US20010029377A1 - Spinal disc space distractor - Google Patents

Abstract

A distractor for separating adjacent elements, such as vertebrae. The distractor preferably has a scissors-type distracting mechanism, either in a simple scissors or double-acting scissors configuration. A set of blades is provided on each jaw such that an implant may be inserted between the spaced apart blades. The set of blades includes at least two blades.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application is a continuation of copending U.S. patent application Ser. No. 09/411,161, filed Oct. 1, 1999, which claims priority to U.S. Provisional Application No. 60/102,669, filed Oct. 2, 1998.[0001]
FIELD OF THE INVENTION
• The present invention relates to a device and method for spreading apart adjacent vertebrae of a vertebral column so that an implant may be inserted therebetween. More particularly, the present invention relates to a distractor device shaped and configured for minimally invasive insertion and use, such as for distraction of vertebrae using an anterior or anterolateral approach.[0002]
BACKGROUND OF THE INVENTION
• Back pain can be caused by either one or a combination of the following: a loss of disc height, compression of nerve roots, degenerative disc disease, spondylolisthesis, and other causes. The current standard of treatment for people suffering from severe back pain requiring surgical intervention due to different types of pathology is by intervertebral fusion. Intervertebral fusion is achieved by fusing two adjacent vertebral bodies together by removing the affected disc and inserting a suitably sized implant into the disc space that allows for bone to grow between the two vertebral bodies bridging the gap left by the disc removal.[0003]
• Known intervertebral fusion procedures typically involve the steps of removing a portion or all of the affected disc material, spreading apart adjacent vertebrae with a distractor, and inserting an implant into the space previously occupied by the removed disc material. This procedure can be done either from the front of the patient (anterior interbody fusion) or from the back (posterior interbody fusion). If done from the front, it is important to reduce the size of the distractor so that the procedure is as minimally invasive as possible and thus minimally interferes with and traumatizes the organs and vasculature between the vertebral region being treated and the insertion point. Posterior fusion can utilize larger implants and tools since the insertion space is more accommodating.[0004]
• Current implants used for interbody fusion include allograft rings/dowels and cages such as threaded cages. However, the technique for the insertion of these implants generally does not achieve distraction because of their height limitations, thus making it difficult to restore the natural disc height. The force necessary to insert these implants (such as by drilling and tapping) may cause damage to the vertebrae or vertebral endplates at the insertion site. Moreover, allograft products and cages made out of other brittle materials (e.g., carbon fiber and ceramics) may break during insertion, particularly when distraction is not used and external force is necessary to insert the implant. Threaded cages on the other hand do not restore lordosis, and do not allow for atraumatic distraction to restore disc height. Thus, there remains a need for improvements in this area.[0005]
SUMMARY OF THE INVENTION
• In accordance with the principles of the present invention, a spinal disc distractor is provided to allow for an implant insertion technique to be performed during distraction of the disc space. The implants are slid into the disc space between the distractor blades, preferably while the blades are in contact with the upper and lower surfaces of the adjacent vertebral bodies. The distractor of the present invention is formed to be as minimally invasive and atraumatic as possible such that it may readily be used in an anterior or anterolaterial approach. Thus, the distractor of the present invention is configured to be used in the confined spaces of the human anatomy through a small surgical incision and permits the use of laparoscopic approaches like Balloon Assisted Endoscopic Retroperitoneal Gasless (“BERG”).[0006]
• In a preferred embodiment, the distractor of the present invention has a scissor-like configuration with a pair of handles pivotally connected together. A distractor jaw is coupled to a distal end of each handle such that movement of the handles together draws the jaws apart to separate the vertebrae being treated. In an even more preferred embodiment, the jaws and handles are pivotally coupled together in a double-acting scissor-like configuration to further reduce the space required to move the jaws apart and thus further minimize the invasiveness of the device and procedure.[0007]
• Although the handles, jaws, and distractor mechanism of the present invention may all lie in the same plane, in order to facilitate visualization of the treatment site during distraction and insertion of an implant, at least the handles may be angled away from the plane of the distractor jaws. In a preferred embodiment, the distractor mechanism is angled downwardly with respect to the jaws and the handles are angled downwardly with respect to the distractor mechanism to further enhance visualization and also to permit greater space for the implant holder adjacent the proximal end of the distractor during insertion of the implant.[0008]
• A locking mechanism preferably is provided adjacent to or in the handle to maintain distraction. The locking mechanism may include a spindle or threaded bolt mounted on a first handle and passing through the second handle. An internally threaded speed nut is rotatably mounted on the threaded bolt such that movement of the speed nut along the bolt selectively inhibits movement of the second handle away from the first handle and thus maintains the vertebrae at the desired distracted position.[0009]
• The blades of the distractor of the present invention are configured to increase versatility of the distractor. In a first embodiment of the present invention, the blades are removably coupled to the distractor jaws. Thus, the blades maybe changed, as necessary or desired, for a given procedure or patient.[0010]
• In another embodiment, the blades of the distractor are gradually curved to be out of the plane of the distractor mechanism. Because of the gradual curve, the distal end of the jaws may safely be manipulated through the patient's body with as minimal contact as possible with organs and vasculature including major blood vessels such as the vena cava and aorta. Moreover, such curvature permits insertion through a smaller incision because of the increased manipulability of the gradually curved blades through small openings and spaces.[0011]
• In yet another embodiment, the blades of the distractor are configured to permit insertion of any type of implant. In particular, although certain implants may be provided with slots for engagement with a surface of the distractor blades during insertion, other implants do not have such slots. The blades of the third embodiment of the present invention are configured and sufficiently spaced apart to permit insertion of either type of implant, regardless of whether slots are provided for engaging distractor blades.[0012]
• The spinal disc distractor of the present invention is thus designed to distract disc space atraumatically with respect to both the vertebrae and the implant during endplate preparation, implant sizing, and implant insertion. The distractor may be used in a straight anterior, anterolateral, or lateral approach, and may be used in either an open or a laparoscopic procedure. Moreover, the distractor is designed to ensure the selection of an anatomically correct implant size by permitting the annulus to be fully stretched so that the largest possible implant may be inserted and compressed upon release of the vertebrae, thereby enhancing stability and assuring correct placement of the implant. Thus, the present invention permits disc height and lordosis to be restored. The jaws are shaped and configured to preserve the endplate and the vertebral body during distraction, as well as to permit insertion of an implant during distraction. The risk of breakage of allograft implants and other cages made from brittle materials during insertion is thereby reduced.[0013]
BRIEF DESCRIPTION OF THE DRAWINGS
• The detailed description will be better understood in conjunction with the accompanying drawings, wherein like reference characters represent like elements, as follows:[0014]
• FIG. 1 is a top elevational view of a distractor with removable blades formed in accordance with the principles of the present invention;[0015]
• FIG. 2 is a side elevational view of the distractor of FIG. 1;[0016]
• FIG. 3 is a top elevational view of the distractor of FIG. 1 in a working configuration with the jaws separated for distraction;[0017]
• FIG. 4 is a perspective view of a femoral ring implant which may be used with a distractor formed in accordance with the principles of the present invention;[0018]
• FIG. 5 is a perspective view of a cage implant which may be used with a distractor formed in accordance with the principles of the present invention;[0019]
• FIG. 6 is an isolated top elevational view of the blade of the distractor of FIG. 1;[0020]
• FIG. 7 is a perspective exploded view of the distractor of FIG. 1;[0021]
• FIG. 8 is a side elevational view of the blade of the distractor of FIG. 1;[0022]
• FIG. 9 is a side elevational view partially in cross-section of the distractor of FIG. 1 with the blade removed;[0023]
• FIG. 10 is a schematic illustration of the distractor of FIG. 1 with blades of different lengths in use;[0024]
• FIG. 11 is a schematic illustration of the distractor of FIG. 1 with blades in use which are positioned at an angle which is not parallel with the distractor mechanism;[0025]
• FIG. 12 is a side elevational view of a distractor with curved blades formed in accordance with the principles of the present invention;[0026]
• FIG. 13 is a top elevational view of the distractor of FIG. 12;[0027]
• FIG. 14 is a side elevational view of a distractor with a pair of blades coupled to each handle in accordance with the principles of the present invention;[0028]
• FIG. 15 is a top elevational view of the distractor of FIG. 14; and[0029]
• FIG. 16 is a front perspective view of the distractor of FIG. 14.[0030]
DETAILED DESCRIPTION OF THE INVENTION
• In accordance with the principles of the present invention, a[0031]distractor10 is provided with a pair ofhandles12a,12bmovable with respect to each other to actuate a pair ofjaws14a,14bcoupled thereto, as shown in FIG. 1. Althoughdistractor10 may be used for a variety of procedures, a preferred procedure for whichdistractor10 is used is spinal disc distraction. Thus,distractor10 is preferably configured such that actuation of handles12 (12a,12b) moves jaws14 (14a,14b) apart substantially alongdistraction axis16 to a working position corresponding to the desired resulting relative position of the endplates. For example, the blades may be moved to a substantially parallel or lordotic position to separate adjacent vertebrae to be treated.
• In order to be optimally useful for use in an anterior approach, handles[0032]12 andjaws14 are configured to movejaws14 apart along distraction axis16 a sufficient amount to adequately separate adjacent vertebrae to be treated (typically 5 mm-20 mm, most typically 13 mm-15 mm) yet to occupy a minimal amount of space within the insertion region during the procedure. Thus, handles12 andjaws14 preferably are pivotally coupled together in a scissors configuration such that movement ofhandles12aand12btogether causesjaws14aand14bto move apart and effect distraction of vertebrae between whichjaws14 are positioned. Thus, proximal ends18 ofhandles12 are configured to facilitate gripping. In a preferred embodiment, the outer surface of handle proximal ends18 are contoured to increase user comfort, as shown in FIG. 2.
• A biasing[0033]element20, such as a pair of leaf springs, maintainshandles12a,12bin a spaced apart configuration such thatjaws14a,14bare close together, ready for insertion through a small incision and narrow passage through the patient in the neutral configuration of FIG. 1. Alocking mechanism22 is provided to counteract biasingelement20 as desired, such as to maintainjaws14 at a desired spaced apart position for operation on the distracted vertebral region. Locking element may be in any desired configuration, such as a threadedbolt24 coupled (typically pivotally) to one handle and slidably passing through the other handle, and a lockingnut26 threadedly and rotatably mounted on the end ofbolt24 extending past the other handle (i.e., the portion not between handles14). Movement ofnut26, as a result of rotation, alongbolt24 thus shortens the length ofbolt24 betweenhandles14 and prevents the handles from moving apart, thus maintaininghandles12 in a position closer together than the neutral position.
• A[0034]distractor mechanism30 is provided such that movement ofhandles12 to actuatedistractor mechanism30causes jaws14 to move apart to effect distraction of adjacent elements such as vertebrae.Distractor mechanism30 may have a simple scissors configuration (such as in FIGS.14-16 described below) such that handle12aandjaw14aare at opposite ends of a first lever arm and handle12bandjaw14bare on opposite ends of a second lever arm pivotally coupled to the first lever arm. In a preferred embodiment,distractor mechanism30 is in the form of a double-acting scissor configuration having greater than one pivot point, thus reducing the amount of space required alongdistraction axis16 and laterally away from distractor mechanismlongitudinal axis31 to effectuate distraction. As may be appreciated with reference to FIGS. 1 and 3, in order to form a double-acting scissor configuration, handles12 andjaws14 are provided on separate lever arms which are pivotally coupled together. In particular, handle12ais formed at a proximal end ofproximal lever arm31 a, handle12bis formed at a proximal end oflever arm31b,jaw14ais formed at a distal end ofdistal lever arm32a, andjaw14bis formed at a distal end ofdistal lever arm32b.Distal end34aofproximal lever arm31 a is pivotally coupled toproximal end36aofdistal lever arm32aanddistal end34bofproximal lever arm31bis pivotally coupled toproximal end36bofdistal lever arm32b. In order to actuate the double-acting mechanism to effectuate distraction and hence movement ofjaws14a,14bapart upon movement ofhandles12a,12btogether, one set of lever arms is laterally pivotally coupled together and the other set of lever arms is crosswise pivotally coupled together. Indistractor mechanism30 of FIGS. 1 and 3,proximal lever arms31a,31bare laterally pivotally coupled together anddistal lever arms32a,32bare crossed over each other and pivotally coupled together. However, it will be appreciated that, instead,proximal lever arm31a,31bmay be crossed-over each other anddistal lever arms32a,32bmay be laterally pivotally coupled. The double-acting configuration breaks the pivoting action into two components, reducing the total movement ofdistractor mechanism30 required alongdistraction axis16.
• An additional feature of[0035]distractor10 which facilitates use thereof during distraction is the relative offset positions ofjaws14a,14b, handles12a,12b, anddistractor mechanism30 with respect to one another, as may be appreciated in the side elevational view of FIG. 2. In particular, in a preferred embodiment, distal jaw ends38a,38bare to be positioned to properly distract adjacent vertebrae anddistractor mechanism30 and handles12a,12bare offset relative to distal jaw ends38a,38bto permit optimal visualization of distal jaw ends38a,38bfrom the proximal end of distractor10 (outside the patient's body) during distraction. For example, adistal bend40 may be provided immediately proximal of distal jaw ends38a,38b, as may be appreciated with reference to FIG. 2. Thus, the remainder of distractor10 (i.e., the proximal portions ofdistractor10 such asdistractor mechanism30 and handles12a,12b) is in a different plane from the plane of distal jaw ends38a,38band the distraction site. With such an offset, visualization of the distraction site and of insertion of the implant therein is enhanced. Additionally or alternatively, aproximal bend42 may be provided immediately distal ofhandles12a,12bsuch that proximal handle ends18a,18bare not in the same plane as distal jaw ends38a,38band the distraction site. The provision of either or both ofbends40,42 causes at least a proximal portion ofdistractor10 to be in a plane different from the plane of distal jaw ends38a,38band the distraction site such that the line of site to view distraction is not obstructed by the distractor. Moreover, such offset of portions ofdistractor10, such asdistractor mechanism30 and handles12a,12b, from the distal jaw ends38 accommodate an implant holder for insertion of the implant to permit a substantially straight insertion of the implant holder.Bend40 may be between 0°-30°, most preferably 10°, and bend42 maybe between 0°-30°, most preferably 15°, to achieve the desired improved visualization and increased area for the implant holder.
• A distractor provided in accordance with the principles of the present invention is configured to distract adjacent vertebrae so that an implant may be inserted therebetween. Preferably, each jaw of a distractor formed in accordance with the principles of the present invention is provided with a blade shaped and configured to contact a vertebral endplate and also to permit insertion of an implant therebetween. Once the implant is properly positioned between the vertebral endplates, the distractor, along with its blades, may be removed from the distraction site in the patient.[0036]
• In the embodiment of FIGS.[0037]1-3,blades44a,44bare provided onjaws14a,14b, respectively, to engage the vertebrae to be distracted. In a preferred embodiment,blades44a,44bare configured and shaped to correspond to aslot45 in an implant such ascage46 of FIG. 4 orfemoral ring48 of FIG. 5. Thus, as the selected implant is moved toward the treatment site with a desired insertion tool,implant contacting surfaces50a,50b(FIG. 3) ofblades44a,44bcontactrespective slots45. Preferably,implant contacting surfaces50a,50bofblades44a,44bare closer together than the point ofconnection51a,51bofblades44a,44btorespective jaws14a,14b. Thus,jaws14a,14bare sufficiently spaced apart to permit insertion of the thickest dimension of the implant therebetween, yetblades44a,44bare closer together to account for the narrower dimension of the implant in the region ofslots45 and thereby to securely grasp the implant viaslots45.
• [0038]Blades44 may converge toward each other in a distal direction before actuation ofdistractor mechanism30 as may be appreciated with reference to FIG. 1. Thus, upon actuation ofdistractor mechanism30 and pivoting apart ofjaws14,blades44, and particularly outwardly facingdistracting surfaces52a,52b(positioned to contact the endplates in the treatment site), may be moved into an orientation appropriate for the vertebral region being treated. For example, actuation ofdistractor mechanism30 may movedistracting surfaces52a,52binto a parallel orientation with respect to each other to securely engage endplates which are parallel with respect to each other.
• Distracting[0039]surfaces52a,52bofblades44a,44bpreferably are shaped to securely engage the vertebrae being treated, particularly the endplates thereof. In a preferred embodiment, distractingsurfaces52a,52bare configured to securely engage the anterior lip of the vertebral endplates being treated, as shown in the isolated view ofblade44 in FIG. 6. For instance, distractingsurfaces52a,52bmay be provided withvertebral engagers54a,54b(FIGS. 2 and 6), such as in the form of ridges, which engage the endplates.Transverse engagement walls56a,56b(FIGS. 2 and 6) may be spaced fromvertebral engagers54a,54bsuch that an anterior lip of the vertebral endplates fits therebetween.Engagement surface58a,58b(FIGS. 2 and 6) betweenvertebral engagers54a,54bandengagement walls56a,56bpreferably is curved to accommodate the anterior lip of the vertebral endplates as well as to provide a smooth transition from distractingsurfaces52a,52btotransverse engagement walls56a,56b.
• In accordance with the principles of the present invention, the distractor blades preferably are configured to increase versatility of use of the distractor of the present invention. It will be appreciated that[0040]distractor10 preferably is formed from a surgical grade sterilizable metal such that the same distractor may be used for different patients. In order to increase the versatility ofdistractor10 and its usefulness for different patients and situations, at least one ofblades44a,44bmay be removably coupled to itsrespective jaw14a,14b, as illustrated in FIG. 7. Thus, in such embodiment,jaws14a,14bare provided with asocket60a,60bshaped to receive a mountingpost62 of ablade44, as shown in FIGS. 7 and 8.Post62 may be releasably held within a bore60 of ajaw14 in any desired manner. For example, a ball detent attachment may be formed by providing adepression64 in post62 (FIG. 8) for matingly receiving abiased detent ball66 housed within atransverse bore68 in jaw14 (FIG. 9). Blade post62 preferably is fitted within socket60 to permit pivotable movement ofblade44 aboutlongitudinal axis70 ofblade post62. Such pivotable movement facilitates manipulation ofblade44 with respect to the vertebral endplates to ease removal ofblade44 anddistractor10. If desired, in order to limit the range of pivotal motion ofblade44, a stop plate72 (FIGS.6-8) may be provided onpost62 to fit within range limiting groove74 (FIG. 7) injaw14. Stopplate72 extends transversely frompost62, as may be appreciated with reference to FIG. 6 and has stop surfaces76a,76bengaging respective range limiting surfaces78a,78bofrange limiting groove74.
• Removable attachment of[0041]blades44 tojaws14 permits a plurality of differently configured blades to be used withdistractor10 depending on the situation or application. For example, the size of the blade may be selected based on the implant to be inserted, different implants potentially having differently sized slots for receiving a distractor blade. The size of the blade may also be selected depending on the size of the vertebrae being treated or the curvature of the vertebral column. For example, it may be desirable to select blades of different insertion lengths IL₁, IL₂, as shown in FIG. 10, to account for spondylolisthesis which results in one vertebra V₁being closer to the distractor than the other vertebra V₂. Blade selection may also depend on the vertebral region being treated, which may affect the difficulty of the approach. For example, in the pelvic region organs and bony structures may complicate insertion and the use ofblades44′ which are angled, such as 20°-30°, with respect to thelongitudinal axis31 ofdistractor mechanism30 may be desired. Suchangled blades44′ would permit an angled approach ofdistractor10 to avoid bony structures such as the pelvis.
• Although the removability of[0042]blades44 ofdistractor10 provides a significant versatility advantage over prior art distractors having blades which are rigidly and fixedly connected to the remaining elements of the distractor, versatility is achievable in accordance with the principles of the present invention in other manners as well. For instance,distal end102 ofdistractor100 of FIGS. 12 and 13 is curved such thatblades144 lie in a plane spaced from the remainder of distractor100 (i.e., the proximal portions ofdistractor100 such asdistractor mechanism130 and handles112). Such curvature provide several advantages over prior art distractors thus increasing versatility thereof.
• For instance, in prior art distractors, the insertion hole commonly is sized to accommodate the distance between spaced apart elements of the distractor. However, the gradual and smooth curvature of[0043]jaws114 andblades144 permits distractor100 to be manipulated to fit through the insertion hole such as by “snaking”distractor100 through. Thus, the curvature ofjaws114 of distractor is selected and configured such that the insertion hole may be sized based on the single element of the distractor with the largest cross-section. Additionally, the curvature ofjaws114 andblades144 is smooth and selected such that upon insertion, no sharp edges are present which may injure vasculature, organs, etc., along the insertion path. The curvature thus is sufficiently gentle and wide such thatjaws114 andblades144 are readily manipulated through the patient's body without causing internal injuries or damage. Preferably the curvature has an S-shape to permit such manipulation and rounded surfaces.
• In order to provide the above-described curvature in the distal end of[0044]distractor100, a smooth (e.g., radiused without sharp edges)curve140 which gradually results in distal jaw ends138 being at an obtuse angle with respect to proximal jaw ends136 may be provided injaws114. Additionally, a similarly smooth andgradual curve141 preferably is provided between distal jaw ends138 andblades144 to result in at least a proximal portion ofdistractor100 being in a different plane from that ofblades144 for enhanced visualization as described with respect to bend40 ofdistractor10. Preferably,curve141 results in an angle A betweenblades144 and proximal jaw ends136 of between 0°-30° and most preferably 10°. Abend142 may also be provided inhandles112 such that proximal handle ends118a,118bare not in the same plane as distal jaw ends138a,138band the distraction site to further enhance visualization, as described above with respect to bend42 ofdistractor10. Bend142 may be between 0°-30° and most preferably 15°.
• It will be appreciated that[0045]distractor mechanism130 is similar todistractor mechanism30 and the description ofdistractor mechanism30 thus is applicable todistractor mechanism130 and is not repeated herein. Preferably, ifdistractor mechanism130 is similar todistractor mechanism30, thenblades144a,144bconverge towards each other in a distal direction, as may be appreciated with reference to FIG. 13, as doblades44 to permit a relative working orientation appropriate for the treatment site, as described above.
• Like[0046]blades44 ofdistractor10,blades144a,144bpreferably are closer together than distal jaw ends138a,138b, as may be appreciated with reference to FIG. 13, such thatblades144a,144bsecurely fit withinslots45 of an implant (as in FIGS. 4 and 5) to grasp the implant yetjaws114 permit insertion of an implant therethrough. Additionally,vertebral engagers154a,154bandtransverse engagement walls156a,156b, similar to above-describedvertebral engagers54a,54bandtransverse engagement walls56a,56b, may be provided to enhance engagement ofblades144a,144bwith the endplates at the treatment site as described above in connection withdistractor10. However, unlikeblades44 ofdistractor10,blades144 ofdistractor100 preferably are fixedly secured tojaws114, such as by formation ofblades144 andjaws114 as a unitary piece. Thus,distractor100 may readily be used in severely calcified areas requiring significant strength and durability of the distractor blades.
• The dimensions of[0047]blades44a,44bofdistractor10 andblades144a,144bofdistractor100 are preferably similar. The thickness T (FIGS. 8 and 12) ofblades44a,44b,144a,144b(e.g., the working surface, distractingsurfaces52a,52b) is preferably approximately 2-15 mm and most preferably approximately 6-10 mm. The width W (FIGS. 6 and 13) ofblades44a,44b,144a,144bis preferably approximately 0.5-4 mm and most preferably approximately 1.5-1.8 mm. The length L (FIGS. 6 and 12) ofblades44a,44b,144a,144bis preferably approximately 5-50 mm and most preferably approximately 25-35 mm.
• Versatility of a distractor formed in accordance with the principles of the present invention may alternatively be achieved by the provision of a[0048]distractor200 as shown in FIGS.14-16 withjaws214 which permit insertion of any kind of implant, including those not provided with slots as described above with respect toimplants46,48 of FIGS. 4 and 5. Accordingly, eachjaw214 has a pair ofblades244 sufficiently spaced apart to permit insertion of an implant therebetween without necessarily contacting the implant. Most preferably,blades244a,244bare spaced apart a distance D (FIG. 16) to permit insertion of an implant with a medial-lateral width and/or an anterior-posterior width of at least 50% of the corresponding dimension (i.e., medial-lateral or anterior-posterior) of the endplates between which the implant is to be inserted.
• As may be appreciated upon comparison of FIGS. 12 and 13,[0049]blades244 have a width W alongdistraction axis216 greater than thickness T perpendicular to distraction axis216 (along the working surface). Such dimension minimizesdistracting surfaces252a,252bto minimize the surface of the endplates contacted byblades244 and to permit sufficient space for insertion of an implant betweenblades244. Thus, contact thickness T of distractingsurfaces252a,252bis selected to be as small as possible (such that a minimum amount of annulus need be removed and a sufficient amount of space is provided for the insertion of an implant betweenblades244a,244b) while still permitting safe distraction of adjacent vertebrae without causing damage thereto. Additionally, the width W ofblades244 alongdistraction axis216 preferably is selected to ensure the strength ofblades244 so thatblades244 do not deform or buckle during distraction despite the relatively small thickness T of distractingsurfaces252a,252b. Preferred dimensions are approximately 3-15 mm (most preferably approximately 7-10 mm) for width W and approximately 0.5-8 mm (most preferably approximately 1.5-3 mm) for thickness T. Because of such dimensions,blades244a,244bpreferably overlap one another whendistractor mechanism230 is in a neutral configuration (withblades244a,244bare in their closest relative positions), thereby minimizing the space alongdistraction axis216 occupied byblades244a,244band the size of the insertion path necessary for insertion ofblades244 into the treatment site. The length L ofblades244, like length L ofblades44 and144, is preferably approximately 5-50 mm and most preferably approximately 25-35 mm.
• [0050]Vertebral engagers254a,254bandtransverse engagement walls256a,256b, similar to above-describedvertebral engagers54a,54bandtransverse engagement walls56a,56b, may be provided to enhance engagement ofblades244a,244bwith the endplates at the treatment site as described above in connection withdistractor10.Blades244 ofdistractor200 preferably are fixedly secured tojaws214, such as by formation ofblades244 andjaws214 as a unitary piece. Thus,distractor200 may readily be used in severely calcified areas requiring significant strength and durability of the distractor blades.
• It will be appreciated that[0051]distractor mechanism130 is similar todistractor mechanism30 and the description ofdistractor mechanism30 thus is applicable todistractor mechanism130 and is not repeated herein.
• It will also be appreciated that[0052]distractor mechanism230 ofdistractor200 may be a simple scissors configuration withhandles212 andjaws214 formed along the same lever element, as may be appreciated with reference to FIGS. 12 and 14. However,distractor mechanism230 may instead have substantially the same configuration asdistractor mechanism30 ofdistractor10 ordistractor mechanism130 ofdistractor100. The description ofdistractor mechanism30 thus is applicable todistractor mechanism230 and is not repeated herein. Conversely, it will be appreciated thatdistractor mechanism30 ordistractor mechanism130 may have substantially the same configuration asdistractor mechanism230. Preferably, ifdistractor mechanism230 is either scissors-type configuration (single scissors as in FIGS.12-14 or double-scissors as indistractor mechanisms30 and130), thenblades244 converge towards each other in a distal direction as doblades44 to permit a relative working orientation appropriate for the treatment site, as described above.
• While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions and/or substitutions may be made therein without departing from the spirit and scope of the present invention as defined in the accompanying claims. One skilled in the art will appreciate that the invention may be used with many modifications of structure, forms, arrangement, proportions, materials, and components and otherwise, used in the practice of the invention and which are particularly adapted to specific environments and operative requirements, without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and not limited to the foregoing description.[0053]

Claims (22)

What is claimed is:

1. A distractor comprising:

first and second handles;

first and second jaws respectively associated with said first and second handles;

a first set of blades extending from said first jaw;

a second set of blades extending from said second jaw; and

a distractor mechanism coupled between said handles and said jaws such that movement of said handles actuates said distractor mechanism to move said jaws apart,

wherein:

said first and second sets of blades each comprise at least first and second blades spaced apart to contact anatomical elements to be distracted and permit insertion of an implant between said first and second set of blades and said anatomical elements.

2. The distractor of

claim 1

, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and

the first set of blades includes at least a portion that is spaced from at least a portion of the second set of blades when the distractor is in the closed position to permit placement of an implant therebetween for insertion between said anatomical elements.

3. The distractor of

claim 1

, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and

the first jaw includes at least a portion that is spaced relative to at least a portion of the second jaw when the distractor is in the closed position to permit the placement of an implant prior to insertion between the first and second set of blades.

4. The distractor of

claim 1

, wherein the first set of blades lie in the same plane and the second set of blades lie in the same plane; and the at least first and second blades of each set are laterally spaced relative to one another.

5. The distractor of

claim 1

, wherein the first set of blades has an insertion length and the second set of blades has an insertion length, and the insertion length of the first set of blades is different from the insertion length of the second set of blades.

6. The distractor of

claim 1

, wherein the first and second set of blades are integrally attached to their respective first and second jaws.

7. The distractor of

claim 1

, wherein at least one of the first and second sets of blades is removably attached to its respective first and second jaws.

8. The distractor of

claim 1

, wherein the distractor mechanism further comprises:

a pair of first and second proximal lever arms each having proximal and distal ends; and

a pair of first and second distal lever arms each having proximal and distal ends,

wherein:

said first handle is located at said proximal end of said first proximal lever arm;

said second handle is located at said proximal end of said second proximal lever arm;

said first jaw is located at said distal end of said first distal lever arm;

said second jaw is located at said distal end of said second distal lever arm;

one of said pair of proximal lever arms and said pair of distal lever arms is crosswise pivotally coupled; and

the other of said pair of proximal lever arms and said pair of distal lever arms is laterally pivotally coupled.

9. The distractor of

claim 1

, wherein the first and second jaws each include a mating fixture and the first and second set of blades each include a mating portion, wherein each mating portion is shaped for removable association with each mating fixture.

10. The distractor of

claim 9

, wherein each mating portion is a post and each mating fixture is a socket.

11. The distractor of

claim 9

, wherein each mating portion is a socket and each mating portion is a post.

12. The distractor of

claim 9

, wherein the mating fixture is positioned on an upper surface of the first and second jaws and at least a portion of the first and second blades extends substantially perpendicular to the upper surface of the first and second jaws.

13. The distractor of

claim 1

, wherein the first and second jaws are removably associated with the first and second handles.

14. The distractor of

claim 1

, wherein the first and second set of blades are removably associated with the first and second jaws.

15. The distractor of

claim 9

, further comprising a locking mechanism for locking the position of the mating portion relative to the mating fixture.

16. The distractor of

claim 15

, wherein the locking mechanism includes a ball portion.

17. The distractor of

claim 1

, wherein at least a portion of the first set of blades extends at a first angle relative to the first jaw and at least a portion of the second set of blades extends at a second angle relative to the second jaw.

18. The distractor of

claim 17

, wherein the first angle is substantially the same as the second angle.

19. The distractor of

claim 17

, wherein the first and second angles range from about 20° to 30° relative to a longitudinal axis of the distractor mechanism.

20. The distractor of

claim 1

, wherein the first and second set of blades include at least one curved portion.

21. The distractor of

claim 1

, wherein the first and second jaws include at least one curved portion.

22. A method of distracting adjacent vertebrae comprising the steps of:

providing a distractor comprising first and second handles, first and second jaws respectively coupled to said first and second handles, a first set of spaced apart blades extending from said first jaw, a second set of spaced apart blades extending from said second jaw, and a distractor mechanism coupled between said handles and said jaws;

positioning said first set of spaced apart blades against spaced apart ends of a first vertebral endplate;

positioning said second set of spaced apart blades against spaced apart ends of a second vertebral endplate adjacent and facing said first vertebral endplate;

actuating said distractor mechanism to distract said first and second vertebral endplates; and

inserting an implant between said first and second sets of blades and said first and second vertebral endplates.

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