Abstract:
An inter-transverse process spacer system comprises a first spacer device. The first spacer device comprises opposing end portions. The first spacer device is adapted for insertion between a first pair of adjacent transverse processes, and the opposing end portions of the first spacer device are adapted to engage the first pair of adjacent transverse processes. The inter-transverse process spacer system further comprises a first connection device connected to the first spacer device and adapted to engage at least one of the first pair of adjacent transverse processes.

Description:
BACKGROUND 
     Severe back pain and nerve damage may be caused by injured, degraded, or diseased spinal joints and particularly, spinal discs. Current methods of treating these damaged spinal discs may include vertebral fusion, nucleus replacements, or motion preservation disc prostheses. Disc deterioration and other spinal deterioration may cause spinal stenosis, a narrowing of the spinal canal and/or the intervertebral foramen, that causes pinching of the spinal cord and associated nerves. Current methods of treating spinal stenosis include laminectomy or facet resection. Alternative and potentially less invasive options are needed to provide spinal pain relief. 
     SUMMARY 
     In one embodiment of the present disclosure, an inter-transverse process spacer system comprises a first spacer device. The first spacer device comprises opposing end portions. The first spacer device is adapted for insertion between a first pair of adjacent transverse processes, and the opposing end portions of the first spacer device are adapted to engage the first pair of adjacent transverse processes. The inter-transverse process spacer system further comprises a first connection device connected to the first spacer device and adapted to engage at least one of the first pair of adjacent transverse processes. 
     In another embodiment, an inter-laminar spacer system comprises a first connection device adapted to engage a lamina of a first vertebra and a second connection device adapted to engage a lamina of a second vertebra. The inter-laminar spacer system further comprises a first lamina spacer extending between the first and second connection devices. 
     In another embodiment, a method of spinal decompression comprises accessing a pair of transverse processes and inserting a spacer device between the pair of transverse processes. The method further comprises engaging a connection device with the spacer device and at least one of the pair of transverse processes. 
     In another embodiment of the present disclosure, a method of decompressing a spinal joint comprises accessing an interlaminar space between first and second lamina and inserting a spacer system into the interlaminar space. The method further comprises connecting the spacer system to inner and outer faces of the first lamina. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vertebral column with an inter-transverse process spacer system according to one embodiment of the present disclosure. 
         FIG. 2  is an assembled perspective view of the spacer system of  FIG. 1 . 
         FIG. 3  is a perspective view of a component of the spacer system of  FIG. 1 . 
         FIG. 4  is a sectional view of the component of  FIG. 3 . 
         FIG. 5  is a perspective view of a vertebral column with an inter-laminar spacer system according to one embodiment of the present disclosure. 
         FIG. 6  is an assembled perspective view of the spacer system of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates generally to the field of orthopedic surgery, and more particularly to systems and methods for decompressing a spinal joint. For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments or examples illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alteration and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. 
     Referring first to  FIG. 1 , the numeral  10  refers to a vertebral joint which includes an intervertebral disc  12  extending between vertebrae  14 ,  16 . The vertebra  14  includes a lamina  18 , and the vertebra  16  includes a lamina  20 . The vertebrae  14 ,  16  also include vertebral bodies  14   a ,  16   a , respectively. The vertebra  14  further includes transverse processes  22 ,  24 ; a spinous process  26 ; and caudal articular processes  28 ,  30 . The vertebra  16  further includes transverse processes  32 ,  34 ; a spinous process  36 ; and rostral articular processes  38 ,  40 . Although the illustration of  FIG. 1  generally depicts the vertebral joint  10  as a lumbar vertebral joint, it is understood that the devices, systems, and methods of this disclosure may also be applied to all regions of the vertebral column, including the cervical and thoracic regions. Furthermore, the devices, systems, and methods of this disclosure may be used in non-spinal orthopedic applications. 
     A facet joint  42  is formed, in part, by the adjacent articular processes  28 ,  38 . A facet joint  44  is formed, in part, by the adjacent articular processes  30 ,  40 . Facet joints may also be termed zygapophyseal joints. A healthy facet joint includes a facet capsule extending between the adjacent articular processes. The facet capsule comprises cartilage and synovial fluid to permit the articulating surfaces of the articular processes to remain lubricated and glide over one another. The type of motion permitted by the facet joints is dependent on the region of the vertebral column. For example, in a healthy lumbar region, the facet joints limit rotational motion but permit greater freedom for flexion, extension, and lateral bending motions. By contrast, in a healthy cervical region of the vertebral column, the facet joints permit rotational motion as well as flexion, extension, and lateral bending motions. As the facet joint deteriorates, the facet capsule may become compressed and worn, losing its ability to provide a smooth, lubricated interface between the articular surfaces of the articular processes. This may cause pain and limit motion at the affected joint. Facet joint deterioration may also cause inflammation and enlargement of the facet joint which may, in turn, contribute to spinal stenosis. Removal of an afflicted articular process may result in abnormal motions and loading on the remaining components of the joint. The embodiments described below may be used to decompress a deteriorated facet joint and/or restore more natural motion constraint to a resected joint. 
     Injury, disease, and deterioration of the intervertebral disc  12  may also cause pain and limit motion. In a healthy intervertebral joint, the intervertebral disc permits rotation, lateral bending, flexion, and extension motions. An axis of flexion  46  may extend between the vertebral bodies  14   a ,  16   a  and through the intervertebral disc  12 . As the intervertebral joint deteriorates, the intervertebral disc may become compressed, displaced, or herniated, resulting in excess pressure in other areas of the spine, particularly the posterior bony elements of the afflicted vertebrae. This deterioration may lead to spinal stenosis. The embodiments described below may restore more natural spacing to the posterior bony elements of the vertebrae, decompress an intervertebral disc, and/or may relieve spinal stenosis. 
     Referring still to  FIG. 1 , in one embodiment, a spacer system  50  may be used to support the transverse processes  24 ,  34 ; decompress the disc  12  and the facet joint  44 ; and/or relieve stenosis. The spacer system  50  includes a spacer device  52  which may be monolithically formed of an elastic, multi-directionally flexible material such as silicone, polyurethane, or hydrogel. The spacer device  52  may include two pairs of legs  54 ,  56  integrally formed with and extending from a cross member  58 . As shown in greater detail in  FIGS. 3 and 4 , the cross member  58  may comprise transverse conduits  60 ,  62 . The openings of the conduits  60 ,  62  may be widened and curved to minimize sharp edges that could present a point of wear. The internal faces of the legs  54  are angled to converge toward a recessed area  66 , and the internal faces of the legs  56  are angled to converge toward a recessed area  68 . The cross member  58  has a thickness  64  which may be slightly greater than the inter-transverse process space between the processes  24 ,  34  when the vertebra  14 ,  16  are in a natural position. For example, the cervical and lumbar regions of the vertebral column may be in lordosis when in a natural position. 
     Referring now to  FIGS. 1 and 2 , in this embodiment, the spacer system  50  further includes connection devices such as cables  70 ,  72  which extend through the transverse conduits  62 ,  64 , respectively, of the cross member  58 . At least one end of each of the cables  70 ,  72  may be attached to stopper devices  74 ,  76 , respectively. The connection devices may be either elastic or inelastic and able to carry tensile forces. They may be formed, for example, of biocompatible reinforcing materials such as wire, cable, cord, bands, tape, or sheets. They may have a braided, knitted, or woven construction. 
     A surgical procedure to implant the spacer system  50  may be ultra minimally invasive. Using a posterior, posterolateral, lateral, anterolateral or anterior approach, a small incision may be created in the patient&#39;s skin. The transverse processes  24 ,  34  may be visualized directly or with radiographic assistance. The spacer device  52  may be compressed and inserted between the transverse processes  24 ,  34 . The spacer device  52  may then expand slightly so that the recess  68  comes into firm contact with the transverse process  24  and the recess  66  comes into firm contact with the transverse process  34 . The cross member  58  may remain slightly compressed after implantation so that the recesses  66 ,  68  may continue to exert pressure on the transverse processes  34 ,  24 , respectively, minimizing the opportunity for the spacer device  52  to be come dislodged. The compression of the cross member  58  may bias the legs  56  to compress together, creating a firm grip on the transverse process  24 . This holding action, together with the flexibility of the device  52 , minimizes friction and the associated material and bone wear. The legs  54  may, likewise, grip transverse process  34 . 
     The connection device  72 , led for example by a needle, may be inserted through the conduit  60  and around the transverse process  24 . The connection device  72  may then be inserted through the stopper  76 . The location of the spacer device  52  may still be adjusted while the connection device  72  is relatively loose. For example, the spacer device  52  may be placed close to the base of the transverse processes  24 ,  34 , near the vertebral bodies  14   a ,  16   a , to reduce the torsional forces placed on the spacer device by the transverse processes. With the spacer device  52  in the desired position, the connection device  72  may be tightened, and anchored to the stopper device  76 . The stopper device  76  may thus anchor both ends of the connection device  72 . The connection device  70  may similarly anchor the spacer device to the transverse process  34 . 
     In certain anatomies, the spacer system  50  may be used alone to provide decompression to a single targeted facet joint or to relieve pressure on a particular side of the intervertebral disc, such as a herniation area. But, as shown in  FIG. 2 , a second spacer system  80  may be installed on the opposite lateral side from the spacer system  50 , between transverse processes  22 ,  32 . The spacer system  80 , when used in conjunction with the spacer system  50 , may provide more balanced support and equalized decompression. The spacer system  80  may be substantially similar to system  50  and therefore will not be described in detail. 
     The spacer system  50 , as installed, may axially separate the vertebrae  14 ,  16 , relieving pressure on the intervertebral disc  12  and the facet joint  44  and reducing wear and further degeneration. The spacer device  52  may also dampen the forces on the intervertebral disc  12  and facet joint  44  during motion such as flexion and extension. Because the spacer device  52  may be positioned relatively close to the natural axis of flexion  46 , the spacer system  50  may be less likely to induce kyphosis as compared to systems that rely upon inter-spinous process devices to provide decompression. Additionally, the system  50  may be installed minimally invasively with less dissection than the inter-spinous process devices of the prior art. Furthermore, an inter-transverse process system can be used on each lateral side of the vertebrae  14 ,  16 , and may provide greater and more balanced decompression than the single inter-spinous process devices of the prior art. 
     In an alternative embodiment, the conduits through the spacer device may be omitted and the connection devices attached to other connection points on the spacer device such as side handles. The connection device may extend through or into one or both of the transverse processes. In still another alternative, the connection device may be eliminated and the spacer device held in place by the compressive forces of the transverse processes. The connection device may also take the form of a clamp, spike, threaded connection or any other type of mechanical or adhesive connection for attaching devices to bone. 
     In another alternative embodiment, the spacer device may be shaped to address various patient anatomies and afflictions. In one embodiment, the legs of the spacer device may be angled such that the spacer device provides not only cephalad-caudal axial decompression but also anterior or posterior decompression. For example, in a patient recovering from disc surgery, the spacer device may be angled toward lordosis to take pressure off the intervertebral disc temporarily. Likewise the spacer device may be angled toward kyphosis to temporarily reduce pressure on a recovering facet joint. 
     In another alternative embodiment, the material of the spacer device may be completely or partially rigid. A sheath may be also surround the spacer device to limit direct contact between the spacer device and the surrounding tissue. The sheath may also serve to contain wear debris and limit over stretching of the spacer device. 
     Referring now to  FIGS. 5 and 6 , in one embodiment, a spacer system  100  may be used to support the laminae  18 ,  20 ; decompress the disc  12  and the facet joint  44 ; and/or relieve stenosis. The spacer system  100  includes a spacer device  102  which may be monolithically formed of an elastic, multi-directionally flexible material such as silicone, polyurethane, or hydrogel. The spacer device  102  may have a wider midsection and may taper slightly toward the ends. The spacer device may have a height  108  which may be slightly greater than the inter-laminar space between the processes  18 ,  20  when the vertebra  14 ,  16  are in a natural position. For example, the cervical and lumbar regions of the vertebral column may be in lordosis when in a natural position. 
     The spacer system  100  further includes connection devices  104 ,  106  such as laminar hooks which are attached to the opposite ends of the spacer device  102 . The laminar hook  104  may comprise an outer arm  110  and an inner arm  112 . The laminar hooks  104 ,  106  may be formed of any suitable biocompatible material including metals such as cobalt-chromium alloys, titanium alloys, nickel titanium alloys, and/or stainless steel alloys. Ceramic materials such as aluminum oxide or alumnia, zirconium oxide or zirconia, compact of particulate diamond, and/or pyrolytic carbon may be suitable. Polymer materials may also be used, including any member of the polyaryletherketone (PAEK) family such as polyetheretherketone (PEEK), carbon-reinforced PEEK, or polyetherketoneketone (PEKK); polysulfone; polyetherimide; polyimide; ultra-high molecular weight polyethylene (UHMWPE); and/or cross-linked UHMWPE. 
     A surgical procedure to implant the spacer system  100  may be relatively minimally invasive. Using a posterior, posterolateral, lateral, or other suitable approach, a small incision may be created in the patient&#39;s skin. The ligamentum flavum or other soft tissues may be mobilized and the laminae  18 ,  20  may be visualized directly or with radiographic assistance. The spacer device  102  may be compressed and the laminar hooks  104 ,  106  may be inserted between the laminae  18 ,  20 . The spacer device  102  may then expand slightly so that hooks  104 ,  106  come into firm contact with the laminae  20 ,  18 , respectively. The spacer device  102  may remain slightly compressed after implantation so that the hooks  104 ,  106  may continue to exert pressure on the laminae  20 ,  18 , respectively, minimizing the opportunity for the spacer device  102  to be come dislodged. With the system  100  installed, the arms  110 ,  112  of the hook  104  may firmly contact the outer and inner faces, respectively, of the lamina  20 . The hook  106  may similarly engage the lamina  18 . 
     In certain anatomies, the spacer system  100  may be used alone to provide decompression to a single targeted facet joint or to relieve pressure on a particular side of the intervertebral disc, such as a herniation area. However, a second spacer system may also be installed on the opposite lateral side from the spacer system  100 . The spacer system  100 , when used in conjunction with a second spacer system, may provide more balanced support and equalized decompression. 
     The spacer system  100 , as installed, may axially separate the vertebrae  14 ,  16 , relieving pressure on the intervertebral disc  12  and the facet joint  44  and reducing wear and further degeneration. The spacer device  102  may also dampen the forces on the intervertebral disc  12  and facet joint  44  during motions such as flexion and extension. Because the spacer device  102  may be positioned relatively close to the natural axis of flexion  46 , the spacer system  100  may be less likely to induce kyphosis as compared to systems that rely upon inter-spinous process devices to provide decompression. Additionally, the system  100  may installed with less dissection than the inter-spinous process devices of the prior art. Furthermore, an inter-laminar system can be used on each lateral side of the vertebrae  14 ,  16 , and may provide greater and more balanced decompression than the single inter-spinous process devices of the prior art. 
     In an alternative embodiment, the laminar hooks may have a spring action which draws the arms together to engage the lamina, or the hooks may have a vise mechanism which draws the arms together to engage the lamina. This holding action, together with the flexibility of the device  102 , may minimize friction and the associated material and bone wear. 
     In still another alternative, the spacer device may be formed of a rigid material such as those listed above for the laminar hooks. A rigid spacer device may be height adjustable such that a decreased height may be set to provide easy access for the laminar hooks, and an increased height may be set to bring the hooks into firm contact with the laminar walls. 
     In still another alternative embodiment, the connection devices may attach to other posterior bones such as the adjacent articular or spinous process. A connection device such as the cabling system  72  described above may also be used to connect the spacer device between the laminae. For example, a cable could extend around the lamina, through the spinal foramen to tether the spacer device to the lamina. 
     Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications and alternative are intended to be included within the scope of the invention as defined in the following claims. Those skilled in the art should also realize that such modifications and equivalent constructions or methods do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. It is understood that all spatial references, such as “horizontal,” “vertical,” “top,” “upper,” “lower,” “bottom,” “left,” “right,” “cephalad,” “caudal,” “upper,” and “lower,” are for illustrative purposes only and can be varied within the scope of the disclosure. In the claims, means-plus-function clauses are intended to cover the elements described herein as performing the recited function and not only structural equivalents, but also equivalent elements.