Abstract:
A spinal interbody implant includes a two-component cage and expander. The two-component cage, when assembled, accepts the expander through a reverse dovetail configuration between the assembled cage and the expander. The expander has a pair of legs that move within and along lateral channels formed by and between the two cage components for increasing the height of the two cage components relative to one another. The amount of expansion of the cage is determined by the height of the pair of expander legs. The cage accepts different expanders each having pairs of legs of different heights in order to provide different amounts of cage expansion and thus the interbody implant. The front of each expander leg is arch shaped for reception in the lateral channels of the assembled cage and to progressively expand the two cage components relative to one another as the expander is received by the assembled cage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional patent application claims the benefit of and/or priority under 35 U.S.C. §119(e) to U.S. provisional patent application Ser. No. 62/298,951 filed Feb. 23, 2016 titled “Expandable Lateral Spine Cage With Reverse Dovetail Configuration,” the entire contents of which is specifically incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to orthopedic implants for the spine and, particularly, to interbody cages for spinal fusion. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many people contend with spine issues as a result of age, disease, and trauma, as well as congenital and acquired complications and conditions. While some of these issues can be alleviated without surgery, other issues respond better to surgery. In some cases, surgery may include placing an implant into the spine. If vertebral fusion is required, a spine implant known as an interbody cage along with bone graft or bone graft material may be used. 
         [0004]    An interbody cage is a device that is placed in the disc space between adjacent vertebrae of a recipient&#39;s spine. The interbody cage includes openings, bores, and/or is porous or the like to permit the introduction and/or carrying of bone graft/bone graft material in order to allow the bone graft/bone graft material to grow from one vertebra through the interbody cage and into the adjacent vertebra. Such interbody cages provide excellent fixation such that most recipients do not require additional implants such as plates and/or bone screws. 
         [0005]    In some instances it is desirable that the interbody cage be able to expand once it has been implanted in the spine. Various expandable interbody cages have been designed, but are either complicated in their expansion mechanisms, are not reliable once implanted, or suffer from other expansion issues. 
         [0006]    It is therefore an object of the present invention to provide an expandable interbody cage that overcomes the deficiencies of the prior art. 
       SUMMARY OF THE INVENTION 
       [0007]    A spinal interbody cage implant includes a two-component cage and expander. The two-component cage, when assembled, accepts the expander through a reverse dovetail configuration between the cage and the expander. The expander has a pair of legs that move within and along lateral channels formed by and between the two cage components in order to expand (i.e. increase the height of) the two cage components relative to one another. 
         [0008]    The amount of expansion (height increase) of the cage is determined by the height of the pair of legs of the expander. The cage accepts different expanders each having pairs of legs of different heights in order to provide different amounts of expansion (heights) of the cage and thus the interbody cage implant. 
         [0009]    The two components of the cage, when assembled, define an end having an opening with upper and lower sidewalls that are angled inwardly in a generally trapezoidal manner. An end of the expander has upper and lower sidewalls that are angled upwardly in a generally trapezoidal manner, opposite to that of the generally trapezoidal end opening of the assembled cage. The end of the expander is thus shaped for reception in the end opening of the assembled cage in a reverse dovetail configuration. 
         [0010]    The front of each leg of the expander is in the shape of an arch for reception in the lateral channels of the assembled cage and to progressively expand the two cage components relative to one another as the expander is inserted into/received by the assembled cage. 
         [0011]    The lower component has a central opening with a configured sidewall extending generally transverse to the plane of the lower component. The upper component has a central opening separated by a cross member with a configured sidewall extending generally transverse to the plane of the upper component. When the upper and lower components are assembled, the configured sidewall of the upper component fits within the sidewall of the lower component. In addition, the upper component has openings in its upper surface that receive the configured sidewall of the lower component. 
         [0012]    The upper component includes a plurality of spikes, projections or the like that extend generally upwards from the upper surface of the upper component, preferably, but not necessarily, about the central opening. The lower component includes a plurality of spikes, projections or the like that extend generally downwards from the lower surface of the lower component, preferably, but not necessarily, about the central opening. 
         [0013]    The lower component has an upwardly curved lower front surface and an angled upper rear surface. The upper component has a downwardly curved upper front surface and an angled lower rear surface. The upwardly curved lower front surface of the lower component and the downwardly curved upper surface of the upper component provide an angled nose that allows easy insertion of the cage implant into a space between adjacent vertebrae. 
         [0014]    The spinal interbody cage implant may be used in a lateral insertion procedure, a posterior insertion procedure, or an anterior insertion procedure. 
         [0015]    Further aspects of the present invention will become apparent from consideration of the drawings and the following description of a form of the invention. A person skilled in the art will realize that other forms of the invention are possible and that the details of the invention can be modified in a number of respects without departing from the inventive concept. The following drawings and description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The features of the invention will be better understood by reference to the accompanying drawings which illustrate a form of the present invention, wherein: 
           [0017]      FIG. 1  is an exploded isometric view of the two components of the cage of an exemplary spine cage implant fashioned in accordance with the present principles; 
           [0018]      FIG. 2  is an exploded side (lateral) view of the two components shown in  FIGS. 1 ; 
           [0019]      FIG. 3  is an exploded end view of the two components shown in  FIG. 1 ; 
           [0020]      FIG. 4  is a top plan view of the two components shown in  FIG. 1  presented side-by-side; 
           [0021]      FIG. 5  is a bottom plan view of the two components shown in  FIG. 1  presented side-by-side; 
           [0022]      FIG. 6  is an isometric upper front lateral view of the assembled cage of the present spine cage implant; 
           [0023]      FIG. 7  is an isometric upper view of the assembled cage of the present spine cage implant; 
           [0024]      FIG. 8  is a lateral view of the assembled cage of the present spine cage implant; 
           [0025]      FIG. 9  is an upper lateral view of the assembled cage of the present spine cage implant; 
           [0026]      FIG. 10  is an isometric view of a third component of the present spine cage implant; 
           [0027]      FIG. 11  is an isometric front lateral view of the third component shown in  FIG. 10 ; 
           [0028]      FIG. 12  is an exploded isometric view of the assembled cage and third component of the present spine cage implant; 
           [0029]      FIG. 13  is a partially exploded isometric view of the assembled cage and third component of the present spine cage implant; 
           [0030]      FIG. 14  is an isometric upper lateral view of the present spine cage implant; 
           [0031]      FIG. 15  is an isometric upper view of the present spine cage implant; 
           [0032]      FIG. 16  is a sectional upper view of the second component on the third component, assembled, of the present spine cage implant; and 
           [0033]      FIG. 17  is an isometric front view of the present spine cage implant. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Referring to the figures, there is depicted an exemplary form of the present expandable spine cage implant, generally designated  10 . The expandable spine cage implant  10  is made from a biocompatible material such as, but not limited to, titanium, stainless steel, an alloy of titanium or steel, or otherwise. The expandable spine cage implant  10  is characterized by a cage  11  and an expander  66 , the cage  11  is composed of two components, a first, lower, or inferior component  12  (collectively, lower component  12 ) and a second, upper, or superior component  14  (collectively, upper component  14 ), the nomenclature first and second being arbitrary. The expandable spine cage implant  10  may be used between any two vertebrae of the spine. 
         [0035]      FIGS. 1-3  depict the lower component  12  and the upper component  14  in exploded views, while  FIGS. 4-5  depict top plan and bottom plan views of the lower and upper components  12 ,  14 . The exploded views show how the two components are assembled or received on one another thereby forming the cage  11 . The plan views show details of the two cage components. 
         [0036]    The lower component  12  is characterized by a body  16  of a generally rectangular shape having a generally planar lower or inferior surface  17  and a generally planar upper or superior surface  18 . The body  16  has a first, generally elongated lateral side  34  and a second, generally elongated lateral side  35 , the nomenclature first and second being arbitrary. A first end  36  of the body  16  has a generally planar platform  19  at its upper/superior surface and its lower/inferior surface  25  curved upwardly, while a second end  37  of the body  16  has a generally planar lower/inferior surface and an upwardly angled portion  31  that meets with its generally planar upper/superior surface  19 , the nomenclature first and second being arbitrary. The body  16  further has a central opening, window or the like  32  that is generally oval in shape. The opening  32  is provided with a configured sidewall  33  that extends about a majority of the opening  32 , with the exception of an area proximate the second end  37 . 
         [0037]    The configured sidewall  33  has a first portion  26  situated proximate the second end  37  and lateral side  34  of the body  16  that extends upwardly or transverse to the plane of the body  16 . The first portion  26  is slightly curved near the second end  37 , the curved section following the curvature of the opening  32 . The configured sidewall  33  also has a second portion  27  situated proximate the first end  36  and lateral side  34  of the body  16  that extends upwardly or transverse to the plane of the body  16 . The second portion  27  is generally curved near the first end  36 , the curved section following the curvature of the opening  32 . The second portion  27  of the sidewall  33  is spaced from the first portion  26  of the sidewall  33  to provide a space or gap between the first and second portions  26 ,  27 . The configured sidewall  33  further has a third portion  28  situated proximate the front  36  and lateral side  35  of the body  16  that extends upwardly or transverse to the plane of the body  16 . The third portion is generally curved near the first end  36 , the curved section following the curvature of the opening  32 . The third portion  28  of the sidewall  33  is spaced from the second portion  27  of the sidewall  33  to provide a space or gap between the second and third portions  27 ,  28  such that the third portion  28  is generally opposite to the second portion  27 . The height of the first, second and third portions  26 ,  27 ,  28  are preferably, but not necessarily, all the same. The configured sidewall  33  furthermore has a fourth portion  30  that is adjacent to the third portion  28  proximate the lateral side  35  of the body  16  that extends upwardly or transverse to the plane of the body  16 . The fourth portion  30  is generally planar and has a height that is preferably, but not necessarily, less than the height of the first, second and third portions  26 ,  27 , and  28 . The configured sidewall moreover has a fifth portion  29  situated proximate the second end  37  and the lateral side  35  of the body  16  that extends upwardly or transverse to the plane of the body  16 . The fifth portion is generally curved hear the second end  37 , the curved section following the curvature of the opening  32 . The fifth portion  29  of the sidewall  33  is adjacent the fourth portion  30 . The height of the fifth portion  29  is preferably, but not necessarily, the same as the height of the first, second and third portions  26 ,  27 , and  28 . Because of the difference in height of the fourth portion  30  relative to the adjacent third and fifth portions  28 ,  29  a gap or space is defined between the third and fifth portions  28 ,  29 . It should be appreciated that the nomenclature first, second, third, fourth, and fifth is arbitrary here and throughout. 
         [0038]    Situated laterally along the first and second sidewalls  26 ,  27  is a first rail  20  that extends along the upper surface  18  of the body  16  from the raised superior surface  19  to the upwardly angled portion  31 . Situated laterally along the third, fourth and fifth sidewalls  28 ,  29 ,  30  is a second rail  21  that extends along the upper surface  18  of the body  16  from the raised superior surface  19  to the upwardly angled portion  31 . As best seen in  FIG. 3 , a first angled trough or channel  22  is formed at the lower outwardly lateral side of the first rail  20  adjacent the lateral side  34 . A second angled trough or channel  23  is formed at the lower outwardly lateral side of the second rail  21  adjacent the lateral side  35 . The first angled trough  22  forms part of an elongate lateral dovetail groove  64  between the assembled lower component  12  and the upper component  14  (see, e.g.  FIG. 8 , and below). The second angled trough  23  forms part of an elongate lateral dovetail groove  65  between the assembled lower component  12  and the upper component  14  (see, e.g.  FIG. 8 , and below). 
         [0039]    The lower component  12  lastly has a plurality of spikes, projections, or the like  24  (collectively, spikes  24 ) situated on the lower or inferior side  17  of the body  16 . As best seen in  FIG. 5 , the plurality of spikes  24  are linearly arranged laterally adjacent the opening  32 . While only a single row of spikes  24  is provided on each side of the opening  32 , more or less spikes may be provided in any pattern as desired. The shape of the spikes  24  may also be changed as desired. 
         [0040]    The upper component  14  is characterized by a body  40  of a generally rectangular shape having a generally planar upper or superior surface  42  and a generally planar lower or inferior surface  41 . The body  40  has a first, generally elongated lateral side  59  and a second, generally elongated lateral side  60 , the nomenclature first and second being arbitrary. A first end  80  of the body  40  has a downwardly curved upper/superior front surface  43  with a generally planar lower/inferior surface  49 , while a second end  81  of the body  40  has a generally planar upper/superior surface  55  and a downwardly angled lower portion  41  that meets with its generally planar lower/inferior surface  42 . The body  40  further has a central opening, window or the like  82  that is generally oval in shape with a cross bar  56  extending between lateral sides of the oval opening  82  thereby dividing the oval opening  82  into a first opening  57  and a second opening  58 , the nomenclature first and second being arbitrary. As best seen in  FIG. 8 , the cross bar  56  has a central bore  61  with a first configured window  62  on a first lateral side of the bore  61  and a second configured window  63  on a second lateral side of the bore  61 , the windows allowing bone graft material to migrate between the openings  57 ,  58 . The opening  82  is provided with a configured sidewall  50  that extends about a majority of the opening  82 , with the exception of an area proximate the second end  81 . The configured sidewall  50  extends downwardly or transverse to the plane of the body  40 . 
         [0041]    Situated laterally along the sidewall  50  adjacent the lateral end  59  of the body  40  is a third rail  44  that extends along the upper surface  41  of the body  40 . Situated laterally along the sidewall  50  adjacent the lateral end  60  of the body  40  is a fourth rail  45  that extends along the upper surface  41  of the body  40 . As best seen in  FIG. 3 , a third angled trough or channel  46  is formed at the upper outwardly lateral side of the third rail  44  adjacent the lateral side  59 . A fourth angled trough or channel  47  is formed at the upper outwardly lateral side of the fourth rail  45  adjacent the lateral side  60 . The third angled trough  46  forms part of the elongate lateral dovetail groove  64  between the assembled lower component  12  and the upper component  14  (see, e.g.  FIG. 8 , and below). The fourth angled trough  47  forms part of the elongate lateral dovetail groove  65  between the assembled lower component  12  and the upper component  14  (see, e.g.  FIG. 8 , and below). 
         [0042]    As best seen in  FIG. 4 , the upper component  14  has four arced openings  51 ,  52 ,  53 ,  54  extending from the upper/superior surface to the lower/inferior surface of the body  40  that are situated about the opening  82 . A first arced opening  51  is situated proximate to the lateral side  59  and the rear  81  of the body  40 . A second arced opening  52  is situated proximate to the lateral side  59  and the first end  80  of the body  40 . A third arced opening  53  is situated proximate to the lateral side  60  and the first end  80  of the body  40 , opposite to the second arced opening  52 . A fourth arced opening  54  is situated proximate to the lateral side  60  and the second end  81  of the body  40 , opposite to the first arced opening  51 . The first arced opening  51  corresponds in placement to the first portion  26  of the configured sidewall  33  of the lower component  12  when the upper and lower components  14 ,  12  are joined (assembled) such that the first portion  26  can be received in the first arced opening  51 . The second arced opening  52  corresponds in placement to the second portion  27  of the configured sidewall  33  of the lower component  12  when the upper and lower components  14 ,  12  are joined (assembled) such that the second portion  27  can be received in the second arced opening  52 . The third arced opening  53  corresponds in placement to the third portion  28  of the configured sidewall  33  of the lower component  12  when the upper and lower components  14 ,  12  are joined (assembled) such that the third portion  28  can be received in the third arced opening  53 . The fourth arced opening  54  corresponds in placement to the fifth portion  29  of the configured sidewall  33  of the lower component  12  when the upper and lower components  14 ,  12  are joined (assembled) such that the fifth portion  29  can be received in the fourth arced opening  54 . 
         [0043]    The upper component  14  lastly has a plurality of spikes, projections, or the like  48  (collectively, spikes  48 ) situated on the upper or superior side  42  of the body  40 . As best seen in  FIG. 4 , the plurality of spikes  48  are linearly arranged laterally adjacent the opening  82 . While only a single row of spikes  48  is provided on each side of the opening  82 , more or less spikes may be provided in any pattern as desired. The shape of the spikes  48  may also be changed as desired. 
         [0044]      FIGS. 6-9  depict the upper and lower components  14 ,  12  joined or assembled together to form the cage  11  of the present expandable spinal cage implant. These figures depict the cage  11  at its smallest height, i.e. before expansion. The sidewall  50  of the upper component  14  fits inside the first, second, third, fourth, and fifth portions  26 ,  27 ,  28 ,  30 ,  29  of the sidewall  33  of the lower component  12 . The first rail  20  of the lower component  12  and the third rail  44  of the upper component  14  abut one another such that their respective troughs  22 ,  46  form the elongated dovetail groove  64  along the lateral sides  34 ,  59  of the cage  11 . The second rail  21  of the lower component  12  and the fourth rail  45  of the upper component  14  abut one another such that their respective troughs  23 ,  47  form the elongated dovetail groove  65  along the lateral sides  35 ,  60  of the cage  11 . The configurations of the second end  37  of the lower component  12  and of the second end  81  of the upper component  14  define a reverse dovetail opening of the cage  11 . 
         [0045]      FIGS. 10-11  depict the expander  66  of the present expandable spine cage implant  10 . The expander  66  is characterized by a generally elongated U-shaped body  67  having a base  68 , a first elongated leg  70  extending from one lateral side of the base  68 , and a second elongated leg  72  extending from another lateral side of the base  68 . The base  68  has a boss  74  extending from an inner side thereof having an arced end  75 . The boss  74  further includes a first angled cutout  76  on a first lateral side and a second angled cutout  77  on a second lateral side. A bore  69  extends through the base  68  and the boss  74 . The first elongated leg  70  has a first height that is preferably, but not necessarily, constant along its length and terminates in a distal, arched end  71 . The second elongated leg  72  has a second height that is preferably, but not necessarily, constant along its length and terminates in a distal, arched end  73 . The first height of the first elongated leg  70  and the second height of the second elongated leg  72  are preferably, but not necessarily, the same. The base  68  is generally dovetail-configured for reception in the reverse dovetail opening of the cage  11 . 
         [0046]      FIGS. 12-14  depict the sequence of expanding the cage  11  once the cage  11  has been assembled (i.e. the upper and lower components  14 ,  12  have been joined).  FIG. 12  depicts the alignment of the expander  66  relative to the cage  11 . The legs  70 ,  72  are directed into respective elongated lateral dovetail grooves  64 ,  65 . As the legs  70 ,  72  are received in the elongated lateral dovetail grooves  64 ,  65  ( FIG. 13 ), the height of the legs  70 ,  72  separates or expands the upper and lower components  14 ,  12  relative to one another, the amount of expansion dependent upon the height of the legs  70 ,  72 .  FIG. 14  depicts the expander  66  fully received by the cage  11  with the dovetail base  68  of the expander  66  received in the reverse dovetail opening of the rear of the cage  11 . 
         [0047]      FIG. 15  shows an upper view of the expanded spine cage implant  10 .  FIG. 17  is a rear view of the expanded spine cage implant  10 .  FIG. 16  is a sectional view of the expanded spine cage implant  10  cut along a plane of the expander  66  illustrating how the sidewalls  26 - 30  of the lower component  12  are received about the sidewall  50  of the upper component  14 , and the expander  66  is received on the lower component  12 . 
         [0048]    The present expandable spine cage implant may be used in a lateral insertion procedure, an anterior insertion procedure, or a posterior insertion procedure. 
         [0049]    It should be appreciated that dimensions of the components, structures, and/or features of the present expandable spine cage implant may be altered as desired within the scope of the present disclosure.