Patent Publication Number: US-2010121379-A1

Title: Pedicle and non-pedicle based interspinous and lateral spacers

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/668,029, filed Jan. 27, 2007, which claims priority from U.S. Provisional Patent Application Ser. No. 60/762,586, filed Jan. 27, 2006, the entire content of each application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to spinal stabilization devices and, in particular, to pedicle and non-pedicle based interspinous and lateral spacers. 
     BACKGROUND OF THE INVENTION 
     Natural intervertebral discs serve multiple purposes. First, they preserve correct anatomical spacing between adjacent vertebral bodies, allowing branching nerve bundles to function normally, without pain. Discs also facilitate natural flexion, extension, and lateral bending in support of daily physical activities. Discs further serve as “shock absorbers” for spinal loading. 
     However, for many reasons, natural discs can loose functionality, often leading to back pain. These sources may include physical trauma, degenerative disc disease, and other maladies. Today there are many options to stabilize spinal segments which may exhibit a loss of functionality. One option is spinal fusion, wherein a complete or partial discectomy is performed, with one or more cages or other mechanical devices being inserted into the disc space. Another option gaining in popularity is the use of “artificial discs,” which typically include either a resilient central portion or mechanical elements that facilitate a certain degree of articulation. 
     Various types of intervertebral spacers are also available as valuable tools to promote spinal stabilization. Such devices may be used in conjunction with fusion, for example, to relieve pressure from the central vertebral column. Spacers may also be valuable in relieving spinal stenosis and other conditions resulting in back pain. 
     SUMMARY OF THE INVENTION 
     This invention is directed to pedicle and non-pedicle based interspinous and lateral spacers. Each embodiment includes some form of spacer component having an upper surface configured for engagement with an inferior surface of a fifth lumbar vertebral body, and a lower surface configured for engagement with an outer surface of a sacrum. 
     A first preferred embodiment includes a component having two opposing upper arms and two opposing lower arms. The spacer component has two ends and a central section, each end of the spacer component being configured for attachment to a respective one of the two opposing upper arms, and the central section of the spacer has a height configured for placement between a spinous process of a fifth lumbar vertebral body and a superior surface of an uppermost spinous process of a sacrum. The ends of the spacer component may be attached to the upper arms using pedicle screws, or may use snap-and-lock or other connectors. 
     The two lower arms may either engage directly with the outer surface of a sacrum on either side of a medial ridge, or may interconnect with a separate component also having two lower arms that engage with the outer surface of a sacrum on either side of a medial ridge. Such arms are preferably bent outwardly and include inward serrations to engage with the outer surface of a sacrum on either side of a medial ridge. 
     A different embodiment includes two spacer components, one on each end of a horizontal bar, each spacer component having a lower, concave end configured for engagement with a sacral notch. The horizontal bar preferably further includes a pair of downwardly extending elements, each being bent outwardly to engage with the outer surface of a sacrum on either side of a medial ridge. 
     In a further embodiment the spacer component includes an upper concave surface configured to engage with the inferior surface of a transverse process and a lower concave surface configured to engage with a sacral notch. A link member may be provided to connect the spacer component to a pedicle using a pedicle screw, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a posterior view of an interspinous spacer according to the invention; 
         FIG. 1B  is a drawing of a preferred interspinous insert; 
         FIG. 1C  is a side view of the insert of  FIG. 1B ; 
         FIG. 1D  is a side view of an alternative insert utilizing snap/lock interconnects; 
         FIG. 2A  is a drawing of an alternative spacer that facilitates stacking; 
         FIG. 2B  is a lateral view of the arrangement of  FIG. 2A , showing sacral engagement features; 
         FIG. 3A  is the posterior view of an alternative interspinous spacer according to the invention; 
         FIG. 3B  is a side view showing the way in which a lower sacral portion is bent for enhanced anatomical engagement; 
         FIG. 3C  is a posterior view drawing showing how the arms of  FIG. 3A  may be hinged through interlocking; 
         FIG. 4A  is a drawing showing a sacral notch sling according to the invention; 
         FIG. 4B  is side view of the device of  FIG. 4A ; 
         FIG. 4C  is a detailed view showing the way in which the device of  FIG. 4A  cooperates with a sacral notch; 
         FIG. 5A  is a posterior view of a pedicle-based lateral spacer according to the invention; 
         FIG. 5B  is a detailed drawing showing the way in which the spacer of  FIG. 5A  cooperates with a sacral notch and the inferior surface of a transverse process; 
         FIG. 6A  is a posterior view of lateral spacers that do not require fasteners such as pedicle screws; and 
         FIG. 6B  is a detailed drawing showing the way in which the lateral spacers of  FIG. 6A  cooperate with a sacral notch and the inferior surface of a transverse process. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings,  FIG. 1A  is a posterior view of an interspinous spacer system according to the invention. The device includes first and second upper arms  110 ,  112 , which intersect a region  120  between spinous process  104  of L5 and  106 , the upper spinous process of the sacrum, sometimes referred to as the upper spinous tubercle on the medial sacral crest. The device further includes first and second lower arms  122 ,  124  which continue down past  106  and engage with the surface of the sacrum on either side of the medial sacral crest. 
     The arms may extend from a unitary structure, or two crossing pieces may be used, in which case they may be permanently joined or hinged to accommodate varying recipient physiology. One or more removable insertion pegs  126  may be located as shown, or with respect to other portions of the device. 
     The upper arms  110 ,  112  in this embodiment include holes or slots  114 ,  116 , which receive a spacer between spinous process  102  of L4 and spinous process  104 .  FIG. 1B  shows a preferred spacer, including a central portion  130  physically configured to achieve the desired level of separation or distraction, with outward aims  132 ,  134 . Pedicle screws  136 ,  138  are provided through the arms  132 ,  134 , and the screws  136 ,  138  continued through apertures  114 ,  116 , into pedicles (not shown). This creates a highly stable configuration in the lower lumbar and sacral region. 
       FIG. 1C  is a side-view drawing of the spacer of  FIG. 1B , showing pedicle screws  136 ,  138  with their threaded portions.  FIG. 1D  is a side-view drawing of an alternative spacer according to the invention, having a central distraction portion  140  and outward arms  142 ,  144  to which they are connected snap-in ends  146 ,  148  which cooperate with apertures  114 ,  116  without the need for pedicle screws. 
     In these embodiments, all of the components can be made out of any appropriate biocompatible materials, such as metals like chrome-cobalt, titanium, or the like, ceramics, or compressible/resilient materials where appropriate, assuming acceptable longevity. To install the spacer, it is assumed that the supraspinous ligament is sacrificed between spinous processes  102 ,  104 . However, the supraspinous ligament may be preserved in the region of  120 . Arms  122 ,  124 , preferably include serrations to engage with outer sacral surfaces as discussed in further detail below. 
       FIG. 2A  is a posterior view of an alternative embodiment of the invention, showing the way in which separate components may be stacked to achieve a result similar to that introduced with respect to  FIG. 1 . In this embodiment, an upper portion  220 , having lower arms  224 ,  226 , separates spinous processes  102 ,  104 . At the lower ends of the arms  224 ,  226 , are holes to receive pedicle screws  230 ,  232  which penetrate through a separate unit  210  disposed between spinous process  104  and spinous process  106  present on the sacrum. Component  210 , in turn, includes lower arms  212 ,  214 , preferably with serrations  240 , shown in  FIG. 2B , which engage with the sacrum  106 .  FIG. 2B  is a side-view drawing and partial cross-section better illustrating anterior-posterior (A-P) positioning of the components depicted in  FIG. 2A . 
       FIG. 3A  is a posterior view drawing of a further alternative embodiment of the invention, showing how a criss-cross or scissors-like device  302 , similar to that introduced with respect to  FIG. 1 , may be used with bent lower portions  322 ,  324  for conformity with the sacral surface, as better seen in  FIG. 3B . Such a structure also facilitates interlocking separate arms  303 ,  305 , as shown in  FIG. 3C . A spacer of the types depicted in  FIG. 1  is used between the spinous processes  102 ,  104 , engaging with apertures or slots  304 ,  306 . Again, in the region  320 , the arms may join in unitary fashion, or a hinged configuration may be used. 
       FIG. 4A  is a posterior view drawing of yet a further embodiment of the invention in the form of a sacral notch sling. The spinous process of L5 is shown at  401 . The device,  402 , includes a central bar portion  404 , having ends  406 ,  408 , which engage with the sacral notch  400 ′ on either side, as best shown in  FIG. 4C . The sacral notch is defined as the concave groove between the sacral ala and sacral horns or superior articular processes on either side of the sacrum. The outer surface of the groove is generally smooth and convex. 
     From the lateral view of  FIG. 4C , it can be seen portions  420 ,  422  have concave surfaces oriented on either side of the outer surface of the sacral notch  400 ′. The device  402  further includes lower arms  410 ,  412 , which, as in other embodiments, may be bendable to suit different patients and which may include serrations (not shown) to better engage with the other surface of the sacrum on either side of the medial crest. 
       FIG. 5A  is a posterior view drawing of yet a different embodiment of the invention, in the form of a lateral spacer  510 , including a pedicle-based fixation arrangement. The spinous process for L5 is shown at  501 , and the sacrum is indicated generally at  500 . The spacer,  510 , best seen in  FIG. 5B , includes a superior portion  512  having a surface that engages with the inferior surface of the transverse process  503 , and a lower surface  514  engages with the superior surface of the sacral notch  500 ′. 
     One or more elements are interconnected to the spacer  510 , such as horizontal arm  520  which in turn connects to a vertical arm  522  which, in turn, attaches to a receptacle  530  for a pedicle screw  532 . The various links  520 ,  522 ,  530 , and so forth, may be adjusted laterally or from anterior to posterior, to ensure that the spacer  510  is correctly positioned, and that the pedicle screw  532  is properly received. Although a single spacer is shown in  FIG. 5A , it will be appreciated that the spacer on the other side, or on both sides, may be accommodated depending upon the case. 
       FIG. 6A  is a posterior view drawing of yet a further, different embodiment of the invention, in the form of more simplified spacer  610 ,  612 , which do not require the use of fasteners such as pedicle screws. Again, the spinous process for L5 is shown at  501 , and the sacrum is shown at  500 .  FIG. 6B  is a lateral view, showing how the spacer  610 ,  612 , each have a superior surface  614  that interfaces to a transverse process  603 , and a lower portion  616  which conforms to sacral notch  600 ,  500 ′. Although only a single one of the spacers,  610 ,  612 , may be used, they are generally used in pairs due to the lack of fasteners.