- 1 PERCUTANEOUS FACET FUSION SYSTEM AND METHOD CROSS-REFERENCE TO RELATED APPLICATIONS 5 This application claims the benefit of U.S. Provisional Patent Application Serial No. 60/744,871, filed on April 14, 2006, which is expressly incorporated herein in its entirety by reference thereto. FIELD OF THE INVENTION 10 The present invention relates generally to facet fusion. More particularly, the present invention relates to a system and method for percutaneous facet fusion. BACKGROUND INFORMATION Any discussion of the prior art throughout the specification should in no way be 15 considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. The present invention relates to the clinical practice of fusing facet joints of the spine during spinal surgery. In this regard it is common practice in today's spinal surgery to remove the cartilaginous articular surfaces of the facet(s) in an effort to induce 20 arthrodesis of this joint. It is typical for a surgeon to place autograft around the facet to augment the biological fusion process and to yield a larger fused volume. This procedure is routinely performed as an adjunct to a posterolateral and/or interbody fusion for degenerative spinal disorders and for scoliosis, trauma and tumor. Supplemental fixation for these fusions is typically supplied by pedicle screw and plate systems placed either 25 posteriorly or plates and screw systems placed anteriorly (e.g., Blackstone Medical Spinal Fixation System, Unity ALP). Of note, with the advent of minimally invasive or tissue sparing techniques for the placement of supplemental fixation, particularly pedicle screws, there exists a need for a percutaneuos system to achieve facet fusion. Using an open technique for this surgical 30 step would offset many of the benefits driving the use of percutaneous pedicle screws. Accordingly, various embodiments of the present invention provide a new and novel system/method that enable a surgeon to re-create a surgical procedure, e.g., facet -2 fusion along with pedicle screw or other fixation, while preserving the tissue sparing nature of the minimally invasive approach. Various limitations existing with conventional percutaneous pedicle screw approaches may be reduced or eliminated. Moreover, it is noted that new and improved technologies for image guidance of 5 devices and for improved intra-operative navigation have opened the door for more accurate percutaneous therapies. This may help avoid risks (such as nerve and vessel injury) associated with less advanced, older generation technologies. With accuracies today approaching Imm placement error, it is conceivable that localization of guide wires in near critical structures, such as major vessels and nerve roots will become 10 commonplace. SUMMARY According to a first aspect of the invention, there is provided a percutaneous facet fusion system, comprising: 15 an implantable component configured to promote fusion of a facet joint; and a percutaneous delivery system configured to arrange the implantable component in the facet joint, wherein the percutaneous delivery system comprises at least one guide component. According to a second aspect of the invention, there is provided a method for 20 percutaneous facet fusion, comprising: arranging an implantable component in a facet joint using a percutaneous delivery system, the implantable component configured to promote fusion of the facet joint, and the percutaneous delivery system comprising at least one guide component. Unless the context clearly requires otherwise, throughout the description and the 25 claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". According to an example embodiment of the present invention, a percutaneous facet fusion system includes a bone dowel and a percutaneous delivery system 30 configured to arrange the bone dowel in a facet joint. The delivery system may include a guide wire, a cannulated drill and a transfer device, the guide wire arranged in the facet joint, the cannulated drill advanced over the - 2a guide wire to create a hole in the facet joint and the transfer device configured to arrange the bone dowel in the hole. The cannulated drill may include a depth stop. The bone dowel may be a cannulated bone dowel. The transfer device may include a tube and plunger configured to align coaxially the cannulated bone dowel and the hole 5 via the guide wire and to deliver a pressing force to fit the cannulated bone dowel into the hole. The guide wire may be a K-wire. The fusion system may also include an imaging system. The imaging system may be used to locate the guide wire in the facet joint. The imaging system may include a 10 fluoroscope. According to an example embodiment of the present invention, a percutaneous facet fusion system includes an implant and a percutaneous delivery system configured to arrange the implant in a facet joint. The delivery system may include a guide wire, a cannulated drill and a transfer device, the guide wire arranged in the facet joint, the cannulated drill configured to 15 advance over the guide wire and to create a hole in the facet joint and the transfer device configured to arrange the implant in the hole. The delivery system may include a guide wire, a dilator and a guide tool, the guide wire arranged in the facet joint, the dilator configured to advance over the guide wire into the facet joint, the guide tool configured to slide over the dilator and seat around the 20 facet joint and the implant arranged in the facet joint via the guide tool. The delivery system may include an inner tube inside the guide tool and the implant may be arranged in the facet joint via the inner tube. The guide tool may include a quick connect. The quick connect may be WO 2007/120903 PCT/US2007/009343 configured to be attached to at least one of a handle and a surgical table. An end of the guide tool may include a curved surface with teeth. The delivery system may include a preparation tool. The preparation tool may be a cutter, sweeper, scraper or any other tool configured to prepare the fusion joint for an implant, device and/or biological matter. An end of the preparation tool may include a scraping surface. An end of the preparation tool may include a cutting surface. An end of the preparation tool may be expandable. The end of the preparation tool including the scraping surface and/or the cutting surface may be expandable. The preparation tool may also include a bore. The bore may be configured to delivery the implant into the facet joint. The preparation tool may be configured to rotate. The preparation tool may also be configured to be placed inside a guide tool as described above. The implant may include a securing mechanism. The securing system may be a barb, a clip, a wire or any combination thereof. The implant may include fenestrations, rims, protrusions or any combination thereof. The implant may include a biological agent. The biological agent may be an autograft, allograft, xenograft, DBM, TCP, stem cell products, TrinityTM, BMP or any combination thereof. The implant may be a metallic implant. The metallic implant may be made of titanium, a titanium alloy, stainless steel or any combination thereof. The metallic implant may be a tube with holes. The holes may be configured to provide for bony ingrowth. The transfer device may include a tube and plunger configured to coaxially align the metallic implant and the hole via the guide wire and to deliver a pressing force to fit the metallic implant into the hole. The metallic implant may include includes threads. The metallic implant may be configured for use with bone taps. The metallic implant may be self-tapping or self-drilling. The metallic implant may be a cage with threads. The cage may be configured for use with bone taps. The cage may be self-tapping or self-drilling. The metallic implant may be configured to be compatible with a biological agent. The biological agent is at least one of autograft, allograft, xenograft, DMB, TCP, stem cell products and BMP. The metallic implant may include at least one of fenestrations, rims and protrusions. The fusion system may include a supplemental fixation device configured to supplement the percutaneous facet fusion system. The supplemental fixation device may be at least one of pedicle screws and lumbar plates. The supplemental fixation device may be at least one of unilateral and bilateral pedicle screws. The implant may have radio-opacity. The implant may be bio-resorbable. The implant may be a screw, bone graft screw, dowel, wedge, plug, and basket or a spacer. The WO 2007/120903 PCT/US2007/009343 spacer may include an aperture and teeth, the teeth may be located on at least one of a top surface and a bottom surface of the spacer. According to an example embodiment of the present invention, a percutaneous facet fusion system includes a biological material and a percutaneous delivery system configured to arrange the implant into a facet joint. The biological material may include at least one of bone, BMP, DBM and TrinityTM. The delivery system may include a guide wire, a dilator and a guide tool, the guide wire arranged in the facet joint, the dilator configured to advance over the guide wire into the facet joint, the guide tool configured to slide over the dilator and seat around the facet joint, wherein the biological material is arranged in the facet joint via the guide tool. The delivery system may include an inner tube inside the guide tool. The biological material may be arranged in the facet joint via the inner tube. The guide tool may include a quick connect. The quick connect may be configured to be attached to at least one of a handle and a surgical table. The delivery system may be disposable. The delivery system may include a preparation tool configured to interact with the facet joint. The preparation tool may include a scraping surface. An end of the preparation tool may include a cutting surface. An end of the preparation tool may be expandable. The preparation tool may include a bore. The bore may be configured to delivery the biological material into the facet joint. The delivery system may include a basket configured to arrange the biological material in the facet joint via the guide tool. The basket may be a wire mesh basket. According to an example embodiment of the present invention, a method for percutaneous facet fusion includes placing a guide wire into a facet joint, drilling a hole in the facet joint by advancing a cannulated drill over the guide wire and placing an implant in the hole. The method may include verifying the guide wire is in proper position using an imaging system. The implant may be placed in the hole using a transfer device. The transfer device may include a tube and plunger configured to coaxially align the implant and the hole via the guide wire and to deliver a pressing force to fit the implant into the hole. The implant may be a bone dowel or a cannulated bone dowel. The implant may be a metallic implant. The implant may be a dowel, wedge, plug, spacer, screw, cage or basket. According to an example embodiment of the present invention, a method for percutaneous facet fusion includes placing a guide wire into a facet joint, opening the facet joint with a dilator, sliding a guide tool over the dilator, removing the guide wire and dilator and placing at least one of an implant and a biological material in the facet joint via the guide
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WO 2007/120903 PCT/US2007/009343 tool. The method may include verifying the guide wire is in proper position using an imaging system. The method may also include inserting an inner tube in the guide tool, the at least one of the implant and biological material placed in the facet joint via the inner tube. The method may also include seating the guide tool on the facet joint. The biological material may be bone, BMP, DBM or TrinityTM. The implant may be a bone dowel, metallic implant, wedge, screw, plug, spacer, cage or basket. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a fragmented perspective view of a percutaneous facet fusion system according to an example embodiment of the present invention. Figure 2 shows a cross-sectional view of the percutaneous facet fusion system shown in Figure 1. Figure 3 shows a perspective view of a cannulated bone dowel according to an example embodiment of the present invention. Figure 4 shows a fragmented perspective view of a K-wire according to an example embodiment of the present invention. Figure 5 shows a fragmented perspective view of a drill according to an example embodiment of the present invention. Figure 6 shows a top view of a cannulated bone dowel arranged in a facet joint according to an example embodiment of the present invention. Figure 7 shows a side view of a cannulated bone dowel arranged in a facet joint according to an example embodiment of the present invention. Figure 8 shows a top view of a section of the spine with cannulated bone dowels arranged in facet joints and a supplemental fixation device according to an example embodiment of the present invention. Figure 9 shows a side view of the system shown in Figure 8. Figures 10 to 12 show perspective views of a delivery system according to an example embodiment of the present invention. Figures 13 and 14 show a perspective view and a top view, respectively, of the delivery system in Figures 10 to 12 interacting with a facet joint. Figures 15 and 16 show perspective views of a sweeper tool according to an example embodiment of the present invention. Figure 17 shows a side view of a metallic implant with an external thread according to r% WO 2007/120903 PCT/US2007/009343 an example embodiment of the present invention. Figure 18 shows a front view of the metallic implant shown in Figure 17. Figure 19 shows a perspective view of the metallic implant shown in Figure 17. Figures 20 shows a perspective view of a spacer according to an example embodiment of the present invention. Figure 21 shows a side view of the spacer in Figure 20. Figures 22 shows a perspective view of a spacer according to an example embodiment of the present invention. Figure 23 shows a front view of the spacer in Figure 22. Figures 24 shows a perspective view of a spacer according to an example embodiment of the present invention. Figure 25 shows a front view of the spacer in Figure .24. Figure 26 shows a perspective view of a dowel according to an example embodiment of the present invention. Figure 27 shows a perspective view of a wedge according to an example embodiment of the present invention. Figure 28 shows perspective view of a spacer according to an example embodiment of the present invention. Figure 29 shows perspective view of a cage according to an example embodiment of the present invention. Figures 30 to 36 shows perspective views of different configurations for securing implants according to example embodiments of the present invention. Figures 37 and 38 show exploded perspective views of a spacer and screw according to two example embodiments of the present invention. DETAILED DESCRIPTION Like reference characters denote like parts in the drawings. Referring to Figures 1 to 9, an example embodiment of a facet fusion system is shown. Figure 1 shows percutaneous facet fusion system 10. Fusion system 10 includes a cannulated bone dowel 12 (see, e.g., Figure 3) and a percutaneous delivery system 14 configured to arrange cannulated bone dowel 12 in a fusion joint 16 (see, e.g., Figures 6 and 7). As set forth herein, although cannulated bone dowel 12 is shown, other implants, devices and/or biological matter, may also be used with fusion system 10. Delivery system 14 includes a guide wire 18, which is illustrated as a K-wire (see also Figure 4), a cannulated 6 WO 2007/120903 PCT/US2007/009343 drill 20 (see Figure 5), and a transfer device 22. Cannulated drill 20 includes a depth stop 24 and a cannulated drill bit tip 30. Transfer device 22 includes a tube 26 and a plunger 28. Figure 2 shows a cross-sectional view of fusion system 10. A surgeon places K-wire 18 into facet joint 16 using imaging such as fluoroscopy. Once the distal tip of the K-wire 18 is confirmed in the proper location within the facet joint 16, the surgeon may advance a cannulated drill 20 over the K-wire 18 to the facet joint 16. The drill may be used to create a hole 32 centered on the junction between inferior and superior articular surfaces 34, 36 of the vertebra 38 being fused (see, e.g., Figures 6 and 7). In one example (which example is intended to be illustrative and not restrictive), the hole may be approximately 8mm in diameter and may extend between 1cm and 1.5cm deep into facet joint 16. As set forth above a depth stop 24 may be incorporated onto drill 20 to prevent drilling too deeply. Depth stop 24 may be a step, a shoulder or a similar structure (see Figure 5). Drilling too deeply may result in neural or vascular damage as anterior to the facet reside nerve roots and vessels. Next, the surgeon removes drill 20, maintaining the K-wire 18 in position, and advances cannulated bone dowel 12 to hole 32 over K-wire 18. The sizes of cannulated bone dowel 12 and drill 20 may be matched to provide an appropriate press fit between cannulated bone dowel 12 and the drilled facet. The delivery of cannulated bone dowel 12 is accomplished via delivery system 14, which includes transfer device 22. Transfer device 22 includes tube 26 and plunger 28. Delivery system 14 is configured to coaxially align cannulated bone dowel 12 and hole 32 via K-wire 18 and to deliver the pressing force to fit the dowel into the hole (see, e.g., Figures 1, 2, 6 and 7). Finally, transfer device 22 and K-wire 18 may be removed and the patient's wound may be closed. Fusion system 10 may also be implemented in conjunction with other supplemental fixation devices such as pedicle screws (which may be unilateral or bilateral), rods and/or lumbar plates. In one example, as shown in Figure 8 and 9, fusion system 10 is used in conjunction with unilateral pedicle screws 40. In Figures 8 and 9 unilateral pedicle screws 40 have been placed percutaneously into the spine. Figure 6 shows target sites 42 for ipsolateral pedicle screws. Fusion system 10 may be used regardless of the orientation of the facet joint. This is beneficial in view of the changing orientation of the facets along the length of the spine and varying anatomies of patients. Referring to Figures 10 to 14, a delivery system 200 is shown. Delivery system 200 includes a guide wire 218, a dilator 220 and a guide tool 222. Guide tool 222 includes a quick connect 224 and a handle 226 that is attachable to quick connect 224. Quick connect 224 and/or handle 226 may be configured to be attached to a surgical table. The end of guide 7 WO 2007/120903 PCT/US2007/009343 tool 222 includes a curved surface 230 with teeth 232 configured to grip facet joint 216 for a stable interface. Guide wire 218 is arranged in facet joint 216 (in the same or a similar way as K-wire 18 described above). Dilator 220 (or a series of dilators) is then advanced over guide wire 218 into facet joint 216. Guide tool 222 is slid over dilator 220 and seated around facet joint 216. Dilator 220 and guide wire 218 may then be removed and an inner tube 228 placed inside guide tool 222. The facet joint is then prepared for fusion (which may include the use of a preparation tool as described below) and an implant, device, biological material (e.g., bone, BMP, DBM, TrinityTM, etc.) or any combination thereof is then arranged in facet joint 216 via inner tube 228. Inner tube 228 is removable to control the exact placement of the implant, device, biological material or any combination thereof. Alternatively, inner tube 228 may not be used and the implant, device, biological material or any combination thereof may be arranged in facet joint 216 via guide tool 222. Figures 13 and 14 show delivery system 200 interacting with facet joint 216. Delivery system 200 may also be configured to deliver the implant in the facet joint without a guide wire or a dilator. In such a configuration the implant, device and/or biological matter are delivered directly into the facet joint via the guide tool. Additionally, a tube may be inserted in the guide tool and the implant, device and/or biological matter may be arranged in the facet joint via the tube. Delivery system 200 may be used regardless of the orientation of the facet joint. This is beneficial in view of the changing orientation of the facets along the length of the spine and varying anatomies of patients. Referring to Figures 15 and 16, a preparation tool is shown in the form of a sweeper 300. Although a sweeper is shown, alternative preparation tools may be utilized for preparing the facet joint for fusion. The preparation tools may include cutting surfaces, cleaning surfaces, scraping surfaces etc. For example, the preparation tool may be a cutter with a cutting surface configured to cut a space in the fusion joint. The geometry of the cutting surface may be arranged to cut a space in the fusion joint in the shape of the implant. The preparation tools may be used with fusion system 10 and delivery system 200. Sweeper 300 includes a holder 302, which may be a fixed holder, and a sweeper 304. Holder 302 includes a foot 306 that is configured to rest on a facet joint and prevent sweeper 304 from traveling too deep in the facet joint. Sweeper 304 includes an expandable end 308. The end of sweeper 304 may also be configured such that it does not expand. Expandable end 308 expands when wedge 310 is placed in sweeper 304 (see, e.g., Figure 16). Expandable end 308 also includes a scraping surface 312 and/or a cutting surface. Sweeper 304 may also include a bore and/or delivery tube. The bore may be configured to deliver an implant, 8 WO 2007/120903 PCT/US2007/009343 device, biological matter (e.g., TrinityTM, autograft, allograft, xenograft, DBM, TCP, stem cell products, BMPs and/or other fusion promoting devices or any combination thereof) into the facetjoint. Sweeper 30.4 is connected to holder 302 via a pivot joint 314. Pivot joint 314 permits sweeper 304 to rotate and/or pivot. Sweeper 300 is configured to be placed in the facet space and expanded in order to clear/scrape tissue from the boney surfaces of the facet. Sweeper 300 may also be configured to rotate and act as a cutter. Sweeper 300 may expand inside of the facet joint and make a wedge shaped pocket (or similarly shaped pocket) in which bone graft and/or biologics may be packed. The wedge shaped pocket may form a large packed area of bone graft and/or biologics that would be less likely to expel out of the smaller hole created by a non-expanded portion of sweeper 304. The cutting surface of sweeper 300 may also be configured to cut a space in the fusion joint in the shape of the implant. Sweeper 300 may be used regardless of the orientation of the facet joint. This is beneficial in view of the changing orientation of the facets along the length of the spine and varying anatomies of patients. Referring to Figures 17 to 19, facet fusion system 10 may employ a metallic implant 50 in place of cannulated bone dowel 12. Metallic implant 50 may be constructed of any metal or metal alloy including titanium, a titanium alloy and/or stainless steel and may serve to add precision and stability to the arthrodesis. Metallic implant 50 is in the form of a tube 52 with holes 54 for bony ingrowth. Metallic implant 50 may, however, also be provided in other configurations suitable for facet fusion. Metallic implant 50 includes threads 56 and is threaded into facet joint 16. Metallic implant 50 may also be threadless. Metallic implant may also be in the form of a cage. Metallic implant 50 may be designed for use with bone taps and may be self tapping and/or self-tapping/self-drilling. The fixation benefit of the implant may vary as metallic implant 50 may be used with various types of supplemental fixation, including the supplemental fixation systems described herein. The strength provided by such systems varies. For example, the strength of the metallic implant may vary when it is used with unilateral and/or bilateral pedicle screws, which also vary in strength. Metallic implant 50 may also be designed for compatibility with biologic agents such as TrinityTM, autograft, allograft, xenograft, DBM, TCP, stem cell products, BMPs and/or other fusion promoting devices. The compatibility may be achieved by the form of metallic implant 50. Fenestrations, rims and/or protrusions that help maintain the biologic agent within the implant during delivery and in the short term post operative period during which the fusion is occurring may also be provided. Metallic implant 50 may be adapted to be delivered through delivery system 200 and guide tool 222 or through the bore of sweeper 9 WO 2007/120903 PCT/US2007/009343 300. Referring to Figures 20 to 29, other implants and/or devices, e.g., screws, cages, wedges, dowels, spacers, plugs, baskets, etc., are shown that may be used in place of or in conjunction with cannulated bone dowel 50 and/or metallic implant 50 (see, e.g., Figures 17 to 19). Each of these implants may be configured to be compatible with biologic agents such as, for example, autograft, allograft, xenograft, DBM, TCP, stem cell products, BMPs, TrinityTM and/or other fusion promoting devices. Additionally, each of these implants may be adapted for placement along a guide wire. For example, a similar configuration, as shown in Figure 18 for metallic implant 50 (a tube with holes for receiving a guide wire), may be employed with these implants or devices. Alternatively, these implants or devices may be delivered using delivery system 200 and/or a sweeper 300 (as described above) and may or may not have a structure for receiving a guide wire. In conjunction with these implants and/or devices, biological material may be packed in the facet joint via a delivery system, e.g., sweeper 300 as described above. The biological material may also be packed in the facet joint via other mechanisms. The implants and/or devices may have radio-opacity (e.g., for post operation imaging) and/or may be of an absorbable design. Any combination of the implants, devices and/or biological matter described herein may be used. For example, several dowels may be used on a patient or dowels and spacers my be used on a patient. Figures 20 to 25 show different spacers that may be used for facet fusion as described herein. Figures 20 and 21 show a standard tooth configuration spacer 60. Figures 22 and 23 show a pointed tooth configuration spacer 62. Figures 24 and 25 show a one row pointed tooth configuration spacer 64. In one example (which example is intended to be illustrative and not restrictive), spacers 60, 62 and 64 may be approximately lOxlOx5mn with the teeth approximately .020" deep. Figures 26 to 29 show different implants that may be used for facet fusion as described herein. Figure 26 shows a dowel 70. Figure 27 shows a wedge 72. Figure 28 shows a spacer 74. Figure 29 shows a cage 76. Cage 76 includes openings 78 for TrinityTM or other biologic materials to promote fusion. Cage 76 may also be provided with a coating to promote fusion. In one example (which example is intended to be illustrative and not restrictive), the front surfaces 80, 82, 84 of wedge 72, spacer 74 and cage 76, respectively, may be approximately 2mm to approximately 5mm high and approximately 8mm to approximately 10mm wide. Figures 30 to 36 show different configurations for securing implants, e.g., spacers, cages, etc. in a facet joint 96. These configurations may be used with the systems for facet I n WO 2007/120903 PCT/US2007/009343 fusion described herein. Figure 30 shows a spacer 90 with a hole 92 through it. Figure 31 shows spacer 90 in facet joint 96 with wire 94 passing through hole 92 and securing spacer 90 in facet joint 96. Figure 32 shows spacer 90 in facet joint 96 with wire 94 passing through hole 92. Wire 92 has knots 98 that secure spacer 90 in facet joint 96. Figure 33 shows spacer 100 in facet joint 96. Spacer 100 is secured in facet joint 96 by clip 102. Figure 34 shows clip 102 with a "C" type shape. Other securing mechanism could also be used in place of the clip, e.g., staples or other mechanisms suitable for securing spacer 100 in place. Clip 102 may also serve the purpose of applying pressure against the facet joint to promote fusion. Clip 102 may also be configured such that it holds a graft inside a spacer. Figure 35 shows an implant 110 with openings 112 and 114. Figure 36 shows a barb 116. After implant 110 is inserted in the fusion joint, barb 116 is pushed through opening 114 and spikes 118 expand through opening 112 to secure implant 110 to the facet joint. Multiple barbs may be used. Spikes 118 may burrow or tack into the end plates of the facets. Barb 116, or multiple barbs, may be provided integral with implant 110 to aid in ease of insertion. The aforementioned securement configurations prevent unintentional back out and/or unwanted movement of the implant/spacer. Such unwanted movement may result in the spacer sliding out of the facet joint and dropping on a nerve root. Figures 37 and 38 show the placement of a spacer 120 and a threaded screw 122 in facet joints 124 and 126, respectively. Spacer 120 and threaded screw 122 may be placed in facet joints 124 and 126, respectively, via the delivery systems described above. Alternate implants and/or biological material, as described above may be used in place of or in conjunction with spacer 12 and threaded screw 122. Further still, in example embodiments (which are intended to be illustrative and not restrictive), other implantation instruments may be used for: (a) removing cartilage more aggressively than drilling; (b) treating the facet with schlerosing agents, RF, ultrasound, microwaves, cryotherapy, drugs, injectables, mechanical energy, electromagnetic energy, heat; and/or (c) compatibility with image guidance and/or navigation systems (e.g., Stealth, Treon, Iso-C). Similar to fusion system 10 as discussed above, all of the fusion systems discussed herein may also be implemented in conjunction with other supplemental fixation devices, such as pedicle screws, which may be unilateral or bilateral, rods and/or lumbar plates. While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. For example, the 11 WO 2007/120903 PCT/US2007/009343 present invention may be placed at any desired level of the spine. Further, any element described herein may be provided in any desired size (e.g., any element described herein may be provided in any desired custom size or any element described herein may be provided in any desired size selected from a "family" of sizes, such as small, medium, large): Further still, one or more of the components may be made from any of the following materials: (a) any biocompatible material (which biocompatible material may be treated to permit bone ingrowth or prohibit bone ingrowth - depending upon the desire of the surgeon); (b) a plastic; (c) a fiber; (d) a polymer; (e) a metal (a) pure metal such as titanium and/or an alloy such as Ti-Al-Nb, Ti-6Al-4V, stainless steel); (f) any combination thereof. Further still, any steps described herein may be carried out in any desired order (and any desired steps may be added and/or deleted). It is to be understood that each of the examples given in connection with the various embodiments of the invention are intended to be illustrative, and not restrictive. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting. 192