Abstract:
Embodiments of the invention being disclosed are directed to a spine implant that allows for in situ adjustment or steering during implantation which allows for precise placement. The structure of the device is composed of a series of hinged link components connected by dowel or shear pins allowing for the links to rotate with respect to each other. The steering feature of the device is activated by a series of tension members connected or coupled to the links. As the tension members are placed in tension, typically by pulling the appropriate member, forces are placed on the individual links to actuate/rotate them in a clockwise or counterclockwise direction. By controlling the rotation of the links, the device may be steered in the desired direction.

Description:
[0001]    This application claims priority to U.S. Provisional Application 61/383,582, filed Sep. 16, 2010. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to systems, methods, and devices applicable to surgery. More specifically, the present invention is directed to a steerable spine implant and system for use by medical personnel (i.e., doctor) in spinal and other surgical procedures. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vertebrae are the individual irregular bones that make up the spinal column—a flexuous and flexible column. There are normally thirty-three vertebrae in humans, including the five that are fused to form the sacrum (the others are separated by intervertebral discs) and the four coccygeal bones which form the tailbone. The upper three regions comprise the remaining 24, and are grouped under the names cervical (7 vertebrae), thoracic (12 vertebrae) and lumbar (5 vertebrae), according to the regions they occupy. This number is sometimes increased by an additional vertebra in one region, or it may be diminished in one region, the deficiency often being supplied by an additional vertebra in another. The number of cervical vertebrae is, however, very rarely increased or diminished. 
         [0004]    A typical vertebra consists of two essential parts: an anterior (front) segment, which is the vertebral body; and a posterior part—the vertebral (neural) arch—which encloses the vertebral foramen. The vertebral arch is formed by a pair of pedicles and a pair of laminae, and supports seven processes, four articular, two transverse, and one spinous, the latter also being known as the neural spine. 
         [0005]    When the vertebrae are articulated with each other, the bodies form a strong pillar for the support of the head and trunk, and the vertebral foramina constitute a canal for the protection of the medulla spinalis (spinal cord), while between every pair of vertebrae are two apertures, the intervertebral foramina, one on either side, for the transmission of the spinal nerves and vessels. 
         [0006]    Conventional interbody implants are used in spinal fusion procedures to repair damaged or incorrectly articulating vertebrae. These implants are typically rigid and are inserted between vertebrae in a straight manner or direct approach. 
         [0007]    In some cases, the direct approach to the spine may be difficult and the current technologies do not allow for in situ steering of a spine implant. There exists a need for further improvements in the field of spine implants of the present type that may be steerable. 
       SUMMARY OF THE INVENTION 
       [0008]    Embodiments of the invention being disclosed are directed to a spine implant that allows for in situ adjustment or steering during implantation which allows for precise placement. The steerable spine implant includes a plurality of links rotatably coupled together at a hinge point including a proximal link, one or more intermediate links, and a distal link; and a plurality of tension members coupled to the intermediate and distal links, each link being coupled with first and second tension members on opposite sides of the hinge point. Activating the first tension member rotates the plurality of links in a clockwise direction and activating the second tension member rotates the plurality of links in a counterclockwise direction. 
         [0009]    In other features, the links further include a central channel sized to carry the plurality of tension members. The tension members exit a channel at a proximal portion of the proximal link. The links further include a top portion and a bottom portion having a plurality of protrusions or teeth. The protrusions are configured to prevent movement of the steerable implant once the steerable implant is implanted. The proximal link includes one or more adapter features or apertures configured to couple to one or more instruments. One or more of the plurality of links includes openings for a graft or a DBM. The distal link includes a tapered or shaped portion configured for insertion into a spinal area. Activating the first or second tension member comprises pulling the tension member proximally. At least one of the plurality of links includes at least one of a varying height, length, thickness, and lordosis angle. The plurality of links of the steerable implant comprises a biologically inert material. Two or more of the plurality of links comprise two or more different biologically inert materials. 
         [0010]    A steerable spine implant system includes a guide wire and a plurality of links rotatably coupled together at a hinge point including a proximal link, one or more intermediate links, and a distal link, each of the plurality of links include an aperture sized to slide over the guide wire, wherein when the plurality of links are coupled together, the apertures form a continuous guide wire channel from a proximal end to a distal end of the implant. 
         [0011]    In other features, the links further include a top portion and a bottom portion having a plurality of protrusions or teeth. The protrusions are configured to prevent movement of the steerable implant once the steerable implant is implanted. The proximal link includes one or more adapter features or apertures configured to couple to one or more instruments. One or more of the plurality of links includes openings for a graft or a DBM. The distal link includes a tapered or shaped portion configured for insertion into a spinal area. At least one of the plurality of links includes at least one of a varying height, length, thickness, and lordosis angle. The plurality of links of the steerable implant comprise a biologically inert material. 
         [0012]    Further features and advantages of the invention, as well as structure and operation of various embodiments of the invention, are disclosed in detail below with references to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. 
           [0014]      FIG. 1  is perspective view showing one embodiment of a steerable spine implant. 
           [0015]      FIG. 2  is a side view of the implant shown in  FIG. 1 . 
           [0016]      FIGS. 3A and 3B  are sectional views of the implant shown in  FIG. 1 . 
           [0017]      FIGS. 4 ,  5 A, and  5 B show one embodiment of an instrument that may be used to steer the steerable implant shown in  FIG. 1 . 
           [0018]      FIGS. 6A and 6B  are sectional views illustrating steering of the implant shown in  FIG. 1  using the instrument shown in  FIGS. 4 ,  5 A, and  5 B. 
           [0019]      FIGS. 7A and 7B  illustrate a steerable spine implant being steered into a space between vertebrae. 
           [0020]      FIGS. 8-11B  illustrate another embodiment of the steerable implant that travels along a guide wire. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 1  is a perspective view and  FIG. 2  is a side view showing one embodiment of a steerable spine implant  100  having a number of hinged links  102 , including a proximal link  102   a,  one or more intermediate links  102   b,  and a distal link  102   c.  The links  102  are configured to rotatably link together. In some embodiments, proximal and distal end portions of the links have hinge features that interdigitate with each other and are held together with dowel or shear pins  104 . This allows each of the links  102  to rotate with respect to each other. A plurality of tension members  118  are coupled to the links  102 , such that pulling of the tension members rotates the links either clockwise or counterclockwise to steer the implant  100 . 
         [0022]    The implant  100  may be sized for use in many areas of the spine and may have varying height, length, thickness, and/or lordosis angle. In addition, each of the links  102  may have varying height, length, thickness, and/or lordosis angle. Links  102  may be added or removed to alter the length or configuration of the implant  100 . 
         [0023]    Each of the links  102  includes a top portion  106 , a bottom portion  108 , side portions  110 , a proximal portion  112 , and a distal portion  114 . As discussed above, there are at least three different types of links: the proximal link  102   a,  one or more intermediate links  102   b,  and a distal link  102   c.    
         [0024]    The proximal portion  112   a  of the proximal link  102   a  includes one or more adapter features or apertures  116  which can be configured as attachment points for instrumentation. The apertures may be threaded circular apertures  116   a  for attachment to an insertion instrument. There may also be other shaped apertures  116   b  used for other attachment features. The distal portion  114   a  is configured to rotatably couple with the proximal portion  112   b  of intermediate link  102   b.  Each of the intermediate links  102   b  are rotatably coupled together, with the distal portions  114   b  being coupled with the proximal portions  112   b.  The distal link  102   c  has a proximal portion  112   c  coupled to the distal portion  114   b  of the adjacent intermediate link  102   b.  The distal portion  114   c  of the distal link  102   c  may include a tapered or shaped portion configured for insertion into the spinal area. 
         [0025]      FIGS. 3A and 3B  are sectional views showing one embodiment of a steering feature of the implant  100  using a plurality of tension members  118 . While only tension members  118   a  and  118   b  are shown attached to the distal link  102   c,  there may be other tension members for the other links. The links include a channel  120  for the tension members to go through from the link  102   c  to the proximal end of the implant  100 , exiting through one of the apertures  116   b  of proximal link  102   a.  It should be understood that each of the links  102   b  and  102   c  are coupled to at least two tension members  118  to control their rotation. The tension members are attached to each link on opposite sides of the pin  104  such that pulling on one of the tension members rotates the link in a clockwise direction and the pulling the other rotates the link in the counter clockwise direction. This allows the links to be rotated separately or together and steer the implant  100  in the desired direction. In  FIG. 3A , when tension member  118   a  is pulled, link  102   c  is rotated in a counterclockwise direction, steering the implant in a downward direction. In the example shown in  FIG. 3B , tension member  118   b  is pulled, rotating link  102   c  in a clockwise direction, steering the implant in an upward direction. 
         [0026]    The top portion  106  and the bottom portion  108  may include a plurality of protrusions or teeth  122  (hereinafter, referred to as “teeth”). The teeth  122  may be spaced throughout the top portion  106  and the bottom portion  108  and are positioned so as not to interfere with the rotating of the links. As can be understood by one skilled, the teeth  122  can be configured to have variable thickness, height, and width as well as angles of orientation. The teeth  120  can be further configured to provide additional support after the steerable implant  100  is implanted in the vertebrae of the patient. The teeth  122  can reduce movement of the steerable implant  100  in the vertebrae and create additional friction between the vertebrae and the steerable implant  100 . In the embodiment shown, the teeth  122  have a shape of triangular protrusions extending away from the surfaces of the top and bottom portions of the steerable implant  100  in a saw-tooth configuration. As can be understood by one skilled in the art, the teeth  122  can be configured to have any shape, size, and/or angular or any other orientation as well and can protrude any distance away from the surfaces of the steerable implant and can have any distance between them. In some embodiments, the tooth patterns have a quad-directional configuration (i.e., teeth  122  are facing in four different directions). 
         [0027]    In some embodiments, the links  102  may have openings  103  configured to allow graft and Demineralized Bone Matrix (“DBM”) packing. 
         [0028]    The rotation of the links  102  allow better movement and flexibility of the steerable implant  100  to match the shape of the vertebrae discs of the patient. As shown in  FIGS. 7A and 7B , rotating the links in the caudal/cephalic direction allows the steerable implant  100  to be inserted into disk spaces that non-steering implants may have difficulty reach. As can be understood by one skilled in the art, the links  102  may have varying heights. For example, the height distal link  102   c  may be less than the height of intermediate  102   b  or proximal link  102   a.  Further, in some embodiments, the height of the links  102  can vary throughout the device. In other embodiments, the height can also vary between each side of the link  102 . This means that, for example, a portion of the front side  110  can have a lesser height than another portion of the back side  110 . Such variation in heights throughout the sides of the steerable implant  100  can be based on a particular design choice and further configured to accommodate various dimensions of the vertebrae of the patient. 
         [0029]      FIGS. 4 ,  5 A, and  5 B show one embodiment of an instrument  130  that may be used to implant the steerable implant  100 . The instrument includes a shaft portion  132  having a distal end  134  that is coupled to the proximal end  112   a  of the implant  100  at apertures  116  and a proximal end  136  coupled to a handle  138  having a steering lever  140 . The tension members  118 A and  118 B extend through the shaft  132  and handle  138  and are coupled to the steering lever  140 . In use, by moving the steering lever  140  up or down (arrow  142 ), the implant links  102  move in either a clockwise or counterclockwise direction. There may also be various knobs  144  that used to attach the instrument  130  to the implant using attachment shafts or components not shown, or the knobs  144  may be used to disassemble the instrument  130 . 
         [0030]      FIGS. 6A and 6B  are sectional views illustrating steering of the implant  100  using the instrument  130  and actuation lever  140 . Note, not all of the components are shown in these illustrations. In  FIG. 6A , when the actuation lever  140  is moved in a downward direction  142   a,  tension member  118   a  (dashed line), is pulled, rotating the links  102  in a counterclockwise direction and steering the implant down. In  FIG. 6B , when the actuation lever  140  is moved in an upward direction  142   b,  tension member  118   b  (solid line) is pulled, rotating the links  102  in a clockwise direction and steering the implant up. In the embodiments shown, the tension members  118   a  and  118   b  are attached to the links such that all of the links rotate or move in unison. In other embodiments, each of the links  112  may be attached to separate tension members  118  such that each of the links  112  may rotate or move separately. This may allow additional steering capability for the steerable implant  100 . 
         [0031]      FIGS. 7A and 7B  illustrate installation of the steerable implant  100  into patient&#39;s vertebrae  124 .  FIG. 7A  illustrates the steerable implant  100  being in a curved configuration for steering into the spinal opening  126 .  FIG. 7B  illustrates the steerable implant  100  fully inserted between the vertebrae  124 . 
         [0032]      FIGS. 8-11B  illustrate an embodiment of a steerable spine implant system in which the steerable spine implant  100  travels along a guide wire  218 . For example, in some surgical procedures, the guide wire  218  may be inserted into the spinal opening  126  to enable insertion of various instruments including dilators, discectomy tools, and suction devices. The guide wire  218  may also be threaded through one of the various apertures  116 , such as aperture  116   a  of the implant  100 . When the links  102  are coupled together, the apertures  116  form a continuous guide wire channel from a proximal end to the distal end of the implant  100 . The implant  100  then slides along the guide wire  218  into the spinal opening  126  and the guide wire  218  may subsequently be released. In this embodiment, the tension member  118  may be used in conjunction with the guide wire  218  or may be omitted. 
         [0033]    In some embodiments, the steerable implant  100  can be manufactured from a biologically accepted inert material, such as PEEK (Polyetheretherketone) or metal. The steerable implant can be configured to be implanted between the vertebrae for treating degenerative or ruptured discs and/or for replacing damaged vertebral bodies. Each link can be particularly shaped and sized for its particular application. 
         [0034]    In some embodiments, the steerable implant  100  can be sized larger than the vertebral body and/or configured to be implanted so that it rests on an apophyseal ring of a vertebrae (which is one of the strongest portions in a vertebral body). As can be understood by one skilled in the art, the steerable implant  100  can be sized and shaped as well as implanted as desired in accordance with a particular medical necessity or other factors. 
         [0035]    Example embodiments of the methods and components of the present invention have been described herein. As noted elsewhere, these example embodiments have been described for illustrative purposes only, and are not limiting. Other embodiments are possible and are covered by the invention. Such embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.