Patent ID: 12186202

DESCRIPTION OF THE EMBODIMENTS

For the purposes of promoting and understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.

Referring toFIG.1, there is shown an expandable interbody fusion device10and an associated instrument200for inserting device10into an intervertebral disc space, expanding device10and for use in delivering graft material into device10once expanded within the disc space. In accordance with a particular arrangement, device10and instrument200are sized and configured for introducing device10in a posterolateral approach through Kambin's triangle in a transforaminal lumbar interbody fusion (TLIF) procedure. Kambin's triangle is well known and is defined as a right triangle over the dorsolateral disc: the hypotenuse is the exiting nerve root, the base (width) is the superior border of the caudal vertebra, and the height is the traversing nerve root, (See M. Hardenbrook et al., “The Anatomic Rationale for the Transforaminal Endoscopic Interbody Fusion: a Cadaveric Analysis”, Neurosurgical Focus Volume 40, February 2016, incorporated herein by reference). As will be described, device10is small enough to fit through Kambin's triangle yet is capable of expanding both in the vertical direction to accommodate spinal lordosis and in the lateral direction to provide sufficient structural support for opposing vertebral bodies laterally within the disc space. It should be appreciated that while device10is particularly configured for use as spinal implant in a TLIF procedure, it is not limited to use through Kambin;s triangle and, as such, may also be used as an expandable interbody fusion device that may be introduced in other approaches, such as in the posterior, anterior or lateral directions at different levels of the spine, or percutaneously.

Turning now toFIGS.2and3A-3Gdetails of expandable interbody fusion device10are described. Device10comprises a cage12having a hollow interior12fand a wedge100slidable within said hollow interior12f. Cage12has a distal end12aand a proximal end12b. Cage12is generally elongate defining a longitudinal axis12c, as depicted inFIG.3A, extending through distal end12aand proximal end12b. Wedge100is sized and configured to be slidably moved within cage12to expand cage12, as will be described. Cage12includes a base14at the proximal end12band a plurality of flexibly movable arms16projecting from base14toward distal end12a. Arms16are free and unattached to each other at distal end12athereby allowing cage12to expand at its distal end12a. In the arrangement shown, cage12has four movable arms16including a pair of upper arms16aand16band a pair of lower arms16cand16d. Arms16are attached respectively to base14at hinge points18a,18b,18c(not seen) and18din a manner to allow deflection of arms16relative to base14in two transverse directions. Cage12further includes a top opening11between arms16aand16b, a bottom opening13between arms16cand16d, and a pair of side openings, one opening15between arms16aand16cand the other opening17between arms16band16d(See alsoFIGS.13A and13B). In use, the transverse directions may be mutually orthogonal, namely in a vertical direction to expand the device height at distal end12aand thereby accommodate lordosis in the disc space, and horizontally to increase the device width and hence the lateral support of opposing vertebral bodies within the disc space.FIG.3Cshows the unexpanded device height H1and the unexpanded device width W1. In a particular arrangement, cage10may be formed monolithically as a unitary device to have a quadrangular shape, as shown inFIG.3D. It should be understood that other cage shapes, such as cylindrical may also be used.

As seen inFIGS.2and3Geach of upper arm16aand lower arm16cincludes an inclined cam surface20aand20c, respectively facing each other vertically, for cooperative engagement with wedge100. Upper arm16band lower arm16dalso include similar inclined cam surfaces20band20das shown inFIGS.2and3Bthat respectively face each other vertically for cooperative engagement with wedge100. Each of upper arms16aand16bfurther includes an inclined cam surface22aand22bas shown inFIG.3A, respectively facing each other laterally, for cooperative engagement with wedge100. Each of lower arms16cand16dalso include similar inclined cam surfaces22cand22das shown inFIG.3Gthat face each other laterally for cooperative engagement with wedge100. Each of lower arms16cand16dadditionally includes a locking notch23cand23das shown inFIG.3G, while each of upper arms16aand16badditionally includes a locking notch23a(not seen) and23b, shown inFIG.3B. Locking notches23a,23b,23cand23d, are each disposed adjacent distal end12aof cage12for receipt of portions of wedge100to lock the plurality of arms16in the expanded position of cage12.

Referring now toFIGS.4A-4Cdetails of wedge100are described. Wedge100serves as an expander of device10and is sized and configured to be movably contained within cage12to expand the distal end12aof cage12upon distal movement. Wedge100is generally cruciform in shape and has a threaded hole101extending generally centrally therethrough for threaded engagement with a threaded shaft of instrument200, as will be described. Wedge100has a vertical section102and a transverse horizontal section104that in a particular arrangement lie mutually orthogonal to each other. Vertical section102has angled side surfaces102aand102bformed above horizontal section104and angled side surfaces102cand102dformed below horizontal section104. During movement of wedge100in cage12toward distal end12a, curved side surfaces102aand102bare arranged to respectively engage inclined cam surfaces22aand22bon upper arms16aand16bas shown inFIG.3A, while angled side surfaces102cand102dare arranged to respectively engage inclined cam surfaces22cand22don lower arms16cand16d. Such movement of wedge100and cooperative engagement with cage12will cause each of the distal ends of arms16a,16b,16cand16dto deflect laterally away from centerline12cin a cantilevered manner about hinge points18a,18b,18cand18dto thereby expand the width of cage12at distal end12a.

Horizontal section104has curved upper surfaces104aand104bformed on opposite lateral sides of vertical section102above horizontal section104and curved lower surfaces104cand104dformed on opposite lateral sides of vertical section102below horizontal section104. As such, during movement of wedge100in cage12toward distal end12a, curved upper surfaces104bis arranged to engage inclined cam surface20bon upper arms16bwhile curved lower surface104dis arranged to engage inclined cam surface20don lower arm16d, as shown inFIG.3B. Similarly, curved upper surfaces104ais arranged to engage inclined cam surface20aon upper arm16awhile curved lower surface104cis arranged to engage inclined cam surface20con lower arm16c. Such movement of wedge100and cooperative engagement with cage12will cause each of the distal ends of arms16a,16b,16cand16dto deflect vertically away from centerline12cin a cantilevered manner about hinge points18a,18b,18cand18dto thereby expand the height of cage12at distal end12a. In addition, each of curved upper surfaces104aand104bterminate respectively in an engagement edge106aand106bwhile each of curved lower surfaces104cand104dterminate respectively in an engagement edge106cand106d. Engagement edges are configured to engage and reside in respective locking notches23a,23b,23cand23dto lock cage12in the expanded position, as will be described.

In a particular arrangement, wedge100and inclined cam surfaces20a-dand22a-don arms16a-dare configured and oriented in manner to cause simultaneous movement of the plurality of arms16. It should be appreciated that inclined surfaces20a-dand22a-dmay also be configured and oriented relative to wedge100to cause sequential movement whereby the plurality of arms16are first moved in a lateral direction followed by movement in a vertical direction, or vice versa as desired.

Cage12and wedge100are both formed of suitable metallic or polymeric biomaterials. Suitable biocompatible metallic materials include pure titanium, tantalum, cobalt-chromium alloys, titanium alloys (e.g., nickel titanium alloys and tungsten titanium alloys), stainless steel alloys, molybdenum rhenium (MoRe), and NiTinol (for superelastic properties). Suitable polymeric materials include members of the polyaryletherketone (PAEK) family, e.g., polyetheretherketone (PEEK), carbon-reinforced PEEK, polyetherketoneketone (PEKK); polysulfone; polyetherimide; polyimide; ultra-high molecular weight polyethylene (UHMWPE); or cross-linked UHMWPE. Ceramic materials such as aluminum oxide or alumina, zirconium oxide or zirconia, compact of particulate diamond, or pyrolytic carbon may be included in such polymers. It should be appreciated that these materials may be used independently or in a composite arrangement, as desired.

Referring again toFIGS.3C,3D,3E and3F, and also toFIG.5, details of the attachment of expandable interbody fusion device10and instrument200are described. As noted above, in a particular arrangement, device10is sized and configured to fit into an intradiscal space through Kambin's triangle. As a result, the cross-sectional profile of device10as defined by its height and width is dimensioned in a manner to allow use through Kambin's triangle. In addition, since at least the distal end of the instrument200for inserting device10may also need to fit through Kambin's triangle, the dimensions of the distal end of instrument200, including an attachment end202, are likewise configured to be consistent with introduction through Kambin's triangle. In this manner, instrument200is configured to attach to proximal end12bof cage12with at least the distal end of instrument200having a maximum dimension within the confines of the outer cross-sectional profile of cage12.

While the size of the outer cross-sectional profile of cage12is configured as small as practicable for introduction through Kambin's triangle, the open interior configuration of cage12is desirably as large as practicable to facilitate subsequent introduction of graft material into expanded cage12. As an example, when sized and configured for a TLIF fusion procedure at the L1/L2 lumbar level, the unexpanded height H1of cage12as shown inFIG.3Cmay be 8.0 mm with the unexpanded width W1being 8.5 mm. As so dimensioned in this example, the outer cross-sectional profile is nearly square. To maximize graft entry into cage12, an inner graft circular opening24may be provided to have a diameter of up to about 5.0 mm. As so dimensioned, the ratio of the graft opening area to the cross-sectional area of cage12is at least a minimum of approximately 29%. While these dimensions and minimum graft opening ratio are desirable for graft delivery, such dimensions leave relatively little material for attachment of cage12to instrument200in either the height or width directions. Accordingly, opposite diagonal corners12das seen inFIG.3Care used for purposes of attachment of cage12to instrument200.

FIG.5illustrates attachment portion202of instrument200oriented in a position ready for secured attachment to cage12. Instrument200, which will be described in further detail below, includes an outer tube204that supports a rotatable cylindrical inner tube206. In a particular arrangement, outer tube204may have a rectangular cross-section not greater in size than the cross-section of the unexpanded cage12. Inner tube206includes attachment portion202at its distal end. Attachment portion202comprises a pair of lugs208that project radially outwardly from inner tube206in diametrically opposite directions. As illustrated also inFIG.3D, cage12comprises an instrument attachment feature13at base14that includes an outer wall26at proximal end12band an inner wall28spaced interiorly of outer wall26. Inner wall28includes graft opening24in communication with cage hollow interior12f. Outer wall26includes an entrance opening30that is in communication with graft opening24and cage hollow interior12f. Entrance opening30has a configuration different from the configuration of graft opening24and in a particular arrangement has a circular portion30aand a pair of arcuate lobes30bthat project radially outwardly from circular portion30ain diametrically opposite directions. Lobes30bare arranged to be disposed along a diagonal axis12ethat extends toward opposite corners12dof cage12as illustrated inFIG.3C. Axis12ein this arrangement lies at an acute angle with respect to both the height and width of cage12. Circular portion30aof entrance opening30is sized to relatively closely receive cylindrical inner tube206of instrument200, while lobes30bare sized to relatively closely receive respective lugs208on inner cylindrical inner tube206. While attachment portion202of instrument200can be received through entrance opening30, graft opening24is sized to be of lesser dimension than circular portion30aof entrance opening30, and as such, attachment portion202of instrument200cannot pass through graft opening24of inner wall28.

While entrance opening30is formed in one arrangement to have a circular portion with oppositely projecting lobes, it should be appreciated that other shapes of entrance opening30may also be provided. For example, entrance opening30may be formed in the shape of an oval or other shapes having a longer extent along diagonal axis12eand a shorter extent transverse thereto.

The space between outer wall26and inner wall28defines a locking pocket32as depicted inFIGS.3D and3F. Locking pocket32has a circular portion32athat is configured to receive cylindrical inner tube206of instrument200and a pair of extended lobes32bthat extend radially outwardly from circular portion32a. Extended lobes32bare configured to have a greater arcuate extent along the circumference of circular portion32athan lobes30bof entrance opening30. As such, extended lobes32bcommunicate in alignment with lobes30bfor an arcuate portion and extend arcuately further not in alignment with lobes330bbehind outer wall26. Accordingly, once extended through entrance opening30as shown inFIG.6Ainner tube206may be rotated at a suitable angle, such that lugs208are arcuately moved within extended lobes32buntil lugs208reside between inner wall28and outer wall26, as shown inFIG.6B. In the particular example of the cage12having an unexpanded height H1of 8.0 mm and a width W1of 8.5 mm, inner tube206may be rotated approximately 41° to move lugs208in position between inner wall28and outer wall28. Points32cat the transition of circular portion32aand extended lobes32bas shown inFIG.3Fmay serve as mechanical stops upon engagement by lugs208to prevent further rotation of attachment portion202within locking pocket32. In this position attachment portion202may not be withdrawn from cage12and can be securely locked to cage12, as will be described.

Turning now toFIGS.7and8further details of instrument200are described. Instrument200includes an elongate instrument handle210, outer tube204, inner tube206and wedge driver212. As described, outer tube204may have at its distal end204aa rectangular cross-section not greater in size than the cross-section of the unexpanded cage12. The remaining extent of outer tube204may have a cylindrical outer surface204c. Outer tube204has an interior lumen204bextending longitudinally therethrough. Inner tube206includes attachment portion202at distal end206athat comprises the pair of lugs208as described above. Inner tube206has a cylindrical exterior surface206dfor sliding engagement within lumen204bof outer tube204. Inner tube206has an interior lumen206bextending longitudinally therethrough. A locking handle214is included at the proximal end206cof inner tube206. Locking handle214is fixedly secured to inner tube206for rotational and axial movement therewith and includes a radially projecting shaft214aterminating in a locking lever214bthat facilitates manual rotation of locking handle214and hence inner tube206, as will be described.

Wedge driver212comprises an elongate cylindrical shaft212ahaving a distal end212band a proximal end212c. Cylindrical shaft212ais sized and configured to extend slidingly into lumen206bof inner tube206. A threaded portion212dis included at the distal end212bof shaft212a, threaded portion212dbeing configured to threadably engage threaded hole101of wedge100, as will be described. An enlarged cylindrical portion212eis disposed at the proximal end212cof wedge driver212.

Referring particularly now also toFIG.8, handle210comprises a handle body210a, a handle cover210b, and an end cap211. Handle cover210bis suitably attached to handle body210aby fastening members, such as set of four screws216. End cap211is suitably attached to handle body210aand may be oriented by a key213formed at the proximal end of handle body210a. Handle210fixedly supports outer tube204at its distal end and includes a channel210cadjacent its distal end for receipt and support of inner tube206. An opening211aextends through end cap211in alignment with an opening210dthrough the proximal end of handle body210afor receipt of a portion of a T-handle to drive wedge driver212axially distally, as will be described. A camming element218is supported in a pocket220defined by ledges222and224at the distal end of handle body210a. Camming element218has an angled cam surface218afacing proximally for interaction with cam surface214cof locking handle214(SeeFIGS.9B and10B) as will be described. Camming element218may be secured within pocket220by suitable fastening members, such as screws226and228. Handle body210asupports a depressible locking button230adjacent the distal end of handle body210afor pivotal movement within handle body210a. Locking button230may be spring biased by a compression spring232captured in a recess210ethat normally biases locking button230in the locking position, as will be described. Handle body210aalso includes adjacent camming element218an opening234configured and sized to receive shaft214aof locking handle214therein for limited rotational movement relative to handle body210a. Handle body210afurther supports a drive nut236. Drive nut236may have a substantially rectangular configuration for receipt and retention in a compatible rectangular recess238formed interiorly of handle body210a. With handle cover210battached to handle body210adrive nut236is suitably retained within handle210and is prevented from either axial or rotational movement therein. Drive nut236in a particular arrangement includes interior threads236afor engagement with a suitable tool to drive wedge driver212and hence wedge100axially distally to expand cage12, as will be described. A relatively flat surface240may be formed at the proximal end of handle end cap211to allow slight impaction for assisting the insertion of interbody fusion device10into the disc space.

Referring still toFIGS.7and8, in a particular aspect, handle210of instrument200may be formed to receive a grafting cartridge to facilitate the introduction of graft material into an expanded device10, as will be further described. In this regard, handle body210aand handle cover210bare formed to have side openings215and217, respectively for lateral receipt of a cartridge that contains graft material. A movably releasable detent242that may be manually overcome upon lateral force to the cartridge may be supported in a recess244within handle body210a.

Turning now toFIGS.9A-9C,10A-10B and11, further details and function of the locking button230are described.FIGS.9A-9Cshow the locking button230in a normally locked position. Locking button230is rotatably supported within handle210by a pivot pin246. Locking button230includes a depressible portion230aat one end and a projecting lock230bat the opposite end. Depressible portion230may be of circular configuration or other suitable shape and is accessible to the user through opening248in handle210. In the position shown inFIGS.9A,9B and9C, biasing spring232urges depressible portion230adownwardly and thereby urges lock230bupwardly causing a free end230cof lock230bto enter a locking groove214din locking handle214.FIGS.10A and10Bshow the locking button230in a released position. The user may manually push depressible portion230aupwardly causing lock230bat the opposite end to move downwardly, thereby moving free end230cof lock230bout from locking groove214dof locking handle214. In this position locking handle214may freely rotate within handle opening234as shown inFIG.11, thereby causing rotation of inner shaft206relative to handle210. In this position, free end230dof lock230bmay reside in a secondary groove214ein locking handle214that may be overcome upon rotating locking handle214back to the locked position. The position of locking handle214inFIG.11is the same as the locking handle214as shown inFIG.1.

Having described the details of interbody fusion device10and instrument200, use of instrument200to insert device10into a disc space between two opposing vertebral bodies, expand device10therein and facilitate graft delivery into expanded device10is now described. An incision is made through tissue of a patient to establish a working corridor to the spinal surgical site, for example, through Kambin;s triangle, for a TLIF procedure. The corridor may be formed with suitable instruments and the disc space may be suitably prepared through the corridor for insertion of interbody fusion device10. Instrument200, without wedge driver212, may be attached to device10by initially aligning lugs208at attachment end202of inner tube206with lobes30bof opening30at outer wall26of cage12, as depicted inFIG.2. Attachment end202may then be inserted into cage12through opening30as illustrated inFIG.5and into locking pocket32with lugs208being situated within extended lobes32b, as shown inFIG.6A. At this point, locking handle214is in an angular position relative to handle210as shown inFIG.1. Locking handle214is then rotated manually in a clockwise direction looking from the proximal end of instrument200toward the patient until handle214is in the vertical position as shown inFIGS.9A-9C and12. Structural features, such as projections204d(seeFIGS.2and5) at the distal end of outer tube204enter and engage the lobes30bat the proximal end of device10to prevent relative rotation between outer tube204and device10during rotation of locking handle214. In the above example of a cage12having an unexpanded height H1of 8.0 mm and a width W1of 8.5 mm, locking handle214may be rotated approximately 41°. During rotation of locking handle214to the vertical position, shaft214aof locking handle214engages locking button230and pushes locking button230axially proximally against the bias of spring232. As locking handle214reaches the vertical position shown inFIG.12free end230cis moved out from secondary grove214eof locking handle214allowing locking button230to snap free end230cof lock230binto locking grove214dto thereby lock locking handle214in such position until locking button230is manually depressed upwardly relative to handle210.

During such rotation of locking handle214lugs208are moved arcuately to extend into extended lobes32bbehind outer wall26, as illustrated inFIG.6B. In this position, proximal wall26is captured between lobes208and the distal end204aof outer tube204of instrument200. Simultaneously during such rotation cam surface214con locking handle214slidingly engages cam surface218aon camming element218causing inner tube206, which is securely affixed to locking handle214, to move slightly axially proximally relative to handle210. The amount of axial proximal movement of inner tube206is sufficient to cause outer wall26to be sandwiched between lobes208at the distal end of inner tube206and the distal end204aof outer tube204. Upon locking handle214reaching the vertical position shown inFIG.12sufficient compression force is applied to outer wall26to securely tighten instrument200to cage12of device10.

Upon attachment of instrument200to cage12instrument200is used to insert device10into the suitably prepared disc space. Flat surface240of instrument handle210may be appropriately tapped or malleted to gently urge device10into the disc space, if desired by the surgeon. Wedge driver212is then introduced into lumen206bof inner tube206and threaded portion212dis manually threaded into threaded hole101of wedge100to suitably attach wedge100to wedge driver212. Wedge driver212may alternatively in accordance with the surgeon's practice be attached to wedge100prior to introduction of device10into the disc space. Once attached, wedge driver212may be suitably driven axially distally to push wedge100axially distally within cage12to expand cage12within the disc space as described above. Wedge100which is initially disposed approximately centrally between distal end12aand proximal end12bof cage12is moved toward distal end12auntil engagement edges106a,106b,106cand106dengage and reside in respective locking notches23a,23b,23cand23dto lock cage12in the expanded position as shown inFIG.13A

A suitable tool to drive wedge driver212and hence wedge100axially may be a T-handle (not shown). Such a T-handle may have an elongate cylindrical tube that has external threads at a distal end. T-handle may be configured such that the cylindrical tube slides within opening211aof handle end cap211until the external threads at the distal end of the T-handle are threadably received within interior threads236aof drive nut236. An interior transverse surface may be provided within T-handle to engage enlarged cylindrical portion212eat the proximal end212cof wedge driver212. Suitable rotation of T-handle will cause T-handle to move axially distally relative to handle210under the influence of the threaded engagement between external threads of the T-handle and interior threads236aof drive nut236, causing interior transverse surface of T-handle to push against enlarged cylindrical portion212eand thereby push wedge driver212axially in the distal direction. Such rotation of T-handle is continued until cage12is properly expanded as shown inFIGS.13A-13Cand wedge100is suitably locked within locking notches23a-d.

After interbody fusion device10is expanded, wedge driver212and, if used, the T-handle, may be removed from instrument200, which remains attached to expanded device10. Graft material may be introduced into expanded interbody fusion device10using instrument200. As shown inFIGS.14and15, an elongate cartridge300containing a plurality of individually spaced pellets302of graft material may be slidingly inserted into opening215in the side of instrument handle210as illustrated inFIG.14. Cartridge300may contain any suitable number of individual pellets302, with five pellets being shown inFIG.15. Cartridge300includes a plurality of recesses304, each of which is associated and aligned with one of the individual pellets302. Each recess304is configured to receive movably releasable detent242as depicted inFIG.15. Receipt of detent242into a respective recess304tentatively holds cartridge300in a position such that one of the pellets is aligned with interior lumens206band204bof inner tube206and outer tube204, respectively. As a manual force is applied against cartridge300in the lateral direction, the tentative position is overcome as detent242is moved transversely out from a respective recess304allowing cartridge300to move further into handle210until another recess304is aligned with detent242. Cartridge300may be moved laterally through handle210until it emerges through opening217on the opposite side of handle210, at which time it may be removed. As each pellet302is aligned with inner tube206and outer tube204, a suitable plunger250may be introduced through opening211aof handle end cap211to push pellets302individually one at a time through graft opening24into interior hollow12fof expanded interbody device10until sufficient graft material has been placed. As noted above, graft opening24of cage12of interbody fusion device10may in some instances be provided to have a diameter of up to about 5.0 mm, which facilitates an effective and easy delivery of a suitable quantity of graft material. As graft material fills interior hollow12fgraft material may further pass through cage top opening11and bottom opening13to make contact with the endplates of opposing vertebral bodies of a spine to facilitate fusion thereto. Graft material may also emanate from cage side openings15and17so as to occupy the intervertebral space adjacent cage12to promote additional fusion to the opposing vertebral bodies.

As an alternative, a separate graft delivery device may be used in conjunction with instrument200to deliver an appropriate amount of graft material to the surgical site and into expanded device10. One such suitable graft delivery device is described in U.S. Pat. No. 10,492,925, issued on Dec. 3, 2019 to Hollister et al. (the '925 Patent) and assigned to the same assignee as the subject application. The entire contents of the '925 Patent are incorporated herein by reference. The graft delivery device described in the '925 Patent is commercially available under the brand name GraftMag. In use, the channel12described in the '925 Patent made be introduced through inner tube206of instrument200to place graft into device10through opening30of cage12.

Upon delivery of suitable graft material and completion of the surgical procedure, instrument200may then be detached from the expanded cage12. To effect such detachment depressible portion230aof locking button230is manually depressed upwardly releasing lock230bfrom locking groove214das described hereinabove thereby allowing locking handle214to move radially within opening234of handle210to the angular position shown inFIG.1. During such movement, the compression of cage outer wall26between lugs208and the distal end204aof instrument outer tube204is loosened while lugs208are radially moved back into alignment with lobes30b. At this point, instrument200may be withdrawn from expanded device10and from the surgical site.

In the example provided above for use in a TLIF fusion procedure at the L1/L2 lumbar level, cage12may have an unexpanded height H1of 8.0 mm and an unexpanded width W1of 8.5 mm. Upon expansion, distal end12aof cage may be increased to an expanded height H2of 10 mm and an expanded width W2of 11 mm, as shown inFIGS.13A,13B and13C. The increase in height to H2results in a lordotic angle of eight degrees at distal end12aand an increase in the width of cage12at distal end12aof approximately 29%. As noted above, interbody fusion device10may also be used in TLIF fusion procedures at other spinal levels. For example, cage12when used in a TLIF fusion procedure at the L4/L5 level may have an unexpanded height H1of 16.0 mm and an unexpanded width W1of 8.5 mm consistent with introduction through Kambin's triangle. Upon expansion, distal end12aof cage12at this level may be increased to an expanded height H2of 18 mm resulting in a lordotic angle of eight degrees and an expanded width W2of 11 mm. At such other level, cage12may have an opening30at the proximal end12bof 5.0 mm to be compatible with the graft delivery instruments, although other suitable dimensions for opening30may be used.

Turning now toFIG.16, a cage112that is a variation of cage12is shown. Cage112is identical to cage12except for the provision of textured top and bottom surfaces. Since the texturing of both top and bottom surfaces are the same, only the details of top textured surface are shown and described, it being understood that the details of bottom textured surface are the same. Textured top surface34is formed on both upper arms16aand16b. As shown, textured top surface34is formed on the entire top surface34of upper arms16aand16b. In some instances, texturing may be included only on those portions that are configured to contact a vertebral endplate of a superior vertebral body adjacent the disc space. The textured surface includes those upper portions of arms16aand16bthat have fixation structures, such as a plurality of serrations36. Such serrations36are not included adjacent hinge points18aand18b. In other instances, no textured surfaces may be formed at the distal end12aof cage112that is curved in a manner to facilitate entrance of cage112into the disc space.

Textured surface34may be formed in a three-dimensional geometric pattern having a plurality of projections and recesses. Such a pattern may be formed by various methods, including without limitation, laser ablation, acid etching and machining. Textured surfaces in such a pattern are believed to promote the formation of intimate tissue integration between the endplates of the opposing vertebral bodies and cage112. In a particular arrangement where cage112is formed of titanium, textured surface34may be formed by ablating the upper and lower surfaces of cage112by a pulsed laser in the nanosecond range to create a porous surface comprising projections and recesses having a depth of up to at least 100 μm. Such a process may be performed in accordance with the nanosecond laser devices and methods taught and described, for example, in U.S. Pat. No. 5,473,138, entitled “Method for Increasing the Surface Area of Ceramics, Metals and Composites”, issued to Singh et al on Dec. 5, 1995, the entire contents of which are incorporated herein by reference.

In an effort to further enhance the tissue integration aspects of cage112, textured upper surface34may be subsequently treated by further ablating those previously formed surfaces by an ultrafast pulsed laser to create additional, smaller projections and recesses having a depth less than 1 μm and preferably not greater than 200 nm. Such a process may be performed with a picosecond pulsed laser or a femtosecond pulsed laser device in accordance with, for example, the methods and laser devices taught and described in U.S. Pat. No. 6,951,627, entitled “Method of Drilling Holes With Precision Laser Micromachining”, issued October 2005 to Li et al., the entire contents of which are incorporated by reference herein. Other picosecond and femtosecond pulsed lasers may also be used, such as those described in U.S. Pat. No. 10,603,093, entitled “Bone Implant and Manufacturing Method Thereof”, issued on Mar. 31, 2020 to Lin et al., the contents of which are incorporated by reference in their entirety. In a particularly preferred arrangement, textured surface34is formed by initially laser ablating the surfaces of cage112with the nanosecond laser devices to form a porous surface followed by laser ablation with the femtosecond laser to further alter the surface to produce nano-scale structures.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. For example, the inventive concepts described herein may be used with non-expandable as well as expandable spinal implants, and the textured surfaces formed by the laser ablation processes described herein may also be used with other spinal implants and in spinal surgical procedures other than TLIF applications. Accordingly, it is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.