Abstract:
Surgical cross-connecting apparatuses in which the components of the apparatuses are adjustable as a result of being provided with a number of degrees of freedom. The components are movable axially and rotatably. The components are rotatable in several different ways taken from the perspective of the axially extending cross connecting member of the apparatuses. The apparatuses include a lever and set screw for locking a spinal rod in position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a surgical cross-connecting apparatus and a cross-connecting surgical screw apparatus for use with implantation rods, and related methods of securing implantation rods using a surgical cross-connecting apparatus. 
     The bones and connective tissue of an adult human spinal column consists of more than 20 discrete bones coupled sequentially to one another by a tri-joint complex. The complex consists of an anterior disc and two posterior facet joints. The anterior discs of adjacent bones are cushioned by cartilage spacers referred to as intervertebral discs. The over 20 bones of the spinal column are anatomically categorized as one of four classification: cervical, thoracic, lumbar, or sacral. The cervical portion of the spine which comprises the top of the spine up to the base of the skull, includes the first 7 vertebrae. The intermediate 12 bones are thoracic vertebrae, and connect to the lower spine comprising the 5 lumbar vertebrae. The base of the spine is a sacral bones (including the coccyx). 
     The spinal column of bones is high complex in that it includes the over 20 bones coupled to one another, housing and protecting critical elements of the nervous system having innumerable peripheral nerves and circulatory bodies in close proximity. Despite its complexity, the spine is a highly flexible structure, capable of a high degree of curvature and twist in nearly every direction. 
     Genetic or developmental irregularities, trauma, chronic stress, tumors and disease, however, can result in spinal pathologies which either limit this range of motion, or which threatens the critical elements of the nervous system housed within the spinal column. A variety of systems have been disclosed in the art which achieve this immobilization by implanting artificial assemblies in or on the spinal column. These assemblies may be classified as anterior posterior or lateral implants. Lateral and anterior assemblies are coupled to the anterior portion of the spine which is in the sequence of vertebral bodies. Posterior implants generally comprise pairs of rods, which are aligned along the axis which the bones are to be disposed, and which are then attached to the spinal column by either hooks which couple to the lamina or attach to the transverse processes, or by screws which are inserted through the pedicles. In order to provide enhanced torsional rigidity, these implants generally include cross-connecting devices which couple the rods together transverse to the axis of the implants. These cross-connecting devices may couple directly to the rods themselves, or may be attached to the pedicle screws. 
     Exemplary prior art references include U.S. Pat. Nos. 5,005,562, 5,334,203, 5,688,272, 5,716,355, and 5,947,966. 
     It is desirable to provide cross-connecting devices that are adjustable and can form angular installments by taking advantage of various degrees of freedom possessed by components of the device. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to surgical cross-connecting apparatuses in which the components of the apparatuses are adjustable as a result of being provided with a number of degrees of freedom. For instance, the components are movable axially and rotatably. The components are rotatable in several different ways taken from the perspective of the axially extending cross connecting member of the apparatuses. 
     In one embodiment, the surgical cross-connecting apparatus comprises a cross connecting member extending in an axial direction having at least one end provided with a hook that is mounted in an opening in the end, wherein the hook has an opening sized to receive a spinal rod, the hook being rotatable in the plane in which the cross connecting member extends, and a screw member fitted into an aperture which engages the spinal rod and locks the rod within the hook. In another embodiment, this hook is also provided at a second end of the cross connecting member. 
     In yet a further embodiment, the opening in the first end is a slot in which the hook is moveable in the axial direction in which the cross connecting member extends. In yet another embodiment, the cross connecting member is provided with a second end having a hook that is mounted in an opening in the second end, the opening of the second end being a slot in which the hook is moveable within the axial direction in which the cross connecting member extends. 
     Yet another embodiment is a surgical cross-connecting apparatus comprising at least one body positioned at an end of a cross connecting member extending in an axial direction, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The body is rotatably mounted over the cross connecting member to rotate around the axial direction in which the cross connecting member extends. In yet another embodiment, in addition to having the body at a first end of the cross connecting member, a second end of the cross connecting member has an aperture, wherein the aperture is sized to receive an end of a hook, the end of the hook defining a second aperture in which means for fixing in place a spinal rod placed within the hook, wherein the hook is rotatable around the axis formed by the cross connecting member. In yet another embodiment, the bodies are located at both ends of the cross connecting member. 
     Still another embodiment is a surgical cross-connecting apparatus, comprising at least one body positioned at an end of a cross connecting member that extends in an axial direction, the end having a thickness that is less than the thickness of a central portion of the cross connecting member, the end being provided with a pin extending into a slot provided on the body, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The pin is located on an underside of the cross connecting member and the slot is located on an underside of the body. The structure of this embodiment allows the body to rotate in the plane in which the cross connecting member extends. Also, the body is movable in the axial direction in which the cross connecting member extends. Other embodiments incorporate this body at a second end of the cross connecting member, or any of the other bodies previously described. 
     Yet another embodiment is a surgical cross-connecting apparatus comprising at least one body positioned at an end of a cross connecting member extending in an axial direction, the end having a thickness that is less than the thickness of a central portion of the cross connecting member, a first pin positioned adjacent the end of the cross connecting member, the pin inserted in an opening in the body, the body being provided with a cavity for receiving a spinal rod, a lever pivotally mounted to the body, a set screw mounted in a through hole in the lever that is positioned proximate to the cross connecting member so that the set screw bears against the cross connecting member when the set screw is tightened, wherein at least a portion of the lever defines a portion of the cavity. The body is rotatably mounted over the cross connecting member to rotate around the axial direction in which the cross connecting member extends. Other embodiments incorporate this body at a second end of the cross connecting member, or any of the other bodies previously described. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of another embodiment of the surgical cross-connecting apparatus of the present invention. 
     FIG. 2 is a perspective view of another embodiment of the surgical cross-connecting apparatus of the present invention. 
     FIG. 3 is a perspective view of another embodiment of the surgical cross-connecting apparatus of the present invention. 
     FIG. 4 is a top plan view of the FIG. 20 embodiment of the surgical cross-connecting apparatus of the present invention. 
     FIG. 5 is a view taken along line C—C of FIG.  21 . 
     FIG. 6A is a top plan view of another embodiment of the surgical cross-connecting apparatus of the present invention. 
     FIG. 6B is a view taken along line B—B of the embodiment of FIG.  6 A. 
     FIG. 6C is a view taken along line A—A of the embodiment of FIG.  6 A. 
     FIG. 6D is a bottom plan view of the embodiment of FIG.  6 A. 
     FIG. 7, a top plan view, illustrates “hook  206  rotatable R in the plane P in which the cross connecting member  201  extends.” 
     FIG. 8, a top plan view, illustrates “hook  206  [or body  300 ] is moveable M within the axial direction A in which the cross connecting member  201  extends.” 
     FIG. 9, a side elevational view, illustrates “lever  314  pivotally mounted P to the body  300 .” 
     FIG. 10, an end elevational view illustrates “body  300  is rotatably mounted R over the cross connecting member  201  to rotate R around the axial direction in which the cross connecting member  201  extends.” 
     FIG. 11, a top plan view, illustrates “body  300  [can] rotate R in the plane P in which the cross connecting member  201  extends.” 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates an embodiment of a cross-connecting apparatus. Here, cross connecting member  201  has a first end  202  and a second end  204 . First end  202  is provided with a hook-shaped spinal rod engaging member  206  which is provided with an end  207  that is snap-fitted into aperture  208 . A set screw  210  threaded through the aperture  209  in end  207  is engageable with the hook  206 , which provides a means for clamping the spinal rods while simultaneously fixing the angular position of the hook. In other words, prior to being fixed in placed, the hook  206  is rotatable R in the plane in which the cross connecting member  201  extends. This permits the surgeon to more easily position the cross connecting on spinal rods which may be oriented obliquely to each other. 
     The second end  204  of the cross connecting member  201  is provided with a slotted opening  212  into which the end  216  of hook-shaped spinal rod engaging member  214  is snap fitted. The hook  214  can be moved in the axial direction in which the cross connecting member  201  extends by sliding the hook  214  in the slot. This provides a means for adjusting the axial distance between the spinal rods. The end  216  has an opening  218  in the middle thereof to receive a set screw  220  which engages threads provided on the opening of the end  216 . As set screw  220  is tightened, it pushes against the spinal rod, locking it in place while simultaneously fixing the axial position of the hook. 
     In a further embodiment shown in FIG. 2, the cross connector is provided with slotted openings  212  at ends  202  and  204 , which permit the hooks  206  to each move M within the axial direction A in which of the cross connecting member  201  extends. As shown in FIG. 2, threaded bolts  216 , which extend from the hooks, pass through the slotted openings  212 , and are held in the cross connecting member by locking nuts  222  which are threaded over the bolts. When the locking nuts  222  are tightened, the axial position of the hooks (i.e.—position along the axis formed by the cross connecting member  201 ) and angular position of the hook (i.e.—the angle at which a spinal rod intersects the cross connecting member  201  due to the position of the hook) are set. Prior to tightening the axial and angular position of the hooks are adjustable by the surgeon. 
     FIGS. 3,  4 , and  5  show a further embodiment of the present invention. Cross connecting member  201  has first end  202  and second end  204 . Though second end  204  as shown is the same as the one of the embodiment of FIG. 2, it can be any of the ends herein described, including the first end  202  that will now be described. 
     A body  300  is provided at the first end  202  of the cross connecting member  201 . The body  300  has a first dimension which extends in the axial direction of the cross connecting member  201  and a second dimension which extends across the axial dimension of the cross connecting member  201 . The body is constructed of a suitable durable material such as metal or plastic. The body is provided with an opening  302  at a first body end  304 , which opens into a passageway  305  in the body extending in the axial direction. The opening  302  and passageway  305  are sized to receive the cross connecting member  201 . Proximate the second body end  306 , the body is provided with a cavity  308  that is sized to receive a spinal rod. 
     The body is provided with walls  310  on each side of the device which define a channel  312 . The channel  312  extends in the axial direction from near the intermediate point of the device to the second end  306 , and then in the cross axial direction along the second end  306 . A lever  314  is mounted within the channel by a pin  316 , which is fitted within a through hole  318  located in the walls  310  of the body that is placed within the second end. 
     The lever  314  is provided with two portions: a first lever portion  320  that extends in the axial direction of the cross connecting member  201 , from the first body end  202  to the second body end  306 , and an arm portion  324  which extends along the second body end in the cross axial direction. Together with the body  301 , the arm portion  324  provides the walls of the cavity, so that arm portion  324  is located next to the spinal rod when it is placed in the cavity. The lever  314  is further provided with a through hole near the second end at the upper end of the body, which is sized and positioned to receive the pin, thereby mounting the lever  319  to the body. 
     Near the first body end  202 , the first lever portion  320  is provided with a through hole  326  which is aligned with a through hole in the body  328 . Each of these through holes extend in the cross axial direction. These through holes receive a set screw  330 , which passes through the lever and through the body, and when tightened, forms a locking interference fit with the cross connecting member  201 . As shown in FIG. 5, the set screw  330  is threaded on its exterior and it mates with a complimentary threaded profile provided on the through hole  326  on the first lever portion  320 . The body  300  is rotatably mounted R over the cross connecting member  201  to rotate R around the axial direction in which the cross connecting member extends and is free to do so prior to tightening the set screw. This allows the surgeon to rotate the body around the cross connecting member  201 , increasing the ease of positioning the cross connector on obliquely oriented rods. 
     The head  332  of the set screw  330  has a recess dimensioned and sized to receive a drill bit or screwdriver so that the set screw can be tightened or loosened to the locked or unlocked position. In FIGS. 20 and 21, the groove is shown as having a hexagonal shape, but other shapes are possible, such as a groove that can receive a flat head screwdriver. 
     When the set screw  330  is tightened, it moves through the through holes  326  and  328  and contacts the cross connecting member  201 . Once contact is made, the screw can travel no further and it locks the cross connecting member into place. Further turning of the screw causes the lever to pivot, causing the arm portion  324  of the lever to contact the spinal rod, creating a tight fit between the lever and the spinal rod, locking the rod in the cavity. Since the lever can no longer pivot, the set screw is fixed in place against the cross connecting member, locking the cross connecting member in place. 
     Prior to tightening, the body is free to rotate around the axial direction in which the cross connecting member extends. This provides a degree of freedom that the surgeon is free to take advantage of and adjust the device to suit the specific needs of the patient. Once suitable adjustments are made, the device is tightened as aforedescribed. 
     Further embodiments, shown in FIGS. 6A-D, include further modifications on the embodiment of FIGS. 3-5. In these further embodiments, the body, lever, and set screw are generally the same as shown and described with respect to FIGS. 3-5, except as indicated below. The cross connecting member  201  is provided with a flat planar region  340  at the first end  202 . The flat planar region  340  is provided on the top side  345  and the underside  346  of the cross connecting member. The flat planar region  340  has a reduced thickness relative to the central portion  342  of the cross connecting member  201 . The flat planar region  340  is received in the body through the opening  302 . 
     Referring to FIG. 6D, the underside  346  of the flat planar region  340  of the cross connecting member  201  is provided with a pin  348  which is received in a slot provided  349  on the underside  347  of the body. The cross connecting member  201  is rotatable in the plane P in which the cross connecting member  201  extends. Furthermore, the slot  349  may be sized to have a length dimension greater than the length dimension of the pin, wherein the length dimension extends in the axial direction of the cross connecting member  201 . Thus, the body  300  is moveable M within the axial direction in which the cross connecting member  201  extends, providing a further degree of movement that the surgeon can use to adjust the distance between the spinal rods prior to tightening the set screw. When the set screw bears upon the cross connecting member when it is tightened, fixing the body against the cross connecting member  201 . 
     In a further embodiment, also shown in FIGS. 6A-D, the cross connecting member is provided at the second end with a flat planar region  350  which renders the end of cross connecting member received in the body less thicker on the lateral sides  351  of the cross connecting member. That is, the flat planar region  350  is less thick than the central portion  342  cross connecting member  201 . The body is provided with a through hole  352  placed adjacent the flat planar region of the cross connecting member. A pin  354  is placed in the through hole  352 . In this embodiment, the body rotatably mounted R over the cross connecting member  201  to rotate around the axial direction in which the cross connecting member  201  extends. However, rotation is limited to about 30° by the pin. This is due to the pin residing within space that would be occupied by the cross connecting member if the flat planar region did not exist in the cross connecting member. As the cross connecting member is rotated the edge of the flat planar region comes into contact with the pin, limiting the rotational movement of the cross connecting member. 
     The various components of the cross connector apparatus described and illustrated in the embodiments of the invention discussed above are preferably constructed of a titanium metal alloy. Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the attendant claims appended thereto, this invention may be practiced otherwise than as specifically disclosed herein.