Abstract:
A device having an adjustable height and angle to space vertebral members. The device includes a plurality of links that extend between a plate and a deployer. A first section of the deployer is moved to change the angle of the plurality of links and expand the height of the spacer. A second section of the deployer is moved to change the angle of the plate relative to the centerline. A method of using the spacer is also disclosed and includes positioning the spacer while in the closed orientation between the vertebral members. The spacer is then expanded to a second height. The angle of the spacer is than adjusted as necessary to space the vertebral members.

Description:
BACKGROUND 
     Various devices are used for controlling the spacing between vertebral members. These devices may be used on a temporary basis, such as during surgery when it is necessary to access the specific surfaces of the vertebral members. One technique in which this type of device may be used is during preparing the endplates of a vertebral member. The devices may also remain permanently within the patient to space the vertebral members. 
     It is often difficult to position the device between the vertebral members in a minimally invasive manner. A device that is small may be inserted into the patient and between the vertebral members in a minimally invasive manner. However, the small size may not be adequate to effectively space the vertebral members. A larger device may be effective to space the vertebral members, but cannot be inserted into the patient and between the vertebral members in a minimally invasive manner. 
     The devices may also only allow for a minimum amount of adjustability. Once placed in the patient, the devices can only be altered to a small extent. Additionally, adjusting the devices may be difficult either from an ergonomic standpoint, or from the amount of force necessary for adjustment. 
     SUMMARY 
     The present invention is directed to a spacer to space vertebral members. Both the height and the angle of the spacer may be adjusted as necessary. The device includes a spacer positioned on a distal end of a deploying device. The deploying device has an elongated shape such that the spacer can be positioned between the vertebral members, and a proximal section of the mechanism is positioned a distance away to allow a physician to manipulate the height and angle. 
     In one embodiment, the device includes first and second plates. A distal end of a deploying device may be positioned between the plates. First, second, and third link pairs may each comprise a first end connected to the first plate, and a second end connected to the second plate. The first link pair may be connected to a first section of the deploying device at a first connection. The second link pair may be connected to a second section of the deploying device at a second connection. The third link pair may be connected to a third section of the deploying device at a third connection. The deploying device may adjust the spacer height by moving the first section relative to the second section to adjust the spacer between open and closed orientations. Additionally, the deploying device may adjust the angle of the spacer by moving the third section relative to the second section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the spacer in an open orientation according to one embodiment of the present invention; 
         FIG. 2  is a side view illustrating the spacer in a closed orientation according to one embodiment of the present invention; 
         FIG. 3  is a side view illustrating the spacer in an open orientation according to one embodiment of the present invention; 
         FIG. 4  is a side view illustrating the spacer in another open orientation according to one embodiment of the present invention; 
         FIG. 5  is a perspective view of the distal end of the deploying device in a first orientation according to one embodiment of the present invention; 
         FIG. 6  is a perspective view of the distal end of the deploying device in a second orientation according to one embodiment of the present invention; 
         FIG. 7  is a perspective view of the spacer attached to the deploying device according to one embodiment of the present invention; 
         FIG. 8  is an exploded view of the first member, second member, and third member according to one embodiment of the present invention; 
         FIG. 9  is a partial side view of the proximal section of the first member and second member according to one embodiment of the present invention; 
         FIG. 10  is a partial side view of the proximal section of the second member and third member according to one embodiment of the present invention; 
         FIG. 11  is a partial perspective view of the first deploying device according to one embodiment of the present invention; 
         FIG. 12  is an exploded view of the first deploying device according to one embodiment of the present invention; and 
         FIG. 13  is an exploded view of the second deploying device according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is directed to tool to space vertebral members. The tool includes a spacer  10  and a deploying device  60  as illustrated in  FIG. 7 . The deploying device  60  controls both the height and the angle of the spacer  10 . The spacer  10  positioned on a distal end of the deploying device  60 . The deploying device  60  has an elongated shape such that the spacer  10  is positioned between the vertebral members, and a proximal section of the mechanism is positioned a distance away to allow a physician to manipulate the height and angle. 
     The spacer  10  is selectively positionable between a closed orientation ( FIG. 2 ) and an open orientation ( FIGS. 3 and 4 ). The spacer  10  has an enlarged height in the open orientation defined by the distance between the upper and lower plates  41 ,  42 . The plates  41 ,  42  move outward from a centerline C as the spacer  10  expands to the open position. The plates  41 ,  42  may also be angled relative to the centerline C to adjust for a variety of angles. 
     The first plate  41  and second plate  42  contact the vertebral members and form the outer surfaces of the spacer  10 . As illustrated in embodiment of  FIG. 2 , each of the plates  41 ,  42  has an angled shaped towards the distal end. A nose  73  at the distal end of the first member  70  of the deploying device  60  conforms to the angled shapes giving the device a bullet shape that facilitates insertion between the vertebral members. Ridges  43  may be positioned on the plates  41 ,  42  to secure the device  10  in the disc space between the vertebral members. 
     A deploying device  60  controls the positioning of the plates  41 ,  42 . A distal end of the deploying device  60  is positioned within the plates  41 ,  42 . As illustrated in  FIGS. 5 and 6 , the deploying device between the plates  41 ,  42  include a first member  70 , a second member  80 , and a third member  90 . Relative movement of these members results in the deployment of the spacer  10  as will be explained in detail below. First member  70  includes a nose  73  having an angled configuration at the distal end. An aperture  71  and slot  72  are proximal to the nose. The distal end of the second member  80  includes a pair of arms  81 ,  82  that extend around the first member  70 . Apertures  83  in each of the arms  81 ,  82  align with the slot  72  in the first member  70 . The distal end of the third member  90  includes a first third member  91  and a second third member  92  that align on opposite sides of the second member  80 . Apertures  93  are positioned towards the distal end of each third member  91 ,  92 . 
     A series of links extend between the plates  41 ,  42  and the deploying device  60 . The device includes links extending along both a first side and second side of the deploying device  60 . Each side is substantially identical and only a first side will be explained in detail with the understanding that a corresponding link structure is also included on the second side. In one embodiment, each of the links has the same length. 
     Each of the links includes a first end attached to the deploying device  60 , and a second end attached to one of the plates  41 ,  42 . Specifically, the series of links include: link  24  extending between the first member  70  and the upper plate  41 ; link  25  extending between the first member  70  and the lower plate  42 ; link  26  extending between the second member  80  and the upper plate  41 ; link  27  extending between the second member  80  and the lower plate  42 ; link  28  extending between the third member  90  and the upper plate  41 ; and link  29  extending between the third member  90  and the lower plate  42 . 
     Each of the links is positioned in a two-pair combination that connects to the upper plate and the lower plate (i.e., link pair  24  and  25 , link pair  26  and  27 , link pair  28  and  29 ). The link pairs are constructed to overlap to conserve space and allow the plates  41 ,  42  to be positioned in closer proximity when the spacer  10  is in the closed orientation. In one embodiment as illustrated in  FIG. 1 , each link in the pair includes a complementary recessed shape  51 . The recessed shapes  51  mate together in the closed orientation. 
     Links  24  and  26 , and links  25  and  27  are operatively connected to form a linkage. Movement of one of the links of the linkage causes movement of the other link of the linkage. Embodiments of links, link pairs, and linkages are disclosed in U.S. patent application Ser. No. 10/178,960 entitled “Minimally Invasive Expanding Spacer and Method” filed Jun. 25, 2002, assigned to SDGI Holdings, Inc., the owner of the current application, and is herein incorporated by reference in its entirety. 
     Connection members pivotally connect the links to the plates  41 ,  42  and the deploying device  60 . In one embodiment, a first connection member  30  extends through links  24 ,  25 , through the aperture  71  in the first member  70 , and through the corresponding links on the second side of the deploying device  60 . Second connection member  31  extends through links  26 ,  27 , apertures  83  in the second member  80 , slot  72  in the first member  70 , and through the corresponding links on the second side of the deploying device  60 . Third connection member  32  extends through links  28 ,  29 , and through aperture  93  in the third member  90 . The third connection member  32  does not extend through the first member  70  or the second member  80 . A corresponding connection member connects the two proximal links on the second side of the deploying device  60   10  to the third member  90 . Additional connection members  39  connect the links to the plates  41 ,  42 . 
     Deployment of the spacer  10  is caused by relative movement of members of the deploying device  60 .  FIG. 2  illustrates a side view of the spacer  10  in a closed orientation. In one embodiment, spacer  10  has a length of about 30 mm, a width of about 27 mm, and a height H of about 8.5 mm measured at the point of maximum convexity of the plates  41 ,  42 . The first connection member  30  is distanced from the second connection member  31  a distance X. The second connection member  31  is distanced from the third connection member  32  a distance Y. 
       FIG. 3  illustrates the spacer  10  in an open orientation. The open orientation features the plates  41 ,  42  spaced from the centerline C. The expansion is caused by the first member  70  moving proximally relative to the second member  80  and the third member  90 . The relative position of the first connection member  30  has moved relative to the second connection member  31  and the third connection member  32 . This is seen as the distance X has decreased from that illustrated in  FIG. 2 . The distance Y between the second and third connection members  31 ,  32  remain the same. The force of the first member  70  moving proximally results in the links being deployed. 
     During the deployment, the first member  70  is proximally moved along the spacer  10 . The movement results in the first connection member  30  that is positioned within aperture  71  also moving proximally. The second connection member  31  slides within the slot  72  in the first member  70  from a proximal end of the slot  72  when the spacer  10  is closed, to a distal end of the slot  72  when the spacer is deployed. This movement is illustrated in  FIGS. 5 and 6  (second connection member  31  is removed in  FIGS. 5 and 6  for clarity). The third connection member  32  is not connected to the first member  70  and therefore does not move. The deployment by moving the first member  70  results in the plates  41 ,  42  being substantially parallel during the range of deployment. The height of the spacer  10  is controlled by the amount of movement of the first member  70 . In one embodiment, the height H of the spacer is about 15.4 mm measured from the points of maximum convexity of the plates  41 ,  42 . 
       FIG. 4  illustrates the spacer  10  with the plates  41 ,  42  in the open orientation and at an angle relative to the centerline C. The angle α is the angle formed by both plates  41 ,  42 . In one embodiment, angle α is referred to as the lordotic angle. In one embodiment, the angle α may range from about 0° to about 19°. The angle α is formed by moving the third connection member  32  relative to the second connection member  31 . As illustrated in  FIGS. 3 and 4 , third member  90  is moved proximally causing the plates  41 ,  42  to form the angle α. The distance Y between the second and third connection members  31 ,  32  is decreased causing the proximal links  28 ,  29  to push outward on the proximal sections of the plates  41 ,  42 . The relative movement between the second and third connection members  31 ,  32  controls the degree of the angle α. In one embodiment, the distance between the distal ends of the plates  41 ,  42  is about 6.7 mm. 
       FIGS. 5 and 6  illustrate the relative movement of the second and third members  80 ,  90  (third connection member  32  has been removed from  FIGS. 5 and 6  for clarity). The third connection member  32  positioned within aperture  93  extends through the third member  90  without extending through the second member  80 . Therefore, movement of the third member  90  does not result in movement of the second member  80 . As the third member  90  moves in the direction of arrow A, the amount of angle α increases accordingly. 
     The deploying device  60  causes the spacer  10  to move between the open and closed orientations, and also between a variety of angles α. Deploying device  60  includes a first deploying device  61  for changing the height of the spacer  10 , and a second deploying device  62  for changing the angle α. As illustrated in  FIGS. 7 and 8 , the proximal end of deploying device  60  is distanced from the distal end for the physician to remotely control the size and angle of the spacer  10 . In one embodiment, the first member  70  includes an elongated proximal section that fits within an elongated section of the second member  80 . The first member  70  is sized to move within the second member  80 . The elongated section of the second member  80  with the internal proximal first member fits within the third member  90 . The third member  90  is sized to move relative to the second member  80 . 
     A first deploying device  61  for changing the height of the spacer  10  is illustrated in  FIGS. 7 and 9 . First member  70  includes a lock  100  mounted to the proximal end. Lock  100  includes a seat  101  and a sleeve  102  each having a larger cross-sectional size than a hollow interior of the second member  80 . The first member  70  may be moved axially along the second member  80  between a point where the distal end of the sleeve  102  contacts the proximal end of the second member  80 , and a distance where the distal sleeve end is spaced from the proximal second member end (as illustrated in  FIG. 9 ). In one embodiment, an axial force applied to the first member  70  moves the first member relative to the second member  80 . In another embodiment, the distal end of the first member  70  is threaded and mates with threads on the interior of the sleeve  102 . Rotation of the sleeve  102  causes the sleeve to move along the first member  70  with the distal end of the sleeve  102  contacting and pushing the proximal end of the second member  80 . Continued rotation causes the first member  70  to be pulled proximally relative to the second member  80 . In both embodiments, the proximal movement of the first member  70  causes the height of the spacer  10  to increase. A force applied in the opposite direction, or rotation of the sleeve  102  in the opposite direction allows for the first member  70  to be moved distally relative to the second member  80  to reduce the height of the spacer  10 . 
     In the rotational embodiment explained above, a knob  109  may be connected to the sleeve  102  as illustrated in  FIG. 7 . A gauge  102  may be positioned adjacent to the knob  101  to determine the height of the spacer  10 . In one embodiment, gauge  102  includes a progressive scale that aligns with a reference point  103 . The height of the spacer  10  can be determined by the position of the gauge  102  relative to the reference point  103 . 
     A second deploying device  62  controls the angle α. As illustrated in  FIGS. 8 and 10 , the proximal end of the third member  90  includes an extension  94  and a pair of spaced apart fingers  95 . The proximal end of the second member  80  includes a threaded section  84  with a threaded knob  85  ( FIG. 7 ). The knob  85  is rotated about the threaded section  84  with a distal end of the knob contacting the extension  94  to move the third member  90  in a distal direction and thus adjusting the amount of angle α. The amount of rotation of the knob  85  controls the amount of angle α. As illustrated in  FIG. 9 , a gauge  99  may be placed adjacent to the knob  85  to determine the amount of rotation and thus the amount of spacer angle α. 
       FIG. 7  illustrates a cover  110  extending over the proximal section of the deploying device  60 .  FIG. 11  illustrates the proximal section without the cover  110 .  FIG. 12  illustrates an exploded view of the proximal section of the first deploying device  61  that controls the spacer height. A screw  111  is connected to the seat  101  and a frame  114  is connected to the second member  80 . A sleeve  112  is mated to the frame  114  and is retained by a retaining ring  115 . The retaining ring  115  rotates freely about the third member  90  (not illustrated). Rotation of the knob  109  rotates the sleeve  112  and moves the screw  111  proximally. This proximal movement provides the distraction of the spacer  10 . Lock  113  is inserted into an aperture in screw  111  and mates with machined flats on seat  101 . 
       FIG. 13  illustrates an exploded view of the second deploying device  62 . The distal end of the third member  90  includes spaced apart forks  95 . The second member  80  is positioned within the third member and the threaded section  84  is positioned at a proximal end of the forks  95 . A sleeve  120  extends over the fork  95  and is retained by a retaining ring  125 . The retaining ring rotates freely about the third member  90 . An internal thread on the sleeve  120  engages with the threaded section  84  on the second member  80 . The forks  95  are machined to index with machined edges of the threaded section  84 . Rotation of the knob  85  rotates the sleeve  120  that travels along the thread of the threaded section  84  and moves the third member  90  to move distally. 
     The arrangement of the first member  70 , second member  80 , and third member  90  may have a variety of configurations. In the embodiments illustrated, the first member  70  and second member  80  are nested within the third member  90 . In other embodiments, the first member  70  and/or second member  80  may be positioned external to each other and the third member  90 . The various arrangements should provide for relative movement of the members of the deploying device  60  to allow for changes in height and angles. 
     The angle α of the spacer  10  may also be negative with the proximal ends of the plates  41 ,  42  being in closer proximity than the distal ends. This is accomplished by moving the third connection member  32  proximally relative to the second connection member  31 . 
     The term vertebral member is used generally to describe the vertebral geometry comprising the vertebral body, pedicles, lamina, and processes. The spacer  10  may be sized and shaped, and have adequate strength requirements to be used within the different regions of the vertebra including the cervical, thoracic, and lumbar regions. In one embodiment, spacer  10  is positioned within the disc space between adjacent vertebra. Plates  50  contact the end plates of the vertebra to space the vertebra as necessary. In one embodiment, the spacer  10  is inserted posteriorly in the patient. In another embodiment, the spacer  10  is inserted from an anteriorly into the patient. In another embodiment, the spacer is inserted laterally into the patient. 
     In another embodiment (not illustrated), spacer  10  includes only one moving plate. A first plate moves as discussed above, and a second plate is stationary. The links move outward from the stationary plate to expand the height of the spacer  10  to the open orientation. This embodiment may include any number of links depending upon the desired spacing and strength requirements. In one embodiment, the first plate  41  expands away from the plate  42  by links  24 ,  26 ,  28 . 
     The spacer  10  may be removable from the deploying device  60 . The spacer  10  may be temporarily left between the vertebral members with the deployment mechanism removed during the procedure to provide the physician with a better view and greater work area. After the procedure, the spacer  10  may remain within the patient between the vertebral members, or the deploying device  60  may be re-engaged for spacer removal. The spacer  10  may also be returned to the closed orientation after re-engagement and prior to the spacer  10  being removed from the patient. 
     The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. In one embodiment, spacer  10  and delivery device  80  are constructed of stainless steel. In one embodiment, the distal ends of the plates  41 ,  42  contact in the closed orientation. The first deploying device  61  may be positioned proximal to or distal to the second deploying device  62 . The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.