Abstract:
A device for inserting an intervertebral implant into a body includes a flexible end portion having a free end, a thickened portion including an outward protrusion on the flexible end portion at or adjacent the free end, and a stop including an outward protrusion on the flexible end portion positioned at a distance from the free end and spaced apart from the thickened portion, wherein a portion of the flexible end portion between the thickened portion and the stop has outer walls separated by a distance that is less than distances separating outer walls of the thickened end portion and the stop, respectively, and wherein the flexible end portion can assume a first state wherein the outer walls of the portion of the flexible end portion between the thickened portion and the stop are separated by a first distance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    The present application claims the benefit of U.S. Provisional Patent Application Ser. No, 61/496,804, filed Jun. 14, 2011, the contents of which are hereby incorporated by reference in their entirety, and claims priority to European Patent Application EP 11 169 886.6, filed Jun. 14, 2011 the contents of which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a device for inserting an intervertebral implant into a body, and to a system including the intervertebral implant and the device. The intervertebral implant has a top surface configured to engage a first vertebral body, a bottom surface configured to engage a second vertebral body, and a side wall connecting the top surface and the bottom surface. In the side wall, an elongate opening is provided. The device for inserting the intervertebral implant includes a flexible end portion that can assume a first state where the end portion can be introduced into and removed through the opening, and a second state where the end portion cannot be removed from the implant. In the second state the device may be connected to the intervertebral implant, where the implant and the device may be movable relative to each other along the elongate opening. 
         [0004]    2. Description of Related Art 
         [0005]    A device for the insertion of surgical implants is known from U.S. Pat. No. 7,235,082 B2. The device includes a shaft defining a conduit and having proximal and a distal end. At least one movable element is provided that includes a leg extending through the conduit and a foot. The movable element is movable relative to the shaft between a first position, wherein the foot extends beyond the distal end and a second position, wherein the foot is substantially adjacent to the distal end and wherein the distal end extends through an opening of the implant. 
         [0006]    An intervertebral implant configured to engage with an insertion device for inserting between first and second vertebral members is known from US 2007/0162129 A1. The intervertebral implant has an opening including an elongated shape that extends through the side wall. A connection member including a receptacle is contained within the side wall. The insertion device has a first end that may be configured to connect with the connection member of the implant body. The first end may be selectively positionable between orientations to provide for the connection. 
       SUMMARY 
       [0007]    It is an object of the invention to provide a device for inserting an intervertebral implant, and a system including such an intervertebral implant and device, that is simplified in terms of its use and that is more flexible or adjustable in terms of the final positioning of the implant. 
         [0008]    The device for inserting the intervertebral implant simplifies the procedure of insertion, since the connection between the device and the implant can be easily fixed and loosened. When the connection is loose, the implant can be moved into a desired position by rotating the implant relative to the device in a plane that extends through the center of the side wall. A design of the device for inserting the implant ensures that a maximum or large portion of a hollow interior space of the implant can be used for fusion. 
         [0009]    When the intervertebral implant is rotated to achieve a desired position between vertebrae, it is safely held by the device and protected against being disconnected from the device. 
         [0010]    Final positioning of the implant and removal of the device is also simplified. 
         [0011]    Existing intervertebral implants can also be modified to be adapted to the insertion device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Further features and advantages of the invention will become apparent from the description of the accompanying drawings. In the drawings: 
           [0013]      FIG. 1  shows a perspective view of an embodiment of a system including an intervertebral implant and a device for inserting or implanting the intervertebral implant; 
           [0014]      FIG. 2  shows an exploded perspective view of the system of  FIG. 1 , where a portion of the device for insertion is depicted; 
           [0015]      FIG. 3   a  shows a cross-sectional view of the intervertebral implant and an end portion of the device for insertion according to an embodiment, where the cross-section is taken along line C-C of  FIG. 3   b;    
           [0016]      FIG. 3   b  shows a top view of the system including the intervertebral implant and the portion of the device shown in  FIG. 3   a;    
           [0017]      FIG. 4   a  shows a cross-sectional view of the intervertebral implant and the device for insertion according to an embodiment, where the device is in a first state that allows for introduction or insertion into an opening of the implant; 
           [0018]      FIG. 4   b  shows a top view of the system shown in  FIG. 4   a;    
           [0019]      FIG. 5   a  shows a cross-sectional view of the intervertebral implant and the device introduced into the opening of the implant according to an embodiment, where a pin of the device is in a retracted position; 
           [0020]      FIG. 5   b  shows a top view of the intervertebral implant and the device of  FIG. 5   a;    
           [0021]      FIG. 6   a  shows a cross-sectional view of the intervertebral implant and the device introduced into the opening of the implant according to an embodiment, where the pin of the device is in a protruding or extended position; 
           [0022]      FIG. 6   b  shows the intervertebral implant and the device of  FIG. 6   a  in a top view; 
           [0023]      FIG. 7  shows the intervertebral implant and the device inserted into the opening of the intervertebral implant according to an embodiment, where the intervertebral implant is rotated relative to the device in a plane extending through the center of the side wall of the implant; 
           [0024]      FIG. 8  shows the intervertebral implant and the device removed from the intervertebral implant according to an embodiment; and 
           [0025]      FIGS. 9   a  to  9   f  show steps for inserting and positioning the intervertebral implant into a body according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]      FIG. 1  shows a perspective view of one embodiment of an intervertebral implant  1  and a device  20  for inserting the intervertebral implant  1  into, for example, a patient, where the device  20  is attached to the implant  1 . As shown in particular in  FIGS. 1 and 2 , the intervertebral implant  1  includes a top face  2  and a bottom face  3  that are configured to engage respective end plates of a first vertebral body and a neighboring second vertebral body. The top face  2  and the bottom face  3  are connected via a side wall  4  that defines an interior hollow section  5 . Generally, the top face  2  and the bottom face  3  have openings so that the hollow interior section  5  extends into the top face  2  and the bottom face  3 . In the embodiment shown, the top face  2  and the bottom face  3  are formed by the upper and lower rims of the side wall  4 , respectively. Furthermore, a center wall  6  may be provided that separates the hollow interior section  5  in two parts. The height of the side wall  4  is sized so as to allow insertion of the implant  1  between a first and a second vertebral body. The height of the implant  1  may be larger at the center wall  6  and may decrease towards outer ends of the implant  1 . Teeth  7  or other engagement portions are provided that project from the top face  2  and the bottom face  3  for engaging the respective end plates. 
         [0027]    In the embodiment shown, the implant  1  has two opposing long sides  4   a  and two opposing short sides  4   b  connecting the long sides  4   a . The short sides  4   b  may be rounded. The contour of side wall  4  may be arcuate, for example it may have a kidney-shape or a banana-shape. 
         [0028]    As shown in particular in  FIG. 2 , an opening  8  in the side wall  4  is provided that extends completely through the side wall  4  into the interior hollow section  5 . The opening  8  has an elongate shape and extends preferably over a length in a circumferential direction along a short side  4   b . The opening  8  may have a substantially rectangular contour with an upper edge  8   a  and a lower edge  8   b , and may be located substantially in a middle of the side wall  4  along a vertical direction between the top face  2  and the bottom face  3 . 
         [0029]    The implant  1  shown in the embodiment is only an example. The contour and shape of the implant may be different according to the specific clinical requirements. For example, the contour may have any other shape, such as circular, rectangular, oval, etc. In some embodiments, the height of the side wall may be constant throughout the implant. The opening can be at another position. Only one opening or more than one opening may be provided. Also, it may be possible to adapt existing intervertebral implants without an opening, by providing it with such an opening. Further, in some embodiments, the center wall can be omitted. 
         [0030]    An embodiment of the device for inserting the intervertebral implant into, for example, a body of a patient, will now be explained with reference to  FIGS. 1 to 8 . The device  20  includes an end portion  21  that is configured to be introduced into the opening  8  of the intervertebral implant  1  and to hold the intervertebral implant  1 . The end portion  21  is a sleeve-like member having a flexible front portion  22 . The flexible front portion  22  is formed by two opposing tongues  23   a ,  23   b  that are formed or separated by a slot  24  extending from a free edge of the sleeve-like end portion  21  through opposing portions or sides of the end portion  21 . 
         [0031]    Each tongue  23   a ,  23   b  includes at its free end a thickened portion  25   a ,  25   b . The thickened portions  25   a ,  25   b  extend outward so that an outer diameter of the tongues is increased, as can be seen, for example, in  FIGS. 3   a  and  3   b . A contour or shape of the thickened portions  25   a ,  25   b  seen in a direction perpendicular to the sleeve axis A may be substantially rectangular. The thickened portions  25   a ,  25   b  each have a chamfered front wall  26   a ,  26   b  and a chamfered rear wall  27   a ,  27   b . The rear walls  27   a ,  27   b  may be curved, with a curvature corresponding to a curvature of the side wall  4  in the region of the opening  8 . 
         [0032]    In addition, each tongue  23   a ,  23   b  has an outwardly extending rib  28   a ,  28   b  positioned at a distance from the thickened portion  25   a ,  25   b , where said distance is equal or greater than a wall thickness of the side wall  4  of the implant  1  at the opening  8 . Hence, portions of the side wall  4  around the opening  8  of the intervertebral implant  1  fit into portions  29   a ,  29   b  between portions  25   a ,  25   b  and ribs  28   a ,  28   b , respectively. In a top view, as shown in  FIGS. 3   b  and  4   b , a side of the ribs  28   a ,  28   b  that face the free end of the sleeve-like end portion  21  may be inwardly curved. The curvature may correspond to the curvature of the side wall  4  in the region of the opening  8 . The portions  29   a ,  29   b  between the thickened portions  25   a ,  25   b  and the ribs  28   a ,  28   b  may be flat to allow for even contact with the upper and lower edges  8   a ,  8   b  of the opening, respectively. 
         [0033]    The outer diameter of the flexible front portion  22  of the sleeve-like end portion  21  is sized such that in a non-compressed state of the tongues  23   a ,  23   b  (e.g., when the tongues  23   a ,  23   b  are not biased towards one another) the thickened portions  25   a ,  25   b  form a maximum outer diameter or height that is greater than a height of the opening  8 . Also, when the tongues  23   a ,  23   b  are not compressed, the outer diameter or height formed by the portions  28   a ,  28   b  is also slightly larger than the height of the opening  8 . Meanwhile, an outer diameter or height of the end portion  21  formed by the portions  29   a ,  29   b  is smaller than the height of the opening  8 . The length and width and other sizes and properties of the slot  24  are such that it allows compression of the tongues  23   a ,  23   b  towards each other and introduction of the flexible front portion  22  into the opening  8  of the intervertebral implant  1 . An outer diameter or width of the sleeve-like end portion  21  at the position of the slot  24  is smaller than the length of the elongate opening  8 , so that the flexible front portion  22  may move along the length of the elongate opening  8  in a circumferential or horizontal direction. 
         [0034]    The sleeve-like end portion  21  has a rear portion  30  with a larger outer diameter. The rear portion  30  may be connected to a first grip portion  51  of a tongs-like handle  50  that includes the first grip portion  51  and a second grip portion  52 . 
         [0035]    The device  20  for inserting the implant  1  further includes a pin  40  extending into the sleeve-like end portion  21 . The pin  40  has an outer diameter that allows it to slide within the sleeve-like end portion  21 . An inner diameter of the flexible front portion  22  of the sleeve-like end portion  21  is slightly smaller than the outer diameter of the pin  40 , so that, when the pin  40  is moved between the tongues  23   a ,  23   b , it slightly spreads the tongues  23   a ,  23   b  apart from each other. Thus, the sleeve-like end portion  21  and the pin  40  cooperate in the manner similar to a collet chuck with pin. The pin  40  is mounted to a portion  41  with an outer diameter greater than that of the pin  40 , and can slide in or relative to a connection bar  31  that connects the sleeve-like end portion  21  with the grip portion  51 . The pin  40  is connected through or via a connection bar  42  with the other grip portion  52  of the handle  50 . The grip portions  51 ,  52  are connected via hinges  61 ,  62  to the connection bars  31 ,  42 , respectively, so that, like with tongs, a moving of the grip portions  51 ,  52  towards each other moves the pin  40  relative to the sleeve-like end portion  21 . 
         [0036]    The pin  40  can assume a first position in which it is retracted relative to the tongues  23   a ,  23   b , as shown, for example in  FIGS. 3   a  to  4   b . The pin further can assume a second position in which it protrudes into the sleeve-like end portion  21  between the tongues  23   a ,  23   b , and spreads them apart. 
         [0037]    The grip portions  51 ,  52  are biased away from each other via leaf springs  53 ,  54 . Due to the hinges  61 ,  62 , the handle  50  is arranged at an angle with respect to the connecting bars  31 ,  42 . This facilitates handling and increases the possibilities for bringing the implant to its final position. 
         [0038]    The connection of the pin  40  and the sleeve-like end portion  21  to the handle  50  is only exemplary. Other constructions and other types of handles can be used to achieve the relative movement of the pin with respect to the sleeve-like end portion as described above. 
         [0039]    The implant  1 , as well as the portions of the device  20  for inserting the implant  1 , that may come in contact with a patient&#39;s body, are made of a biocompatible material. For example, the implant  1  and/or the device  20  may be made of stainless steel or titanium, or of a biocompatible metal alloy, such as a nickel-titanium alloy, or may be made of a biocompatible plastic material, such as for example, PEEK (polyetheretherketone). 
         [0040]    Operation of the device  20  for inserting the implant  1  will now be explained with reference to  FIGS. 3 to 9 . The device  20  and the implant  1  are oriented relative to each other such that the slot is parallel to or aligned with the upper and/or lower edge of the elongate opening. Hence, the tongues are on top of each other as seen from a height direction of the implant (See, e.g.,  FIG. 3   a ). First, as shown in  FIGS. 3   a  and  3   b , the pin  40  is in the first position, which is the retracted position. The tongues  23   a ,  23   b  are configured to be flexibly pressed towards each other, as shown in  FIG. 4   a . When the tongues  23   a ,  23   b  are pressed towards each other, the flexible front portion  22  can be introduced into the elongate opening  8  of the implant  1 , During introduction, the chamfered front walls  26   a ,  26   b  of the tongues  23   a ,  23   b  slide along the upper and lower edges  8   a ,  8   b  of the elongate opening  8 , respectively, until the uppermost and lowermost portions of the thickened portions  25   a ,  25   b  are in contact with the upper and lower edge  8   a ,  8   b  of the elongate opening  8 , respectively. This maintains or keeps the tongues  23   a ,  23   b  in a compressed state during the introduction. The tongues  23   a ,  23   b  may be slightly pre-compressed by bending them towards each other when the pin  40  is in the retracted position. 
         [0041]    When the thickened portions  25   a ,  25   b  of the flexible front portion  22  have passed the elongate opening  8  and have entered the hollow interior section  5  of the implant  1 , the tongues  23   a ,  23   b  spread back apart from each other until the upper and lower edges  8   a ,  8   b  of the elongate opening rest in the space portions  29   a ,  29   b , respectively, as can be seen in  FIGS. 5   a  to  6   b . In this condition, the tongues  23   a ,  23   b  can still initially be compressed towards each other. This makes it possible to move the flexible front portion  22  in the elongate opening  8  along the lengthwise direction of the opening. Hence, the flexible front portion  22  can be moved to a suitable position relative to implant  1  for introducing the implant  1  into the surgical site. The ribs  28   a ,  28   b  act as stops that prevent further introduction or insertion of the device  20  into the implant  1 . 
         [0042]    When the implant  1  and the device  20  for inserting the implant  1  are positioned correctly or in a desired position with respect to each other, the pin  40  is pushed further into the flexible front portion  22 , thereby spreading the tongues  23   a ,  23   b  slightly apart from each other until they abut against the upper and lower edges  8   a ,  8   b  of the elongate opening  8 , respectively. Thereby, the implant  1  is firmly held through engagement of the upper and lower edges  8   a ,  8   b  of the opening  8  with the portions  29   a ,  29   b  of the sleeve-like end portion  21 . This is shown in particular in  FIGS. 6   a  and  6   b.    
         [0043]    After the implant  1  has been positioned at the desired implantation site, the pin  40  is moved back from its second position into the retracted position, and the tongues  23   a ,  23   b  may be drawn out and removed from the opening  8 . Due to the chamfered rear walls  27   a ,  27   b , the tongues  23   a ,  23   b  can be pressed together when the flexible front portion  22  is drawn out from the implant  8 . This allows for retracting the flexible front portion  22  back through the elongate opening  8 . 
         [0044]    The use and implantation of the implant  1  during surgery will now be described with respect to  FIGS. 9   a  to  9   f .  FIGS. 9   a  to  9   f  show steps for inserting and positioning the intervertebral implant  1  into a body. First, as shown in  FIG. 9   a , the device  20  is connected to the implant  1 , preferably in such a way that the flexible front portion  22  is positioned at approximately a center of the elongate opening  8  in a lengthwise direction. By moving the pin  40  into the second position, the connection between the implant  1  and the device  20  can be fixed. Then the implant  1  is introduced into an intervertebral space between two neighboring vertebrae, where one of them is shown as vertebra  100  in the drawings. The narrow side  4   b  of the implant  1  opposite to where the device  20  is connected may serve as a leading side. In the method shown, the intervertebral implant  1  is introduced in the space between the vertebral bodies  100  using a posterior and lateral approach to access the space between the vertebral bodies  100 . 
         [0045]    When the implant  1  and the device  20  experience resistance and cannot be pushed further, for example, as shown in  FIG. 9   c , the fixation between the implant  1  and the device  20  is loosened by, for example, retracting the pin  40  back into the first position. Then, the implant  1  and the device  20  may be movable relative to each other, because the sleeve-like end portion  21  can move in the elongate opening  8 . By means of this, an angle between the implant  1  and the device  20  can be changed. As shown in  FIGS. 9   c  to  9   e , the implant  100  can then be pushed into its end position between the vertebral bodies  100 . 
         [0046]    Thereafter, the device  20  is removed or detached from the implant  1  by drawing the flexible front portion  22  out of the opening  8 . 
         [0047]    Since the device  20  can be connected to and separated from the implant  1  in an easy manner, handling of the respective parts is simplified. In addition, due to the thickened portions and the ribs of the device  20  that act as stops, inadvertent removal of the device  20  during the process of inserting the implant  1  can be prevented. 
         [0048]    Various modifications of the device for inserting the implant are also possible. For example, a number of the flexible tongues may vary. Also the shape of the tongues can vary. Further, in some embodiments, instead of the pin, another spreading member or mechanism can be used. 
         [0049]    While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is instead intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.