Abstract:
An implant device having a non-conductive base structure with at least two exposed or exterior surfaces wherein at least one of the exposed or exterior surfaces has attained electrical conductivity on at least portions of the surface by an energy exposure wherein portions of the exposed or exterior surfaces are transformed by the energy exposure to attain the electrical conductivity.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to implants generally, more particularly to implant devices that have enhanced recessed surface features that extend from inside the base structure of the implant to stimulate new bone growth formation on and into the implant. 
       BACKGROUND OF THE INVENTION 
       [0002]    The use of skeletal implants is common in surgical repairs. Implants are employed in a variety of procedures such as spinal repair, knees, hips or shoulders and others. A common and most important feature of many implants is the integration of the implant into the skeletal structure. Mechanical fasteners, surface modifications, coatings, sutures and adhesives and other ways of affixing the device to the bone structure are used. These implants can be fashioned from human bone or other biological material or alternatively can be made from implantable grade synthetic plastics, ceramics or metals like stainless steel, titanium or the alloys of metals suitable for implantation. 
         [0003]    One of the benefits of these plastic or metal implants is the strength and structure can be specifically designed to be even more durable than the bone being replaced. 
         [0004]    As mentioned, one concern is properly securing the implant in place and insuring it cannot be dislodged or moved after repair. One of the best solutions to this issue is to allow the surrounding bone structure to grow around the implant and in some cases of hollow bone implants to allow new bone growth to occur not only around, but throughout the implant as well to achieve interlocked connectivity. Enhancing surface area by blasting, etching, or in some other way increasing the relative surface energy interface with the biologic component is desirable. 
         [0005]    This is not particularly easy in many of the metal implants or hard plastic implants. In fact, the surface structure of the implant material is often adverse to bone formation. On some implant surfaces this may in fact be a desirable characteristic, but in those procedures where new bone growth formation is desirable this is problematic. 
         [0006]    It is therefore an object of the present invention to provide an improved implant device that encourages new bone growth formation at selected surfaces of the device. The selected surfaces can be some or all external or internal exposed surface features of the implant device. The device with exposed surfaces that have selected surfaces for bone growth formation can be prepared by the methods as described below. 
       SUMMARY OF THE INVENTION 
       [0007]    A spinal implant for insertion between two adjacent vertebrae has a body structure having load supporting exterior walls extending to a pair of load bearing outer surfaces, one being an upper surface, the other a lower surface; a cavity interposed between the load supporting exterior walls, the cavity being an opening through both load bearing outer surfaces; and a plurality of non-load bearing recessed projections. Each recessed projection extends from an interior surface of at least one load supporting wall into the cavity at an elevation above the lower surface and below the upper surface. Each projection has an enhanced osteoconductive treated exterior surface for the stimulation of new bone growth. Preferably, the enhanced osteoinductive treated exterior surface has a roughened surface or a textured surface or a bone mimicking surface or a coated surface of increased osteoinductivity. 
         [0008]    The implant can be made from a non-conductive polymer and has one or more of the exterior surfaces of the projections laser etched to form electrically conductive pathways for new bone formation. The implant polymer can be polyether ether ketone (PEEK) or any other suitable implantable polymer. 
         [0009]    The spinal implant has each of the recessed projections extend at least partly across the cavity toward an interior surface of an opposing exterior wall. In one embodiment, one or more of the recessed projections extends to an opposing interior wall to form a recessed strut. Each recessed strut can have a cross sectional shape in the form of opposing stepped plateaus. Each plateau has a planar top or bottom surface with the enhanced osteoinductive exterior surface wherein the cross sectional shape has a maximum width at a center of the strut and progressively narrower width at each subsequent adjacent stepped plateau. In another embodiment, the implant has three or more recessed struts, each adjacent strut having a different elevation. The three or more struts in combination form a cascading elevation highest at the center of the implant and lower toward ends. Alternatively, the three or more struts in combination form sequential rising elevations from one end toward an opposing end of the implant. Each recessed strut can have a rectangular or square cross section. Preferably, each recessed strut has a cross sectional width greater than its height, and wherein the exterior surfaces across at least the width is the enhanced osteoinductive treated exterior surface. In another embodiment, the implant has two pairs of recessed struts. Each strut in a pair is aligned and spaced apart to form an open pathway between the ends of the implant. This implant has a distal and a proximal end having a hole aligned with the pathway and configured to receive a guide wire. 
       Definitions 
       [0010]    As used herein and in the claims: 
         [0011]    “Exposed surface” means surfaces that are typically an outer or planar feature of 2-dimensions as used herein and throughout this description. “Exposed surface” means an outer skin or surface having a depth providing a 3-dimensional character, this depth being the distance the surface pattern penetrates into the body structure of the device to produce a roughened or textured pattern or coating for enhancing bone formation on the implant device. The exposed surface might also include an open trabecular structure wherein the voids extend from the surface throughout the structure. The exposed surface might also be defined in 4 dimensions, wherein time imposes specific and characteristic metabolic deposits which functionally mature the surface and guide phenotypic responses that are resonant with differentiated tissues and structures of the adjacent vertebral body. 
         [0012]    “Mimetic patterns” mean to mimic a natural or man made or conceived pattern with the capability to replicate these patterns at an exposed surface to at least a depth sufficient to replicate at least the pattern. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention will be described by way of example and with reference to the accompanying drawings in which: 
           [0014]      FIG. 1  is a top view of a first exemplary embodiment of the present invention. 
           [0015]      FIG. 1A  is a perspective view of the first exemplary embodiment of  FIG. 1 . 
           [0016]      FIG. 2  is a top view of a second exemplary embodiment of the present invention. 
           [0017]      FIG. 2A  is a perspective view of the second exemplary embodiment of  FIG. 2 . 
           [0018]      FIG. 3  is a top view of a third exemplary embodiment of the present invention. 
           [0019]      FIG. 3A  is a perspective view of the third exemplary embodiment of  FIG. 3 . 
           [0020]      FIG. 3B  is a partial section view taken along line  3 - 3  of  FIG. 3 . 
           [0021]      FIG. 4  is a top view of a fourth exemplary embodiment of the present invention. 
           [0022]      FIG. 4A  is a perspective view of the fourth exemplary embodiment of  FIG. 4 . 
           [0023]      FIG. 4B  is a partial section view taken along line  4 - 4  of  FIG. 4 . 
           [0024]      FIG. 5  is a top view of a fifth exemplary embodiment of the present invention. 
           [0025]      FIG. 5A  is a perspective view of the fifth exemplary embodiment of  FIG. 5 . 
           [0026]      FIG. 5B  is a partial section view taken along line  5 - 5  of  FIG. 5 . 
           [0027]      FIG. 6  is a top view of a sixth exemplary embodiment of the present invention. 
           [0028]      FIG. 6A  is a perspective view of the sixth exemplary embodiment of  FIG. 6 . 
           [0029]      FIG. 6B  is a partial section view taken along line  6 - 6  of  FIG. 6 . 
           [0030]      FIG. 7  is a top view of a seventh exemplary embodiment showing a recessed projection extending from a leading distal end, a trailing proximal end interior wall and recessed projections extending only partially across the cavity. 
           [0031]      FIG. 7A  is a perspective view of the seventh embodiment of  FIG. 7 . 
           [0032]      FIG. 7B  is a cross section view taken along line  7 - 7  of  FIG. 7 . 
           [0033]      FIG. 8  shows an exemplary mimetic pattern. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    With reference to the following drawings, several exemplary spinal implant embodiments are illustrated in  FIGS. 1-7B . In each of the embodiments, the implants  10 A- 10 G illustrate the same base structure. The base structure  20  includes an upper load bearing surface  24  and a lower load bearing surface  26 . Interposed between the load bearing surfaces  24 ,  26  extend load bearing walls  23 . The load bearing walls  23  extend around the periphery of the entire implant base structure  20 . These load bearing walls and upper and lower load bearing surfaces support the weight of the adjacent vertebrae. As shown in each of the exemplary embodiments, the load bearing surfaces  24 ,  26  have a plurality of ridges  30 . These ridges  30  provide gripping surfaces onto which the implant can be held tightly against the adjacent bone. Alternatively, roughened or other non-slip surfaces can be used. As further shown, in  FIG. 1A , each implant body  20  has a proximal end  29  and a distal end  28 . As illustrated, the proximal end  29  is shown having a slot  40  with a threaded opening  42 . The slot  40  and the threaded opening  42  and the exterior surface of the end of the implant  21  allow an insertion tool (not illustrated) to be inserted such that when the implant is positioned between the vertebrae, the insertion tool can be used to hold the implant in place and push through an incision between the prepared vertebrae surfaces to position the implant  10 A- 10 G into the prepared space between the adjacent vertebrae. As further illustrated, there is an enlarged cavity  60 . The enlarged cavity  60  is an opening that extends between the upper surface  24  and the lower load bearing surface  26 . This cavity  60  is a hollow opening across which a pair of recessed projections is illustrated. The projections  50  are shown recessed from both the upper outer surface  24  and the lower outer surface  26 . These recessed projections  50  extend from one interior surface of the walls  23  of the implant as illustrated in  FIGS. 1 and 1A , these projections  50  can extend to an opposing wall  23 . When they extend to an opposing wall, the recessed projections  50  form struts across the implant body  20 . With each of the exemplary implant embodiments shown it is noted that these recessed projections  50  can extend from one wall  23  and terminate not contacting an opposing wall  23 . This is best illustrated in  FIGS. 7-7B . It is important to note that the projections do not have to extend to both walls  23  in any of the various exemplary embodiments shown in  FIGS. 1 through 6B . The implants  10 A- 10 F, as illustrated, have the recessed projections  50  extend to both opposing walls  23 . This is not a requirement as the projections  50  could extend only from one wall and project approximately half way or more towards the opposing wall. In any event, the recessed projections  50  whether formed as a strut contacting both walls  23  or simply as a projection extending from one wall  23  are recessed in such a manner that they provide no vertical load bearing support to the implant structure. When the projections  50  extend to both walls  23  and form struts they may have some stresses implanted along their length due to the support of the walls in terms of keeping the opposing walls aligned and together so they can&#39;t flex. In such a case the stresses or forces on the struts  50  are all longitudinally extending basically parallel to the vertebrae. However, depending on the thickness of the walls  23  around the periphery of the body  20  it is likely that no loads are applied onto the projections when formed as struts  50 . 
         [0035]    Most importantly, it is important to note that these recessed projections  50  provide exterior surfaces particularly on the top  52  and bottom  54  of the projections  50 . These surfaces  52 ,  54  are exposed surfaces that are ideal for treatment. Additionally, the sides  56  of the projections  50  can equally be treated if so desired with an osteoconductive bone growth enhancing texturing, patterning or coating  70 . The coating can be a biologic including stem cells and the texturing can be any type of roughened osteoconductive surface treatment including, but not limited to a mimetic pattern. It is important to note that these textured surfaces will increase the osteoinductive capability and enhance new bone growth and they do so in a rather efficient manner. 
         [0036]    Each projection  50 , as shown in the various embodiments, has at least one if not more than one of these surfaces  52 ,  54 ,  56  treated with an enhanced bone growth surface. This surface can be roughened or textured in such a fashion that new bone growth is actively encouraged to be initiated within the cavity  60  along these recessed exposed surfaces. What is unique about the present invention is that the exterior surfaces of the walls do not have to be treated with osteoinductive material, the objective is to ensure that the new bone growth formation is driven into the cavity  60 , to encourage this it is the exposed surfaces  52 ,  54 ,  56  of the projections  50  that allow the osteoinductive capacity of the treated or patterned  70  surfaces to encourage the upper superior vertebrae or inferior vertebrae between which the implant is inserted to extend and grow into the cavity  60 . Once the bone growth is created inside the cavity  60 , an interlocking capability fuses the implant  10 A- 10 G directly to the adjacent vertebrae. It is believed that by having the exposed surfaces of the projections  50  recessed and treated or patterned  70  in such a fashion that new growth formation is actually accelerated. Since there are no load bearing stresses within the projections  50 , the material is simply in position to provide an enhanced bone growth capability. 
         [0037]    Having only the projections  50  having exposed surfaces  52 ,  54 ,  56  treated or patterned  70  enables the rest of the implant device to be basically molded as is without any additional treatment. This is significant in that particular treatments in roughening of the material are quite expensive and time consuming. By limiting the surface area available for treatment or patterning  70 , the cost of preparing an implant with improved osteoinductive capability is dramatically reduced. For example, the area needed to treat or pattern  70  the projections  50  is substantially less than a fraction of the overall surface of the implant. Thus, by selectively texturing and treating only that needed within the cavity  60  the cost of preparing such an implant is dramatically reduced. This enables implants to be used, preferably without any additional allograft material that is normally packed within the cavity  60 . By avoiding this, the exposed surfaces become the conductive path for accepting and receiving an enhancing new bone growth formation. As the new bone growth forms in the recess it automatically interlocks the adjacent vertebrae into the cavity  60  of the implant both on the upper surface and lower surface as illustrated due to the fact that all the projections  50  are recessed. 
         [0038]    With reference to  FIG. 2 , the implant  10 B is illustrated having basically the same features as those illustrated in  FIGS. 1 and 1A . The implant  10 B, however, has the projections  50  formed as struts that are aligned in pairs creating a gap between the adjacent projections  50 . As shown in  FIG. 2A , this gap  62  ensures that the implant  10 B is open between the struts  50 . This is important in some embodiments wherein a guide wire can be positioned through an entire implant and the implant can be inserted between vertebrae using the guide wire as a path to ensure easy and proper placement of the implant device. To accomplish this feature the implant  10 B has the opening  42  wherein the guide wire can pass through the opening  42  when an insertion tool that is cannulated is attached to the implant  10 B. The guide wire than can be passed directly through the opening  44  such that the proximal end and the distal end are both guided through these openings by a guide wire, not illustrated. As shown, the projections  50  are similarly recessed and the exposed surfaces can be treated with the enhanced osteoinductive materials as previously mentioned. 
         [0039]    With reference to  FIG. 3 , a modification to the implant  10 C is shown wherein the recessed projection  50  is made in the form of struts wherein the struts have stepped plateaus as shown in the cross sectional view of  FIG. 3B . This projection  50  provides a plurality of exposed surfaces onto which a texturing can be provided that will provide the enhanced bone growth. As illustrated, this projection  50  in the form of struts has a plurality of surfaces. The upper surfaces can be solid as illustrated or can have interruptions  53  as illustrated in  FIG. 4 . The interruptions  53  in the upper step  55  create additional locking capability for new bone growth. 
         [0040]    With reference to  FIG. 4 , another embodiment using the same projections  50  as shown in  FIG. 3A  is illustrated. In this embodiment, the projections  50  are shown forming a plurality of struts across the cavity  60  wherein the struts are at different elevations relative to the upper surface  24  and the lower surface  26 . What this enables the implant  10 D to do is to get in close proximity and yet still be unloaded against the lower vertebrae at the lateral extremes wherein the center projection  50  is in closer proximity to the superior vertebrae. This enables the bone growth to occur in such a fashion that the lower bone can most rapidly enter in along the lateral extremes being enhanced by the treated surfaces wherein the center projection allows the superior vertebrae to grow towards the center. This creates an additional locking capability and is one way of making the implant device with enhanced osteoinductive capability. 
         [0041]    With reference to  FIGS. 5-5B , an alternative embodiment  10 E is shown where the implant  10 E has the struts  50  formed as substantially flat rectangular features. Again with the center element strut closer to the superior vertebrae and the lateral projections  50  shown closer to the inferior vertebrae. In this embodiment  10 E, these rectangular projections  50  have flat planar surfaces with large exposed flat surface areas that are treated with the texturing, patterning, roughening or coating  70  on the exposed surfaces  52 ,  54   56  as selectively desired. 
         [0042]    With reference to  FIGS. 6-6B , an embodiment  10 F similar to embodiment  10 E is shown. This implant embodiment  10 F has the features of the other devices however employs rectangular projections  50  that are provided in an increasing elevation from the proximal end  29  toward the distal end  28 . This increasing staircase effect of the projections  50  allows the lower vertebrae to initiate bone growth toward the proximal end  29  and the upper vertebrae to initiate initial bone growth closer to the distal end  28 . As such, as the bone grows, the new bone growth will secure itself within the cavity  60  in a progressive fashion across the exposed surfaces  52 ,  54 ,  56  of the device. 
         [0043]      FIGS. 7-7B , illustrate an alternative embodiment  10 G showing the projections  50  can be made as previously mentioned either from a lateral end extending from the interior surface of the supporting wall  23  or can be projections  50  extending toward the center line of the implant device from one wall  23 , but not extend to the opposing wall  23 . It is important to show this embodiment  10 G applies equally to any of the embodiments previously shown such as the stepped plateau or a tapered cross section of the projection  50  can be produced having the bone growth enhancing features as previously discussed. However, the devices do not necessarily need to form struts in the sense that the ends can be truncated short of the opposing wall  23 . This takes advantage of the capability of having a non-load bearing surface on implants that enhances bone growth, the inventors want to their device is not limited only to struts that contact both walls  23 , but is contemplated to cover projections  50  that could extend only from one wall  23  or one end, but be treated in such a fashion that only the recessed surfaces have the treatment that can induce bone growth into the cavity  60 . 
         [0044]    With reference to  FIG. 8 , an exemplary mimetic pattern is illustrated. 
         [0045]    Treatments can be coatings with stem cells or other biologically active material as taught in US 2013/0018471 and U.S. Pat. No. 8,679,189 which are each incorporated herein by reference in their entirety. Laser etchings or patterns forming electrically conductive pathways as taught in U.S. Pat. No. 8,679,189. Also by mechanical roughening to form a texturing or three dimensional effect, the depth being 150 microns or less. By material addition using 3-dimensional printing to form the porosity of the projections at the exposed surfaces. 
         [0046]    Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described, which will be within the full intended scope of the invention as defined by the following appended claims.