referring to fig1 - 6 , the above described problem can be solved in the thoracic and lumbar spine by insertion into the denuded intervertebral disc space multiple embodiments of screw box constructs with bdft screws . fig1 a - d illustrate three - dimensional views of the lumbar intervertebral expandable screw box 100 with two bdft screws 101 , 102 ; one lateral and one medially oriented ( embodiment ia ). fig1 e illustrates a sagittal - oblique view of the lumbar intervertebral expandable screw box 120 with two lateral oriented bdft screws 121 , 122 ( embodiment ib ). the expandable box 100 consists of top and bottom triangular sliding bases 103 , 104 ( fig1 - d ). the superior and inferior segments of the height / depth adjusting screw 105 are integrated and connected to the two separate top and bottom triangular bases 103 , 104 , respectively . by turning this adjusting screw 105 back and forth i . e . clock - wise , and counter clockwise , the sliding rails 106 of the top triangular base 103 ( fig1 d ) slide up and down the rail inserts 107 on the bottom triangular base 104 ( fig1 d ). this action will simultaneously alter the intervertebral height and depth of the screw box 100 allowing individualized custom fitting of the screw box 100 conforming to the dimensions of the disc space . transvertebral screw 101 penetrates the top base 103 , and transvertebral screw 102 traverses the bottom base 104 of the screw box 100 . the two screws 101 , 102 traverse the screw box 100 in opposing directions , bi - directionally ( whether they are lateral or medially oriented ). the external edges of the triangular bases 103 , 104 in contact with vertebral body surfaces include ridges 107 . this facilitates the screw box &# 39 ; s 100 incorporation into and fusion with the superior and inferior vertebral bodies ( fig1 a - e ). both top and bottom screw box bases 103 , 104 are perforated with holes 108 to allow bone placement for fusion . the entire construct , furthermore , is hollow to allow bone filling . hence this device functions as both an intervertebral bone fusion spacer and bi - directional transvertebral screw fusion device . fig2 a - 2e illustrate three - dimensional views of the lumbar intervertebral non - expandable screw box 200 with two bdft screws 201 , 202 ( embodiment ii ). screws 201 and 202 perforate and orient in opposing , superior and inferior directions . there are holes 208 and hollow spaces allowing packaging with bone . there are also holes which allow the traversal of screws . the superior and inferior edges include ridges 207 to facilitate integration and fusion with superior and inferior vertebral bodies . the expandable screw box 200 may include a screw insert 209 to attach a horizontal mini - plate ( not shown ). the self - contained internalized drill guides are at a 25 degree angle . the screw boxes can be designed with the internalized drill guides with different angles and / or different positions within the box . as shown in fig2 a and 2b , each longitudinal end of the screw box 200 can include a slot or indentation 12 formed adjacent to an edge of an upper surface of the screw box 200 for engaging a protuberant extension of a tool ( as shown in fig5 a - 5j ). fig3 illustrates a three - dimensional view of left and right lumbar intervertebral non - expandable screw boxes 300 a , 300 b with one bdft screw 301 or 302 ( embodiment iii ). it is roughly half the width of embodiments i and ii . screw 301 is inserted into screw box 300 a ( left ) and screw 302 is inserted into screw box 300 b ( right ). there are holes 308 and hollow spaces allowing packing of bone to achieve biological fusion . the combined effect of one superior oriented and one inferior oriented screw fuses the superior and inferior vertebral bodies with small constructs . this also enables placement of larger dimension screws compared to embodiments i and ii . fig4 a and b illustrate three - dimensional views of the horizontal intervertebral zero profile mini - plate 400 with two non - expandable lumbar intervertebral screw boxes 300 a , 300 b housing two bdft screws 301 , 302 . fig4 a illustrates the perforations 401 within the plate 400 through which small plate securing screws 310 will be inserted to connect it to the built - in screw holes of the screw box 300 a , 300 b ( fig4 b ). the horizontal mini - plate 400 together with the top surfaces of left and right screw boxes 300 a , 300 b provide a physical barrier between the underlying bone placed beneath it ( not illustrated ), and the thecal sac and nerve roots above it ( not illustrated ). fig4 c illustrates two screw boxes 300 c , 300 d within a circumferential cage 420 ( 2 in 1 ) construct which is designed for anterior placement into the lumbar spine . there are slots 308 a , 308 b for bone graft placement , both outside and inside the boxes . the circumferential cage 420 has perforations 401 a for the placement of transvertebral screws ( not shown ). fig5 a - c illustrate three - dimensional views of the external drill / screw guide - box expander 500 which assists in screw trajectory and box expansion ( embodiments ia - b ). for embodiments ii and iii , the same instrument is utilized ; however , an expanding allen key component is not used . the key components of this device include an allen key 501 , a spring 502 , a handle 503 , a griper 504 and a screw guide 505 . the allen key 501 when inserted in the insertion 514 and turned , turns the screw adjuster ( fig5 c ) which in turn regulates top and bottom triangular screw box base sliding , and hence box 200 width and depth . the griper 504 has griper prongs 506 which insert into grooves of the screw guide 505 . the griper prongs 506 include medially oriented male protuberant extensions 506 a that engage the slot or indentation 12 of and the screw box 200 ( fig5 a - d ) thus perfectly aligning them . fig5 d and 5j illustrate a superior oblique view of the screw guide 505 demonstrating insertions 509 for griper prong 506 , built - in trajectory guides 511 , 512 for insertions of screws 101 and 102 , and the allen key 501 . fig5 e - g illustrate three - dimensional views of the sequential steps necessary for the external guide assembly . fig5 e illustrates the insertion of the allen key 501 into the handle 503 . fig5 f illustrates the insertion of the handle 503 through the spring 502 and griper 504 . fig5 g illustrates insertion of the griper 504 into the screw guide 505 . fig5 h - i illustrate three - dimensional views of a positioning tool 500 a for impaction and placement of two transvertebral screws 201 , 202 in the non - expandable screw box 200 . the driver assembly 550 consists of a screw driver 551 , a flexible shaft 552 and a square recess bit 553 . this facilitates turning the screws 201 , 202 into the bone . the flexible shaft 552 facilitates the avoidance of spinous processes which might hinder the screw driving if the shaft 552 were straight . the positioning tool 500 a can have a rectangular handle , embodiment i ( fig5 h ), or a circular handle , embodiment ii ( fig5 i ). this serves to position the screw box within the intervertebral space , and screws 201 , 202 within the screw box . once positioned , the screw box can be impacted by tapping the handle with a mallet ( not shown ). the positioning tool &# 39 ; s 500 a griper handle inserts into the screw guide and the box , which maintains alignment . fig6 a illustrates a three - dimensional view of insertion of the construct ( embodiment i ) into the lumbar intervertebral disc space . fig6 b illustrates a three dimensional lateral view of insertion of the construct ( embodiment i ) into the disc space with short screws . placement with longer screws would capture more bone . fig7 a and b illustrate three - dimensional views of the two - pronged cervical facet staple 700 ( embodiment i ). there is a staple base 701 which is contoured to align with the curved surface of the cervical facet joints . there is a superior impactor threaded insert 702 . an impactor can be screwed into this insert 702 and then impacted with a mallet . the two spikes 703 , 704 perforate the inferior and superior facets of the superior and inferior vertebral bodies hence leading to cervical facet joint fusion . the spikes can be designed with ridges and / or fishhooks to facilitate irreversible extraction . fig8 a - c illustrate three - dimensional views of the four - pronged cervical facet staple 800 ( embodiment ii ). likewise it has a staple base 805 contoured specifically for the surface of the facet joint . it also has an impactor insert 806 . the insertion of a device with four prongs 801 - 804 instead of two prongs further limits the degrees of motion of the joint hence making the fusion more rigid . fig9 a - b illustrate a three - dimensional view of the two - pronged cervical staple impactor 900 . it has a handle 901 , a stem 902 , and a screw insert 903 which can be screwed into the threaded staple insert . the impactor has two wings 904 which keep the staple base edges in place facilitating staple impaction . the handle 901 of the impactor 900 is broad in order to allow impaction by a mallet . fig1 a - c illustrate three - dimensional views of the four - pronged cervical staple impactor 1000 ( embodiment ii ). it has the same features as the two - pronged impactor 900 , except its wings 1004 are broader accommodating the broader staple base . the impactor 1000 also includes a handle 1001 , a stem 1002 , and an impact screw 1003 . fig1 a illustrates a three - dimensional view of placement of the two pronged cervical facet staple 700 into a cervical spine model having vertebral body 1103 and lamina 1104 . one staple 700 is perched on the joint 1101 prior to impaction . the other staple 700 is impacted . fig1 b illustrates a three - dimensional view of placement of the four pronged cervical facet staple 800 into a cervical spine pre and post impaction . fig1 c illustrates the concept of modularity and incremental diminution of movement of the joint by the modular placement of different combinations and permutations of varying numbers of two and four pronged cervical facet staples 700 , 800 . if one wishes to have the most flexible ( least rigid ) fusion , one would place a unilateral two pronged staple 700 . one can increase i . e . calibrate increasing degrees of rigidity by increasing the number of prongs penetrating the facet joints bilaterally . in fig1 c each facet joint is fused using a total number of six prongs . one side this is accomplished by using three two pronged staples 700 , and on the other side using one four pronged staple 800 and one two pronged staple 700 . these two embodiments can be mixed and matched unilaterally or bilaterally to vary the degree of rigidity and conversely flexibility of fusion . the most flexible fusion at one level would be accomplished by one staple 700 ( 2 prongs ). the highest level of rigidity would be achieved by placing two four pronged staples 800 on both sides totaling sixteen prongs . intermediate degrees of relative joint motion can be modulated by insertion into the cervical facet joints staples in two - four prong increments from 2 - 16 . each additional prong further limits the degree of facet joint motion hence increasing rigidity , and conversely decreasing flexibility . thus the novel modular use of these embodiments heralds an era of flexible cervical spine fusion . fig1 a - b illustrate a lumbar facet joint staple 1200 in open and closed positions and having staple prongs 1203 . this lumbar facet staple has been thoroughly described in our previous co - pending patent application ser . no . 11 / 536 , 815 , filed on sep . 29 , 2006 , and ser . no . 11 / 208 , 644 , filed on aug . 23 , 2005 , the relevant portion of each of which is hereby incorporated by reference hereinafter . the new improvement of this device includes a ratchet 1201 . the staple 1200 can be incrementally closed with increased ratcheting over increasing number of spurs 1202 . this achieves increasing calibrated levels of lumbar facet joint fusion , and conversely diminishing joint flexibility . this new designs further enhances the capacity to achieve flexible fusions in the lumbar spine . exemplary surgical steps for practicing one or more of the foregoing embodiments will now be described . the posterior lumbar spine implantation of all the screw box 100 , 200 , 300 embodiments , with bdft screws , and horizontal mini - plate 400 can be implanted via previously described posterior lumbar interbody fusion ( plif ) or posterior transforaminal lumbar interbody fusion ( tlif ) procedures . the procedures can be performed open , microscopic , closed tubular or endoscopic . fluoroscopic guidance can be used with any of these procedures . after adequate induction of anesthesia , the patient is placed in the prone position . a midline incision is made for a plif procedure , and one or two parallel paramedian incisions or a midline incision is made for the tlif procedure . for the plif , a unilateral or bilateral facet sparing hemi - laminotomy is created to introduce screw box 100 , 200 , 300 embodiments i - iii into the disc space , after it is adequately prepared . for the tlif procedure , after unilateral or bilateral dissection and drilling of the inferior articulating surface and the medial superior articulating facet the far lateral disc space is entered and a circumferential discectomy is performed . the disc space is prepared and the endplates exposed . then one screw box 100 , 200 , 300 of either embodiments i - iii is placed on either right , left or both sides . then another screw box of embodiments 100 , 200 , 300 i - iii is placed on the contralateral side . for embodiment i the external screw guide 505 / box expander is attached to the screw box ( fig5 a - h ). first the allen key 501 is screwed until the box conforms perfectly to the height and depth of the space . then a pilot hole can be drilled or an awl can start a pilot hole in the vertebral bodies . then a transvertebral screw is screwed into the vertebral body via the built - in box screw guides 505 . for difficult angles , an angled screw driver can be employed . for embodiments ii - iii the same method is used for placing screws , except the allen key 501 is not utilized in the absence of plate expansion . if bilateral constructs have been inserted , bone is packed into the intervertebral space , as well as within the device . then the horizontal intervertebral zero profile mini - plate 400 is slid beneath the thecal sac and is secured to both left and right screw boxes with small mini - plate screws 210 ( fig4 a - b ). this prevents bone intrusion into the thecal sac and hence possible nerve root compression . fig6 a and b illustrate the process of insertion and final placement of the construct into the lumbar spine . the mini - plates 400 can come in different horizontal lengths and widths to accommodate different intra and inter - patient disc space diameters . the bdft screws can come in different widths , lengths and thread designs . the anterior thoracic and lumbar spine implantation of one , two or three screw box constructs 100 , 200 , 300 and bdft screws can be performed in a similar manner to the posterior application . likewise , a horizontal mini - plate 400 can be used to cap two or three screw box constructs 100 , 200 , 300 ( one placed midline deeply , one placed left and one placed right , forming a triangulation ). alternatively two screw box constructs may be placed into a circumferential ring for anterior placement . anterior placement of these devices can be performed into the l4 / 5 and l5 / s1 spaces on the supine anesthetized patient via previously described open microscopic or endoscopic techniques . once the disc space is exposed and discectomy and space preparation are performed , placement of one , two or three screw box embodiments 100 , 200 , 300 ( i - iii ) or a 2 in i construct can be placed . the screw placement is facilitated by the internal screw guides , and different positioning tools (( fig5 ). a right angled screw driver and / or ratchet could alternatively be employed a capping mini - plate 400 may be applied if desirable . the mechanism of screw placement and mini - plate 400 attachment are identical to what was described above . the posterior placement of screw box constructs 100 , 200 , 300 alone or combined with horizontal mini - plates 400 into the thoracic spine can be performed via previously described transpedicular approaches ; open or endoscopic . the anterior placement into the thoracic spine can be accomplished via a trans - thoracic approach . once the disc space is exposed via either approach , any combination of the above mention embodiments ( i - iii ) can be inserted . engagement of the devices is identical to what was mentioned above . for posterior placement of cervical facet staple 700 , 800 embodiments , after adequate induction of anesthesia the patient is flipped prone and his head and neck secured . a single midline or two para - median incisions are made for unilateral or bilateral or multilevel placement of staples . ultimately the facet joint is exposed . alternatively and preferably this can be performed percutaneously under fluoroscopic guidance with intravenous sedation . the staple 700 , 800 ( embodiments i or ii ) is loaded into the impactor 900 , 1000 . the staple 700 , 800 is placed on the two articulating cervical facets , and then impacted into the joint . to achieve modular calibrated fusion different combinations and permutations of cervical facet stales can be inserted ranging from a single unilateral two pronged staple providing a high degree of flexibility to a total of four bilaterally placed four pronged staples 800 ( 16 prongs ) leading to the highest degree of rigidity . additional bone may or may not be placed in its vicinity to facilitate permanent and solid fusion . this procedure can be performed open , closed , percutaneously , tubulary , endoscopically or microscopically . fig1 a - c illustrates placement of the staples 700 , 800 in the cervical spine . we have previously described surgical placement of the lumbar facet joint staple in our two co - pending patents . the surgical procedure for this device is identical to that which has been previously mentioned . the present inventions may provide effective and safe techniques that overcome the problems associated with current transpedicular based cervical , thoracic and lumbar fusion technology , and for many degenerative stable and unstable spine disease . these inventions could replace much pedicle screw - based instrumentation in many but not all degenerative spine conditions . the speed and simplicity of placement of cervical and lumbar facet staples , and placement of lumbar screw box - bdft constructs far exceeds that of current pedicle screw technology . furthermore , these devices have markedly significantly decreased risk of misguided screw placement , and hence decreased risk of neural and vascular injury , and blood loss . in the lumbar spine bdft screw constructs and facet staples could be applied modularly in different combinations to achieve different degrees of rigidity ( flexibility ). patients having these devices would have decreased recovery and back to work time . these devices most likely lead to similar if not equal fusion with significantly less morbidity , and hence overall make them a major advance in the evolution of spinal instrumented technology leading to advances in the care of the spinal patient . another major novelty and advance is the introduction of simple and safe modular calibrated cervical flexible fusion . to our knowledge neither a similar device nor a similar mathematical concept of modular joint flexibility / fusion calibration has been postulated for the cervical spine or for any other articulating joint . to our knowledge there have not been any previously described similar posterior lumbar and thoracic combined spacer and screw constructs . these devices can similarly be modified to stabilize bone fractures throughout the entire body . to our knowledge the description of zero to subzero profile anterior or posterior horizontal spinal plates which traverse the diameter of the disc space has not been previously described .
a self - drilling bone fusion screw apparatus is disclosed which includes at least first and second sliding boxes . a first screw member having a tapered end and a threaded body is disposed within the first sliding box , and a second screw member having a tapered end and a threaded body disposed within the second sliding box . an adjuster adjusts the height of the sliding boxes . the screw members are screwed into vertebral bodies in order to fuse the vertebral bodies together . a plurality of the self - drilling bone fusion screw apparatuses may be attached together and / or integrated via a plate or cage . also disclosed is a cervical facet staple that includes a curved staple base and at least two prongs attached to the bottom surface of the curved staple base .