Patent Publication Number: US-2005119667-A1

Title: Clip-type surgical instrument for spinal implant

Description:
The present invention relates to a clip-type surgical instrument allowing the introduction and positioning of an immobilizing element in the head of a bone anchoring element that is a member of a spinal implant.  
      The surgical instrument according to the present invention is more particularly designed for spinal implants comprising a bone anchoring element comprising a U-shaped head provided to cooperate with an immobilizing element allowing through a tightening screw the immobilization in translation and rotation of a connection rod, interconnecting each bone anchoring element.  
      The surgical instrument according to the present invention is provided for improving and facilitating the introduction of each immobilizing element within the U-shaped head of the corresponding bone anchoring element.  
      The surgical instrument according to the present invention comprises a main body comprising a horizontal tube extending by a frame forming an integral unit with a fixed handle, a movable handle acting on a driving device guided within the frame and allowing, according to the pressure force applied on the movable handle on the one hand, the immobilization of the surgical instrument on the head of a bone anchoring element and on the other hand, the introduction under a pushing force F of an immobilizing element, previously positioned and guided within the tube, in the head of the bone anchoring element.  
      The surgical instrument according to the present invention comprises a movable handle that cooperates with the fixed handle through an axis of rotation and a laminated spring allowing the driving device to be activated under a pressure force and to return to its position of rest after releasing the pressure force.  
      The surgical instrument according to the present invention comprises a movable handle that comprises above the axis of rotation a head presenting a domed profile from which a fork extends wherein each branch comprises a free extremity at the rounded profile.  
      The surgical instrument according to the present invention comprises a frame that is comprised of two walls, i.e., a vertical wall and an opposite wall interconnected by upper and lower perforated walls, said vertical wall being formed as an integral unit with the horizontal tube presenting an internal bore opening within the frame, while the opposite wall is pierced by a hole carried by the same main axes as that of the internal bore, said upper wall presenting a central rectangular-shaped recess and an extension extending beyond the vertical wall and in which an oblong groove is pierced, while the lower wall comprises another recess disposed below the latter, said recess comprising internal shoulders designed to form a stop at the fixed handle.  
      The surgical instrument according to the present invention comprises a locking tube comprising at one of its extremities fork-shaped branches, each notched so that the free extremities of each branch of the movable handle cooperate respectively with said notches to allow under the action of the movable handle the sliding of the locking tube around the tube, and at the opposite extremity a cylindrical sleeve extending by parallel tabs.  
      The surgical instrument according to the present invention comprises a cylindrical plunger that crosses the frame through the hole provided in the vertical wall to slide in the internal bore of the tube.  
      The surgical instrument according to the present invention comprises a driving device that is comprised of a first plate elastically loaded by a spring and disposed within the frame so as to cooperate with the recesses of the upper and lower walls and the cylindrical plunger and of a second plate elastically loaded by a spring and disposed within the extension groove of the upper wall so as to cooperate with the cylindrical plunger, said first plate being provided for bearing, under the force of the spring, against the domed profile of the movable handle head allowing during the activation of the latter the displacement in translation of the cylindrical plunger within the tube, due to the straight position of the first plate.  
      The surgical instrument according to the present invention comprises a tube that comprises in the extension of the cylindrical internal bore and at its free extremity, another internal bore wherein the internal profile is complementary to the external profile of the immobilizing element in order to be able to receive and guide the latter before its introduction in the head of the bone anchoring element.  
      The surgical instrument according to the present invention comprises a cylindrical tube that is extended at its free extremity by a roughly rectangular sleeve wherein each parallel and opposite wall comprises a U-shaped cutout designed to cooperate with the connection rod of the spinal implant.  
      The surgical instrument according to the present invention comprises a cylindrical tube wherein the internal profile of the sleeve is measured in slightly greater dimensions than those of the internal bore in order to conform the shoulders forming a stop to the input of the latter.  
      The surgical instrument according to the present invention comprises a cylindrical tube that comprises on its external profile flat parts that are extended on each wall of the sleeve, each flat part being pierced at the tube of the first and second holes opening within the bore and at the walls of the sleeve of a third hole opening.  
      The surgical instrument according to the present invention comprises a cylindrical tube wherein each first hole presents an internal threading allowing it to cooperate with a tightening screw for fixing two elastic strips in each flat part.  
      The surgical instrument according to the present invention comprises a cylindrical tube wherein each elastic strip is formed as an integral unit with a pin cooperating with the second corresponding hole and within the bore to allow the immobilizing elements to be held within the latter.  
      The surgical instrument according to the present invention comprises a cylindrical tube wherein each elastic strip is formed as an integral unit with a pin cooperating with the third hole of the sleeve in order to be able to penetrate within the latter when the strips are deformed by an external pushing force coming from the tabs of the locking tube in order to allow the surgical instrument to be fixed on the head of the bone anchoring element. 
    
    
      The description that is going to follow with regards to the attached drawings is given by way of non-limiting example, and will allow the invention, the characteristics that the invention presents and the advantages that the invention is likely to bring to be better understood:  
       FIG. 1  is an exploded perspective view illustrating for example a bone anchoring element of a spinal implant for which the surgical instrument according to the present invention may be utilized.  
       FIG. 2  is a view representing the surgical instrument according to the present invention.  
       FIG. 3  is a detailed view showing the driving device of the surgical instrument according to the present invention.  
       FIG. 4  is a perspective view illustrating the movable handle of the surgical instrument according to the present invention.  
       FIG. 5  is a perspective view showing the frame of the main body of the surgical instrument according to the present invention.  
       FIG. 6  is a view illustrating the cylindrical plunger of the surgical instrument according to the present invention.  
       FIGS. 7 and 8  are detailed views representing the free extremity of the main body to be fixed on that of the bone anchoring element.  
       FIGS. 9 and 10  are views showing the different stages of use of the surgical instrument according to the present invention. 
    
    
      In  FIG. 1  is shown an example of an embodiment of a spinal implant  1  comprising a bone anchoring element  2  for immobilizing in rotation and in translation a connection rod  3  at each instrumented vertebrae of the vertebral column.  
      The bone anchoring element  2  cooperates with an immobilizing element  4  allowing the fixation in rotation and in translation of the connection rod  3  through a tightening screw  5 .  
      The bone anchoring element  2  comprises an anchoring part  6  and a receiving part  7  that is comprised of a U-shaped head  8  open in its upper part for cooperating with the connection rod  3  and the immobilizing element  4 .  
      The anchoring part  6  may present either a hook shape, or a threaded profile that is formed or not formed as an integral unit with the receiving part  7  to be fixed on or in the vertebral body of the vertebrae to be instrumented.  
      The head  8  comprises two vertical walls  9 ,  10  disposed one facing the other and in parallel planes in order to delimit a first U-shaped central opening  11  carried by the axis XX′ of the connection rod  3  and wherein the bottom  12  presents a profile in a portion of a cylinder.  
      Each vertical wall  9 ,  10  is separated, for example, from the bottom  12  of the central opening  11  by a vertical slot  13  giving a certain elasticity to each wall in the direction of the center of the head  8 , according to the geometric axis VV′.  
      The vertical walls  9 ,  10  respectively comprise at each extremity an engagement part  14 ,  15  disposed one facing the other and on both sides of the central opening  11 .  
      Each vertical wall  9 ,  10  comprises on its internal surface and between the engagement parts  14 ,  15  a vertical housing  16  presenting a profile in a portion of a cylinder provided on both sides of a groove  17  allowing the immobilizing element  4  to be guided during its positioning by means of the surgical instrument  100  in the head  8  of the bone anchoring element  2 .  
      Each vertical wall  9 ,  10  is pierced between the engagement parts  14 ,  15  by a hole  18  opening within the central opening  11  and designed to cooperate with the surgical instrument  100  during the introduction of the immobilizing element  4 .  
      The immobilizing element  4  presents an external profile that is roughly parallelepiped shaped comprising, measured parallel to the axis XX′ and in its lower part, a housing  19  presenting a profile in a portion of a cylinder in order to receive and cooperate with the connection rod  3 .  
      The immobilizing element  4  comprises in its middle a tightening screw  5  that opens within the housing  19  to come into contact by pressing against the connection rod  3  to allow its immobilization in rotation and in translation.  
      The immobilization element  4  comprises in a plane parallel to the axis XX′ tooth-shaped catches  20 ,  21  separated by a vertical housing  22  laterally bordered by ribs  23  allowing said immobilizing element to be guided during its introduction in the head  8  of the anchoring element  2 .  
       FIGS. 2 and 3  show a surgical instrument  100  allowing the immobilizing element  4  to be positioned and introduced between the walls  9 ,  10  of the head  8  of the anchoring element  2 .  
      The surgical instrument  100  is comprised of a body  101  comprising a horizontal tube  102  extending from a perforated frame  103  that forms an integral unit measured parallel to axis ZZ′ with a handle  104  called the “fixed handle.” 
      The fixed handle  104  cooperates with another handle  105  called the “movable handle” that is connected to the first by an axis of rotation  106  and a laminated spring  107  allowing a double acting driving device  108  to be activated under the pressure force.  
       FIG. 4  illustrates the movable handle  105  comprising above the axis of rotation  106  a head  109  presenting a domed profile  110  from which extends a fork  111  wherein each branch  112  comprises a rounded profile free extremity  113 .  
       FIG. 5  represents the frame  103  of the body  101  that is comprised of two walls, i.e., a vertical wall and an opposite wall  114  and  115  interconnected by perforated upper  116  and lower  117  walls.  
      The vertical wall  114  is formed as an integral unit with the horizontal tube  102  presenting an internal bore  118  opening within the frame  103 , while the opposite wall  115  is pierced by a hole  119  carried by the same main axes as that of the internal bore  118 .  
      The upper wall  116  presents a rectangular-shaped central recess  120 , while the lower wall  117  comprises another recess  121  disposed below that of  120 . The recess  121  comprises internal shoulders  122  at the fixed handle  104  designed to form a stop.  
      The upper wall  116  of the frame  103  comprises an extension  123  that extends beyond the vertical wall  115  and in which an oblong groove  124  is pierced.  
      The surgical instrument  100  comprises a locking tube  125  comprising at one of its extremities fork-shaped branches  127  each provided with notches  126 . The tube  125  comprises at the extremity opposite from that in the shape of a fork  127  a cylindrical sleeve  128  extending by parallel tabs  129 . The locking tube  125  is constructed around tube  102  so that the free extremities  113  of each branch  112  of the movable handle  105  respectively cooperate with the notches  126  of each branch  127  to allow the sliding of the locking tube  125  around the tube  102  under the action of the movable handle  105 .  
      The surgical instrument  100  comprises a cylindrical plunger  130  that crosses the frame  103  through a hole  119  provided in the vertical wall  115  for sliding in the internal bore  118  of the tube  102  ( FIG. 6 ).  
      The cylindrical plunger  130  is comprised of a rod comprising at one of its extremities a head  152  in the shape of a domed disk allowing the surgeon to grasp said plunger. The cylindrical plunger  130  has from its head  152  a first cylindrical part  153  that is extended by a second cylindrical part  154  with an outer diameter less than that of the first part.  
      The driving device  108  of the surgical instrument  100  is comprised of a first plate  131  disposed within frame  103  measured vertically and parallel to axis ZZ′ so as to cooperate with the recesses  120  and  121  of the upper  116  and lower  117  walls to allow it to be guided laterally during its displacements.  
      The plate  131  is pierced in its middle by a hole opening allowing the passage of the cylindrical plunger  130 . The driving device  108  comprises a compression spring  132  that is constructed around the cylindrical plunger  130  so that it can push against the plate  131  and the vertical wall  114  of the frame  103 .  
      The driving device  108  of the surgical instrument  100  is also comprised of a second plate  133  that is positioned according to a direction roughly parallel to axis ZZ′ in order to be guided and held within the groove  124  of the extension  123  of said upper wall  116  of the frame  103 .  
      The second plate  133  is pierced in its middle by a hole opening allowing the passage of the cylindrical plunger  130  in order that the latter crosses, according to a horizontal axis YY′, the frame  103  of the surgical instrument  100 .  
      The driving device  108  comprises a compression spring  134  that is constructed around the cylindrical plunger  130  so as to push against the plate  133  and the vertical wall  115  of the frame  103 .  
      The first plate  131  is provided to push against, under the effect of the spring  132 , the domed profile  110  of the head  109  of the movable handle  105  allowing during the activation of the latter the displacement in translation of the cylindrical plunger  130  within the tube  102  and the frame  103 .  
       FIGS. 7 and 8  show the free extremity of tube  102  located opposite from the frame  103  of the body  101  of the surgical instrument  100 .  
      The cylindrical internal bore  118  of the tube  102  is extended at its free extremity by another bore  135  presenting in section a roughly rectangular profile and a shape complementary to that external shape of the immobilizing element  4  of the spinal implant  1 .  
      In fact, the internal bore  135  is provided to receive a certain number of immobilizing elements  4 , as for example at least 10 immobilizing elements  4 , in order to be able to be presented above each bone anchoring element  2  for their positioning.  
      Thus, the internal bore  135  comprises, on each parallel and opposite wall  136 , a guiding groove  137  provided to each receive the ribs  23  of the corresponding immobilizing element  4 .  
      The cylindrical tube  102  is extended at its free extremity by a sleeve  138  with a roughly rectangular profile wherein each parallel and opposite wall  139  comprises a U-shaped cutout  140  designed to cooperate with the connection rod  3  of the spinal implant  1 .  
      It should be noted that the walls  139  of the sleeve  138  are disposed in planes perpendicular to those containing the walls  136  of the internal bore  135 .  
      It should be noted that the internal profile of the sleeve  138  is measured in dimensions slightly larger than those of the internal bore  135  in order to conform the shoulders  151  forming a stop to the input of the latter.  
      The cylindrical tube  102  comprises on its external profile and in the planes parallel to those containing the walls  136  of the internal bore  135  flat parts  141  that are extended on each wall  142  of the sleeve  138 .  
      At the cylindrical tube  102 , each flat part  141  is pierced by a first hole  143  and a second hole  144  opening within the grooves  137  of the bore  135 .  
      At the walls  142  of the sleeve  138 , each flat part  141  is pierced by a third hole opening  145  that is carried by the same main axis as that of the first hole  143  and the second hole  144 .  
      Each first hole  143  presents an internal threading allowing it to cooperate with a tightening screw  146  allowing two elastic strips  147  and  148  to be fixed in each flat part  141 .  
      Each elastic strip  147  is formed as an integral unit with a pin  149  cooperating with the second hole  144  and penetrating within the bore  135  to allow the immobilizing elements  4  to be held within the bore.  
      Each elastic strip  148  is formed as an integral unit with a pin  150  cooperating with the third hole  145  of the sleeve  138  in order to be able to penetrate within the latter when the strips  148  are deformed by an external pushing force.  
      One can easily understand from the previous description and from  FIGS. 8 and 9  that the operation of the surgical instrument  100  is as follows:  
      One starts with loading the immobilizing elements  4  within the tube  102  and more particularly within the bore  135 . The immobilizing elements  4  are introduced by the lower extremity of the tube  102  at the sleeve  138 . During the passage of each immobilizing element  4 , the immobilizing pins  149  part due to the elasticity of the strips  147 , thus allowing at least 10 immobilizing elements  4  to be introduced within the bore  135  of the tube  102 .  
      One proceeds to the positioning of the surgical instrument  100  on the head  8  of the bone anchoring element  2  of the spinal implant  1  so that the head is positioned in the sleeve  138  and is pushing against the shoulders  151  forming a stop. The orientation of the surgical instrument  100  is defined by the connection rod  3  that must be introduced in the passage of the rod comprised of cutouts  140 . In this position, the pins  150  of the elastic strips  148  are positioned facing the holes  18  provided in the head  8  of the bone anchoring element  2 .  
      The surgical instrument  100  is activated by pressing on the movable handle  105  allowing the tube  125  to be displaced in translation through its branches  112  in the direction of the free extremity of the tube  102 . During this displacement in translation, the tube  125  pushes by means of the tabs  129  on the elastic strips  148 , thus immobilizing the pins  150  in the lateral holes  18  provided in the head  8  of the bone anchoring element  2 . This first movement of the handle  105  allows the surgical instrument  100  to be fixed on the bone anchoring element  2 .  
      The introduction of the immobilizing element  4  is done by continuing the pressure on the handle  105  extending its rotation movement and allowing firstly the extremities of each branch  112  of the notches  126  of the tube  125  to be released, which ends the translation of the tube  125  and secondly to come into contact with the plate  131  through the domed profile  110 . Due to the thrust exercised on the lower extremity of the plate  131 , the latter is positioned straight on the cylindrical plunger  130 .  
      The continuous movement of the handle  105  leading to the plate  131  allows by the straight position of the latter the displacement in translation of the cylindrical plunger  130  within the tube  102 .  
      The cylindrical plunger  130  pushes on the last immobilizing element  4  placed in the internal bore  135  applying a pushing force F to the immobilizing elements  5  assembly contained in the bore  135 , allowing the expulsion of the immobilizing element  4  located directly above the head  8  of the bone anchoring element  2  and its introduction in said head  8 .  
      The release of the surgical instrument  100  is obtained by releasing the pressure on the handle  105  which returns through the laminated spring  107  to its position of rest. By returning to its position of rest, the handle  105  leads to the tube  125 , due to the notches  126 , thus releasing the strips  148  which due to their elasticity separate from the tube  102 . The pins  150  leave the holes  18 , thus releasing the surgical instrument  100  from the head  8  of the bone anchoring element  2 .  
      Due to the spring  132 , the plate  131  returns to its position of rest, stopping on the shoulders  122  of the recess  121  of the frame  103 . The cylindrical plunger  130  does not recoil, due to the pressure exercised by the plate  133  that is positioned straight due to the spring  134 .  
      When the last immobilizing element  4  has been introduced, the cylindrical plunger  130  and more particularly the first cylindrical part  153  arrives at the bottom of the bore  118  of the tube  102  while the second cylindrical part  154  is for its part introduced in the bore  135  without penetrating within the sleeve  138 . By pushing on the plate  133 , the cylindrical plunger  130  is released and may be reassembled. Immobilizing elements  4  may then be reintroduced, as has been previously explained.  
      In addition, it must be understood that the previous description was given only by way of example and does not limit in any way the scope of the invention, wherein details of the executions described may be replaced by other equivalents without any departure from this scope.