Abstract:
Interspinous process implants are disclosed. Also disclosed are systems and kits including such implants, methods of inserting such implants, and methods of alleviating pain or discomfort associated with the spinal column.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is generally directed to intervertebral or interspinous process implants, systems and kits including such implants, methods of inserting such implants, and methods of treating spinal stenosis or for alleviating pain or discomfort associated with the spinal column. 
       BACKGROUND OF THE INVENTION 
       [0002]    Occurrences of spinal stenosis are increasing as society ages. Spinal stenosis is the narrowing of the spinal canal, lateral recess or neural foramen, characterized by a reduction in the available space for the passage of blood vessels and nerves. Clinical symptoms of spinal stenosis include extremity pain, radiculopathy, myelopathy, sensory or motor deficit, bladder or bowel dysfunction, and neurogenic claudication. Pain associated with such stenosis can be relieved by surgical or non-surgical treatments, such as medication, physical therapy, back braces and the like. While spinal stenosis is generally more prevalent of the elderly, it can occur in individuals of all ages and sizes. 
         [0003]    There is a need for implants that may be placed between spinal processes for minimally or less invasive surgical treatment of spinal stenosis and, in particular, for implants that may be installed unilaterally and/or without removal of the supraspinous ligament. 
       SUMMARY OF THE INVENTION 
       [0004]    Certain embodiments of the present invention are generally directed to minimally or less invasive implants, in particular, interspinous process implants or spacers. Other embodiments of the invention are further directed to systems and kits including such implants, methods of inserting such implants, and methods of alleviating pain or discomfort associated with the spinal column. 
         [0005]    Some embodiments of the present invention provide spacers or implants and methods for relieving pain and other symptoms associated with spinal stenosis, by relieving pressure and restrictions on the blood vessels and nerves. Such alleviation of pressure may be accomplished in the present invention through the use of an implant placed between the spinous process of adjacent vertebra. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention will be more readily understood with reference to the embodiments thereof illustrated in the attached figures, in which: 
           [0007]      FIG. 1  is a side perspective view of one embodiment of an implant according to the invention for creating, increasing, or maintaining distraction between adjacent spinous processes; 
           [0008]      FIG. 2  is a cross-sectional view of the implant of  FIG. 1  shown in a first position; 
           [0009]      FIG. 3  is a side perspective view of the implant of  FIG. 1  shown in a second position; 
           [0010]      FIG. 4  is a cross-sectional view of the implant of  FIG. 1  shown in a second position; 
           [0011]      FIG. 5  is a proximal perspective view of the implant of  FIG. 1  shown in a first position; 
           [0012]      FIG. 6  is a distal end view of the implant of  FIG. 1  shown in a first position; 
           [0013]      FIG. 7  is a distal perspective view of the implant of  FIG. 1  shown in a second position; 
           [0014]      FIG. 8  is a distal end view of the implant of  FIG. 1  shown in a second position; 
           [0015]      FIG. 9  is an exploded view of the implant of  FIG. 1 ; 
           [0016]      FIGS. 10-11  are perspective views of a wing member of the implant of  FIG. 1 ; 
           [0017]      FIGS. 12-13  are perspective views of a barrel insert of the implant of  FIG. 1 ; 
           [0018]      FIG. 14  is a perspective view of a central body of the implant of  FIG. 1 ; 
           [0019]      FIG. 15  is a perspective view of a rotatable insert of the implant of  FIG. 1 ; 
           [0020]      FIG. 16-20  are side views demonstrating various steps according to one embodiment of a method of installation of the implant of  FIG. 1 ; 
           [0021]      FIGS. 21-22  are side and distal perspective views of another embodiment of an implant according to the invention, shown in a first position extending over a guidewire; 
           [0022]      FIGS. 23-24  are side and distal perspective views of the implant of  FIG. 21  shown in a second position; 
           [0023]      FIGS. 25-26  are proximal perspective and distal end views of the implant of  FIG. 21  shown in a second position; 
           [0024]      FIGS. 27-28  are side and distal perspective views of another embodiment of an implant according to the invention, shown in a first position extending over a guidewire; 
           [0025]      FIGS. 29-30  are side and cross-sectional views of the implant of  FIG. 27  shown in a first position; 
           [0026]      FIGS. 31-32  are side and distal perspective views of the implant of  FIG. 27  shown in a second position; 
           [0027]      FIGS. 33-34  are distal end and cross-sectional views of the implant of  FIG. 26  shown in a second position; 
           [0028]      FIG. 35  is a distal perspective view of another embodiment of an implant according to the invention, shown in a first position; 
           [0029]      FIG. 36  is a cross-sectional view of the implant of  FIG. 35 ; 
           [0030]      FIG. 37  is a distal perspective view of the implant of  FIG. 35 , shown in a second position; 
           [0031]      FIG. 38  is a cross-sectional view of the implant as depicted in  FIG. 37 ; 
           [0032]      FIG. 39-40  are cross-sectional views of another embodiment of an implant according to the invention, shown in first and second positions, respectively; 
           [0033]      FIG. 41  is a distal end view of the implant of  FIG. 40 ; 
           [0034]      FIG. 42  is a cross-sectional view of another embodiment of an implant according to the invention, shown in a first position; 
           [0035]      FIG. 43  is a distal end view of the implant of  FIG. 42 , shown in a second position; 
           [0036]      FIGS. 44-45  are cross-sectional and perspective views of a portion of another embodiment of an implant according to the invention; 
           [0037]      FIGS. 46-47  are side views of the implant of  FIGS. 44-45  shown in first and second positions, respectively; 
           [0038]      FIGS. 48-49  are end views of another embodiment of an implant according to the invention, shown in first and second positions, respectively; 
           [0039]      FIGS. 50-56  are perspective views demonstrating various steps according to one embodiment of a method of installation of the implant of  FIG. 1 ; 
           [0040]      FIGS. 57-58  depict perspective views of the implant of  FIG. 1  shown in an implanted position; and 
           [0041]      FIG. 59  is a perspective view of one embodiment of a trial instrument according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]    Embodiments of the invention will now be described. The following detailed description of the invention is not intended to be illustrative of all embodiments. In describing embodiments of the present invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. It is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
       Implants 
       [0043]    Some embodiments of the present invention are directed to minimally or less invasive implants, in particular, interspinous process spacers. Implants in accordance with the invention may come in many shapes and sizes. The illustrative embodiments provided herein-below provide guidance as to the many types of implants that may be advantageously used in accordance with the present invention. In particular, the implants are adapted such that their insertion technique (including methods of the present invention) is minimally or less invasive, and generally simpler, and/or safer than those installed in open or more invasive techniques. According to one aspect, implants according to the present invention may be advantageously inserted into a patient as an out-patient procedure. 
         [0044]    Embodiments of the present invention include implants adapted to be placed between first and second adjacent spinous processes. The implants may be adapted such that after insertion of an implant into a patient, a portion of the implant maintains a desired amount of distraction or spacing between two adjacent spinous processes. The implants or portions thereof that substantially maintain a desired spacing between spinous processes are also referred to herein as “spacers.” In various embodiments described herein, the implants may include spinous process support surfaces, indented portions or saddle portions spaced apart by a distance (a) ( FIG. 1 ), which generally corresponds to a desired distance for distraction or spacing of two adjacent spinous processes. Other embodiments similarly provide a desired distance for distraction or spacing of two adjacent spinous processes. Depending on the material and/or design of the implant, the desired distraction or spacing distance may vary somewhat after insertion, for example if a patient moves its spine into a position that causes further distraction. For example, in certain embodiments the implant may be resiliently compressible or expandable in the cranial-caudal direction such that the implant may support and or adjust to dynamic movement of the spine. Although not depicted in the figures discussed below, it is contemplated that embodiments of the present invention may be extended to provide distraction or spacing of more than two adjacent spinous processes. 
         [0045]    Implants according to the present invention may be adapted to be inserted between a first and second spinous process at any region in the spine. Although typically implants according to the present invention may be inserted in the lumbar region, it is contemplated that it is possible to configure inserts according to the present invention for insertion into other regions such as for example, the thoracic or cervical region. In general, implants according to the invention may have varying profiles when viewed in a sagittal plane. In this regard, the implants can have varied cross-sectional shapes to conform to the varied anatomical shapes of the interspinous spaces of the spine. 
         [0046]    Certain embodiments of implants of the invention may secure themselves in place without a supplemental attachment mechanism or fastening device attached directly to a spinous process or other portion of the spine. Alternatively, implants in accordance with the invention may be attached to one or more spinous processes or other portion of the spine, or may attach to itself in such a manner as to secure the implant between two adjacent spinal processes. By way of example, implants in accordance with the present invention may be attached to one or both spinous processes or other portion of the spine by one or more pins, screws, wires, cables, straps, surgical rope, sutures, elastic bands, or other fastening devices. Other exemplary implants, attachment mechanisms, and methods that may be utilized are disclosed in U.S. patent application Ser. Nos. 11/366,388; 11/691,357; and 12/107,222, the entire contents of which are incorporated herein by reference. “Securing” implants between spinous processes, does not require that the implant not move at all, but rather means that the implant does not move so far away from between the spinous processes that it does not perform the function of maintaining a desired distraction distance or space between the adjacent spinous processes. 
         [0047]    Implants in accordance with the present invention may be secured between spinous processes by methods other than using a fastening device. For example, according to certain embodiments, implants in accordance with the present invention may be secured in place with respect to spinous processes by mechanical forces resulting from the design of the implant, including the shape itself. Exemplary implants may also be secured to spinous processes, by surface modifications to portions of the implant, such as to create frictional forces or other bonds between the implant and spinous processes. Such surface modifications may include mechanical modifications to the surface and/or one or more coatings. Exemplary coatings which may be utilized include, but are not limited to, titanium plasma sprays and chrome sprays or the like. Such mechanical forces and/or surface modifications may be utilized in addition to, or in place of various other attachment methods described herein. 
         [0048]    Referring now to  FIGS. 1-15 , one exemplary embodiment of an implant  10  according to the invention is shown for creating, increasing, or maintaining distraction between adjacent spinous processes. In general, implant  10  is adapted and configured to be placed between adjacent spinous processes. For example, referring to  FIGS. 57-58 , a posterior and side perspective view, respectively, of implant  10  is shown in implanted positions between to two adjacent spinous processes  5 . As best seen in  FIGS. 1-8 , implant  10  generally comprises an elongate member extending laterally along axis  12  from a distal or first lateral end  14  to a proximal or second lateral end  16 . In one embodiment, implant  10  may be cannulated with a central cannula or opening  18  extending along axis  12 . One skilled in the art may appreciate that, in operation, cannulation  18  may facilitate advancement, travel, or delivery to an implant location over a guidewire. In alternate embodiments, however, implant  10  may not be cannulated but may be generally solid. According to one embodiment, implant  10  may comprise a multi-piece body with a general arrow or barbell-like shape, and generally includes a leading end portion, first end portion, or distraction portion  20  adjacent first end  14 , a second end portion or trailing end portion  22  adjacent second end  16 , and a central support portion or saddle portion  24  disposed between the leading and trailing end portions  20 ,  22 . As best seen in  FIG. 1 , support portion  24  may have a height (a) and width (d), and the implant may have an overall length (E). As best seen in  FIGS. 5 and 7 , in one embodiment, saddle portion  24  has a generally circular profile or perimeter when viewed perpendicular to axis  12 . In alternate embodiments, however, saddle portion need not have a circular cross-sectional profile and the cross-sectional profile may vary along its length. For example, in one exemplary embodiment, central support portion  24  may have a polyganol cross-sectional profile. 
         [0049]    Trailing end portion  22  adjacent second end  16  may comprise a shoulder or flange  38  with generally frustoconical, wedged, or tapered trailing portion narrowing along axis  12  from a major or large diameter or radial dimension adjacent central support portion  24  toward the second end  16 . Those skilled in the art will appreciate that such a tapered feature may be desirable to minimize wear and trauma with adjacent soft tissue and/or bone when implant  10  is installed in a patient. In one embodiment trailing end portion  22  may be generally symmetrical to distraction portion  20  with generally similar lateral length and taper. In alternate embodiments, however, the trailing end portion  22  need not be symmetrical whatsoever and may have any shape irrespective of the dimension of distraction portion  20 . 
         [0050]    Flange  38  generally defines a sidewall adjacent the central support portion  24  configured and dimensioned to be positioned adjacent and/or contact a lateral side of a spinous process when implanted. According to several of the embodiments depicted herein, flange  38  may have numerous features to accommodate the physical anatomy of the spine when implanted in a patient. In one embodiment, shoulder portion  38  generally extends between about 180 degrees and 270 degrees around axis  12 , leaving a portion of the periphery without a sidewall  44  adjacent the support portion  24 . As best seen in  FIG. 6 , a crescent or arcuate shaped cutout portion  39  may be disposed or formed along the perimeter of flange  38  to accommodate the lamina and/or lamina spinous process junction region of the vertebra and to facilitate the anterior placement of the implant thereagainst. A flat perimeter portion  41  may be provided to minimize the flange along the anterior side of the implant such that when implant  10  is implanted in a patient, the implant may be positioned as anterior as possible. As best seen in  FIGS. 57-58 , in one variation, the crescent shaped cutout portion  39  is configured and dimensioned to be positioned adjacent a lamina portion of a superior vertebrae when installed. In another variation, flange  38  may have a thinner section  42  on the upper portion of flange  38  adjacent cutout  39 . As best seen in  FIGS. 57-58 , such a thin section  42  may be configured and dimensioned to accommodate abutting placement against the superior spinous process when implanted. Similarly, a lower portion of flange  38  may have a chamfer  43  or angled inner surface to accommodate a lamina portion of an inferior vertebrae when installed. 
         [0051]    According to one variation, leading end portion  20  generally comprises a pair of wing members  25  movable from a first position, shown in  FIGS. 1-2  and  5 - 6 , to a second position, shown in  FIGS. 3-4  and  7 - 8 . Referring to  FIGS. 1-2 , wing members  25  are depicted in a first or closed position and are configured and dimensioned to facilitate lateral insertion between adjacent spinous processes. In the first position, the exterior of wing members  25  are gradually tapered from a narrow portion adjacent end  14  to a wider shoulder section  28  adjacent support portion  24 . In this regard, when in the closed or first position, wing members  25  generally form a distraction portion  20  having a frustoconical, wedged, or tapered shape widening along axis  12  from a minor diameter  26  adjacent the first end  14  to shoulder  28  adjacent central support portion  24 . In one variation, shoulder  28  may be generally co-extensive with the central support portion  24  such that a generally smooth transition may occur as one or more spinous processes contacts and or slides along exterior wing surface during insertion of implant  10  into the interspinous space. In alternate embodiments, shoulder  28  may protrude longitudinally or radially beyond the support portion  24  when wings  25  are in the first or closed position such that an overdistraction of the spinous processes may occur during insertion of implant  10  into the interspinous space. One skilled in the art may appreciate that with the wing members in the first or closed position, such a configuration may facilitate unilateral insertion between adjacent spinous processes, i.e. implant  10  may be inserted between adjacent spinous processes from only one side. 
         [0052]    Referring now to  FIGS. 3-4 , implant  10  is shown with wing members  25  disposed in a second, expanded, or open position. In this regard, during installation, wing members  25  are configured to remain in the first or closed position and when implant  10  is installed in an implanted position, wing members  25  may be selectively moved into the second position, as shown in  FIGS. 3-4 . In the second position, the wing members  25  generally protrude or extend radially beyond support portion  24  to a greater extent than in the first position. In this regard, the wing members  25  create a flange, or lateral sidewall portion  44  opposite sidewall  44  of shoulder  38  of trailing end  22 . In this position and when implanted, the adjacent spinous processes may be maintained between the wing members  25  and the trailing end portion  22  such that the wall sections  44  may serve to limit or block movement of implant  10  along axis  12  and/or dislodgement from the interspinous space. In this regard, when viewed from the side, as seen in  FIG. 3 , implant  10  may appear to have a general H-like shape or a barbell-like shape, with the lateral sides  20 ,  22 , being longitudinally spaced a distance  27 ,  29 , respectively beyond central support portion  24 . In one variation, distances  27 ,  29  do not need to be equal. According to one embodiment, lateral sides  20 ,  22  may be spaced a distance  27 ,  29  between about 1 mm and about 6 mm from the support portion  24 . In one particular embodiment, distances  27 ,  29  is about 1 mm. In another embodiment, distance  23  is about 2 mm and distance  25  is about 3 mm. As shown in  FIG. 3 , when implant  10  is in the second position, the overall length of implant  10  decreases to a length (e) shorter than the overall length (E) of the implant  10  in the first position. In this regard, such a shortening of the implant along axis  12  is generally caused by the movement of wing members  25  in the direction of arrows  31  shown in  FIG. 3 . 
         [0053]    Referring now to  FIG. 8 , in the second position, wings  25  may abut and/or intermesh at the first end  14 . Those skilled in the art may appreciate that when in such a configuration, the wing members themselves may function to resist any further rotation or sliding movement of wing members  25  with respect to central portion  24  during deployment, and may provide additional support to resist lateral forces that may be placed on the wings once deployed. 
         [0054]    Referring to  FIG. 9 , an exploded view of one embodiment of implant  10  is shown. According to one variation, implant  10  may comprise a multi-piece device generally having wing members  25 , pivot pins  45 , a barrel insert  46 , a central body  48 , a flexible bumper member  50 , and a rotatable insert  52 . In alternate embodiments, more or less components may be provided to achieve similar results. In general, each wing member  25  may comprise a cantilevered body or pivot body  47  freely rotatable or pivotable about a pivot point or pin  45  extending transversely through the wing member via hole  51  of wings  25 . Pins  45  are generally mounted to and/or extend through holes or openings  53  provided at the distal end of barrel insert  46  such that wing members  25  may pivot or rotate with respect to barrel insert  46  about the distal end thereof. Central body  48  has an annular shape with a chamfered or angled tip portion  49  at its distal end to facilitate sliding and/or rotative movement of wing members  25  thereagainst. 
         [0055]    Barrel insert  46  is configured and dimensioned to be received within central body  48  and according to one variation may be keyed with respect to the central body such that barrel insert  46  may translate linearly or move along axis  12  but is prevented from rotating with respect to the central body  48 . In this regard, barrel insert  46  may have ears or ledge portions  54  along a portion of its length configured and dimensioned to fit or ride within grooves  56  provided within the interior of central body  48  ( FIG. 14 ). A pair of cantilevered flexible arm sections  58  may be provided along a portion of its length to facilitate removal of barrel insert  46  from central body  48  after assembly. In this regard, when wing members  25  of implant  10  are in a first position, such as shown in  FIG. 2 , a removal tool (not shown) may be inserted through openings  59  to depress arms  58  and central body  48  may be slidably removed from the back or proximal end of barrel insert  46 . As shown in  FIGS. 12-13 , one or more prongs or protrusions  60  may extend radially outward from the proximal or back end of barrel insert  46  to engage with rotatable insert  52 . In one variation, three protrusions  60  may be angularly spaced about the proximal end of barrel  46 . 
         [0056]    A rotatable insert  52  may be provided adjacent the proximal or second end  16 . As shown in  FIG. 15 , insert  52  may have one or more spiral grooves  62  to accommodate protrusions  60  at the proximal or back end of barrel insert  46 . In this regard, bayonet like openings  64  may be provided at the distal end of insert  52  to accommodate protrusions  60  during assembly. Rotatable insert  52  may be axially fixed within central body  48  yet freely rotatable with respect thereto. When assembled, the back or proximal end of barrel  46  may ride in groove  62  of rotatable insert  52  and when insert  52  is rotated with respect to the central body  48 , the barrel insert  46  may be drawn or moved in the proximal direction along axis  12  towards the second end  16 . The pivot pins  45  located at the distal end of barrel insert  46  will be correspondingly drawn or moved in the proximal direction along axis  12  causing the pivot axis  51  of wing members  25  to move and causing the wing members  25  to engage the central body  48 . In this regard, wing members  25  are configured and dimensioned to be pivotable about a moving axis of rotation. In one variation, spiral groove  62  may extend one quarter of a revolution or 90 degrees about rotatable insert  52  such that a user may cause the wing members to completely deploy upon one quarter turn of rotatable insert  52 . 
         [0057]    According to one embodiment, protrusions  60  may have a rounded section or bump  66  along its periphery to facilitate contact and/or engagement with a correspondingly shaped indentation  68  provided along the profile of groove  62 . In this regard, when bump  66  engages indentation  68  a user may be provided with tactile and/or audible feedback indicating the position of the barrel with respect to the rotation insert. In one variation, indentation  68  is proved adjacent the proximal end of groove  62  such that a user may be indicated that barrel  46  is drawn back proximally as far as possible and in accord therewith, the wing members  25  are completely deployed. Those skilled in the art may appreciate the desirability of such a feature, especially when an implant may be used percutaneously, minimally invasively, or in any procedure with limited ability for direct visualization of the implant during implantation. It may be appreciated that such a bump and indentation feature may also serve as a frictional rotation lock once engaged since a slightly greater rotational force must be applied to overcome the frictional engagement when reversing the rotational direction of insert  52 . In this regard, the rotational lock may limit and/or prevent wing members  25  from undesirably moving back into the first or collapsed position once implant  10  is implanted in a patient. 
         [0058]    As best seen in  FIGS. 10-11 , one embodiment of a wing member  25  according to the invention is shown having a generally shell-like shape. In one variation, the exterior or outwardly facing surface  70  of wing members  25  is generally convex and may have a first ramped or tapered section  72  and a generally flatter second ramped tapered section  74 . In this regard, such a smooth, ramped, and/or tapered exterior generally facilitates direct lateral insertion into an interspinous space by a straight axial pushing force along the direction of axis  12 . In another variation, the interior, underside, or inwardly facing surface  76  of wing members  25  is generally concave and may include a groove  78  along its length to accommodate sliding movement with respect to central body  48 . According to one variation, wing members  25  may be moved toward the second position by moving barrel insert  46  in the proximal direction along axis  12 . When wing members  25  are moved from the first position to the second position, the underside  76  of each wing member  25  is generally rotated or moved to face the central support portion  24  and the undersurface  76  forms the sidewall section  44 . In this regard, wings  25  may be attached to implant  10  such that when in a second position, the interior or inwardly facing surface  76  is generally perpendicular to support portion  24  to create a larger lateral barrier, blocking portion, or wall  44  adjacent central support portion  24 . 
         [0059]    In operation, implant  10  may be first inserted over a guidewire into a space between spinous processes. In this regard, when implant  10  is advanced over a guidewire, the guidewire generally extends within the central cannula  18  and contacts the tail portion  80  of each wing member and the tail portion  80  is forced radially outward, causing the tip portion  82  to pivot inward and/or remain in the first position. One skilled in the art may appreciate that utilizing such a configuration, the wing members  25  may remain in a first position to facilitate implantation over a guidewire and then once the guidewire is removed, the wing members may be selectably moved to the second position to form a larger lateral barrier, wall, or blocking portion adjacent central support portion to limit or reduce the possibility of lateral migration of implant  10  in the body. 
         [0060]    Once installed into the desired position, the guidewire may be removed and the wing members may be deployed or moved to the second position by rotating insert  52  with respect to central body  48 . When rotation insert  52  is turned with respect to central body  48 , an axial force is transmitted to the barrel insert to move the barrel insert  46  in the proximal direction to draw the pivot pins toward the second lateral end  16 . A tip portion  82  of one side of the wing body  47  contacts central body  48  to cause an opposite tail portion  80  of each wing member  25  to pivot about point  51  toward the second position. The inner tail surfaces  76  of wing members  25  ride along the chamfered tip  49  of central body  48  which acts a ramp to force the wings to rotate about pivot point  51  and swing outward and move to the second position. In alternate embodiments, alternative mechanisms may be utilized to achieve the aforementioned result. For example, in one alternative a torsion spring may be positioned adjacent pivot point  51  to bias the wing members  25  toward the second position. Also, in alternative embodiments, the shapes and dimensions of wing members may be altered as desired. 
         [0061]    According to one aspect of this embodiment explained above, the wing members  25  swing outward with the tips  82  generally moving away from the center of the implant. In this regard, the tips  82  are generally configured to move up and under any tissue or muscle that may be abutting against the adjacent spinous processes. Those skilled in the art may appreciate the advantageous nature of such a feature. In particular, such outwardly swinging wing movement may be appreciated to require less activation force and facilitate tissue preservation as compared to alternative wing movements. For example, certain inward swinging movements could easily cause tissue to become trapped between the implant sidewalls and the spinous process and/or cause tissue damage. 
         [0062]    Referring to  FIG. 3 , in one embodiment, one or more sockets, grooves or indentations  37  may be provided on the proximal end of implant  10  and angularly spaced about the periphery thereof to receive an installation or driving tool such as a crucifix shaped driver tool. In alternate embodiments, any other known rotational driving tools and engagement means may also be used, including but not limited to, a flat driver, a star shaped driver, or a threaded driver, among others. As best seen in  FIG. 5 , indentations  37  may be spaced along the perimeter of implant  10  to facilitate insertion with a cannulated driver tool over a guidewire extending through cannula  18 . The proximal end of rotatable insert  52  may have similarly spaced grooves around the proximal perimeter thereof which may be accessed by a concentric rotation driving tool. In this regard, rotatable insert  52  may be rotated relative to central body  48  to, for example, deploy wing members  25 . In one variation, a laterally fixed engagement between the tool and the implant may be provided so that the implant does not dislodge from the trailing end and may efficiently transfer the rotational forces applied on the tool to the implant during installation. One skilled in the art may appreciate that a threaded connection may also facilitate the removal of implant  10  from the body of a patient should a surgeon so desire. 
         [0063]    In some embodiments, all or a portion of implant  10  may be resiliently compressible or expandable in the cranial-caudal direction such that the implant may support and or adjust to dynamic movement of the spine. For example, according to one embodiment, a flexible bumper member  50  may be provided to at least partially cushion the compression of adjacent spinous processes. In one variation, the bumper member  50  may comprise a cylindrical sleeve provided to extend around the periphery of central support portion  24 . In some embodiments, the bumper member may be integrated into the support portion and in alternate embodiments the bumper member may be fit over the support portion. In one variation, the bumper member may be made from a biocompatible polyurethane, elastomer, or other similar material. In still other embodiments, implant  10  may be made from varying materials along its length, such that for example the central support portion may be made from a resilient material, such as polyurethane, elastomer or the like, and the end portions may be made from a rigid material, such as titanium or the like. 
         [0064]    The implant itself may serve to dilate or distract the spinous processes as it is being inserted and/or after insertion. For example, in embodiments in which the implant is similar to that depicted in  FIGS. 1-15 , the first end  14  of implant  10  may be initially inserted or advanced laterally between compressed adjacent spinous processes as shown in  FIGS. 16-20 , for example. The supraspinous ligament may or may not be removed. In an initial pre-implantation condition, shown in  FIG. 16 , the adjacent spinous processes  5  may be compressed or narrowly spaced such that the initial space or longitudinal distance  90  between the processes may be about equal to or slightly larger or smaller than distance (b) of implant  10 . During lateral insertion of the implant, one or more ramp or tapered surfaces or portions of the implant may contact one or both of the spinous processes  5  and may initially distract the processes a distance (b). As the implant is advanced laterally, the ramp or tapered shape of the distraction portion may distract the spinous processes further apart from one another, until the implant is advanced laterally into an implanted position ( FIGS. 19-20 ) and the spinous processes are fitted into the central support portion  24  of the implant  10 . In operation, the ramp surfaces engage the adjacent spinous processes as the implant is laterally advanced to act or perform in a cam-like manner to translate the lateral force to separate the spinous processes in the longitudinal or cranial-caudal direction as the implant is advanced. The maximum distraction of spinous processes by the implant  10  is distance (c) depicted in  FIG. 18 . According to one embodiment, distance (c) is greater than distance (a) such that the spinous processes  5  may be slightly “over distracted” during installation. In this regard, one skilled in that art may appreciate that such an over distraction may facilitate enhanced tactile feedback to a surgeon during installation as the spinous processes drop into the central support portion to signify a desired lateral placement in the patient with the spinous processes positioned within the central support portion. Once the implant is laterally advanced to the position shown in  FIG. 19 , the flange  38  of trailing end portion  22  may contact and/or abut the lateral side of the spinous processes to prevent further lateral translation and rotation insert  52  of implant  10  may be subsequently rotated about one quarter turn or about 90 degrees to deploy the wing members  25  into the final implantation position as shown in  FIG. 20 . In this regard, in the final implantation position, the shoulder wall sections  44  may contact the lateral sides of the spinous processes to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. Also, once the implant is implanted and after the spinous processes are fitted into the central support portion  24 , the implant may maintain the spinous processes in a distracted or spaced condition, for example where the distance (a) of the implant is greater than a pre-implantation distance between the spinous processes. 
         [0065]    Referring to  FIGS. 21-25 , another embodiment of an implant  100  according to the invention is shown. Implant  100  is similar to implant  10  described above except wing members  25  may additionally include a ramped, toothed, fluted, threaded or grooved section  32 . According to one embodiment, grooved section  32  generally comprises helical or spiral ramp peaks  36  extending from first end toward support portion  24 . Ramp peaks  36  of section  32  may have a separation sufficiently narrow to prevent the adjacent spinous process from riding within the grooves  34  defined between the peaks  36 . In this regard, when wing members are in the first position, as shown in  FIGS. 21-22 , the peaks  36  may be configured and dimensioned to engage or contact a portion of the spinous process bone and cause the implant  100  to advance or travel along axis  12  when implant  100  is rotated. In one variation, distraction portion  20  is configured and dimensioned such that when implant  100  is rotated about axis  12 , the adjacent spinous processes ride upon ramp peaks  36  and are distracted or separated apart as implant  10  is advanced laterally along axis  12  during implantation. The rate at which the distraction occurs may be readily controlled by a surgeon by controlling the rate of rotation of implant  10 , so that the surgeon may advance implant  100  along axis  12  as slow or as fast as desired. In this regard, implant  100  may be characterized as self-distracting, as the implant itself distracts or separates the spinous processes as it is being implanted, i.e. without requiring an additional distraction step or device. 
         [0066]    Referring to  FIGS. 23-26 , implant  100  is shown with wing members  25  in a second or expanded condition. Similar to implant  10 , described above, once the implant is laterally advanced to a desired installation position, the flange  38  of trailing end portion  22  may contact and/or abut the lateral side of the spinous processes to prevent further lateral translation and rotation insert  52  of implant  100  may be subsequently rotated about one quarter turn or about 90 degrees to deploy the wing members  25  into the second position as shown in  FIGS. 23-26 . In this regard, in the final implantation position, the shoulder wall sections  44  may contact the lateral sides of the spinous processes to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. As with implant  10  described above, once the implant is implanted and after the spinous processes are fitted into the central support portion  24 , the implant may maintain the spinous processes in a distracted or spaced condition, for example where the distance (a) of the implant is greater than a pre-implantation distance between the spinous processes. Also as described above, the wing members  25  swing outward with the tips  82  generally moving away from the center of the implant. In this regard, the tips  82  are generally configured to move up and under any tissue or muscle that may be abutting against the adjacent spinous processes. 
         [0067]    Referring now to  FIGS. 27-34 , another embodiment of an interspinous process implant  110  is shown. Implant  110  is similar to implant  100  described above, however, in this embodiment, a pair of thin slidable wing fingers  112  are provided within the distraction portion  20 . Like implant  100  described above, distraction portion  20  comprises a include a ramped, toothed, fluted, threaded or grooved section  32  disposed about axis  12  and extending from a narrow first end  14  toward central support portion  24 . In this embodiment, wing fingers  112  are movable from a first position, shown in  FIGS. 27-30 , to a second position, shown in  FIGS. 31-34 . Referring to  FIGS. 27-30 , wing fingers  112  are depicted in a first or closed position and are configured and dimensioned to facilitate lateral insertion between adjacent spinous processes. In the first position, the exterior of wing fingers  112  are generally recessed within distraction portion  20 . One skilled in the art may appreciate that with the wing fingers in the first, or closed, position, such a configuration may facilitate unilateral insertion between adjacent spinous processes. 
         [0068]    Referring to  FIGS. 31-34 , implant  110  is shown with wing fingers  112  in a second position. Similar to implants  10  and  100 , described above, once the implant is laterally advanced to a desired installation position, the flange  38  of trailing end portion  22  may contact and/or abut the lateral side of the spinous processes to prevent further lateral translation and rotation insert  52  of implant  110  may be subsequently rotated about one quarter turn or about 90 degrees to deploy the wing fingers  112  into the second position as shown in  FIGS. 31-34 . In this regard, in the final implantation position, the shoulder wall sections  44  may contact the lateral sides of the spinous processes to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. Also, once the implant is implanted and after the spinous processes are fitted into the central support portion  24 , the implant may maintain the spinous processes in a distracted or spaced condition, for example where the distance (a) of the implant is greater than a pre-implantation distance between the spinous processes. As with implants  10  and  100  described above, the wing fingers  112  swing outward with the tips  82  generally moving away from the center of the implant. In this regard, the tips  82  are generally configured to move up and under any tissue or muscle that may be abutting against the adjacent spinous processes. 
         [0069]    Referring now to  FIGS. 35-38 , another embodiment of an interspinous process implant  120  is shown. Implant  120  is similar to implant  110  described above, however, in this embodiment, a pair of wing fingers or tabs  122  are actuatable by a rotatable gear barrel insert  124 . Barrel insert  124  has a worm gear adjacent its distal portion that is configured and dimensioned to engage teeth or prongs  126  on the interior of tabs  122 . When barrel insert  124  is rotated, tabs  122  may swing inward toward the second position shown in  FIGS. 37-38 . Like implant  100  described above, distraction portion  20  comprises a include a ramped, toothed, fluted, threaded or grooved section  32  disposed about axis  12  and extending from a narrow first end  14  toward central support portion  24 . In this embodiment, wing tabs  122  are movable from a first position, shown in  FIGS. 35-36 , to a second position, shown in  FIGS. 37-38 . Referring to  FIGS. 35-36 , wing tabs  122  are depicted in a first or closed position and are configured and dimensioned to facilitate lateral insertion between adjacent spinous processes. In the first position, the exterior of wing tabs  122  are generally recessed within distraction portion  20 . One skilled in the art may appreciate that with the wing fingers in the first, or closed, position, such a configuration may facilitate unilateral insertion between adjacent spinous processes. 
         [0070]    Referring to  FIGS. 37-38 , implant  120  is shown with wing tabs  122  in a second position. Once the implant is laterally advanced to a desired installation position, the flange  38  of trailing end portion  22  may contact and/or abut the lateral side of the spinous processes to prevent further lateral translation. Barrel insert  124  of implant  120  may be subsequently rotated to deploy the wing tabs  122  into the second position as shown in  FIGS. 37-38 . In this regard, in the final implantation position, the shoulder wall sections  44  may contact the lateral sides of the spinous processes to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. Also, once the implant is implanted and after the spinous processes are fitted into the central support portion  24 , the implant may maintain the spinous processes in a distracted or spaced condition, for example where the distance (a) of the implant is greater than a pre-implantation distance between the spinous processes. When barrel insert  124  is rotated, tabs  122  may swing inward toward the center of the implant. 
         [0071]    Referring now to  FIGS. 39-41 , another embodiment of an interspinous process implant  130  is shown. Implant  130  is similar to previously described implants, however, in this embodiment, a plurality of thin fingers  132  are provided within the distraction or distal portion  20 . In one variation, fingers  132  are pivotably installed adjacent distal portion  20 . As best seen in  FIGS. 39-40 , fingers  132  may be actuated or moved from a first position ( FIG. 39 ) to a second position ( FIG. 40 ) by drawing a front or distal end portion  134  backward in a proximal direction along axis  12 . In this regard, an internal ramp portion  136  may be provided to engage a tip portion of fingers  132  such that as the distal end is drawn back, fingers  132  pivot or rotate about their base  138 . Similar to previously described embodiments, in a first position, fingers  138  are recessed within distal portion  20  and in a second position, fingers  132  extend outward to create a wall section to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. 
         [0072]    Referring now to  FIGS. 42-43 , another embodiment of an interspinous process implant  140  is shown. Implant  140  is similar previously described embodiments, however, in this embodiment, a plurality of wing members  142  are pivotably mounted to a distal portion  144 . Wing members  142  are configured to remain recessed within distraction portion  20  in a fist position ( FIG. 42 ). Wing members  142  are rotatable about an axis parallel to axis  12  and may be actuated by rotating the central body  146  with respect to distal portion  144 . When central body  146  is rotated, wing members  142  swing radially outward toward the second position shown in  FIG. 43 . 
         [0073]    Referring now to  FIGS. 44-47 , another embodiment of an interspinous process implant  150  is shown. Implant  150  generally comprises first and second members  152 ,  154  having a shoulder or larger sized diameter portion  155  adjacent a generally cylindrical midsection  156 . In one variation, the first and second members may be threadably connectable. In alternate embodiments, first and second members  152 ,  154  may snappably connectable. A deformable wing body  157  may be disposed about the first and second members  152 ,  154  and wing body  157  may have bendable ends  158  having one or more flexible joints  159  thereon. First and second members may be concentrically connected at midsection  156  such that the first and second members may be axially moveable with respect to each other such that first and second members  152 ,  154  may be moved relative to each other form a first position ( FIG. 46 ) to a second position ( FIG. 47 ) to contract or shorten the overall length of implant  150 . In this regard, when in the second position as shown in  FIG. 47 , bendable ends  158  hinge or bend at joints  159  and extend radially outward in a direction transverse to axis  12  toward the second position shown in  FIG. 47 . Similar to previously described embodiments, in a first position, bendable ends  158  are retracted and in a second position, ends  158  extend outward to create a wall section to limit or block movement of the implant along axis  12  and/or dislodgement from the interspinous space. 
         [0074]    Referring now to  FIGS. 48-49 , another embodiment of an interspinous process implant  160  is shown. Implant  160  is similar previously described embodiments, however, in this embodiment a pair of geared pins  162  are actuatable by a rotatable gear barrel insert  164 . Barrel insert  164  has a gear teeth profile adjacent its distal portion configured and dimensioned to engage corresponding teeth or prongs on the interior of pins  162 . When barrel insert  164  is rotated, pins  162  extend radially outward in a direction transverse to central axis  12  toward the second position shown in  FIG. 49 . 
         [0075]    According to certain embodiments of the invention, the implants described above may have a trailing end portion  22  with an external hexagonal shaped portion to engage an installation tool such as a hexagonal socket shaped driver tool. In alternate embodiments, however, any other known rotational and/or driving tools and engagement means may also be used. 
         [0076]    Kits having at least one implant such as those depicted in  FIGS. 11-15 , may include various sizes of implants having varying heights (a), widths (d), and overall lengths (e), for example having variations with incremental distances. In one embodiment, a system or kit may be provided that has implants having heights (a) between about 6 mm to about 22 mm. For example, in one variation implants having heights (a) of 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, and 20 mm may be provided. In another variation, a system or kit may be provided that has implants having widths (d) between about 6 mm to about 18 mm. For example, in one variation implants having widths (d) of 8 mm, 12 mm, and 16 mm may be provided. In yet another variation, a system or kit may be provided that has implants having overall lengths (e) between about 20 mm and about 60 mm. For example, in one variation implants having overall lengths (e) of 25 mm and 50 mm may be provided. 
       Material 
       [0077]    Implants in accordance with the present invention may be made of one or more materials suitable for implantation into the spine of a mammalian patient. Materials in accordance with the present invention may be biocompatible with a mammalian patient and/or may have one or more surface coatings or treatments that allow the spacers to be biocompatible. Materials in accordance with the present invention may include one or more materials having sufficient load capability and/or strength to maintain the desired spacing or distraction between spinous processes. Depending on the design employed, certain embodiments may have components or portions made of a material having certain flexibility, as desired for the particular application. Additionally, the materials of the present invention may be made of one or more materials that maintain their composition and shape for as long a time as possible without degrading or decomposing or changing shape, such that replacement of the implant is avoided. 
         [0078]    Suitable materials for use in accordance with the present invention would be known to those skilled in the art. Non-limiting examples include one or more materials selected from medical grade metals, such as titanium or stainless steel, biocompatible polymers, such as polyetheretherketone (PEEK), ceramics, deformable materials, bone, allograft, demineralized or partially demineralized bone, allograft ligament, and polyurethane (for example, for portions of the insert where cushioning is desired). Similarly, any fastening devices may be made of materials having one or more of the properties set forth with respect to the implant itself. For example, screws or pins may include titanium and straps may include polyethylene. In some embodiments, primarily radiolucent material may be used. In this regard, radio-opaque material or markers may be used in combination with the radiolucent material to facilitate implantation. Exemplary radio-opaque material includes but is not limited to titanium alloys, tantalum or other known radio-opaque marker material. As indicated above, implants in accordance with the present invention may have one or more portions that may have modified surfaces, surface coatings, and/or attachments to the surface, which may assist in maintaining the spacer in a desired position, for example by friction. Suitable surface modifications, coatings, and attachment materials would be known to those skilled in the art, taking into consideration the purpose for such modification, coating, and/or attachment. 
       Methods for Treating Stenosis and Methods of Inserting an Implant 
       [0079]    Methods are provided for treating spinal stenosis. Methods are also provided for inserting an implant. These methods may include implanting a device to create, increase, or maintain a desired amount of distraction, space, or distance between adjacent first and second spinous processes. The adjacent first and second spinal processes may be accessed by various methods known by practitioners skilled in the art, for example, by accessing the spinous processes from at least one lateral side/unilateral, bilateral, or midline posterior approach. 
         [0080]    Certain methods of the present invention include creating an incision in a patient to be treated, dilating any interspinous ligaments in a position in which the implant is to be placed in the patient, sizing the space between adjacent spinous processes (for example using trials), and inserting an implant of the appropriate size between the adjacent spinous processes. Methods of the present invention may include securing the implant to one or more of the spinous processes, to one or more other portions of the patient&#39;s spine, and/or to itself such that the implant maintains its position between the spinous processes. 
         [0081]    Methods of the present invention may include dilating or distracting the spinous processes apart from one another before sizing and/or before inserting the implant. Methods may vary depending on which implant is being inserted into a patient. For example, certain implants may require distracting the spinous processes apart before inserting the implant, while other implants may themselves dilate or distract the spinous processes while inserting the implant. In embodiments where the implants themselves dilate or distract the spinous process, the implant may have, for example, a predetermined shape to dilate, distract, or otherwise move or separate apart adjacent spinous processes such as a cam or cam-like profile, it may have a distraction device that is deployed, and/or it may have a tapered expander to distract an opening between the adjacent spinous processes or other features to facilitate distraction of the adjacent spinous processes. 
         [0082]    According to certain embodiments, spacers may be placed between the spinous processes anterior to the supraspinous ligament, avoiding the nerves in the spinal canal. The procedure may be performed under local anesthesia. According to one method for surgical procedures, in which an implant is being inserted into the lumbar region, the patient may be placed in a left or right lateral decubitus position with the lumbar spine flexed or in another flexed position. According to one method, a surgeon may desire to use fluoroscopy to align in parallel the adjacent vertebral bodies corresponding to the adjacent spinous processes to gauge the desired distraction distance. 
         [0083]    According to certain embodiments, one or more probes may be used to locate the space between the spinous processes. Depending on the design of the spacer to be inserted, the space may be widened, for example with a dilator before inserting the implant. 
         [0084]    Referring to  FIGS. 50-57 , one embodiment of a surgical method according to the invention for implanting an implant  10  in the spine is disclosed. According to this embodiment, the adjacent first and second spinal processes  5  may be accessed from one lateral side through a minimally or less invasive procedure. In this regard, according to certain methods of the invention, a unilateral approach may be used to install implant  10  without removal of the supraspinous ligament. In this method, as shown in  FIG. 50 , a guide wire  202 , such as a K wire, is inserted laterally through the skin and into the interspinous space  204 . According to one method, a working portal may be created concentric to the guidewire  202 , as shown in  FIGS. 51-52 , by inserting a series of sequentially larger diameter tubes  206 ,  208 ,  210 ,  212 ,  214  to dilate the tissue surrounding guidewire  202 . Referring to  FIG. 53 , once a dilating tube having a sufficiently large inner diameter to accommodate implant  10  is positioned about guidewire  202 , the smaller diameter tubes  206 ,  208 ,  210 ,  212  may be withdrawn, leaving the guidewire  202  and the outer tube  214 . Referring to  FIG. 54 , one or more trials  215  may then be inserted to appropriately size the interspinous space  204  and the trials  215  may also be utilized to dilate interspinous ligaments. In one exemplary embodiment, a generally cannulated cylindrical trial  215 , shown in  FIG. 54 , may be utilized to size the space between adjacent processes  5 . Referring to  FIG. 59 , an alternate embodiment of a trial  216  that may be used is shown which may comprise a ramped tip portion  217  adjacent its distal end and multiple longitudinal indentations or markings  218  on at least a portion of central portion  219  and may provide visual indication when viewed under fluoroscopy of the width of the spinous processes and facilitate the surgeon&#39;s selection of an appropriately sized implant. Similarly, the appropriate diameter of central portion  219  of trial  216  may be selected to gauge the amount of distraction desired. In this regard, the spacing of the spinous processes may be viewed under fluoroscopy to facilitate the surgeon&#39;s selection of an appropriately sized implant. Finally, an implant of the appropriate size may be inserted between the adjacent spinous processes. 
         [0085]    Referring to  FIGS. 55-56 , one exemplary embodiment of a method of installing implant  10  is shown. Implant  10  is advanced over guidewire  202  through cannulation  18  to the interspinous space  204 . During lateral insertion of the implant between the spinous processes, one or more ramp surfaces or portions of the implant may contact one or both of the spinous processes  5  and may initially distract the processes. Implant  10  may be rotated to further advance implant  10  between the spinous processes and, the wedged or tapered shape of the distraction portion  20  may distract the spinous processes further apart from one another, until the implant is rotated and advanced laterally into an implanted position ( FIGS. 55-58 ) with the distraction portion  20  positioned on the contralateral side of the spinous processes and the spinous processes are fitted into the central support portion  24  of the implant  10 . Referring to  FIGS. 57-58 , once implant  10  is installed, the guidewire may be removed through the cannulation leaving the implant  10  in the interspinous space. 
         [0086]    While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations can be made thereto by those skilled in the art without departing from the scope of the invention.