anterior side 2292 is approximately six degrees although other angles may be selected for particular applications. FIG. 13 is a side view that shows the growth from distal end 2088 to the proximal end 2082 (leading end to trailing end) at a slope approximated at four degrees although other angles may be chosen for particular situations. Note that as shown in FIG. 13, the growth in implant height is in both directions (cephalad and caudal) from the longitudinal centerline.

[0084] Implant Movement Tools.

[0085] The particulars of the tools for movement of the implant are beyond the focus of this application but implant movement tools include insertion tools, extraction tools, and tools that may be used for both purposes. An insertion tool may have a distal tip on a circular shaft such that the distal tip when properly aligned fits through the non-circular bore into the interior of the implant, possibly into the fusion cavity. Rotation of the distal tip of the implant tool results in a lack of alignment between the distal tip of the insertion tool and the non-circular bore so that the insertion tool remains engaged with the implant. Having at least one lateral engagement feature (such as 2096 discussed above) provides a second point of engagement with the insertion tool so that the implant is not free to rotate with respect to the insertion tool.

[0086] One of skill in the art will recognized that a rotated distal tip of an insertion tool that abuts an interior wall of the implant may be used to extract an implant. Force may be applied to the implant thought the use of a reverse slap hammer to enable the surgeon to remove an implant.

[0087] An alternative to a non-circular bore is a threaded bore that engages with a corresponding threaded tip of an implant movement device. The distal tip would rotate relative to the threaded bore. The implant would be precluded from rotating while the distal tip rotates relative to the implant as the implant movement device would be engaged with the implant via the lateral engagement feature (or more than one lateral engagement feature). This may be called a multi-point engagement.

[0088] FIG. 14 shows an implant 2310 that has a threaded bore 2314 and two lateral engagement features 2318. The threaded bore 2314 in FIG. 14 connects the fusion cavity 2330 to a vertical face 2334 of the trailing end portion 2338. The implant 2310 shown in FIG. 14 does not have a cross bar as a cross bar is an optional aspect of an implant.

[0089] The implant 2310 in FIG. 14 uses a three rod marker system with two vertical rods 2322 near the trailing end portion 2338 and one horizontal rod 2326 in the leading end portion 2336.

[0090] The implant 2340 in FIG. 15 is much like the implant 2310 in FIG. 14 except that the engagement with the implant movement tool is through a central bore 2344 and a pair of lateral engagement features 2348. An appropriate tool that squeezes the trailing edge portion 2052 of the implant 2340 between arms that engage the pair of lateral engagement features 2348 would have a firm grip on the implant 2340. Notice that the central bore 2344 is circular and does not extend through the trailing end portion 2352 to the fusion cavity 2356.

[0091] An extraction tool for removing an implant that has been present in a gap between two vertebrae long enough to have bone ingrowth into the fusion cavity may be made with a tap on the external end of the extraction tool to convert a non-threaded bore (including the central bore in the bow-tie shaped non-circular bore) into a tapped connection to allow large forces to be exerted on the implant to remove the implant from between the vertebrae.

[0092] Implants for TLIF or PLIF Access Routes.

[0093] While lateral access to the disc space is one set of access methods, lateral access is not the only non-trans-sacral route as there are other access routes for access to the disc space. An approach from the posterior direction is known as the Posterior Lumbar Interbody Fusion or PLIF. Another related approach from the posterior is the Transforaminal Lumbar Interbody Fusion or TLIF. One difference between a TLIF and PLIF approach is the angle at which the disc is approached but both procedures are done through an incision in the patient's back. A difference in approach from a lateral approach as discussed above may require difference in the implants. Some implants may be adapted to be delivered via either a TLIF or PLIF approach. [0094] Due to the posterolateral angle of approach in a TLIF, a TLIF implant is often inserted at an angle across the disc space. The angle is typically from the posterolateral corner of the disc entry to the anterior contralateral corner of the disc. Since the anterior part of the disc is taller in height than that the posterior part of the disc, it is beneficial to have a TLIF implant that matches the lordosis angle of the endplates for the path of insertion. Thus, it may be useful to have a substantially rectangular and asymmetric oblique-lordotic implant that is tallest at the leading corner closes the anterior side of the disc and progressively gets shorter on an angle towards the posterior lateral corner. The other two corners of the implant are at heights between the tallest corner and the shortest corner. An implant for a TLIF procedure may be designed to be inserted with the anti-migration features initially inserted in an anterior/posterior orientation before the implant is rotated to place the anti-migration features in their traditional cephalad/caudal orientation. This rotation of the implant may increase the distance between the cephalad and caudal vertebrae which is known as distraction. Distraction may decompress and alleviate spinal impingement on nerves.

[0095] The dimensions of a TLIF implant may be different than a lateral implant used for the same spinal level for the same patient as the approach route impacts the dimensions. A straight TLIF/PLIF implant will frequently have a height of between 7 to 17 mm, a width of 10 to 11 mm and a length of 23 to 35 mm. The lordotic angle will be 0 to 8 degrees. [0096] Examples of Implants Adapted for Other Access Routes.

[0097] FIG. 16, FIG. 17, FIG. 18 , and FIG. 19, show four view of an implant 2400 which has more height in the cephalad/caudal direction than width in the anterior/posterior direction. The implant 2400 has wedge shaped nose 2404 on the front end portion 2412. To facilitate placement within the available space within a disc space for an implant delivered via a particular access angle, the trailing end portion 2408 has a cut corner portion 2416 which could be placed on the posterior lateral portion of the disc space. This type of implant 2400 may be useful in a TLIF approach. The optional passages 2456 have elongated dimensions in the cephalad/caudal direction. The bore 2424 is threaded. The TLIF delivery route may encourage a design without stress concentrators so the design may choose as here to avoid a bowtie or other non-circular bore. [0098] The marker set uses three rods 2428. The fusion cavity 2432 does not have the optional cross bar. Representative dimensions for implant 2400 are about 17 millimeters cephalad/caudal, about 10 millimeters width, and about 23 millimeters in length.

[0099] FIG. 20, FIG. 21, FIG. 22, and FIG. 23, show four view of an implant 2500. The implant 2500 uses a threaded bore 2504 and a pair of lateral engagement features 2508. The other features are self-documenting given the discussion of other implants already provided. Representative dimensions for implant 2500 are about 7 millimeters cephalad/caudal, about 10 millimeters width, and about 23 millimeters in length. Ranges for dimensions are about 7 to about 17 millimeters cephalad/caudal, about 10 millimeters width, and about 23 to about 35 millimeters in length.

[00100] FIG. 24, FIG. 25, FIG. 26, and FIG. 27, show four view of an implant 2600 that is similar in many ways to implant 2500. This implant may be used in a TLIF or PLIF procedure to provide an implant with a lordotic angle of approximately six degrees. Note that for an implant inserted from a posterior path, the anterior to posterior difference in cephalad/caudal height is done by varying the height of both connecting walls 2604, 2608 as there is not an anterior sidewall and a posterior sidewall as one would find via a lateral approach.

[00101] FIG. 28, FIG. 29, FIG. 30, and FIG. 31, show four view of a curved implant 2700. A curved implant 2700 may be an advantageous shape for certain access routes to the disc space. The marker set for curved implant 2700 is three vertical rods 2704, 2708, and 2712 with the rod 2712 for the cross bar being wider and shorter than the other two rods 2704 and 2708. Rod 2712 could be replaced with a different marker such as a sphere. Curved implant 2700 does not have passages through the connecting walls 2716 and 2720.

[00102] FIG. 32, FIG. 33, and FIG. 34 show three views of a curved implant 2800 that is similar to curved implant 2700 but has a different height/width aspect ratio compared with curved implant 2700 as curved implant 2700 is wider than it is tall (11 millimeters versus 6 millimeters). In contrast, curved implant 2800 is taller than it is wide (17 millimeters tall versus 1 1 millimeters wide). Curved implant 2800 differs from curved implant 2700 in that curved implant 2800 has a lordotic angle of about eight degrees. The lordotic angle is not as apparent as the lordotic angle in implants with less height, but the lordotic angle is visible in FIG. 33 as the anterior connecting wall 2804 is taller than the posterior connecting wall 2808. [00103] One of skill in the art will recognize that a family of curved implants will likely have various combinations of implant height (as measured on the taller side) of about 6 millimeters to about 17 millimeters, length of about 27 millimeters to about 35 millimeters, or lordotic angle of zero degrees to about 8 degrees. These ranges may be different for different applications such as a different part of the spine or for a special population of patients.

[00104] ALTERNATIVES AND VARIATIONS.

[00105] Cross Bars.

[00106] One of skill in the art will recognize that instead of one cross bar, an implant may have two or more cross bars. As noted above, the cross bar is optional and the implant may not have a cross bar at all. While there is an advantage of having space above and below a cross bar for fusion promoting materials, an implant may be made with a cross bar that forms part of the first vertebral surface or the second vertebral surface or both. The cross bar may include the anti-migration feature if the cross bar is part of a vertebral surface of an implant.

[00107] Open Surgery.

[00108] While the focus of this disclosure has been on a minimally invasive lateral access approach to the disc space, the various implants described in this application may be used with other access routes including open surgery rather than a minimally invasive approach.

[00109] Kits.

[00110] A kit may include many (possibly even all) the components necessary for a particular procedure including the components needed to create the access route, prepare the disc space and even the an assortment of implants.

[00111] One of skill in the art will recognize that some of the alternative implementations set forth above are not universally mutually exclusive and that in some cases additional implementations can be created that employ aspects of two or more of the variations described above. Likewise, the present disclosure is not limited to the specific examples or particular embodiments provided to promote understanding of the various teachings of the present disclosure. Moreover, the scope of the claims which follow covers the range of variations, modifications, and substitutes for the components described herein as would be known to those of skill in the art. Individual claims may be tailored to claim particular embodiments out of the array of embodiments disclosed above. Some claims may be tailored to claim alternative embodiments rather than preferred embodiments. Some claims may cover an embodiment set forth above with a modification from another embodiment as the present disclosure does not include drawings of all possible combinations of feature sets.

[00112] The legal limitations of the scope of the claimed invention are set forth in the claims that follow and extend to cover their legal equivalents.

Claims

CLAIMS What is claimed is:

1. An implant for positioning in a motion segment between a cephalad vertebra and caudal vertebra, the implant comprising:

a trailing edge portion that may be engaged by an implant movement tool;

a leading edge portion on an opposite side of the implant from the trailing edge portion;

a first connecting wall connecting the leading edge portion to the trailing edge portion;

a second connecting wall connecting the leading edge portion to the trailing edge portion, the leading edge portion, trailing edge portion, and first and second connecting walls forming a perimeter frame around a fusion cavity;

a first vertebral side;

a second vertebral side; and

the leading edge portion having a leading vertical face which is a small end of a quadrilateral pyramidal frusta with rounded edges that extends a set of four sloped faces from the leading vertical face to the first connecting wall, second connecting wall, first vertebral side, and second vertebral side.

2. The implant of claim 1 wherein the trailing edge portion has a trailing vertical face which is a small end of a quadrilateral pyramidal frusta with rounded edges that extends a set of four sloped faces from the trailing vertical face to the first connecting wall, second connecting wall, first vertebral, and second vertebral side.

3. The implant of claim 1 wherein the first connecting wall is connected to the second connecting wall through the trailing edge portion, the leading edge portion, and at least one cross bar.

4. The implant of claim 1 wherein:

the first vertebral side that comprises:

a part of a first side of the leading edge portion;

a part of a first side of the trailing edge portion;

a first side of the first connecting wall; and

a first side of the second connecting wall; and

the second vertebral side that comprises:

a part of a first side of the leading edge portion;

a part of a second side of the trailing edge portion;

a second side of the first connecting wall; and

a second side of the second connecting wall; and

wherein the first vertebral side and the second vertebral side have anti-migration features adapted to resist movement of the implant towards the trailing edge more than movement of the implant towards the leading edge.

5. The implant of claim 4 wherein the first connecting wall is connected to the second connecting wall through the trailing edge portion, the leading edge portion, and at least one cross bar.

6. The implant of claim 5 wherein the cross bar does not form part of the first vertebral side or the second vertebral side so that fusion promoting materials may be packed to be between the cross bar and the cephalad vertebra and between the cross bar and the caudal vertebra.

7. The implant of claim 4 wherein an average height of the first connecting wall measured from the first vertebral side to the second vertebral side is different from the average height of the second connecting wall measured from the first vertebral side to the second vertebral side.

8. The implant of claim 1 wherein the implant is made from a material that is much less radio-opaque than a set of markers placed in the implant so that implant orientation may be discerned by fluoroscopy.

9. The implant of claim 1 wherein the trailing edge portion includes:

at least one non-circular bore that engages with the implant movement tool for movement; and

at least one lateral engagement feature such that the tool for movement of the implant can engage the at least one non-circular bore and the at least one lateral engagement feature to provide a multi-point engagement with the tool for movement of the implant.

10. The implant of claim 1 wherein the first connecting wall and the second connecting wall each have at least one passage that connects the fusion cavity from an inner side of the connecting wall to an outer side of the connecting wall.

1 1. The implant of claim 1 wherein an average height of the implant as measured from the first vertebral side and the second vertebral side halfway between the leading edge and the trailing edge exceeds a width of the implant as measured from outside of the first connecting wall to outside of the second connecting wall halfway between the leading edge and the trailing edge.

12. The implant of claim 1 wherein a width of the implant as measured from the outside of the first connecting wall to the outside of the second connecting wall halfway between the leading edge and the trailing edge exceeds an average height of the implant between the first vertebral side and the second vertebral side measured halfway between the leading edge and the trailing edge.

13. The implant of claim 1 wherein an average height of the implant measured between the first vertebral side and the second vertebral side is greater for a trailing edge half of the implant compared to a leading edge half of the implant.

14. An implant for positioning in a motion segment between a cephalad vertebra and caudal vertebra, the implant comprising:

a trailing edge portion that may be engaged by an implant movement tool;

the first connecting wall is connected to the second connecting wall through the trailing edge portion, the leading edge portion, and at least one cross bar;

the implant having a set of four markers located in each of a set of four intersections of the trailing edge portion with the first connecting wall and the second connecting wall, and the leading edge portion and the first connecting wall and the second connecting wall such that a failure of two of the markers to line up at either corner connecting the leading edge portion indicates a lack of alignment with a fluoroscopic view; and

a cross bar marker may be used to center the implant with respect to a spinous process as the cross bar marker is halfway between a leading edge of the implant and a trailing edge of the implant.

15. The invention as described and illustrated in the specification and referenced figures.