Patent Publication Number: US-2023157739-A1

Title: Fusion device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is filed under 35 U.S.C. § 120 as a continuation of U.S. Pat. Application No. 17/062,102, filed on Oct. 2, 2020, which application is a continuation-in-part of U.S. Pat. Application No. 16/774,079, filed on Jan. 28, 2020, which issued as U.S. Pat. No. 11,172,969 on Nov. 16, 2021, which applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD 
     The present disclosure relates to orthopedic surgery, and more particularly to interbone fixation fusion devices and especially interarticular joint fixation, specifically deep tissue joints such as spinal facet joints and sacroiliac (SI) joints. 
     BACKGROUND 
     Fusion of spinal elements has been a long-standing solution to symptoms of degenerating spinal discs. In fact, even though artificial discs have made some progress in the surgical arena, spinal fusion remains the most reliable means of alleviating symptoms referable to degenerating discs and is still the de facto gold standard. 
     One of the consequences of spinal fusion is adjacent level degeneration. Even though a normal functional spinal segment is fused, spinal motion must still occur, with forces being transferred to adjacent normal segments placing them under increases stress and contributing to a more rapid degenerative decline. 
     Since most spinal fusions are done in the low back and include the sacrum, which fuses naturally after birth, caudally transferred forces are dispersed to the sacroiliac (SI) joints causing abnormal stresses upon these joints. 
     While cranially transmitted forces simply go to the disc above, which can be fused by traditional means of interbody and/or posterolateral fusion, the SI joint is unique, complex, and difficult to visualize with traditional fluoroscopic methods. 
     Successful spinal fusions are often plagued after months or years of successful relief of symptomatology by a return of symptoms due to adjacent level degeneration. As many as twenty-five percent (25%) of cases of recurrent pain post spinal fusion are felt to be secondary to increased and abnormal motion at the level of the SI joint which can be severe. 
     While SI joint fusion procedures have been around for many years, recent trends have focused on minimally invasive ways to stabilize the joint thereby alleviating pain caused by the abnormal stresses placed upon them through natural degeneration or accelerated degeneration caused by spinal fusion. The addition of computerized guidance systems to the operating room armamentarium has afforded additional ways that stabilization of complex and deep-seated joints can be achieved surgically. 
     Thus, there is a long-felt need for a fusion device that allows fusion of deep-seated joints by way of minimally invasive surgery. 
     SUMMARY 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a joint, comprising a first screw portion, including a first distal end, a first proximal end, a first radially outward facing surface comprising a first diameter, and a first hole, a second screw portion, including a second distal end, a second proximal end, a second radially outward facing surface comprising a second diameter, and a second hole, and a section, including a first end connected to the first proximal end, a second end connected to the second distal end, a third radially outward facing surface comprising a third diameter, the third diameter being less than the first diameter and the second diameter, and a third hole, wherein the first hole, the second hole, and the third hole are in fluid communication. 
     In some embodiments, the first screw portion further comprises threading arranged on the first radially outward facing surface, at least one flute extending from the first distal end to the first proximal end, and at least one cutting edge operatively arranged to cut through bone. In some embodiments, the second screw portion further comprises threading arranged on the second radially outward facing surface. In some embodiments, the threading on the first radially outward facing surface includes a first pitch and the threading on the second radially outward facing surface includes a second pitch, the second pitch being different than the first pitch. In some embodiments, the first pitch is greater than the second pitch. In some embodiments, the first pitch is less than the second pitch. 
     In some embodiments, the first screw portion comprises a first flute including a first cutting edge, the first cutting edge arranged proximate the first distal end and arranged to cut when the first screw portion is displaced in a first circumferential direction, and a second flute including a second cutting edge, the second cutting edge arranged proximate the first proximal end and arranged to cut when the first screw portion is displaced in a second circumferential direction, opposite the first circumferential direction. In some embodiments, the second screw portion further comprises a head non-rotatably connected to the second proximal end. 
     In some embodiments, the second hole is a through-hole extending from the second proximal end to the second distal end, and the third hole is a through-hole extending from the first end to the second end. In some embodiments, the first distal end comprises at least one cutting surface operatively arranged to cut through cortical bone. In some embodiments, the first distal end comprises a tapered diameter portion. In some embodiments, the fusion device further comprises an aperture extending radially through at least one of the first screw portion, the second screw potion, and the section. In some embodiments, the section does not comprise threading. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a joint, comprising a first screw portion, including a first distal end, a first proximal end, a first radially outward facing surface comprising first threading and a first diameter, and a first hole, a second screw portion, including a second distal end, a second proximal end, a second radially outward facing surface comprising second threading and a second diameter, and a second hole, and a section, including a first end connected to the first proximal end, a second end connected to the second distal end, a third radially outward facing surface comprising a third diameter, the third diameter being less than the first diameter and the second diameter, and a third hole, wherein the first hole, the second hole, and the third hole are in fluid communication. 
     In some embodiments, the first screw portion further comprises at least one flute extending from the first distal end to the first proximal end, and at least one cutting edge operatively arranged to cut through bone. In some embodiments, the first threading includes a first pitch and the second threading includes a second pitch, the second pitch being different than the first pitch. In some embodiments, the first pitch is greater than the second pitch. In some embodiments, the first pitch is less than the second pitch. In some embodiments, the first screw portion comprises a first flute including a first cutting edge, the first cutting edge arranged proximate the first distal end and arranged to cut when the first screw portion is displaced in a first circumferential direction, and a second flute including a second cutting edge, the second cutting edge arranged proximate the first proximal end and arranged to cut when the first screw portion is displaced in a second circumferential direction, opposite the first circumferential direction. In some embodiments, the second hole is a through-hole extending from the second proximal end to the second distal end, and the third hole is a through-hole extending from the first end to the second end. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a joint, comprising a fusion device, including a distal end, a proximal end, a radially outward facing surface including threading, a bore extending from the proximal end, at least one flute arranged proximate the distal end, and at least one aperture arranged adjacent to the at least one flute. 
     In some embodiments, the threading comprises varying pitch. In some embodiments, the fusion device further comprises a plurality of fusion apertures extending from the radially outward facing surface to the bore. In some embodiments, the proximal end further comprises a coupler. In some embodiments, the coupler comprises one or more coupling lobes. In some embodiments, the fusion device further comprises a shaft, the shaft including a first end, a second end operatively arranged to be non-rotatably connected to the proximal end, and a through-bore extending from the first end to the second end. In some embodiments, the shaft is removably connected to the fusion device. In some embodiments, the fusion device further comprises at least one expandable member arranged in the bore, the at least one expandable member operatively arranged to extend radially outward through at least one opening in the radially outward facing surface. In some embodiments, the fusion device further comprises a radially inward facing surface and a nut operatively arranged to engage the at least one expandable member, the nut being threadably engaged with the radially inward facing surface. 
     In some embodiments, the at least one expandable member comprises a first pivot fixedly secured to the radially inward facing surface, a second pivot slidably connected to the radially inward facing surface, and a third pivot, wherein when the first pivot is displaced in a first axial direction relative to the proximal end, the third pivot displaces radially outward from the radially outward facing surface. In some embodiments, when the nut is displaced in a first axial direction relative to the proximal end, the at least one expandable member displaces radially outward from the radially outward facing surface. In some embodiments, the at least one expandable member is flexible. In some embodiments, the distal end is a drill bit. 
     According to aspects illustrated herein, there is provided a fusion device for fusion of a joint, comprising a distal end, a proximal end, a radially outward facing surface including threading, a bore extending from the proximal end, at least one flute arranged proximate the distal end, at least one aperture arranged adjacent to the at least one flute, at least one opening, and at least one expandable member operatively arranged in the bore to expand radially through the at least one opening. 
     In some embodiments, the fusion device further comprises a plurality of fusion apertures extending from the radially outward facing surface to the bore. In some embodiments, the proximal end further comprises a coupler operatively arranged to be non-rotatably connected to a hollow shaft. In some embodiments, the fusion device further comprises a nut arranged in the bore, the nut operatively arranged to engage the at least one expandable member. In some embodiments, when the nut is displaced in a first axial direction relative to the proximal end, the at least one expandable member displaces radially outward from the radially outward facing surface. In some embodiments, the at least one expandable member comprises a first pivot fixedly secured to the radially inward facing surface, a second pivot slidably connected to the radially inward facing surface, and a third pivot, wherein when the first pivot is displaced in a first axial direction relative to the proximal end, the third pivot displaces radially outward from the radially outward facing surface. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a j oint, comprising a fusion device, including a distal end having a drill bit, a proximal end, a radially outward facing surface including threading, a bore extending from the proximal end, at least one flute arranged proximate the distal end, at least one aperture arranged adjacent to the at least one flute, at least one opening, and at least one expandable member operatively arranged in the bore to expand radially through the at least one opening, and a shaft, including a first end, a second end operatively arranged to be non-rotatably connected to the proximal end, and a through-bore extending from the first end to the second end. 
     According to aspects illustrated herein, there is provided a device for fixating the position of proximate elements of a dysfunctional sacroiliac (SI) j oint, though it is recognized that miniaturization of the device would allow its use in smaller joints such as those in the lumbar facets, hands, and foot and ankle. 
     The device broadly comprises a cylindrical inter body implant including a self-drilling tip having full or partial threading internally and/or externally, and a hollow internal chamber into which bone drilling material from the advancing tip is funneled via flutes directing the material into apertures that perforate the device wall. 
     In a fully threaded iteration, the screw pitch is varied such that compression occurs gradually across the joint as the screw advances. In a partially threaded version, threads and flutes are found at the distal end, followed by a non-threaded perforated middle segment and then smaller pitched threads at the proximal end to facilitate joint compression in the manner of a lag-screw. In some embodiments, the device includes a fully threaded regular pitch bone screw configuration. 
     At the distal point or tip of the device, multiple configurations may be employed. In some embodiments, the tip is hollowed such that the device can be advanced along a guide wire, like a Kirschner wire (or K-wire). In some embodiments, the tip is a sharp point that is simply pressed into the bone surface such that it retains its position upon rotation in a manner approximating a Brad point drill bit tip. In some embodiments, the device is employed with image guidance where a previously placed guide wire is not necessary since real time information as to drill depth and direction is constantly available. The guide wire iteration is likely to be used in cases using traditional fluoroscopy, whereas the point tip version is expected to be used where image guided technology is available. 
     Once the tip is apposed to the bone surface, rotation of the device by hand or motor advances the tip of the device in a fashion similar to a standard self-drilling bone drill. Flutes at the tip direct bone drillings into the hollow chamber of the device, where they are housed as graft rather than directed back to the proximal drill hole as a normal twist drill would do. The flutes with their capture apparatus are located in the distal third, closer to the distal tip such that as much bone as possible that is harvested by the distal tip is directed into the inner graft chamber. More proximally, apertures exist in the shaft wall to allow the internal graft to communicate with the outer bone such that through-and-through fusion may occur. Such apertures may be round, oblong, spiral, rectangular, etc., and exist between threads or render the threads discontinuous as desired. 
     In some embodiments, the proximal end of the device is connected to a hollow drive shaft in a reversible fashion. The connection between the device and the hollow drive shaft may comprise any suitable connection known in the art. For example, a reverse thread screw connection, a press fit, a clasp or O-ring, or as a socket connection. In some embodiments, an image array may be connected to the hollow drive shaft so that the deployment of the device is fully image guided. 
     The hollow drive shaft, in turn, at its proximal end, is configured so as to permit engagement with hand or motor-powered attachments available in any standard orthopedic operating room. The shaft allows deployment of the device to its intended inter-bone target whereupon the hand or power drive attachment is removed leaving the device in situ with the hollow drive shaft emanating from the wound. 
     Additional bone product may be placed in the hollow drive shaft and a plunger or ramrod may be used to compress and compact the added bone graft into the device since evidence demonstrates that compression of bone elements facilitates fusion. 
     Once the graft is fully packed into the device, the plunger is held in place until the hollow shaft is disengaged and both the plunger and the shaft can be removed. 
     This process permits a safe and minimally invasive placement of a bone/fusion device. Rapid and accurate device placement lowers risks of infection and tissue trauma while reducing expensive operating room time. 
     By having the deployable device function as its own drill bit, drill tap, autograft harvester, joint fixator, and joint compressor, a SI joint fusion can be accomplished in a fraction of the time and with greater accuracy and success than heretofore possible. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a joint, comprising a first screw portion, including a first distal end, a first proximal end, a first radially outward facing surface, and a first hole, a second screw portion, including a second distal end, a second proximal end, and a second radially outward facing surface, and a section, including a first end slidably engaged with the first hole, a second end non-rotatably secured to the second distal end, and a third radially outward facing surface. 
     In some embodiments, the first screw portion further comprises threading arranged on the first radially outward facing surface, at least one flute extending from the first distal end to the first proximal end, and at least one cutting edge operatively arranged to cut through bone. In some embodiments, the first screw portion comprises a first flute including a first cutting edge, the first cutting edge arranged proximate the first distal end and arranged to cut when the first screw portion is displaced in a first circumferential direction, and a second flute including a second cutting edge, the second cutting edge arranged proximate the first proximal end and arranged to cut when the first screw portion is displaced in a second circumferential direction, opposite the first circumferential direction. In some embodiments, the second screw portion further comprises threading arranged on the second radially outward facing surface. In some embodiments, the second screw portion further comprises a head non-rotatably connected to the second proximal end. 
     In some embodiments, the fusion device assembly further comprises a second hole extending through the second screw portion and the section. In some embodiments, the fusion device assembly further comprises a rod operatively arranged to extend through the second hole and engage the first screw portion. In some embodiments, when the rod is displaced in a first circumferential direction, one of the first screw portion and the second screw portion is displaced relative to the other of the first screw portion and the second screw portion. In some embodiments, when the rod is displaced in a first circumferential direction the second screw portion and the section are displaced in a axial direction toward the first screw portion. In some embodiments, the first screw portion comprises a first diameter, the second screw portion comprises a second diameter, and the section comprises a third diameter, wherein the third diameter is less than the first diameter and the second diameter. In some embodiments, the first hole comprises at least one notch, and the third radially outward facing surface comprises at least one protrusion operatively arranged to engage the at least one notch to non-rotatably connect the section with the first screw portion. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a bone structure or j oint, comprising a first screw portion, including a first distal end, a first proximal end, a first radially outward facing surface, and a first hole, a second screw portion, including a second distal end, a second proximal end, and a second radially outward facing surface, a bone graft section, including a first end slidably engaged with the first hole, a second end non-rotatably secured to the second distal end and a third radially outward facing surface, and a rod extending internally through the second screw portion, the bone graft section, and the first screw portion, wherein the rod is operatively arranged to displace the first screw portion and the second screw portion toward each other. 
     In some embodiments, the first screw portion further comprises threading arranged on the first radially outward facing surface, at least one flute extending from the first distal end to the first proximal end, and at least one cutting edge operatively arranged to cut through bone. In some embodiments, the first screw portion comprises a first flute including a first cutting edge, the first cutting edge arranged proximate the first distal end and arranged to cut when the first screw portion is displaced in a first circumferential direction, and a second flute including a second cutting edge, the second cutting edge arranged proximate the first proximal end and arranged to cut when the first screw portion is displaced in a second circumferential direction, opposite the first circumferential direction. In some embodiments, the second screw portion further comprises threading arranged on the second radially outward facing surface. In some embodiments, the fusion device assembly further comprises a second hole extending through the second screw portion and the bone graft section, the rod engaged with the second hole. In some embodiments, when the rod is displaced in a first circumferential direction the second screw portion and the section are displaced in a axial direction toward the first screw portion. In some embodiments, the first screw portion comprises a first diameter, the second screw portion comprises a second diameter, and the bone graft section comprises a third diameter, wherein the third diameter is less than the first diameter and the second diameter. In some embodiments, an overall length of the fusion device assembly is adjustable via the rod. 
     According to aspects illustrated herein, there is provided a fusion device assembly for fusion of a bone structure or j oint, comprising a first screw portion, including a first distal end, a first proximal end, a first hole, a first radially outward facing surface, including a first threading, a first flute including a first cutting edge, the first cutting edge arranged proximate the first distal end and arranged to cut when the first screw portion is displaced in a first circumferential direction, and a second flute including a second cutting edge, the second cutting edge arranged proximate the first proximal end and arranged to cut when the first screw portion is displaced in a second circumferential direction, opposite the first circumferential direction, a second screw portion, including a second distal end, a second proximal end, and a second radially outward facing surface including a second threading, and a bone graft section, including a first end slidably engaged with the first hole, a second end non-rotatably secured to the second distal end, and a third radially outward facing surface. 
     In some embodiments, the bone material harvested by the cutting edge or edges of the tip are directed by one or more flutes to the slidable unthreaded segment of the screw or fusion device. Such bone drillings accumulate circumferentially around the unthreaded shaft component as a harvested autograft to be held and stored in that position for the purpose of fusion across a bone interface. Said graft is then capable being placed under compression according to Wolff’s law by axial shortening of the unthreaded shaft component which in turn draws together the proximal and distal threaded segments of the screw or fusion device to manifest such compression of not only the harvested autograft, but also the proximate surfaces of the bone elements being fused. 
     These and other objects, features, and advantages of the present disclosure will become readily apparent upon a review of the following detailed description of the disclosure, in view of the drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are incorporated herein as part of the specification. The drawings described herein illustrate embodiments of the presently disclosed subject matter and are illustrative of selected principles and teachings of the present disclosure, in which corresponding reference symbols indicate corresponding parts. However, the drawings do not illustrate all possible implementations of the presently disclosed subject matter and are not intended to limit the scope of the present disclosure in any way. 
         FIG.  1    is a front perspective view of a fusion device assembly. 
         FIG.  2    is a front exploded perspective view of the fusion device assembly shown in  FIG.  1   . 
         FIG.  3    is a front perspective view of a section of the shaft shown in  FIG.  1   . 
         FIG.  4    is a cross-sectional view of the shaft taken generally along line  4 - 4  in  FIG.  2   . 
         FIG.  5 A  is a front perspective view of the fusion device shown in  FIG.  1   . 
         FIG.  5 B  is a rear perspective view of the fusion device shown in  FIG.  1   . 
         FIG.  5 C  is a rear elevational view of the fusion device shown in  FIG.  1   . 
         FIG.  6    is a cross-sectional view of the fusion device taken generally along line  6 - 6  in  FIG.  5 A . 
         FIG.  7    is a front perspective view of a fusion device, in an unexpanded state. 
         FIG.  8    is a front perspective view of the fusion device shown in  FIG.  7   , in an expanded state. 
         FIG.  9    is a cross-sectional view of the fusion device, in the unexpanded state, taken generally along line  9 - 9  in  FIG.  7   . 
         FIG.  10    is a cross-sectional view of the fusion device, in the expanded state, taken generally along line  10 - 10  in  FIG.  8   . 
         FIG.  11    is a front elevational view of the fusion device, in the expanded state, shown in  FIG.  8   . 
         FIG.  12    is a rear elevational view of the fusion device, in the expanded state, shown in  FIG.  8   . 
         FIG.  13    is a front elevational view of a fusion device, in an unexpanded state. 
         FIG.  14    is a front elevational view of the fusion device shown in  FIG.  13   , in an expanded state. 
         FIG.  15    is a cross-sectional view of the fusion device, in the unexpanded state, taken generally along line  15 - 15  in  FIG.  13   . 
         FIG.  16    is a cross-sectional view of the fusion device, in the expanded state, taken generally along line  16 - 16  in  FIG.  14   . 
         FIG.  17    is a posterior view of a fusion device being implanted in a sacroiliac joint. 
         FIG.  18    is a lateral view of the fusion device being implanted in the sacroiliac joint, as shown in  FIG.  17   . 
         FIG.  19    is a rear perspective view of a fusion device assembly in a fully expanded state. 
         FIG.  20    is a rear perspective view of the fusion device assembly shown in  FIG.  19   , in a collapsed state. 
         FIG.  21    is an exploded perspective view of the fusion device assembly shown in  FIG.  19   . 
         FIG.  22    is a cross-sectional view of the fusion device assembly taken generally along line  22 - 22  in  FIG.  19   . 
         FIG.  23    is a cross-sectional view of the fusion device assembly taken generally along line  23 - 23  in  FIG.  20   . 
         FIG.  24 A  is an elevational view of a fusion device assembly engaged with a bone structure in the fully expanded state. 
         FIG.  24 B  is an elevational view of a fusion device assembly engaged with a bone structure in the collapsed state. 
     
    
    
     DETAILED DESCRIPTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements. It is to be understood that the claims are not limited to the disclosed aspects. 
     Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the claims. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure pertains. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the example embodiments. 
     It should be appreciated that the term “substantially” is synonymous with terms such as “nearly,” “very nearly,” “about,” “approximately,” “around,” “bordering on,” “close to,” “essentially,” “in the neighborhood of,” “in the vicinity of,” etc., and such terms may be used interchangeably as appearing in the specification and claims. It should be appreciated that the term “proximate” is synonymous with terms such as “nearby,” “close,” “adjacent,” “neighboring,” “immediate,” “adjoining,” etc., and such terms may be used interchangeably as appearing in the specification and claims. The term “approximately” is intended to mean values within ten percent of the specified value. 
     It should be understood that use of “or” in the present application is with respect to a “non-exclusive” arrangement, unless stated otherwise. For example, when saying that “item x is A or B,” it is understood that this can mean one of the following: (1) item x is only one or the other of A and B; (2) item x is both A and B. Alternately stated, the word “or” is not used to define an “exclusive or” arrangement. For example, an “exclusive or” arrangement for the statement “item x is A or B” would require that x can be only one of A and B. Furthermore, as used herein, “and/or” is intended to mean a grammatical conjunction used to indicate that one or more of the elements or conditions recited may be included or occur. For example, a device comprising a first element, a second element and/or a third element, is intended to be construed as any one of the following structural arrangements: a device comprising a first element; a device comprising a second element; a device comprising a third element; a device comprising a first element and a second element; a device comprising a first element and a third element; a device comprising a first element, a second element and a third element; or, a device comprising a second element and a third element. 
     Moreover, as used herein, the phrases “comprises at least one of” and “comprising at least one of” in combination with a system or element is intended to mean that the system or element includes one or more of the elements listed after the phrase. For example, a device comprising at least one of: a first element; a second element; and, a third element, is intended to be construed as any one of the following structural arrangements: a device comprising a first element; a device comprising a second element; a device comprising a third element; a device comprising a first element and a second element; a device comprising a first element and a third element; a device comprising a first element, a second element and a third element; or, a device comprising a second element and a third element. A similar interpretation is intended when the phrase “used in at least one of:” is used herein. 
     By “non-rotatably connected” elements, we mean that: the elements are connected so that whenever one of the elements rotate, all the elements rotate; and relative rotation between the elements is not possible. Radial and/or axial movement of non-rotatably connected elements with respect to each other is possible, but not required. 
     Adverting now to the figures,  FIG.  1    is a front perspective view of fusion device assembly  10 .  FIG.  2    is a front exploded perspective view of fusion device assembly  10 . Fusion device assembly  10  generally comprises shaft  20  and fusion device  50 . It should be appreciated that fusion devices  150  and  250  are also compatible with shaft  20  and may form fusion device assembly  10  along therewith. Shaft  20  is operatively arranged to drive fusion device  50  (and fusion devices  150  and  250 ) into a joint and allow graft material to be injected therein, as will be described in greater detail below. 
       FIG.  3    is a front perspective view of a section of shaft  20 .  FIG.  4    is a cross-sectional view of shaft  20  taken generally along line  4 - 4  in  FIG.  2   . 
     Shaft  20  generally comprises through-bore  21 , end  26 , and end  32 . Through-bore  21  extends from end  26  through end  32 . In some embodiments, through-bore  21  extends from end  26  through end  38 . In some embodiments, shaft  20  comprises one or more sections (e.g., sections  22 ,  30 , and  36 ). 
     Section  22  is generally cylindrical and comprises end  24  and end  26 . End  26  includes a coupler to non-rotatably connect shaft  20  to fusion device  50 ,  150 ,  250 . For example, end  26  may comprise coupling lobes  28 A-C that engage coupling lobes  56 A-C in fusion device  50 , similar to a socket connection, to non-rotatably connect shaft  20  and fusion device  50 . In some embodiments, section  22  is removably connected to section  30 , such that various coupler sizes or geometries may be assembled on shaft  20 . 
     Section  30  is generally cylindrical and comprises end  32  and end  34 . End  34  is arranged to engage end  24  to non-rotatably connect sections  22  and  30 . End  32  is arranged to engage end  40  to non-rotatably connect sections  30  and  36 . 
     Section  36  comprises end  38  and end  40 . In some embodiments, section  36  is a hollow cylinder. In such embodiments, bone graft material can be inserted into end  38  and injected into fusion device  50 ,  150 ,  250  through through-bore  21 . In some embodiments, section  36  is solid and is removably connected to section  30 . In such embodiments, section  36  can be removed from section  30  such that bone graft material can be inserted into end  32  and injected into fusion device  50 ,  150 ,  250  through through-bore  21 . End  40  is arranged to engage end  32  to non-rotatably connect sections  30  and  36 . End  38  may comprise a universal coupler for connection to tool  12  (see  FIGS.  17 - 18   ), for example, a power drill, torque handle, ratcheting T-handle, etc. In some embodiments, end  38  is a universal hex bit. In some embodiments, end  38  is a universal square bit. 
     Shaft  20  is specifically designed to circumferentially drive fusion device  50 ,  150 ,  250  into a joint. Once fusion device  50 ,  150 ,  250  is properly implanted, bone graft material is then injected into fusion device  50 ,  150 ,  250  through shaft  20 , specifically through through-bore  21 . As previously described, in some embodiments, section  36  is first removed to inject bone material through shaft  20 . A plunger or a ram rod may be employed to force the bone graft material through shaft  20  and into fusion device  50 ,  150 ,  250 . For example, a small rod having a diameter that is less than the diameter of through-bore  21  may be inserted into through-bore  21 , after the bone graft material, to inject or pack the bone graft material into fusion device  50 ,  150 ,  250 , similar to a ram rod of a musket. In some embodiments, bone material is inserted into shaft  20  through end  38 . It should be appreciated that in some embodiments, shaft  20  is a single element (i.e., sections  22 ,  30 , and  36  are integrally formed). 
       FIG.  5 A  is a front perspective view of fusion device  50 .  FIG.  5 B  is a rear perspective view of fusion device  50 .  FIG.  5 C  is a rear elevational view of fusion device  50 .  FIG.   6    is a cross-sectional view of fusion device  50  taken generally along line  6 - 6  in  FIG.  5 A . Fusion device  50  generally comprises bore  51 , end  52 , end  54 , and radially outward facing surface  58 . 
     Fusion device  50  is generally cylindrical and is operatively arranged to engage a joint. Fusion device  50  is a self-boring, self-tapping, fusion screw. In some embodiments, fusion device  50  is hollow and self-harvesting (i.e., harvests bone). As shown, fusion device  50  comprises a twist bit, a multi-purpose bit, or a pilot point bit having a cutting point/tip/edge, i.e., drill bit  53 , at end  52 , which comprises one or more flutes  64 . Flutes  64  may comprise one or more cutting edges. In some embodiments, end  52  comprises a Brad point bit, a Forstner bit, or a spade bit. End  52  and flutes  64  are operatively arranged to bore a hole through the joint, specifically through the bone. Fusion device  50  further comprises one or more apertures  66  formed adjacent to flutes  64 . Flutes  64  and apertures  66  work in conjunction such that as fusion device  50  is being driven into the joint, bone is removed from the joint by the tip at end  52  and flutes  64  and forced into bore  51  via apertures  66 . The removed bone that is forced into bore  51  aids in the fusion of the j oint. Bore  51  extends substantially through fusion device  50 . Specifically, bore  51  extends from end  54  to proximate end  52 . Apertures  66  extend from radially outward facing surface  58  radially inward to bore  51 . End  54  includes a coupler to non-rotatably connect shaft  20  to fusion device  50 . For example, end  54  may comprise coupling lobes  56 A-C that engage coupling lobes  28 A-C in shaft  20 , similar to a socket connection, to non-rotatably connect shaft  20  and fusion device  50  (see  FIG.  5 C ). Radially outward facing surface  58  further comprises threading  60 . Threading  60  is designed not only to secure the joint (two bones) together, but also to tap the hole bored out in the joint by end  52  (the drill tip) and flutes  64 . In some embodiments, threading  60  comprises a varying pitch such that compression occurs gradually across the joint as fusion device  50  advances therein. In some embodiments, radially outward facing surface  58  comprises threading from end  52  to end  54  (i.e., fusion device  50  is fully threaded). In some embodiments, radially outward facing surface  58  is partially threaded. For example, threads and flutes are found proximate end  52  followed by a non-threaded middle section and then smaller pitched threads proximate end  54  to facilitate joint compression in the manner of a lag-screw. In some embodiments, fusion device  50  is a fully threaded regular pitch bone screw. Radially outward facing surface  58  further comprises a plurality of apertures  62 . Apertures  62  extend from radially outward facing surface  58  radially inward to bore  51  and allow for the removed bone material residing in bore  51  (i.e., the bone material fed into bore  51  through apertures  66 ) to engage with the joint such that, over time, joint fusion occurs. Apertures  62  further allow for bone graft material injected into fusion device  50  through shaft  20  to engage the joint for joint fusion. In other words, apertures  62  allow for bony in-growth and through growth/fusion. It should be appreciated that apertures  62  may comprise any geometric shape suitable to allow fusion to occur between graft residing within bore  51  and the joint (e.g., circular, ovular, triangular, square, rectangular, etc.). 
       FIG.  7    is a front perspective view of fusion device  150 , in an unexpanded state.  FIG.  8    is a front perspective view of fusion device  150 , in an expanded state.  FIG.  9    is a cross-sectional view of fusion device  150 , in the unexpanded state, taken generally along line  9 - 9  in  FIG.  7   .  FIG.  10    is a cross-sectional view of fusion device  150 , in the expanded state, taken generally along line  10 - 10  in  FIG.  8   .  FIG.  11    is a front elevational view of fusion device  150 , in the expanded state.  FIG.  12    is a rear elevational view of fusion device  150 , in the expanded state. Fusion device  150  generally comprises bore  151 , end  152 , end  154 , and radially outward facing surface  158 . 
     Fusion device  150  is generally cylindrical and is operatively arranged to engage a joint. Fusion device  150  is a self-boring, self-tapping, fusion screw. In some embodiments, fusion device  150  is hollow and self-harvesting (i.e., harvests bone). As shown, fusion device  150  comprises a Brad point bit having a cutting point/tip/edge, i.e., drill bit  153 , at end  152 , which comprises one or more flutes  164 . Flutes  164  may comprise one or more cutting edges. In some embodiments, end  152  comprises a twist bit, a multi-purpose bit, a pilot point bit, a Forstner bit, or a spade bit. End  152  and flutes  164  are operatively arranged to bore a hole through the joint, specifically through the bone. Fusion device  150  further comprises one or more apertures  166  formed adjacent to flutes  164 . Flutes  164  and apertures  166  work in conjunction such that as fusion device  150  is being driven into the joint, bone is removed from the joint by the tip at end  152  and flutes  164  and forced into bore  151  via apertures  166 . The removed bone that is forced into bore  151  aids in the fusion of the joint. Bore  151  extends substantially through fusion device  150 . Specifically, bore  151  extends from end  154  to proximate end  152 . Apertures  166  extend from radially outward facing surface  158  radially inward to bore  151 . End  154  includes a coupler to non-rotatably connect shaft  20  to fusion device  150 . For example, end  154  may comprise coupling lobes  156 A-C that engage coupling lobes  28 A-C in shaft  20 , similar to a socket connection, to non-rotatably connect shaft  20  and fusion device  150  (see  FIG.  12   ). Radially outward facing surface  158  further comprises threading  160 . Threading  160  is designed not only to secure the joint (two bones) together, but also to tap the hole bored out in the joint by end  152  (the drill tip) and flutes  164 . In some embodiments, threading  160  comprises a varying pitch such that compression occurs gradually across the joint as fusion device  150  advances therein. In some embodiments, radially outward facing surface  158  comprises threading from end  152  to end  154  (i.e., fusion device  150  is fully threaded). In some embodiments, radially outward facing surface  158  is partially threaded. For example, threads and flutes are found proximate end  152  followed by a non-threaded middle section and then smaller pitched threads proximate end  154  to facilitate joint compression in the manner of a lag-screw. In some embodiments, fusion device  150  is a fully threaded regular pitch bone screw. Radially outward facing surface  158  further comprises a plurality of apertures  162 . Apertures  162  extend from radially outward facing surface  158  radially inward to bore  151  and allow for the removed bone material residing in bore  151  (i.e., the bone material fed into bore  151  through apertures  166 ) to engage with the joint such that, over time, joint fusion occurs. Apertures  162  further allow for bone graft material injected into fusion device  150  through shaft  20  to engage the joint for joint fusion. In other words, apertures  162  allow for bony in-growth and through growth/fusion. It should be appreciated that apertures  162  may comprise any geometric shape suitable to allow fusion to occur between graft residing within bore  151  and the joint (e.g., circular, ovular, triangular, square, rectangular, etc.). 
     Fusion device  150  further comprises one or more expandable members  180  operatively arranged to expand radially outward through one or more openings  168  from bore  151  and engage the bone(s) of the j oint. As shown openings  168  are arranged in radially outward facing surface  158  and extend radially inward to bore  151 . In some embodiments, expandable members  180  comprise pivots  182 ,  184 , and  186 . For example, pivot  182  may be fixedly secured to radially inward facing surface  170  and pivot  184  may be slidably connected to radially inward facing surface. As sliding pivot  184  is displaced in axial direction AD 1 , pivot  186  expands radially outward through openings  168  (see  FIGS.  9 - 10   ). As expandable members  180  (e.g., radially expanding pivots  186 ) expand radially outward, they engage the joint or bones of the joint and prevent fusion device  150  from disengaging the joint (i.e., from unscrewing from the joint), and also serves to stabilize proximate elements of the bones or joint such that excess motion which may hinder fusion is thereby mitigated. 
     In some embodiments fusion device  150  further comprises nut  190  and one or more plates (e.g., plates  192  and  194 ) operatively arranged to displace pivot  184  in axial direction AD 1  such that expandable members  180  expand radially through openings  168 . Nut  190  is threadably engaged with radially inward facing surface  170  and comprises through-bore  191 . Nut  190  is connected to plate  192  and/or plate  194  via one or more connectors  196  and/or one or more connectors  198 , respectively. In some embodiments, nut  190  is non-rotatably connected to plate  192  and/or plate  194 . In some embodiments, nut  190  is rotatably connected to plate  192  and/or plate  194 . Plate  192  and plate  194  are operatively arranged to engage or abut against sliding pivots  184  to displace sliding pivots  184  in axial direction AD 1 . In some embodiments, nut  190  directly engages or abuts against sliding pivot  184  without the need for plates or connectors. Once fusion device  150  is properly implanted in a joint, shaft  20  is removed from end  154  and a tool (e.g., screwdriver, Allen wrench, socket, etc.) is inserted into nut  190 . Nut  190  is rotated such that nut  190  is displaced in axial direction AD 1  relative to end  154 . This causes plates  192  and  194  and sliding pivots  184  to displace in axial direction AD 1 , which forces expandable members  180  radially outward through openings  168  to engage the bones of the joint. Through-bore  191  allows bone graft material to be injected into fusion device  150  through end  154  via shaft  20 . In some embodiments, plate  192  comprises a through-bore. In some embodiments, plate  194  comprises a through-bore. In some embodiments, plate  192  and/or plate  194  is threadably engaged with radially inward facing surface  170 . 
       FIG.  13    is a front elevational view of fusion device  250 , in an unexpanded state.  FIG.  14    is a front elevational view of fusion device shown  250 , in an expanded state.  FIG.  15    is a cross-sectional view of fusion device  250 , in the unexpanded state, taken generally along line  15 - 15  in  FIG.  13   .  FIG.  16    is a cross-sectional view of fusion device  250 , in the expanded state, taken generally along line  16 - 16  in  FIG.  14   . Fusion device  250  generally comprises bore  251 , end  252 , end  254 , and radially outward facing surface  258 . 
     Fusion device  150  is generally cylindrical and is operatively arranged to engage a joint. Fusion device  250  is a self-boring, self-tapping, fusion screw. In some embodiments, fusion device  250  is hollow and self-harvesting (i.e., harvests bone). As shown, fusion device  250  comprises a Forstner bit having a cutting point/tip/edge, i.e., drill bit  253 , at end  252 , which comprises one or more flutes  264 . Flutes  264  may comprise one or more cutting edges. In some embodiments, end  252  comprises a twist bit, a multi-purpose bit, a pilot point bit, a Brad point bit, or a spade bit. End  252  and flutes  264  are operatively arranged to bore a hole through the joint, specifically through the bone. Fusion device  250  further comprises one or more apertures  266  formed adjacent to flutes  264 . Flutes  264  and apertures  266  work in conjunction such that as fusion device  250  is being driven into the joint, bone is removed from the joint by the tip at end  252  and flutes  264  and forced into bore  251  via apertures  266 . The removed bone that is forced into bore  251  aids in the fusion of the joint. Bore  251  extends substantially through fusion device  250 . Specifically, bore  251  extends from end  254  to proximate end  252 . Apertures  266  extend from radially outward facing surface  258  radially inward to bore  251 . End  254  includes a coupler to non-rotatably connect shaft  20  to fusion device  250 . For example, end  254  may comprise coupling lobes  256 A-C (not shown) that engage coupling lobes  28 A-C in shaft  20 , similar to a socket connection, to non-rotatably connect shaft  20  and fusion device  250 . Radially outward facing surface  258  further comprises threading  260 . Threading  260  is designed not only to secure the joint (two bones) together, but also to tap the hole bored out in the joint by end  252  (the drill tip) and flutes  264 . In some embodiments, threading  260  comprises a varying pitch such that compression occurs gradually across the joint as fusion device  250  advances therein. In some embodiments, radially outward facing surface  258  comprises threading from end  252  to end  254  (i.e., fusion device  250  is fully threaded). In some embodiments, radially outward facing surface  258  is partially threaded. For example, threads and flutes are found proximate end  252  followed by a non-threaded middle section and then smaller pitched threads proximate end  254  to facilitate joint compression in the manner of a lag-screw. In some embodiments, fusion device  250  is a fully threaded regular pitch bone screw. Radially outward facing surface  258  further comprises a plurality of apertures  262 . Apertures  262  extend from radially outward facing surface  258  radially inward to bore  251  and allow for the removed bone material residing in bore  251  (i.e., the bone material fed into bore  251  through apertures  266 ) to engage with the joint such that, over time, joint fusion occurs. Apertures  262  further allow for bone graft material injected into fusion device  250  through shaft  20  to engage the joint for joint fusion. In other words, apertures  262  allow for bony in-growth and through growth/fusion. It should be appreciated that apertures  262  may comprise any geometric shape suitable to allow fusion to occur between graft residing within bore  251  and the joint (e.g., circular, ovular, triangular, square, rectangular, etc.). 
     Fusion device  250  further comprises one or more expandable members  280  operatively arranged to extend radially outward through one or more openings  268  from bore  251  and engage the bone(s) of the j oint. As shown openings  268  are arranged in radially outward facing surface  258  and extend radially inward to bore  251 . In some embodiments, expandable members  280  are flexible structures that can be fed along a curved path ( FIGS.  15 - 16   ). As one end of expandable member  280  is displaced in axial direction AD 1 , the other end of expandable member  280  is curved radially outward from radially outward facing surface. As expandable members  280  extend radially outward, they engage the joint or bones of the joint and prevent fusion device  250  from disengaging the joint (i.e., from unscrewing from the joint). 
     In some embodiments fusion device  250  further comprises nut  290  and one or more plates (e.g., plate  292 ) operatively arranged to displace one end of expandable members  280  in axial direction AD 1  such that the other end of expandable members  280  extends radially through openings  268 . Nut  290  is threadably engaged with radially inward facing surface  270  and comprises through-bore  291 . Nut  290  is connected to plate  292  via one or more connectors  294 . In some embodiments, nut  290  is non-rotatably connected to plate  292 . In some embodiments, nut  290  is rotatably connected to plate  292 . Nut  290  and/or plate  292  is operatively arranged to engage or abut against expandable members  280  to displace expandable members  280  in axial direction AD 1  (and subsequently radially outward from radially outward facing surface  258 ). In some embodiments, and as shown in  FIGS.  15  and  16   , nut  290  directly engages or abuts against expandable members  280 . Once fusion device  250  is properly implanted in a joint, shaft  20  is removed from end  254  and a tool (e.g., screwdriver, Allen wrench, socket, etc.) is inserted into nut  290 . Nut  290  is rotated such that nut  290  is displaced in axial direction AD 1  relative to end  254 . This causes plate  292  and one end of expandable members  280  to displace in axial direction AD 1 , which forces the other end of expandable members  280  radially outward through openings  268  to engage the bones of the joint. Through-bore  291  allows bone graft material to be injected into fusion device  250  through end  254  via shaft  20 . In some embodiments, plate  292  comprises a through-bore. In some embodiments, plate  292  is threadably engaged with radially inward facing surface  270 . 
       FIG.  17    is a posterior view of fusion device  50 ,  150 ,  250  being implanted in sacroiliac joint  8 .  FIG.  18    is a lateral view of fusion device  50 ,  150 ,  250  being implanted in sacroiliac joint  8 . As shown, sacroiliac joint  8  comprises sacrum  4  and ilium  6 . Sacrum  4  is connected to spinal column  2 . Sacroiliac joint  8  is the connection between spinal column  2  and the pelvis. Fusion device  50 ,  150 ,  250  is implanted into sacroiliac joint  8  and once properly arranged, extends from ilium  6  to sacrum  4 . As previously described, the threading of fusion device  50 ,  150 ,  250  is operatively arranged to pull ilium  6  and sacrum  4  together (i.e., into compression). Fusion device  50 ,  150 ,  250  is driven into sacroiliac joint  8  via shaft  20  and tool  12 . In some embodiments, once fusion device  50 ,  150 ,  250  is in place, tool  12  is removed from shaft  20  and bone material is injected into fusion device  50 ,  150 ,  250  through shaft  20 . Shaft  20  is then removed from fusion device  50 ,  150 ,  250  and the wound is closed. In some embodiments, shaft  20  is removed and expandable members within the fusion device (e.g., fusion device  150 ,  250 ) are expanded radially outward. For example, in fusion device  150 , nut  190  is rotated such that expandable members  180  extend radially outward from radially outward surface  158  and engage sacrum  4  and/or ilium  6 . In fusion device  250 , nut  290  is rotated such that expandable members  280  extend radially outward from radially outward surface  258  and engage sacrum  4  and/or ilium  6 . After radial expansion of fusion device  150 ,  250 , shaft  20  can be reconnected thereto and bone graft material injected therein. Fusion device  50 ,  150 ,  250  left in situ once filled with fusion material. Fusion device  50 ,  150 ,  250  is shown being implanted into sacroiliac joint  8  posteriorly; however, it should be appreciated that fusion device  50 ,  150 ,  250  may be implanted into sacroiliac joint  8  laterally. 
       FIG.  19    is a rear perspective view of fusion device assembly  310  in a fully expanded state.  FIG.  20    is a rear perspective view of fusion device assembly  310  in a collapsed state.  FIG.  21    is an exploded perspective view of fusion device assembly  310 .  FIG.  22    is a cross-sectional view of fusion device assembly  310  taken generally along line  22 - 22  in  FIG.  19   .  FIG.  23    is a cross-sectional view of fusion device assembly taken generally along line  23 - 23  in  FIG.  20   . Fusion device assembly  310  generally comprises distal screw portion  320 , proximal screw portion  360 , bone graft section  380 , and rod  350 . 
     Screw portion  320  is generally cylindrical and comprises end  322 , end  324 , radially outward facing surface  330 , and hole  336 . Hole  336  is arranged in end  324  and extends in axial direction AD 1  toward end  322 . In some embodiments, and as shown, hole  336  comprises one or more notches for non-rotatable connection with bone graft section  380 , as will be described in greater detail below. Radially outward facing surface  330  comprises threading  334  operatively arranged to secure fusion device assembly  310  to/within bone. Radially outward facing surface  330  further comprises one or more flutes, for example, flutes  332  and  335 , and one or more cutting edges or blade tips, for example, cutting edges  326  and  328 . Flute  332  extends from end  322  to end  324  and is operatively arranged to displace bone material (i.e., bone shavings) from end  322  to bone graft section  380 . Cutting edge  326  is arranged on or adjacent to flute  332  at end  322 . As fusion device assembly  310 , specifically screw portion  320 , is rotated in first circumferential direction CD 1 , cutting edge  326  cuts through bone producing bone shavings that are drawn back to bone graft section  380  via flute  332 . Flute or reverse flute  335  extends from end  324  to end  322  and is operatively arranged to displace bone material (i.e., bone shavings) from bone graft section  380  to end  322 . Cutting edge  328  is arranged on or adjacent to flute  335  at end  324 . As fusion device assembly  310 , specifically screw portion  320 , is rotated in second circumferential direction CD 2 , cutting edge  328  cuts through bone arranged in bone graft section  380  (i.e., that has fused) producing bone shavings that are drawn toward end  322  via flute  335 . As screw portion  320  comprises cutting edges on both ends, it can be said that screw portion  320  is a self-tapping screw in both axial directions. 
     As best shown in  FIGS.  22 - 23   , distal screw portion  320  further comprises tube  342  fixedly secured within hole  336 . Tube  342  comprises radially inward facing surface  344  operatively arranged to engage with rod  350 . In some embodiments, radially inward facing surface  344  comprises threading, which is threadably engageable with threading  358  of rod  350 . In some embodiments, screw portion  320  does not comprise tube  344 , but rather is solid and comprises a threaded hole arranged in hole  336  into which threading  358  engages. In some embodiments, end  324  further comprises radially inward extending flange  340 . 
     Screw portion  360  is generally cylindrical and comprises end  362 , end  364 , radially outward facing surface  370 , head  368 , and hole  368 . Head  368  is fixedly secured to end  364  and is operatively arranged to engage a tool such that fusion device assembly  310  can be rotated. In some embodiments, head  368  is hexagonal. It should be appreciated that head  368  may be any geometric shape suitable for engaging with a tool for rotation, for example, square, rectangular, octagonal, triangular, etc. Radially outward facing surface  370  comprises threading  372  operatively arranged to secure fusion device assembly  310  to/within bone. 
     Section  380  comprises end  382 , end  384 , and radially outward facing surface. It should be appreciated that radially outward facing surface  386  comprises a diameter that is less than the diameter of screw portion  320  and screw portion  360 . For example, screw portion  320  comprises diameter D1, screw portion  360  comprises diameter D2, and section  380  comprises diameter D3. Diameter D3 is less than diameters D1 and D2. In some embodiments, diameter D1 is equal to diameter D2. Section  380  is operatively arranged to collect bone material or bone shavings created by cutting edge  326  for bone fusion across a joint or fracture, as will be described in greater detail below. End  384  is non-rotatably connected to end  362 . In some embodiments, section  380  and screw portion  360  are integrally formed. End  382  is slidably engaged with hole  336 . In some embodiments, radially outward facing surface  386  comprises one or more protrusions  388  operatively arranged to engage one or more notches  338  to non-rotatably connect section  380  and screw portion  320 . In some embodiments, end  382  further comprises radially outward extending flange  390 . Flange  390  is operatively arranged to engage flange  340  to prevent end  382  from being removed from hole  336 . In some embodiments, hole  368  extends completely through screw portion  360  and section  380 . Since section  380  is slidably engaged with screw portion  320 , both section  380  and screw portion  360  are axially displaceable with respect to screw portion  320 . However, it should be appreciated that screw portion  320 , screw portion  360 , and section  380  are all non-rotatably connection (i.e., rotationally locked). 
     Rod  350  is generally cylindrical and comprises end  352 , end  356 , and head  356 . Head  356  is arranged at end  354  and is operatively arranged to engage end  364 , specifically head  366 . Rod  350  further comprises threading  358  arranged proximate end  352 . End  352  is arranged to be fed through hole  368  and threading  358  is arranged to threadably engage with threaded hole or radially inward facing surface  344 . Rod  350  is arranged radially inside of screw portion  360 , section  380 , and screw portion  320  which allows the overall length of fusion device assembly  310  to be shortened internally (i.e., an internal threaded rod). As rod  350 , namely head  356 , is rotated in circumferential direction CD 1 , screw portion  360  and section  380  are displaced in axial direction AD 1  with respect to screw portion  320 , thereby creating “compression” across the bone joint, as will be described in greater detail below. As head  356  is rotated in circumferential direction CD 2 , opposite circumferential direction CD 1 , section  380  and screw portion  360  are allowed to displace in axial direction AD 2  with respect to screw portion  320 . In some embodiments, as head  356  is rotated in circumferential direction CD 2 , section  380  and screw portion  360  are displaced in axial direction AD 2  with respect to screw portion  320 . As best shown in  FIG.  22   , when fusion device assembly  310  is in a fully expanded position, fusion device assembly  310  comprises overall length L1. As rod  350  is rotated in circumferential direction CD 1 , screw portion  360  and section  380  are displaced in axial direction AD 1  with respect to screw portion  320 , thereby decreasing the overall length of fusion device assembly  310 , for example, to length L2 as shown in the collapsed position in  FIG.  23   . 
       FIG.  24 A  is an elevational view of fusion device assembly  310  engaged with bone structure  301  in the fully expanded state. Bone structure  301  represents a joint or a fracture and comprises at least two sections, for example, bony anatomy  302  and bony anatomy  303 . Bony anatomies  302  and  303  are separated by space  304 , which comprises length L3. Fusion device  310  is arranged to reduce the length of space  304 . Fusion device assembly  310  is implanted first in bony anatomy  303  and then bony anatomy  302  by screwing it in, namely in circumferential direction CD 1 . As previously described, when rotating fusion device assembly  310  in circumferential direction CD 1 , cutting edge  326  bores a hole in the bony anatomy, for example, hole  305  in bony anatomy  302  and hole  306  in bony anatomy  303 . Bone drillings or shavings  307  from the cutting of the bone are then fed back through flute  332  to section  380  where they are collected. When fusion device assembly  310  is fully implanted in bone structure  301 , screw portion  320  should be at least partially engaged in bony anatomy  302 , screw portion  360  should be at least partially engaged with bony anatomy  303 , and section  380  should be at least partially aligned with space  304 . 
       FIG.  24 B  is an elevational view of fusion device assembly  310  engaged with bone structure  301  in the collapsed state. Once fusion device assembly  310  is properly engaged with bone structure  301 , as shown in  FIG.  24 B , head  366  is rotated in circumferential direction CD 1  thereby displacing screw portion  360 , section  380 , and bony anatomy  303  in axial direction AD 1  with respect to distal screw portion  320 . Alternatively, as head  366  is rotated in circumferential direction CD 1 , screw portion  320  and bony anatomy  302  are displaced in axial direction AD 2  with respect to screw portion  360 , section  380 , and bony anatomy  303 . In both circumstances, the length of space  304  is reduced, for example to length L4, wherein bony anatomy  303  abuts or is arranged substantially proximate to bony anatomy  302 . Additionally, as screw portions  320  and  360  are drawn together, ends  324  and  362  squeeze bone material or drillings  307  thereby forcing bone material  307  into contact with bony anatomies  302  and  303 . The contact of the harvested bone material  307  with bony anatomies  302  and  303  completely surrounding section  380  provides for excellent bone fusion. Fusion device assembly  310  can be left in situ. Alternatively, after fusion occurs (i.e., bone material  307  has fused with bony anatomies  302  and  303  and is hardened), fusion device assembly  310  can be removed by rotating head  366  in circumferential direction CD 2 . As fusion device assembly  310  is rotated in circumferential direction CD 2 , cutting edge  328  cuts through newly fused bone and the drillings are fed through flute  335  toward end  322  allowing fusion device assembly  310  to be removed from bone structure  301 . Furthermore, since cutting edge  328  will “re-bore” a hole to allow the removal of fusion device assembly  310 , any lateral fusion between bony anatomies  302  and  303  will remain. This is advantageous because it allows the option of removing fusion device assembly  310  after fusion occurs, without affecting overall fusion of bone structure  301 . 
     It will be appreciated that various aspects of the disclosure above and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.  
     
       
         
           
               
               
             
               
                 REFERENCE NUMERALS 
               
             
            
               
                 
                   2 
                 
                 Spinal column 
               
               
                 
                   4 
                 
                 Sacrum 
               
               
                 
                   6 
                 
                 Ilium 
               
               
                 
                   8 
                 
                 Sacroiliac joint 
               
               
                 
                   10 
                 
                 Fusion device assembly 
               
               
                 
                   12 
                 
                 Tool 
               
               
                 
                   20 
                 
                 Shaft 
               
               
                 
                   21 
                 
                 Through-bore 
               
               
                 
                   22 
                 
                 Section 
               
               
                 
                   24 
                 
                 End 
               
               
                 
                   26 
                 
                 End 
               
               
                   28 A 
                 Coupling lobe 
               
               
                   28 B 
                 Coupling lobe 
               
               
                   28 C 
                 Coupling lobe 
               
               
                 
                   30 
                 
                 Section 
               
               
                 
                   32 
                 
                 End 
               
               
                 
                   34 
                 
                 End 
               
               
                 
                   36 
                 
                 Section 
               
               
                 
                   38 
                 
                 End 
               
               
                 
                   40 
                 
                 End 
               
               
                 
                   50 
                 
                 Fusion device 
               
               
                 
                   51 
                 
                 Bore 
               
               
                 
                   52 
                 
                 End 
               
               
                 
                   53 
                 
                 Cutting edge/blade/tip/drill bit 
               
               
                 
                   54 
                 
                 End 
               
               
                   56 A 
                 Coupling lobe 
               
               
                   56 B 
                 Coupling lobe 
               
               
                   56 C 
                 Coupling lobe 
               
               
                 
                   58 
                 
                 Radially outward facing surface 
               
               
                 
                   60 
                 
                 Threading 
               
               
                 
                   62 
                 
                 Aperture(s) 
               
               
                 
                   64 
                 
                 Flute(s) 
               
               
                 
                   66 
                 
                 Aperture(s) 
               
               
                 
                   150 
                 
                 Fusion device 
               
               
                 
                   151 
                 
                 Bore 
               
               
                 
                   152 
                 
                 End 
               
               
                 
                   153 
                 
                 Cutting edge/blade/tip/drill bit 
               
               
                 
                   154 
                 
                 End 
               
               
                   156 A 
                 Coupling lobe 
               
               
                   156 B 
                 Coupling lobe 
               
               
                   156 C 
                 Coupling lobe 
               
               
                 
                   158 
                 
                 Radially outward facing surface 
               
               
                 
                   160 
                 
                 Threading 
               
               
                 
                   162 
                 
                 Aperture(s) 
               
               
                 
                   164 
                 
                 Flute(s) 
               
               
                 
                   166 
                 
                 Aperture(s) 
               
               
                 
                   168 
                 
                 Opening(s) 
               
               
                 
                   170 
                 
                 Radially inward facing surface 
               
               
                 
                   180 
                 
                 Expandable member(s) 
               
               
                 
                   182 
                 
                 Fixed pivot 
               
               
                 
                   184 
                 
                 Sliding pivot 
               
               
                 
                   186 
                 
                 Radially expanding pivot 
               
               
                 
                   190 
                 
                 Nut 
               
               
                 
                   191 
                 
                 Through-bore 
               
               
                 
                   192 
                 
                 Plate 
               
               
                 
                   194 
                 
                 Plate 
               
               
                 
                   196 
                 
                 Connector(s) 
               
               
                 
                   198 
                 
                 Connector(s) 
               
               
                 
                   250 
                 
                 Fusion device 
               
               
                 
                   251 
                 
                 Bore 
               
               
                 
                   252 
                 
                 End 
               
               
                 
                   253 
                 
                 Cutting edge/blade/tip/drill bit 
               
               
                 
                   254 
                 
                 End 
               
               
                   256 A 
                 Coupling lobe (not shown) 
               
               
                   256 B 
                 Coupling lobe (not shown) 
               
               
                   256 C 
                 Coupling lobe (not shown) 
               
               
                 
                   258 
                 
                 Radially outward facing surface 
               
               
                 
                   260 
                 
                 Threading 
               
               
                 
                   262 
                 
                 Aperture(s) 
               
               
                 
                   264 
                 
                 Flute(s) 
               
               
                 
                   266 
                 
                 Aperture(s) 
               
               
                 
                   268 
                 
                 Opening(s) 
               
               
                 
                   270 
                 
                 Radially inward facing surface 
               
               
                 
                   280 
                 
                 Expandable member(s) 
               
               
                 
                   290 
                 
                 Nut 
               
               
                 
                   291 
                 
                 Through-bore 
               
               
                 
                   292 
                 
                 Nut or plate 
               
               
                 
                   294 
                 
                 Connector(s) 
               
               
                 
                   301 
                 
                 Bone structure or joint 
               
               
                 
                   302 
                 
                 Bony anatomy 
               
               
                 
                   303 
                 
                 Bony anatomy 
               
               
                 
                   304 
                 
                 Space 
               
               
                 
                   305 
                 
                 Hole 
               
               
                 
                   306 
                 
                 Hole 
               
               
                 
                   307 
                 
                 Bone material or drillings 
               
               
                 
                   310 
                 
                 Fusion device assembly 
               
               
                 
                   320 
                 
                 Distal screw portion 
               
               
                 
                   322 
                 
                 End 
               
               
                 
                   324 
                 
                 End 
               
               
                 
                   326 
                 
                 Cutting edge or blade tip 
               
               
                 
                   328 
                 
                 Cutting edge or blade tip 
               
               
                 
                   330 
                 
                 Radially outward facing surface 
               
               
                 
                   332 
                 
                 Flute or flutes 
               
               
                 
                   334 
                 
                 Threading 
               
               
                 
                   335 
                 
                 Flute or flutes 
               
               
                 
                   336 
                 
                 Hole 
               
               
                 
                   338 
                 
                 Notch or notches 
               
               
                 
                   340 
                 
                 Flange 
               
               
                 
                   342 
                 
                 Tube 
               
               
                 
                   344 
                 
                 Radially inward facing surface 
               
               
                 
                   350 
                 
                 Rod 
               
               
                 
                   352 
                 
                 End 
               
               
                 
                   354 
                 
                 End 
               
               
                 
                   356 
                 
                 Head 
               
               
                 
                   358 
                 
                 Threading 
               
               
                 
                   360 
                 
                 Proximal screw portion 
               
               
                 
                   362 
                 
                 End 
               
               
                 
                   364 
                 
                 End 
               
               
                 
                   366 
                 
                 Head 
               
               
                 
                   368 
                 
                 Hole 
               
               
                 
                   370 
                 
                 Radially outward facing surface 
               
               
                 
                   372 
                 
                 Threading 
               
               
                 
                   380 
                 
                 Bone graft section 
               
               
                 
                   382 
                 
                 End 
               
               
                 
                   384 
                 
                 End 
               
               
                 
                   386 
                 
                 Radially outward facing surface 
               
               
                 
                   388 
                 
                 Protrusion or protrusions 
               
               
                 
                   390 
                 
                 Flange 
               
               
                 AD 1 
 
                 Axial direction 
               
               
                 AD 2 
 
                 Axial direction 
               
               
                 CD 1 
 
                 Circumferential direction 
               
               
                 CD 2 
 
                 Circumferential direction 
               
               
                 D1 
                 Diameter 
               
               
                 D2 
                 Diameter 
               
               
                 D3 
                 Diameter 
               
               
                 L1 
                 Length 
               
               
                 L2 
                 Length 
               
               
                 L3 
                 Length 
               
               
                 L4 
                 Length 
               
               
                 RD 1 
 
                 Radial direction 
               
               
                 RD 2 
 
                 Radial direction