Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is non-provisional application which claims priority to U.S. Provisional Application Ser. No. 61/744,525 filed on Sep. 28, 2012, which is incorporated in its entirety herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to methods and devices for treatment of spinal deformity. 
     BACKGROUND OF THE INVENTION 
     Scoliosis is a spinal deformity characterized by an abnormal curvature of the spine in the coronal plane. Adolescent idiopathic scoliosis (AIS) is the most prevalent type of scoliosis which develops during adolescence in an otherwise healthy patient and typically ceases at the onset of skeletal maturity. The cause of the disease is presently unknown. 
     Current surgical treatment of scoliosis involves manipulation of the spinal column and attachment of corrective devices for fusion of a portion of the spine. One such system, the Cotel-Dubousset system utilizes rigid metal rods attached to the spine. The rods are manipulated during surgery in an attempt to reduce abnormal curvatures and rotations of the spinal column. Large loads are exerted on the spine for correction which risks the patient&#39;s neurological condition. Recovery from these procedures can be lengthy and painful. Also, if normal lordosis and kyphosis are not restored, a condition called “flat back syndrome” may occur causing chronic pain. Even a successful procedure rarely results in a normal spinal curvature and the patient is left with an immobile spinal section. The discs above and below the fusion zone are at risk of future degeneration due to the increased mechanical demands placed on them. 
     It is therefore evident that there are flaws in prior art methods and devices. Most prior art devices are part of the load path of the spinal column. For example, it is understood that the Cotel-Dubgousset system rigidly attaches stiff metal rods to the spine. A structure having two roughly parallel support members relies primarily on the stiffer of the two members for transmission of loads. Therefore, loads exerted on an instrumented spine are transferred through the implant instead of through the spine. Spinal loads can be significantly large, and the implants will not support such loads indefinitely. Fatigue failure of the implant will occur if fusion is delayed. 
     Therefore, there is an unaddressed need that exists to provide a new and better system for correcting spinal deformities. 
     SUMMARY OF THE INVENTION 
     The current invention describes methods and devices for treating spinal deformity which offer significant improvements over prior art methods and devices. In general terms the present invention is used to secure the distance between an ilium and the spine to either correct or maintain spinal curvature. There are many embodiments of the invention which will achieve the stated objectives, some of which will be presented in the following summary. 
     In one embodiment of the invention, at least one device is attached between the spine and the pelvis which incorporates at least one flexible tether. Attachment of the flexible tether to the spine and ilium involves implantation of anchoring means and then attachment of the tether to the anchoring means. For example, at least one bone screw, pedicle screw, cannulated bone screw, clamp, plate, bone anchor, or shackle might be anchored to at least one vertebra and another to a portion of the ilium and the flexible tether may be attached to both. Other means of attachment will be clear to one practiced in the art. Alternatively, a loop of material may be placed around a bony structure (e.g. spinous process, transverse process, lamina or pars) or a hole through a bony structure through which the flexible tether is passed. 
     It should be noted that the present invention enables manipulating the vertebral column to correct the deformity by securing the tether to a portion of the ilium and a portion of the vertebral column; the ability to correct deformity by correcting the effective length of the tether between the ilium and vertebra over time; and correcting deformity by the natural growth of the spine by allowing the tether to maintain effective length between the vertebral column and the ilium. 
     Adjustment of the distance between the spine and ilium is achieved by varying the location at which the tether is attached to the anchoring means. The tether does not change lengths during the adjustment process, but the distance between the attachment points does, much like adjusting a belt around your waist. Taking advantage of the inherent viscoelasticity of spinal structures, the curvature may be gradually corrected by small incremental corrections over a protracted period of time, whereby the original incision is re-opened, or a new incision next to the original incision is created and the attachment means is disengage and then reengaged at a different location along the tether. Alternatively the patient&#39;s growth may be used to achieve correction. 
     Alternatively, the tether may branch into multiple tethers to provide multiple attachments to the spine and/or ilium. If more than one tether is used, each can be attached to a different vertebra, or multiple tethers can be attached to the same vertebra. Tethers can be attached to either or both sides of the vertebral column and either opposing sides of ilium as needed to generate correction of the spinal deformity. A crossing pattern whereby a tether is attached to the right side of the vertebra (e.g. the right pedicle) and left ilia, or vice versa, is possible. Also, a tether may be attached to a vertebra and then passed through an eye screw or other guiding device which is attached to the ilium (or both ilia) and then attached to a second vertebra with a pedicle screw or other means. In can be envisioned by one skilled in the art that guiding devices may be utilized on a number of vertebrae or one the ilium or ilia. The tether may also originate with an attachment to the pelvis, pass through any number of guide members attached to the spine, and then terminate at the pelvis again. 
     These and other aspects of the present invention, will become apparent from the following description of the embodiments taken in conjunction with the following drawings, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure. 
     The present invention provides an improved method of arresting a spinal deformity whereby at least one device is surgically attached between the spine and the ilium. Also, the present invention provides a system and a method for correcting a spinal deformity whereby at least one device is surgically attached between the spine and the ilium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is an illustration of a posterior view of a deformed human spine with an implanted device according to one embodiment of the present invention; 
         FIG. 2  is an illustration of a posterior view of a corrected human spine with the implanted device shown in  FIG. 1 ; 
         FIG. 3  shows a spinal anchoring means in the form of two pedicle screws and a rod onto which is secure an attachment mechanism and the tether; 
         FIG. 4  illustrates an attachment mechanism and the method of attaching it to the spinal anchoring mechanism; 
         FIG. 5  shows the anchoring mechanism of the ilium (not shown) and the method of attaching the tether to it; 
         FIG. 6  shows a long pair of forceps to be used for passing the tether beneath the skin; 
         FIG. 7  illustrates the use of the forceps of  FIG. 6  in passing the tether beneath the skin; 
         FIG. 8  illustrates an alternative embodiment of the tether clamp and elongate rod according to the present invention; 
         FIG. 9  illustrates another embodiment of a clamp or anchor according to the present invention; 
         FIG. 10  shows a cross-sectional view of the device shown in  FIG. 9 ; 
         FIG. 11  shows another embodiment of a clamp or anchor according to the present invention; 
         FIGS. 12 and 13  shows a closed head clamp according to the present invention; 
         FIGS. 14 and 15  shows yet another embodiment of a closed head clamp according to the present invention; and 
         FIGS. 16-18  illustrate various methods of coupling the tether to portions of the spine and/or ilium. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
       FIG. 1  is an illustration of a posterior view of a deformed spine  104  whereby the preferred embodiment of the device  200  is attached to an ilium  102  and a vertebra  100 . Device  200  includes a tether  204  having a free end  206  and that is configured to be attached to the ilium and a portion of the vertebra. Specifically, in one embodiment, two attachment mechanisms such as pedicle screws  300  are anchored to the vertebra of the spine by insertion into opposing pedicles, and a transverse rod  311  is attached to the pedicle screws  300 . It should be noted that although pedicle screws are provided in this particular embodiment, any other type of anchoring mechanism such as hooks may also be used. A tether clamp  310  is attached to rod  311  and the tether  204  is passed though tether clamp  310  and then passed down to the ilium  102  thereby securing a connection between the attached vertebra and the ilium. To attach the tether  204  to the ilium  102 , an ilium anchor  210  is provided. The ilium anchor  210  includes a bore  211  and is configured to be attached to the ilium by inserting the anchor  210  (threading) into a hole which has been drilled or punched through the ilium  102 . It should be noted that any other similar mechanism to attach anchor  210  to the ilium  102  may also be utilized. Tether  204  is passed through hole or bore  211  in the ilium anchor  210  and then brought back to the vertebra  100  and passed again through the tether clamp  310 . In other embodiments, the tether  204  may only be passed once through the tether clamp and ilium anchor  210 . 
       FIG. 2  illustrates the correction of the spine of  FIG. 1  using device  200 . As illustrated in  FIG. 2 , the free end  206  of tether  204  is pulled and the spine is manually manipulated during the surgery to achieve a correction of the deformity. When a satisfactory curve magnitude is achieved, tether  204  is tightened within the tether clamp, effectively locking the distance between vertebra  100  and the ilium  102 . 
     It should be noted that various levels of manipulation of the vertebral column can be coordinated using the device. For instance, different curvatures of the spine can be achieved by changing the position of the anchor and the clamp on the tether with respect to the vertebral column and the ilium. The locations along the tether where the clamp and anchor are attached determine an effective length of the tether, which in turn maximizes the distance that the attached vertebra may move relative to the position where the tether is attached at in the ilium. The scoliotic curve is corrected (or maintained) by adjusting the clamping and anchoring locations along the tether. 
       FIG. 3  shows a detailed view of pedicle screws  300 , transverse rod  311 , tether clamp  310  and tether  204 . In a preferred embodiment tether clamp  310  includes locking screw  312  which clamps tether clamp  310  onto rod  311  as well as locking the tether  204  within the clamp  310 . 
       FIG. 4  shows a detailed view of the tether clamp  310  coupled to the transverse rod. The tether clamp  310  is configured with a slot  501  which is provided through the tether clamp  310  and tether  204  is passed through slot  501 . It should be noted that the tether may be passed through the slot multiple times, if necessary. Locking screw  312  is used to secure the transverse rod  311  onto the tether clamp  310  and applies a compressive force upon the rod  311  onto the tether  204 , thereby clamping the tether  204  securely in place. It should be noted that although a threaded set screw is utilized in the present embodiment, any type of locking element know in the art for securing the tether within tether clamp may be used. 
       FIG. 5  shows a detailed view of an ilium anchor  210 . Ilium anchor  210  includes threads  212  for engagement with ilium  102  (not shown). Tether  204  is passed through bore  211  and then passed back to the vertebral column. A collar  215  is shown which keeps tether  204  adjacent to itself. 
       FIG. 6  shows an extra-long pair of forceps  900 .  FIG. 7  shows the preferred method of passing the tether through an incision  845  and underneath skin and other soft tissues. The forceps  900  are used to pass the tether though the openings in the tether clamp and used to tension the tether to correct the deformity of the curvature in the spine. 
       FIG. 8  illustrates another embodiment of a tether clamp  320  according to the present invention. In this embodiment, the tether clamp  320  is configured with a through hole  322  that is configured to correspond to a through hole  324  in an elongate rod  326  that is fixated to a portion of the spinal column. A fastening element  328  such as a set screw is provided to couple the tether clamp  320  and the elongate rod  326  together. The tether clamp  320  also includes openings  330 ,  332  which are dimensioned to receive and securely couple a tether  334  to the clamp  320 . The tether  334  is pulled through each of the openings  330 ,  332  to securely attach the tether  334  to the clamp  320  and the elongate rod  326 . 
       FIGS. 9 and 10  illustrate an alternative embodiment of a clamp and/or anchor  250  that can be used to secure a tether  252  to either the vertebral column or a portion of the ilium. More specifically, the anchor  250  of  FIGS. 9 and 10  may be configured and dimensioned to be attached to a portion of the vertebral column or may be configured be secure the tether to the ilium. The anchor  250  is configured as a plate  251  having at least two openings  254 ,  256  to receive fasteners  258 ,  260  capable of fixating the plate to bone. The plate  251  includes a middle portion  262  having an opening  264  that is capable of receiving the tether  252 . The middle portion  262  of the plate  251  is further provided with a fastening element  266  to secure the tether  252  to the plate  251 . As more clearly illustrated in  FIG. 10 , the fastening element  266  may be a set screw which directly contacts the tether  252  when tightened to secure the tether  252  to the plate  251 . It should be noted that any other type of fastening element which is capable of securing the tether to the anchor may be used, such as a pin. 
       FIG. 11  illustrates yet another embodiment of a clamp or anchor  400  according the present invention. In this embodiment, the clamp and/or anchor  400  includes a first plate  402  and second plate  404  that are secured to one another via a fastening element  406 . The first and second plates  402 ,  404  are may also include spikes  408  or similar type of features that bite into bone. Either the first or second plate  402 ,  404  or both also includes an opening  410  for receiving a tether. The first and second plates  402 ,  404  are positioned so that bone is in between, such as the ilium or a portion of the vertebral column. As the first and second plates  402 ,  404  are compressed into bone, the tether which is positioned through the opening  410  and in between the first and second plates  402 ,  404 , is also securely locked between the plates and the bone thereby securing the tether to the plates  402 ,  404 . In an alternative embodiment, the tether is passed through the opening and secured to the anchor  400  by a clamp device such a belt clamp or secured by knotting the tether around the edge of the anchor  400 . It should be noted that any type of mechanical mechanism to attach the tether to the anchor may be used. 
       FIGS. 12-15  illustrate yet another embodiment of a clamp according to the present invention. The closed head clamp  420  as illustrated in  FIGS. 12 and 13 , includes a first opening  422  extending through the clamp  420  in a first direction and a second opening  424  extending in a second direction. The first and second direction are generally perpendicular to one another. The first opening  422  is configured to receive an elongate rod  426  and the second opening  424  is configured to receive a tether  428 . The clamp  420  is further provided with a fastening element  430  that is used to secure both the rod  426  and the tether  428 . In this embodiment,  FIGS. 12 and 13  also illustrates that the second opening  424  is positioned at a bottom portion of the clamp  420 , thus, as the fastening element  430  is tightened, the fastening element  430  contacts the rod  426  which is pushed against the tether  428  thereby securing the tether  428  and rod  426  within the clamp. 
     In an alternative embodiment of the closed head clamp as illustrated in  FIGS. 14 and 15 , the closed head clamp  432  includes a first opening  434  and a second opening  436 . The first opening  434  and the second opening  436  are configured to be generally transverse to one another. The first opening  434  is dimensioned to receive an elongate rod  438  and the second opening  436  is dimensioned to receive a tether  440 . The clamp  432  also includes a fastening element  442 , such as a set screw, which when tightened secures and locks the tether  440  and the elongate rod  438  within the clamp  432 . In this particular embodiment, the second opening  436  is positioned between the fastening element  442  and the elongate rod  438 . When the fastening element  442  is tightened, the fastening element  442  directly contacts the tether  440  which contacts the elongate rod  438  thereby securely locking the tether  440  and the elongate rod  438  within the closed head clamp  432 . 
       FIGS. 16-18  illustrate alternative embodiments of the inventive device. Specifically,  FIG. 16  illustrates the use of clamp to attach the tether to the lamina of a vertebra. As illustrated, the tether may encircle the lamina and may be tightened using a belt clamp. The other end of the tether is as shown in the earlier embodiments coupled to a portion of the ilium. Using this mechanism, the deformity of the spine may be corrected by manipulating the tether as well as the positioning of the clamp, as needed. 
       FIG. 17  shows a tether that includes a loop which is used to for coupling the tether to the transverse rod to fixate the tether to the transverse rod.  FIG. 18  illustrates the coupling of the tether directly to the ilium using another type of tether clamp. It should be noted that in the examples provided of both anchor and clamps, these mechanical devices may be interchangeable. 
     It should also be noted that the tether of the present invention may be composed of fabric, polymer, such as PET, or any other biocompatible materials. The tether can be a cable and can be dimensioned to be a wide elastic band which advantageously reduce the risk of damage to tissue lacerations or injury. In some embodiments, the tether can be is between 2 and 900 mm. Also, to ensure that proper correction of deformities, a tensioner can be included as part of the system to make sure that the tether are in proper tension and tightness. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Moreover, the improved bone screw assemblies and related methods of use need not feature all of the objects, advantages, features and aspects discussed above. Thus, for example, those skilled in the art will recognize that the invention can be embodied or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. In addition, while a number of variations of the invention have been shown and described in detail, other modifications and methods of use, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is contemplated that various combinations or subcombinations of these specific features and aspects of embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the discussed bone screw assemblies. Thus, it is intended that the present invention cover the modifications and variations of this invention provided that they come within the scope of the appended claims or their equivalents.

Technology Category: 1