Abstract:
The present invention is a device and method that immobilizes the vertebral bodies by immobilizing the respective spinous process extending therefrom. The device contains a spacer extending from a body with the spacer adapted to be positioned between adjacent spinous processes so that the spacer may be located close to the spine. A strap connected with the body is designed to engage the spinous processes, such that the device may be adjusted to be positioned about the spinous processes. The device ensures that the spacer remains positioned between adjacent spinous processes. The method to insert the device minimizes destruction to body tissue, thus it is less traumatic to the patient and allows for the patient to recover from the procedure faster than conventional methods.

Description:
FIELD OF THE INVENTION 
     The present invention relates to spine fixation devices and methods which supplement a primary spine fusion device, such as by way of example only, an interbody fusion device. 
     BACKGROUND 
     A common procedure for handling pain associated with degenerative spinal disk disease is the use of devices for fusing together two or more adjacent vertebral bodies. The procedure is known by a number of terms, one of which is interbody fusion. Interbody fusion can be accomplished through the use of a number of devices and methods known in the art. These include screw arrangements, solid bone implant methodologies, and fusion devices which include a cage or other mechanism which is packed with bone and/or bone growth inducing substances. All of the above are implanted between adjacent vertebral bodies in order to fuse the vertebral bodies together, alleviating associated pain. 
     It can be advantageous to associate with such primary fusion devices and methods, supplemental devices which assist in the fusion process. These supplemental devices assist during the several month period when bone from the adjacent vertebral bodies is growing together through the primary fusion device in order to fuse the adjacent vertebral bodies. During this period it is advantageous to have the vertebral bodies held immobile with respect to each other so that sufficient bone growth can be established. 
     Such supplemental devices can include hook and rod arrangements, screw arrangements, and a number of other devices which include straps, wires, and bands, all of which are used to immobilize one portion of the spine relative to another. All of these devices generally require extensive surgical procedures in addition to the extensive procedure surrounding the primary fusion implant. 
     It would be advantageous if the device and procedure for supplemental spine fixation were as simple and easy to perform as possible, and would optimally leave intact all bone, ligament, and other tissue which comprise and surround the spine. Accordingly, there needs to be developed procedures and implants which are minimally invasive and are supplemental to spine fixation devices and methods. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is a device that immobilizes the vertebral bodies by immobilizing the respective spinous process extending therefrom. The device contains a spacer adapted to be positioned between adjacent spinous processes so that the spacer may be located close to the spine. A strap connected with the body is designed to engage the spinous processes, such that the device may be adjusted about the spinous processes. The device ensures that the spacer remains properly positioned between adjacent spinous processes. 
     Another object of the present invention is a method to insert the device in a manner that minimizes destruction to body tissues. Such a procedure is less traumatic to the patient. Thus, the patient will recover from the procedure faster than with conventional methods. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an embodiment of the present invention, and 
     FIG. 1 a  is an alternative embodiment of a spacer of the invention; 
     FIG. 2 is a top view of the embodiment of the present invention of FIG. 1 placed about adjacent spinous processes. 
     FIG. 3 is a side view of an alternative embodiment of an interlocking mechanism of the embodiment of the present embodiment of FIG.  1 . 
     FIG. 4 is a side view of a locking finger assembly of an embodiment of the invention utilized by any of the other embodiments of the present invention; 
     FIG. 5 a  is a side view of a locking ring assembly of an embodiment of the invention utilized by any of the other embodiments of the present invention; 
     FIG. 5 b  is a perspective view of the locking ring assembly of FIG. 5 a;    
     FIG. 6 is a side view of an embodiment of the present invention of FIG. 1 illustrating the position of the spacer and its proximity to the spine; 
     FIG. 7 is a top view of another embodiment of the present invention, and 
     FIG. 7 a  is a cross sectional view through line  7   a — 7   a.    
     FIG. 8 a  is a side view of a moveable locking assembly of an embodiment of the invention utilized by any of the other embodiments of the present invention; and 
     FIG. 8 b  is a perspective view of the collapsible locking assembly of FIG. 8 a.   
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, the device  100  contains a spacer  112 , a body  102  and a strap  116 . The spacer  112  is substantially cylindrical in shape and is adapted to be positioned close to the spine between adjacent spinous processes to spread the load placed upon the spacer  112  by the adjacent spinous processes (see FIG.  6 ). However, one of ordinary skill in the art will appreciate that the spacer  112  is not limited to a cylindrical shape. For example, the spacer  112  may be substantially elliptical (FIG. 1 a ) in shape to achieve the same results. The spacer  113  of FIG. 1 a  has narrow ends  115  and  117  which can be placed closer to the spine with the spacer  113  between adjacent spinous processes. The shape of the spacer  112  or  113  is designed so that it conforms to the area that the spacer  112  or  113  is inserted into. 
     The body  102  contains a first end  104 , a second end  106 , and a third end  108 . The first end  104  supports the spacer  112  so that the spacer  112  is offset from the strap  116 , enabling spacer  112  to be closer to the spine than strap  116  in a preferred embodiment. The pin  114  preferably extends from the first end  104  in a substantially perpendicular manner to achieve the offset. Thus, the spacer  112  is offset from the body  102  and from the strap  116 . Accordingly, the spacer  112  is positioned close to the spine when the device  100  engages the adjacent spinous processes (see FIG.  6 ). The spacer  112  can also rotate about the pin  114  so that the spacer  112  can adjust to the contours of the spinous process as the spacer  112  moves closer to the spine. The second end  106  of the body  102  engages the securing end  120  of the strap  116 . The third end  108  of the body  102  engages the interlocking end  118  of the strap  116 . In FIG. 1, the third end  108  of the body  102  has at least one receiving hole  110  which is capable of accepting the ball-shaped interlocking end  118  of the strap  116 . As can be appreciated from reviewing FIG. 5 b , the ball-shaped interlocking end  118  can be trapped in a receiving hole  110  which has a large opening to receive the interlocking end  118  and a restricted neck or recess for capturing the interlocking end  118 . Thus, a secure connection is made when the interlocking end  118  of the strap  116  is inserted into at least one of the receiving holes  110  of the body  102  (see FIG.  2 ). The spacer  112 , body  102  and pin  114  can be made of stainless steel, titanium or other biologically acceptable materials. 
     In a preferred embodiment of the present invention, the body  102  further has a vertical groove  119  that pin  114  slidably engages. The pin  114  is able to translate along the axis of the vertical groove  119 . This allows the spacer  112  to be attached to the body  102 , yet still be able to adjust independently. 
     The strap  116  engages the adjacent spinous processes. The strap  116  can be made of stainless steel or other biologically acceptable materials. Further, the strap  116  may be partly elastic, flexible or elongateable so that a user can secure the interlocking end  118  into the tightest, reachable receiving hole  110 , thereby ensuring that strap  116  is secured about the adjacent spinous processes. When the strap  116  is secured to the adjacent spinous processes, the biologically acceptable material  122  contacts the adjacent spinous processes. The biologically acceptable material  122  prevents sharp edges on the strap  116  from digging or cutting into the adjacent spinous processes when strap  116  is secured to the body  102  (see FIG.  2 ). Such material can include, but is not limited to, silicon. Thus, the strap  116  can be sufficiently tightened about the adjacent spinous processes without damaging them. 
     There are many different methods whereby the interlocking end  118  of the strap  116  and the third end  108  of the body  102  may be fastened together to form a secure connection between the strap  116  and the body  102 . Referring to FIG. 3, the third end  150  of the body  102  contains a strap receiving end  154  and a connector  152 . The third end  150  is functionally equivalent to the third end  108  shown in FIG.  1 . The connector  152  is attached with the strap receiving end  154  such that the third end  150  of the body  102  is more flexible than the third end  108  shown in FIG.  1 . For example, the third end  150  can be made of a flexible biologically compatible material such as, but not limited to, silicon. The strap receiving end  154  has at least one receiving hole  156 , thus allowing the strap  158  to firmly engage the adjacent spinous processes. The strap  158  has a ball  160  at the end. By placing strap  158  into receiving hole  156 , ball  160  locks strap  158  into place similar to the device in FIG.  1 . The purpose of the geometry of the device  150  (FIG. 3) and the device  324  (FIGS. 5 a  and  5   b ) is to provide constant tension on the strap  116 . These devices, in effect, are elliptical springs which are compressed along the y-axis (see FIG. 5 a ) to attach the strap. 
     FIG. 4 illustrates yet another embodiment with the strap engaging the third end of the body. The third end  208  of the body  202  has at least one interlocking finger  210  capable of accepting the anchor finger  211  of the interlocking end  218 . A secure connection is formed when the anchor finger  211  engages the interlocking finger  210 . As the strap  222  may be partly elongateable, the strap  222  may be stretched so that the anchor finger  211  can engage an interlocking finger  210  to ensure that the strap  222  is tightly secured to the adjacent spinous processes. This device functions as a detachable cam lever. For the device to work properly, the attachment of the strap  218  to the lever must be past the anchoring finger  211 . The anchoring finger, once engaged, acts as a pivot for the cam lever as shown in FIG. 4 a.  This is essentially a detachable version of the device in FIG.  8 . To provide additional securing, the interlocking end  218  and the third end  208  may be fastened together by a fastening device  212 , such as by way of example, a screw. Such a design requires both the interlocking end  218  and the third end  208  to have a hole extending through. Only the third end  208  needs a threaded hole  232 . When the interlocking end  218  and the third end  208  are secured by placing the anchoring finger  211  into an interlocking finger  210 , the holes  232  and  234  align. Then fastening device  212  can be inserted through holes  232  and  234  to fasten third end  208  and interlocking end  218  together. The hole  232  has threads to engage the fastening device  212 . 
     FIGS. 5 a  and  5   b  illustrate an additional embodiment with the body and the interlocking end of the strap engaged. The third end  308  of the body may contain an interlocking ring  324 . The interlocking ring  324  can be comprised of, but is not limited to, stainless steel or an elastic material such as silicon if an elastic arrangement is desired. The interlocking ring  324  is substantially circular in shape, and as shown by FIG. 5 b , has a cut-out  319  similar in shape to the interlocking end  318  of the strap. When the ball  322  on the interlocking end  318  of the strap is inserted into the interlocking ring  324 , the interlocking end  318  of the strap cannot easily be removed from the locking ring  324  because the ball  322  is wider than the channel  321  following the cut-out  319  on interlocking ring  324 . 
     The geometry of this device allows it to act as an elliptical spring to provide tension on the strap. Applying compressive force F along the y-axis elongates the elliptical spring along the x-axis allowing connection with the ball end  322 . Once the compressive force is released, the spring  324  maintains constant tension on the strap  318 . 
     FIGS. 8 a  and  8   b  illustrate yet another embodiment with the third end of the body and the interlocking end of the strap engaged to secure the strap around the adjacent spinous processes. The third end  408  of the body contains an upper portion  426  and a lower portion  428 , coupled at one end. The upper portion  426  has an upper surface  436  and a lower surface  438 , and further contains receiving holes  410  and a fastener hole  434 . The lower portion  428  has an upper surface  440  and a lower surface  442 , and further contains a fastener hole  432 . The interlocking end  418  contains a ball  430  at the end of the strap. 
     To secure the third end  408  to the interlocking end  418 , the interlocking end  418  is first placed through one of the receiving holes  410 . Receiving hole  410  is designed, as for example seen in FIG. 1 or FIG. 4, so that the ball  430  can be inserted into receiving hole  410 , but not removed. Then, the upper portion  426  is pivoted down until the lower surface  438  of the upper portion  426  contacts the upper surface  440  of the lower portion  428 . This action tightens strap  116  about the spinous process. As a result, the fastener hole  432  of the lower portion  428  and the fastener hole  434  of the upper portion  426  align. The fastening device  412  can then be placed through the fastener holes  434  and  432 . The fastener hole  432  has threads to engage the fastening device  412 . Thus, the fastener  412  secures the upper portion  426  and the lower portion  428  together. 
     FIG. 7 illustrates another embodiment of the present invention. The device  500  contains a body  502 , a spacer  512  and a strap  516 . The spacer  512  may consist of various shapes, such as, but not limited to, an elliptical shape or egg-shaped. One embodiment of the present invention is illustrated in FIG.  7 . The egg-shaped spacer  512  has a narrow end  513  and a rounded bulbous end  515  (see FIG. 7 a ). A portion of strap  516  has a spring element  532 . The spring element  532  allows the strap  516  to adjust in length to ensure that the u-shaped end  522  which is connected with biologically acceptable material is in contact with the adjacent spinous processes. The U-shaped end  522  is an inner u-shape which is surrounded by an outer u-shaped end  523  to which the strap  516  is secured. However, the strap needs to be able to slide on the u-shaped end pieces. This allows the spacer to float relative to the adjacent spinous processes. This arrangement illustrates the strap, spring and turnbuckle to be spaced from the spinous process. The spring element  532  also provides constant tension on the strap  516  by constricting the strap  516  around the adjacent spinous processes. 
     First, the spacer  512  is inserted between the adjacent spinous processes. Then, the strap  516  is placed around the adjacent spinous processes so that the biologically acceptable material  522  contacts the spinous processes, avoiding any sharp edges of the strap  516  from cutting into the spinous processes. The body  502  secures the strap  516  around the adjacent spinous processes. To secure the strap  516  around the adjacent spinous processes, a physician can tighten strap  516  by turning the turnbuckle device of body  502 . The spacer  512  is connected with the body  502  by attachment element  530 . The attachment element  530  is a flexible biologically acceptable material, such as, but not limited to, silicon. Further, the attachment element  530  offsets the spacer  512  from the body  502  to ensure that spacer  512  is placed near the spine. The combination of the spring element  532  and the body  502  enable a user to tightly secure the device  500  about the adjacent spinous processes. It is to be understood that the spring element  532  can be eliminated from this embodiment if less flexibility is desired. 
     The present invention is designed to allow a physician to insert the spacer  112  between the adjacent spinous processes while destroying a minimum amount of body tissue. For example, the device  100  can be inserted without modifying the spinous processes or cutting the supra-spinous ligament. Specifically, the device  100  is designed so that the spacer  112  may be inserted between the adjacent spinous processes from one direction. This method is less traumatic for the patient&#39;s body, allowing the patient to recover faster. 
     The method includes several steps. First, the spacer  112  is placed between the adjacent spinous processes so that the spacer  112  is close to the spine. Then, the strap  116  is placed around the adjacent spinous processes such that the biologically acceptable material  122  is in contact with both spinous processes. Last, the interlocking end  118  of the strap  116  is secured to the third end  108  of the body  102 . The various methods for securing the interlocking end  118  of the strap  116  to the third end  108  of the body  102  is as previously described. The device  100  as installed is shown in FIG.  2  and FIG.  6 . 
     The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention with various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.