US20080132902A1 - Methods and instrumentation for positioning implants in spinal disc space in an anterior lateral approach - Google Patents

Abstract

Instruments and methods are provided for positioning one or more implants into a spinal disc space. The instruments and methods have application in an anterior lateral approach to the disc space between the L4 and L5 vertebrae. The instruments include a distractor, a housing, a guide member to facilitate positioning of the housing, and a partition member engageable to the housing to facilitate positioning of one or more implants into the disc space.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application is a divisional of U.S. patent application Ser. No. 10/405,816, filed Apr. 2, 2003, and issuing as U.S. Pat. No. 7,326,216, which application is incorporated herein by reference in its entirety.
BACKGROUND
• Access to the disc space between the L4 and L5 vertebrae can be obstructed or difficult due to anatomical considerations. For example, an anterior approach or an anterior oblique approach requires the surgeon to retract or move, or at least work adjacent to, the major vessels extending along the anterior portion of the spinal column. While an anterior oblique approach may reduce or eliminate the requirement for retraction of these major vessels, access for positioning instruments and implants in the posterior portion of the disc space on the side of the approach can be limited. Further, the instruments can still be adjacent the major vessels during the surgery.
• A lateral approach to the disc space anterior of the posterior elements can avoid the major vessels and provide access for disc space preparation and implant insertion, but other anatomical obstructions can be encountered. For example, positioning instruments and implants in the spinal disc space between the L4 and L5 vertebrae from an anterior lateral approach can be obstructed or inhibited by the iliac crest. Instrumentation and methods which facilitate placement of implants in the spinal disc space from an anterior lateral approach are needed to make such procedures a more viable alternative for treatment and correction of spinal deformities.
SUMMARY
• Instruments and methods are provided for positioning one or more implants into a spinal disc space. The instruments and methods have application in an anterior lateral approach to the disc space between the L4 and L5 vertebrae. The instruments and methods can also have application in other approaches to the spine at any level of the spine.
• According to one aspect, instruments are provided that include a distractor, a housing, a guide member to facilitate positioning of the housing, and a partition member engageable to the housing to facilitate positioning of one or more implants into the disc space.
• According to another aspect, a surgical instrument insertable in a spinal disc space between an upper vertebra and a lower vertebra is provided. The instrument comprises a head including an upper surface and an opposite lower surface positionable adjacent endplates of the upper and lower vertebrae, respectively. The head defines a disc space distraction height between the upper and lower surfaces. A shaft extends proximally from the head. The shaft includes a distal portion, a proximal portion, and an offset portion therebetween. The distal portion includes a guide portion adjacent the head. The head and the guide portion extend along a first axis and the offset portion extends proximally from the guide portion along a second axis oriented at a first angle relative to the first axis.
• According to a further aspect, a surgical instrument assembly provides access to a spinal disc space. The assembly comprises a distractor, a housing and a guide instrument. The distractor includes a head positionable in a spinal disc space and a shaft extending proximally from the head. The shaft includes a guide portion along at least a portion thereof adjacent the head. The guide instrument includes a shaft and a guide member at a distal end of the shaft. The guide member is removably engaged to the housing and moveable along the guide portion of the distractor with the shaft of the guide instrument adjacent to the shaft of the distractor to guide the housing along the distractor to the spinal disc space when the head is positioned in the spinal disc space.
• According to another aspect, an instrument assembly for facilitating placement of an implant in a spinal disc space includes a housing and a partition member. The housing includes a frame member defining an opening therethrough between side walls of the housing. The housing is positionable adjacent to the spinal disc space and provides access thereto through the opening. The partition member is engageable to the frame in the opening. The partition member includes an extension extending distally from the frame and positionable in the spinal disc space. The partition member is movable relative to the frame between the side walls.
• According to another aspect, a surgical instrument assembly is provided. The assembly includes a body with a portion positionable in a spinal disc space and a mounting member extending from the body. The assembly also includes a shaft assembly removably engageable to the mounting member. The shaft assembly includes an outer shaft defining a distally opening receptacle and an inner shaft movable relative to the outer shaft and extending distally therefrom. The inner shaft includes a distal engagement member engageable to the mounting member. Movement of the engagement member relative to the outer shaft to position the mounting member in the receptacle secures the body to the shaft assembly.
• According to a further aspect, a method for positioning an implant in a spinal disc space of a patient comprises: accessing the spinal disc space between L4 and L5 vertebrae from a lateral approach to the patient; and positioning a distractor in the spinal disc space with a shaft of the distractor oriented laterally to the patient, the shaft comprising a distal portion extending laterally from the spinal disc space and a proximal portion offset relative to the distal portion anteriorly of the iliac crest.
• According to another aspect, a method for positioning a spinal implant in a spinal disc space of a patient comprises: positioning a housing adjacent the disc space between the L4 and L5 vertebrae in an anterior lateral approach; positioning a partition member through the housing into the disc space; positioning an implant in the disc space anterior of the partition member; and moving the partition member anteriorly to move the implant anteriorly in the spinal disc space.
• These and other aspects are also discussed below.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is an anterior elevation view of a sacro-lumbar segment of the spinal column.
• FIG. 2 is a perspective view of a disc space distractor.
• FIG. 3 is a section view of the distractor ofFIG. 2 along line3-3.
• FIG. 4 is a perspective view of a housing.
• FIG. 5 is a perspective view of a guide instrument attachable to the housing ofFIG. 4.
• FIG. 6 is an elevation view of a portion of the guide instrument ofFIG. 5.
• FIG. 7 is an enlarged perspective view of a guide member at the distal end of the guide instrument ofFIG. 5.
• FIG. 8 is a perspective view of a housing insertion instrument assembly comprising the distractor ofFIG. 3, the housing ofFIG. 4 and the guide instrument ofFIG. 5.
• FIG. 9 is a perspective view of a partition member.
• FIG. 10 is a perspective view of an implant insertion instrument assembly comprising the housing ofFIG. 4 and the partition member ofFIG. 9.
• FIG. 11 is an elevation view of a shaft assembly comprising a portion of the implant insertion instrument assembly.
• FIG. 12 is a perspective view of a wedge displacer instrument.
• FIG. 13 is a perspective view of a second displacer instrument.
• FIG. 14 is perspective view looking down on the distal end portion of the assembly ofFIG. 8 positioned adjacent a lower vertebra of a spinal column segment with the distractor in the spinal disc space and the housing being positioned with the guide instrument to provide access to the spinal disc space.
• FIG. 15 is a perspective view of the distal end portion of the assembly ofFIG. 10 looking up through the endplate of the lower vertebra ofFIG. 14.
• FIG. 16 is a perspective view of the assembly ofFIG. 10 with an implant positioned in the spinal disc space along an anterior side of the partition member.
• FIG. 17 is a perspective of the assembly ofFIG. 10 with the wedge displacer instrument being inserted for positioning along the posterior side of the partition member.
• FIG. 18 is a perspective of the assembly ofFIG. 10 with the second displacer instrument positioned in the disc space along posterior side of the partition member.
• FIG. 19 is a perspective view of the spinal disc space with medial-laterally oriented anterior and posterior implants positioned therein.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
• For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
• Referring toFIG. 1, there is shown aspinal column segment10 that includes asacrum12, anL5 vertebra14, anL4 vertebra16, and adisc space18 betweenL5 vertebra14 andL4 vertebra16. The present invention provides methods and instrumentation adapted for positioning spinal implants indisc space18 from an anterior lateral approach that avoid or minimize the obstruction ofiliac crest20 into an access pathway todisc space18. The instruments and methods provide anterior lateral access to the disc space for endplate preparation and implant insertion intodisc space18 to support of the adjacent vertebrae with one or more medial-laterally oriented implants.
• In surgical procedures for accessingdisc space18, it can be desirable to approachdisc space18 from a lateral approach along the anterior side ofiliac crest20. With such an anterior lateral approach, the major arteries and veins along the anterior portion of the spine can be avoided. Furthermore, the posterior neural elements, musculature, and bony structures can be avoided. With the anterior lateral approach, one or more implants can be positioned indisc space18 in such a manner that the load of the spinal column transmitted by the implants is evenly distributed about the central axis of the spinal column. However,iliac crest20, particularly along itsouter margin22, can extend anteriorly relative todisc space18 such that anterior lateral access todisc space18 is impeded thereby.
• Referring now toFIG. 2, there is shown adisc space distractor30 including adistal head32 and ashaft34 extending proximally therefrom.Head32 can include a firstvertebral endplate surface46 and an opposite secondvertebral endplate surface48. First and second side surfaces47,49 extend between first and second vertebral endplate surfaces46,48. First and second vertebral endplate surfaces46,48 can be spaced from one another to contact the adjacent vertebral endplates, or to provide a desired disc space height between the vertebral endplates whenhead32 is inserted intodisc space18 with first and second vertebral endplate surfaces46,48 adjacent respective ones of the vertebral endplates. It is contemplated thatdistractor30 could be any one of a number of distracters provided in a kit in which the distracters have heads of differing heights so that the distractor corresponding to or providing the proper disc space height can be selected. It is further contemplated thathead32 can be non-distracting, and is positioned in the disc space to facilitate positioning of instruments in the desired operative location relative todisc space18, as discussed below.
• Shaft34 includes aproximal portion41 and adistal portion43 separated by an offsetportion40.Proximal portion41 includes afirst shaft portion38 extending proximally from offsetportion40 along anaxis39. Ahandle36 extends fromfirst shaft portion38 and is oriented transversely toaxis39.Distal portion43 includes aguide portion42 extending distally from offsetportion40 along anaxis44.Head32 extends distally fromguide portion42. As discussed further below,guide portion42 can be adapted to guide placement of a housing therealong to a positionadjacent disc space18 whenhead32 is positioned in the disc space.
• As shown further inFIG. 3, offsetportion40 is angled to positionproximal portion41 anteriorly ofdistal portion43 whendistractor30 is operatively positioned in an anterior lateral approach to the disc space.Distal portion43 can thus be positioned in the disc space posteriorly to avoid the major vessel and other structures along the anterior portion of the spinal column segment.Longitudinal axis39 is offset anteriorly by a distance31 fromlongitudinal axis44. It is contemplated that offset distance31 is sufficient so that withhead32 positioned in the spinal disc in its operative anterior lateral orientation,distal portion43 extends alonglongitudinal axis44 from the disc space andproximal portion41 is offset anteriorly to avoid the iliac crest. In the operative position, handle36 extends anteriorly to provide additional room for access and placement of surgical instruments along the posterior side ofdistractor30.
• In one embodiment, offsetportion40 is spaced proximally about 60 millimeters from the trailing end ofdistraction head32, and offset distance31 is about 20 millimeters. Other suitable dimensions and offsets are also contemplated so that proximal portion avoids the iliac crest whendistractor30 is inserted in an anterior-lateral approach to the disc space.
• InFIG. 4 there is shown ahousing50 comprising aframe portion52 including aposterior side wall53 and ananterior side wall55 connected by anupper wall62 and alower wall66.Walls53,55,62,66 define anopening54 through which in the operative position ofhousing50 instruments and implants can be inserted into the spinal disc space.Opening54 is shown with a rectangular shape. Also contemplated is a square shape or other suitable shape.Frame portion52 includes aposterior extension56 extending fromposterior side wall53 and ananterior extension57 extending fromanterior side wall55.Posterior extension56 can be provided with a length greater than that ofanterior extension57 such thatposterior extension56 extends substantially acrossdisc space18 to protect the posterior portion of the spinal column from intrusion by surgical instruments and implants during the surgical procedure and to maintain disc space distraction.Anterior extension57 has a length sufficient to extend into the disc space to contact the cortical rim to assistposterior extension56 in maintaining spacing of the adjacent vertebrae during the surgical procedure. It is further contemplated that the length ofanterior extension57 does not extend into the implant insertion location in the anterior portion of the disc space and, as discussed further below, allows a spinal implant to be positioned at least in part anteriorly thereof. Other embodiments contemplate ananterior extension57 that extends across all or part of the disc space.
• Upper wall64 offrame portion52 includes anupper slot58 formed therethrough andlower wall66 includes alower slot60 formed therethrough.Slots58,60 facilitate coupling ofhousing50 to an instrument, such asshaft assembly126 discussed further below, so that the shaft assembly can removehousing50 from the disc space.Upper wall62 includes aleading end64 curved to conform to the curvature of the vertebral body against which it is positioned in the operative position ofhousing50. Similarly,lower wall66 includes aleading end68 curved to conform to the curvature of the vertebral body against which it is positioned in the operative position ofhousing50. A proximally-openingnotch70 is provided inposterior wall53.
• InFIGS. 5 and 6 there is shown aguide instrument80 in perspective and side elevational views, respectively.Guide instrument80 includes aproximal handle82, ashaft84 extending distally fromhandle82, and aguide member86 at the distal end ofshaft84.Guide member86 includes apassage90.Shaft84 includes adistal portion89, aproximal portion91, and an offsetportion87 therebetween.Distal portion89 extends along anaxis81, offsetportion87 extends along anaxis83, andproximal portion91 extends along anaxis95.Axis95 andaxis81 can be generally parallel to one another.Axis83 forms anangle85 withaxis81 andaxis95.
• As shown in further detail inFIG. 7,distal portion89 is offset frompassage90 so thatdistal portion89 ofshaft84 can extend adjacent to guideportion42 ofshaft34 ofdistractor30 asguide member86 is moved alongguide portion42. In the illustrated embodiment,distal portion89 is offset posteriorly frompassage90 in the operative anterior lateral orientation so thatshaft84 extends along the posterior side ofshaft34 ofdistractor30 in side-by-side relation. Asguide instrument80 is inserted to the disc space in an anterior lateral approach,angle85 offsetsproximal portion91 cephaladly to avoid the iliac crest. Offsetportion87 can be further configured relative todistal portion89 to offsetproximal portion91 anteriorly by a distance31, such as discussed above with respect todistractor30. In one embodiment,angle85 is about 30 degrees. Other embodiments contemplatedangles85 up to 90 degrees so long asproximal portion91 avoids the iliac crest when positioned in an anterior lateral approach.
• Guide member86 includes abody88 definingguide passage90 extending between a distal end and a proximal end ofbody88.Tapered surfaces92 provide an opening intopassage90 along one side ofbody88.Guide passage90 is sized to receiveguide portion42 ofdistractor30 therein in close-fitting and sliding engagement to permit controlled relative movement ofguide member86 alongguide portion42.Body88 includes adistal portion96 and aproximal portion98.Proximal portion98 includes aflanged wall99 extending about and forming a lip aboutdistal portion96.Distal portion96 is sized for positioning in opening54 ofhousing50 withflanged wall99 in abutting engagement with the proximal end ofhousing50.
• InFIG. 8, a housinginsertion instrument assembly100 is provided that includesdistractor30,housing50 and guideinstrument80.Guide member86 is positioned in opening54 ofhousing50 withprotrusion94 received inreceptacle70 andflanged wall99 in abutting engagement with the proximal end ofhousing50. Withdistractor50 positioned in the desired position indisc space18, offsetportion40 is configured so thatproximal portion41 is positioned away from the iliac crest to provide space to receiveguide instrument80 andhousing50 therebetween.
• Shaft34 ofdistractor30 is positioned inpassage90 ofguide member86 proximal ofguide portion42.Guide member86 andhousing50 are advanced to positionguide portion42 inpassage90.Guide portion42 can have a cross-section enlarged relative to the proximal portion ofshaft34 for sliding engagement withpassage90. It is contemplated thatpassage90 ofguide member86 can be keyed to guideportion42 to prevent rotation ofguide instrument80 thereabout and to ensure the proper orientation ofhousing50 as it is guided to the disc space. Circular cross-sections are also contemplated.Housing50 is guided alongguide portion42 to positionframe52 adjacent the L4 and L5 vertebrae, and to positionposterior extension56 andanterior extension57 in the disc space. Withhousing50 in its proper position relative todisc space18,distractor30 and guideinstrument80 are removed proximally fromhousing50 withhousing50 remaining at the operative site.Opening54 ofhousing50 provides access to the disc space for removal of disc material, endplate preparation and implant insertion. It is also contemplated that disc material removal, endplate preparation and other pre-implant insertion procedures can be conducted prior to positioning ofhousing50.
• Referring toFIG. 9, there is shown apartition member110 having abody114 and acentral extension112 extending distally frombody114.Body114 includes anupper flange member116 and alower flange member118 extending from and transversely oriented tobody114. A mountingmember122 extends transversely to and, in the operative anterior lateral orientation, cephaladly fromupper flange member116. Mountingmember122 includes aslot124 to facilitate attachment to an insertion instrument. Aslot120 inbody114 is provided for engagement by a shaft assembly to facilitate withdrawal and manipulation ofpartition member110 relative tohousing50.
• InFIG. 10 there is shown an implantinsertion instrument assembly200 includinghousing50 andpartition member110.Partition member110 is removably mounted to the distal end of ashaft126 assembly. Aproximal handle128 is provided at the proximal end of aninner shaft130, and adistal handle129 is coupled to anouter shaft131. As shown inFIG. 11, the distal end ofinner shaft130 can include anengagement member133 that includes adistal extension135 and ahook member137 extending from and transversely oriented todistal extension135.Hook member137 can be positioned inslot124 of mountingmember122, andouter shaft131 can be moved distally relative toinner shaft130 to secure mountingmember122 in a distally opening receptacle inouter shaft131 such asslot139. It is contemplated thatouter shaft131 can be threadingly coupled toinner shaft130, or thatouter shaft131 can be spring-biased distally relative toinner shaft130. Movement ofouter shaft131 andinner shaft130 relative to one another can remove mountingmember122 fromslot139 and allowhook member137 to be withdrawn fromslot124 of mountingmember122.
• Partition member110 can be attached toshaft assembly126 and positioned through opening54 ofhousing50 so thatcentral extension112 extends into the disc space betweenposterior extension56 andanterior extension57. When inserted through opening54 ofhousing50,upper flange member116 is positioned alongupper wall62, andlower flange member118 is positioned alonglower wall66. Mountingmember122 extends upwardly fromupper wall62 so thatshaft assembly126 is located above the iliac crest at its proximal end when secured to mountingmember122. Spacing132 between theflange members116,118 andbody114 can be provided to receive the thickness of the upper andlower walls62,66 for sliding engagement therewith aspartition member110 is moved relative tohousing50. Upper andlower walls62,66 can be parallel to one another to facilitate the sliding movement ofpartition member100 therealong.
• InFIG. 12 there is shown awedge displacer instrument140 comprising ahandle142 and ashaft144 extending distally fromhandle142.Shaft144 includes an offsetportion146separating shaft144 into aproximal portion147 and adistal portion148.Distal portion148 can extend generally parallel toproximal portion147. Adisplacer wedge150 extends distally fromdistal portion148 ofshaft144.Displacer wedge150 includes alead end152 and a trailingend154. A firstlateral surface158 and a secondlateral surface160 extend from leadingend152 to trailingend154 between afirst surface159 and an oppositesecond surface161.Surfaces158,160 and ends152,154 form a wedge shape such thatleading end152 has a reduced width relative to trailingend154. The reducedwidth leading end152 facilitates insertion ofdisplacer wedge150 betweenposterior extension56 ofhousing50 andpartition member110. Abore156 can be formed between first andsecond surfaces159,161 ofdisplacer wedge150 to reduce the weight ofdisplacer wedge150, although asolid displacer wedge150 is also contemplated.
• InFIG. 13 there is shown asecond displacer instrument170 comprising ahandle172 and ashaft174 extending distally fromhandle172.Shaft174 includes an offsetportion176separating shaft174 into aproximal portion177 and adistal portion178.Distal portion178 can extend generally parallel toproximal portion176. Adisplacer head180 extends distally fromdistal portion178 ofshaft174.Displacer head80 includes alead end182 and a trailingend184. A firstlateral surface188 and a secondlateral surface190 extend from leadingend182 to trailingend184 between afirst surface189 and an oppositesecond surface191.Surfaces188,190 and ends182,184 form a box shape such thatleading end182 has the same width as trailingend184. Other shapes are also contemplated so long as leadingend182 provides the desired displacement of the implant at the distal end ofpartition member110. Abore186 is formed between first andsecond surfaces189,191 ofdisplacer head180 to reduce the weight ofdisplacer head180, although asolid displacer head180 is also contemplated.
• In use,displacer wedge150 of wedgedisplacer instrument wedge140 can be been inserted betweenpartition member110 andposterior extension56 ofhousing50 to provide an initial separation. Withwedge displacer instrument140 removed,second displacer instrument170 is positioned with leadingend182 ofdisplacer head180 betweenposterior extension56 ofhousing50 andpartition member110. Leadingend182 can provide a separation between the distal ends ofposterior extension56 andpartition member110 that corresponds to the width of leadingend182.
• With reference toFIGS. 14-19, a surgical procedure will be described for positioning a pair of interbody implants inspinal disc space18 through an anterior lateral approach with the instruments discussed above. InFIG. 14 housinginsertion instrument assembly100 includesdistractor30 withdistractor head32 positioned at the desired location indisc space18. The location ofhead32 can be confirmed with fluoroscopy or other suitable viewing system. It is contemplated thathead32 will be located centrally indisc space18 and extend in the medial-lateral direction in its final orientation, although other final orientations are contemplated.Shaft34 ofdistractor30 extends fromdisc space18 laterally, andshaft34 is offset anteriorly to avoid the iliac crest, as discussed above.
• Housing50 is mounted to guidemember86 ofguide instrument80 and then positioned aboutshaft34 ofdistractor30.Guide member86 and thushousing50 are guided alongguide portion42 to positionposterior extension56 laterally along the posterior portion P ofdisc space18 andanterior extension57 laterally along the anterior portion A ofdisc space18.Frame52 is positioned adjacent thevertebrae14,16 outsidedisc space18 so that opening54 can provide access todisc space18 whileextensions56,57 maintain disc space distraction.
• Referring now toFIG. 15,distractor30 and guideinstrument80 are removed fromhousing50. Mountingmember122 ofpartition member110 is attached toshaft assembly126. Since mountingmember122 extends cephaladly fromhousing50,shaft assembly126 is positioned cephaladly of the iliac crest aspartition member110 is inserted through opening54 ofhousing50.Shaft assembly126 is manipulated to positionpartition member110 through opening54 ofhousing50 so thatcentral extension112 extends into the disc space betweenposterior extension56 andanterior extension57.Body114 ofpartition member110 is received inframe portion52 withupper flange116 andlower flange118 positioned alongupper wall62 andlower wall66, respectively, to guidepartition110 as it is moved relative tohousing50.Partition member110 is positioned as close as possible toposterior extension56 to maximize the space anteriorly ofpartition member110 through opening54 for positioning of an implant therethrough. Withpartition member110 secured inhousing50,shaft assembly126 can be uncoupled frompartition member110.
• InFIG. 16 animplant250 is removably attached or engaged to the distal end of animplant inserter300.Implant250 is positioned indisc space18 betweenanterior extension57 ofhousing50 andcentral extension112 ofpartition member110.Implant inserter300 is detached fromimplant250, and, as shown inFIG. 17,wedge displacer instrument140 is positioned so that leadingend152 ofdisplacer wedge150 is located betweenpartition member110 andposterior extension56. A lever, if necessary, can be inserted betweenhousing50 andpartition member110 to provide an initial separation prior to insertion ofdisplacer wedge150.Wedge displacer instrument140 is advanced distally until trailingend154 is positioned betweenframe50 andpartition member110, thereby movingpartition member110 andimplant250 anteriorly indisc space18 and also anteriorly relative tohousing50.
• Tapered leadingend152 ofwedge displacer instrument140 may not positioncentral extension112 andimplant250 anteriorly far enough so thatimplant250 extends in a medial-lateral orientation indisc space18, particularly at the distal end ofcentral extension112. InFIG. 18,second displacer instrument170 is positioned into opening54 betweenposterior extension56 andpartition member110 and advanced distally to move at least the distal end ofcentral extension112 and thus implant250 anteriorly indisc space18 and to alignimplant250 in a medial-lateral orientation. In its medial-lateral position, it is contemplated thatimplant250 can be located indisc space18 adjacentanterior extension57. It is further contemplated thatimplant250 can be displaced anteriorly so that is located in whole or in part anteriorly ofanterior extension57. Thus, the present invention provide positioning of the implant in the anterior portion of the spinal disc space while avoiding the major vessel and other anatomical structures along the anterior portion of the spinal column.
• Withimplant250 in a desired position indisc space18,partition member110 can be removed by, for example, attachingshaft assembly126 thereto and withdrawingpartition member110 fromdisc space18 andhousing50. InFIG. 17, asecond implant270 is positioned indisc space18 through opening54 ofhousing50 in a medial-lateral orientation along a posterior side offirst implant250.
• The instruments and methods of the present invention facilitate placement ofimplants250,270 indisc space18 in a medial lateral orientation to provide bilateral support of theadjacent vertebrae14,16 in the anterior and posterior areas ofdisc space18. It is further contemplated that only a single implant may be inserted indisc space18. Bone graft, bone growth inducing material, and/or therapeutic agents can be positioned in, around or integrated into the one or more implants positioned indisc space18. It is further contemplated that the one or more implants positioned indisc space18 can be fusion devices, bone support devices, artificial disc devices, or other suitable device for implantation between vertebrae. The one or more implants can be provided with an outer surface structure to engage the vertebral endplates, and one or more chambers, cavities and/or recesses for receiving bone growth material. The one or more implants can also be flexible, or include one or more articulating components, to provide segmental motion between the adjacent vertebrae.
• While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. All changes, modifications and equivalents that come within the spirit of the invention as defined by the following claims are desired to be protected

Claims (25)

1. A surgical instrument insertable in a spinal disc space between an upper vertebra and a lower vertebra, comprising:

a head including an upper surface positionable adjacent an endplate of the upper vertebra and an opposite lower surface positionable adjacent an endplate of the lower vertebra; and

a shaft extending proximally from said head, said shaft including a distal portion, a proximal portion, and an offset portion therebetween, said distal portion including a guide portion adjacent said head and engageable to guide an instrument therealong to the spinal disc space, said head and said guide portion extending along a first axis and said offset portion extending proximally from said guide portion and transversely oriented thereto.

2. The instrument ofclaim 1, wherein said proximal portion extends along a second axis generally parallel to said first axis.

3. The instrument ofclaim 2, wherein said proximal portion includes a handle oriented transversely to said second axis.

4. The instrument ofclaim 2, wherein said offset portion extends along a third axis oriented at an angle to said first axis.

5. The instrument ofclaim 1, wherein said guide portion includes a cross-sectional dimension along a length thereof that is greater than a cross-sectional dimension along a length of said proximal portion.

6. A surgical instrument for spinal surgery having an operative orientation including an anterior lateral approach to a spinal disc space between L4 and L5 vertebrae of a patient, comprising:

a distal end portion positionable adjacent the spinal disc space and a proximal portion offset from said distal portion to avoid an iliac crest of the patient when the surgical instrument is the operative orientation.

7. The instrument ofclaim 6, wherein the instrument is a distractor including a head at said distal portion positionable in the spinal disc space and said proximal portion includes a shaft extending distally from said head, said proximal portion being offset anteriorly of the iliac crest in the operative orientation.

8. The instrument ofclaim 6, wherein the instrument is a guide instrument including a guide member at said distal portion and said proximal portion includes a shaft extending distally from said head, said proximal portion being offset cephaladly of the iliac crest in the operative orientation.

9. A surgical instrument assembly for providing access to a spinal disc space, comprising:

a distractor including a head positionable in a spinal disc space and a shaft extending proximally from said head, said shaft including a guide portion along at least a portion thereof adjacent said head;

a housing including an opening therethrough for providing access to the spinal disc space when positioned adjacent thereto; and

a guide instrument including a shaft and a guide member at a distal end of said shaft, said guide member removably engaged to said housing, said guide member moveable along said guide portion of said distractor with said shaft of said guide instrument in side-by-side relation to said shaft of said distractor to guide said housing along said distractor to the spinal disc space when said head is positioned in the spinal disc space.

10. The assembly ofclaim 9, wherein said housing includes a frame portion defining said opening therethrough, said housing further including a first extension along one side of said opening extending distally from said frame portion and a second extension along an opposite side of said opening extending distally from said frame portion, said first and second extensions positionable in the spinal disc space to maintain a disc space distraction when said head is removed from the spinal disc space.

11. The assembly ofclaim 10, wherein said first extension is longer than said second extension.

12. The assembly ofclaim 10, wherein said frame portion includes an upper wall positionable adjacent an upper vertebra and a lower wall positionable adjacent a lower vertebra, said upper and lower walls each including a distal end curvature corresponding to a curvature of a lateral profile of the upper and lower vertebrae, respectively.

13. The assembly ofclaim 9, wherein said opening includes a rectangular shape.

14. The assembly ofclaim 9, wherein said guide member includes a distal portion positionable in said opening to engage said guide member in said opening and a proximal portion forming a lip around said distal portion, said lip in abutting engagement with a proximal end of said housing when said distal portion is positioned in said opening.

15. The assembly ofclaim 14, wherein said housing includes a proximally-opening notch in a wall thereof and said guide member includes a protrusion positionable in said notch.

16. The assembly ofclaim 9, wherein said guide member includes a passage extending between a distal end and a proximal end of said guide member and said guide portion of said distractor is movably received in said passage.

17. The assembly ofclaim 16, wherein said guide member includes tapered surfaces forming an opening into said passage along one side thereof.

18. The assembly ofclaim 16, wherein said passage extends along a center of said guide member and said shaft of said guide instrument is offset from said passage.

19. The assembly ofclaim 18, wherein said shaft of said guide instrument includes a distal portion, a proximal portion, and an offset portion therebetween, said offset portion positioning said proximal portion cephaladly of said distal portion in an operative orientation of said guide instrument.

20. The assembly ofclaim 18, wherein said shaft is offset posteriorly of said passage in said operative orientation of said guide instrument.

21. The assembly ofclaim 9, wherein said shaft of said distractor includes a distal portion, a proximal portion, and an offset portion therebetween, said distal portion including said guide portion, said head and said guide portion extending along a first axis and said offset portion extending proximally from said guide portion along a second axis oriented at a first angle relative to said first axis.

22. The assembly ofclaim 21, wherein said proximal portion extends along a third axis generally parallel to said first axis.

23. The instrument ofclaim 22, wherein said proximal portion includes a handle oriented transversely to said third axis.

24. The instrument ofclaim 21, wherein said guide portion includes a cross-sectional dimension along a length thereof that is greater than a cross-sectional dimension along a length of said proximal portion.

25-56. (canceled)

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