Patent Publication Number: US-2015080951-A1

Title: Vertebral fixation apparatus

Description:
RELATED APPLICATION 
     This application claims the benefit of a Taiwanese patent application, 102133297, filed on Sep. 14, 2013, the specification of which is incorporated here by this reference. 
     BACKGROUND OF THE INVENTION 
     In order for treating spinal conditions such as stenosis, a fixation device is provided for fixing the adjacent spinous processes of the two neighboring vertebrae to decompress the spinal cord and nerve so as to eliminate the pressure on the spinal vessel or nerve for relieving the back pain or other spinal symptoms. 
     U.S. Pat. No. 8,388,657, 8,475,497, 8,591,548 or 8603142 disclosed a spinous process fixation apparatus. U.S. Pat. No. 8,591,548 disclosed a spinous process fusion plate assembly including two fixation plates ( 10 ,  20 ) to “clamp” both sides of the adjacent spinous processes, having projections ( 15 ) inserted into the spinous processes when fastened by a locking element ( 40 ) provided on the brace ( 30 ) for linking the two plates ( 10 ,  20 ) together. 
     Such a prior art may have the following drawbacks:
     1. The projections  15  are stuck into the spinous processes to easily cause breakage or fracture of the spinous processes, especially when “clamping” the two plates ( 10 ,  20 ) under pressure on the weak spinous processes, easily causing fixation failure.   2. The two plates ( 10 ,  20 ) are fastened on the weak spinous processes, not firmly fixed to the strong vertebral portions (such as on the stronger root portion of transverse process), and are easily loosened, when bending or twisting the patient&#39;s body, to be separated from the vertebrae to thereby lose its effect for relieving the pressure on pinched nerves.   3. The plates ( 10 ,  20 ) are generally perpendicular to the vertebral surface, unable to cover the surgery area such as when removing partial vertebral arch or lamina, thereby being unable to preclude the tissue re-growth into the surgery area and thereby still pressurizing the spinal nerve to cause pain.   

     The present inventor has found the drawbacks of the prior art, and invented the present fixation apparition for stably holding the adjacent spinous processes. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a vertebral fixation apparatus including a fixation plate respectively secured to the root portions of adjacent transverse processes, rather than the adjacent spinous processes, a superior saddle portion and an inferior saddle portion respectively formed on an upper and a lower portion of the fixation plate for holding the superior spinous process and the inferior spinous process within the superior and inferior saddle portions for stably securing the fixation plate on the adjacent vertebrae for distracting the adjacent vertebrae for relieving the pressure and pain of the spinal cord and nerve. 
     Another object of the present invention is to provide a fixation apparatus which may cover the surgery area of the vertebral arch to preclude the tissue re-growth into the surgery area to prevent from pressurizing on the pinched nerves, thereby relieving the pain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the present invention. 
         FIG. 2  is a partial enlarged view for the micro-lattice structure of the present invention. 
         FIG. 3  is a perspective view of the present invention when holding adjacent spinous processes. 
         FIG. 4  is a top view illustration based on  FIG. 3  of the present invention. 
         FIG. 5  shows another preferred embodiment of the present invention. 
         FIG. 6  shows still another preferred embodiment of the present invention. 
         FIG. 7  is a top view illustration based on  FIG. 6 . 
         FIG. 8  shows further preferred embodiment of the present invention. 
         FIG. 9  shows still further preferred embodiment of the present invention. 
         FIG. 10  shows a single-leaf plate member combined with a holding means of the present invention. 
         FIG. 11  shows an embodiment of the present invention when combining the elements of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1˜4 , the present invention discloses a vertebral fixation apparatus  10  for holding two spinous processes S 1 , S 2  of the two adjacent vertebrae S, S′ in order for stably spanning the two adjacent vertebrae S, S′ with a proper intervertebral distance, thereby preventing compressing on the spinal blood vessel or nerve and eliminating the back pain or spinal symptoms. 
     The vertebral fixation apparatus  10  of the present invention comprises: a fixation plate  12  having a first saddle portion  111  formed on a first (or superior) portion of the fixation plate  12  for holding a first (or superior) spinous process S 1 , and a second saddle portion  112  formed on a second (or inferior) portion of the fixation plate  12 , opposite to the first saddle portion  111 , for holding a second (or inferior) spinous process S 2 ; a first pair of screws  13  respectively locking the first saddle portion  111  into root portions of a pair of first (or superior) transverse processes T; and a second pair of screws  13  respectively locking the second saddle portion  112  into root portions of a pair of second (or inferior) transverse processes T′. 
     The first saddle portion  111  and the second saddle portion  112  may be cooperatively defined as “a holding means”  11  for stably holding the adjacent spinous processes S 1 , S 2  on the fixation plate  12 . 
     The fixation plate  12  is locked into the root portions of the transverse processes T, T′ by the four screws  13  as shown in  FIGS. 4 and 3 . Since the transverse process is the strongest part of the vertebra, the fixation apparatus  10  of the present invention will be strongly and stably secured on the adjacent vertebrae S, S′. The fixation apparatus  10  is not fixed on the spinous processes S 1 , S 2 , which are weak to be vulnerably broken in comparison with the stronger transverse processes T, T′, so that the breakage of spinous processes S 1 , S 2  can be prevented in accordance with the present invention. 
     The fixation apparatus  10 , once secured on the adjacent vertebrae S, S′, will decompress the spinal cord and nerve in the vertebrae to prevent or eliminate the back pain or spinal symptoms. Meanwhile, such a fixation apparatus  10  may serve as a barrier to protect or shield the vertebra S′, which may be subjected to surgery for treating spinal stenosis (such as by removing or cutting lamina or vertebral arch), in order to prevent intrusion of newly growing tissue into the surgery vertebral area which may re-compress the spinal nerve to cause back pain or other uncomfortable symptoms. 
     Each screw  13  is locked into the root portion of the transverse process T, T′ by inserting through a fixing hole  121  formed in (or adjacent to) the saddle portion  111 ,  112  on the fixation plate  12 . 
     Each fixing hole  121  may be pre-inserted with a screw sleeve  122  therein, and then each screw  13  is locked into the fixing hole  121  by passing through each screw sleeve  122 . The shape of each screw  122  and fixing hole  121  may not be a circular or cylindrical shape in order to prevent from its self-rotation, thereby enhancing the locking stability of each screw  13  and the fixing plate  12  of the present invention. 
     Each fixing hole  121  may be obliquely formed in the fixation plate  10 , not perpendicular to the surface of the transverse process T, T′ as shown in  FIGS. 4 and 3 . 
     An inferior fixing hole  121  adjacent the inferior spinous process S 2  may be obliquely formed in a root portion of the inferior transverse process T′ along a first axis X 1  which is generally projectively aligned with or parallel to an orientation of the inferior transverse process T′ as shown in  FIG. 4 ; while a superior fixing hole  121  adjacent to the superior spinous process T may be obliquely formed in a root portion of the superior transverse process T along a second axis X 2  which is generally projectively perpendicular to the first axis X 1 ; whereby upon fixing of each (lower) screw  13  into each inferior fixing hole  121  along the first axis X 1 , the two (lower) screws  13  will be secured into the two inferior fixing holes  121  to firmly secure the pair of inferior transverse processes T′, the inferior spinous process S 2  with the fixation plate  12  latitudinally; and upon fixing of each (upper) screw  13  into each superior fixing hole  121  along the second axis X 2 , the two (upper) screws  13  will be secured into the two superior fixing holes to firmly secure the superior spinous process S, the superior transverse processes T, with the fixation plate  12  longitudinally, thereby fixing the fixation plate  12  stably firmly among the superior spinous process S 1 , the superior transverse processes T, the inferior spinous process S 2  and the inferior transverse processes T′. 
     Since the superior spinous process S 1  and the inferior spinous process S 2  are snugly held in the superior saddle portion  111  and the inferior saddle portion  112 , without being squeezed, compressed, clamped or “invasively” stuck, the spinous processes S 1 , S 2  will not be broken or fractured and will be stably held by the fixation plate  12  for protecting the vertebrae safely. 
     The definition of the axis X 1  or X 2  as aforementioned is just provided for explanation purpose in the present invention. The orientations and fixing methods for fixing the screws  13  into the vertebral portion are, however, not limited in this invention. 
     The saddle portion  111  or  112  is formed like a “horse saddle” having a depression or recess as recessed in two elevations or peaks for holding each spinous process S 1  or S 2  within the recess. In other words, each spinous process S 1  or S 2  is “riding” on each saddle portion  111  or  112 , and the two spinous processes S 1 , S 2  are thus stably held in between the two saddle portions  111 ,  112  especially as shown in  FIGS. 4 and 3 . As any two adjacent vertebrae S, S′ are spanned or spread apart by the fixation plate  12  and the adjacent vertebrae are also firmly stably “linked” by the fixation apparatus  10  of the present invention, the vertebrae will then be decompressed, distracted, or spaced to release the pressure on the spinal cord or nerve to relieve the patient&#39;s back pain accordingly. 
     As shown in  FIG. 5 , each fixing hole  151  is formed with female threads  121   a  to be engaged with the male threads as formed on each screw  13 . Also, the screw  13  may be a self-attack screw which may be locked into the vertebral portion in situ during the locking process of the screw. However, it should be carefully considered by evaluating the patient&#39;s bone density or strength whenever applying the self-attack screw which may be more destructive than the other screws. 
     As shown in  FIGS. 1˜3 , the fixation apparatus  10  of the present invention may be formed as micro-lattice hollow structure  10 ′, each micro lattice being shaped as: triangular, hexagonal, beehive, polygonal, regular or irregular porosity shapes or structures, adapted for fusion of tissue or bone re-growth into the micro-lattice hollow structure  10 ′ to thereby enhance the vertebral or spinal strength. A well fusion on the fixation apparatus  10  and the linked vertebrae will diffuse any external force to be homogeneously acting on the vertebrae, not merely concentrating the external force on the fixing screws  13  to easily cause fixing failure of the fixation apparatus. 
     The size of each micro lattice may range 100 microns through 400 microns for an optimum fusion effect, but not limited in this invention. For strengthening the whole structure, a solid metallic frame or protection wall W may be provided for fencing the micro-lattice structure. 
     The fixation apparatus  10  of the present invention may be formed by 3-D printing and shaping technique. The fixation apparatus  10  may be made of: titanium, stainless steel, PEEK, metal or alloy materials. Both flexibility and rigidity of the fixation apparatus must be considered. The fixation apparatus  10  may also be formed by conventional mechanical processing or metallic injection molding process, not limited in this invention. 
     As shown in  FIGS. 6 &amp; 7 , each saddle portion  111  or  112  may be further protected with a U-shape or V-shape packing or protecting member  113   a ,  113   b  along a periphery of said saddle portion for well protection of each spinous process S 1  or S 2 . 
     As shown in  FIG. 8 , the fixation apparatus  10   a  may be divided into two half plate members, namely, a left plate member  101  and a right plate member  102 , each having a connecting projection  14 , so that the two half plate members  101 ,  102  may be locked and combined by a fastening screw  103  which is provided to pass each screw opening  141  formed through each connecting projection  14 . 
     As shown in  FIG. 9 , the fixation apparatus  10   b  may be divided into a superior half plate member  101  and an inferior half plate member  102 , which are combined by locking at least a (or two) fastening screw(s)  103  passing through screw opening(s)  141  formed through each connecting projection  14 . A spring  104  may be jacketed on each fastening screw  103 . 
     The two half plate members  101 ,  102  as shown in  FIGS. 9 and 8  may be further provided with a spacer (not shown) in between the two plate members  101 ,  102  for adjusting the length or width of the fixation apparatus to match the distance between two adjacent spinous processes S 1 , S 2  or to match the shape or circumference of the spinous processes. 
     As shown in  FIGS. 10 and 11 , the fixation apparatus  10  may be modified to be a single-leaf plate member  12  and a holding means  11  including a superior saddle portion  111  and an inferior saddle portion  112 , having at least a (or two) fastening screw(s)  103  for locking the single-leaf plate member  12  with the holding means  11 . Such a single-leaf plate member  12  may be a left plate member or a right plate member, depending upon the patient&#39;s requirement. 
     By the way, the minimally invasive surgery may be applied to a patient whose surgery area may be limited to be as minimum as possible, for example, just conducting invasive operation for a left vertebral portion, or for a right portion only, without requiring a large surgical area which may cause patient&#39;s uncomfortableness, pain, or even infection. The holding means  11  may be made with plural sizes for optional choices. 
     The fixation apparatus  10  of the present invention may be made with a plurality of sizes, for example, plural distances between the two saddle portions  111 ,  112  which may be provided for patient&#39;s selections. 
     A recess  15  is formed in a bottom of the fixation apparatus  10  as shown in  FIGS. 1 and 3  to form a “space” between the fixation plate  10  and the vertebral arch, thereby preventing compression on the spinal nerve and the back pain caused by the fixation apparatus. 
     In surgical operation, the vertebral arch may be partially removed to provide “space” for accommodating the spinal cord or nerve to relieve the pressure acting upon the spinal nerve. After the surgery operation, the fixation plate  10  of the present invention may be provided to cover the surgery area (the area by removing the partial vertebral arch) in order to preclude the intrusion of re-growing tissue to further compress the spinal nerve. The bone tissue will grow directly on the fixation plate  10  especially when formed as micro-lattice structure as shown in  FIGS. 1 ,  2  for well fusing the plate  10  and the neighboring vertebral portions. Some bone powders or bone cement may be filled into the proper areas of the fixation apparatus  10  and the vertebrae as held on the apparatus  10  for better fusion. 
     The two spinous processes S 1 , S 2  of the adjacent vertebrae S, S′ are “saddled” by the two saddle portions  111 ,  112  on the fixation plate  12  of the present invention, like riding on a house saddle, will be stably held by the fixation apparatus  10 . No pressurized clamping, fastening or squeezing are acting on the spinous processes. No “invasive” sticking, intrusion, or piercing is performed on the weak spinous process. So, the spinous processes of the adjacent vertebrae can be well protected from breakage or fracture by the present invention. 
     The fixation apparatus  10  is provided to “link” the two adjacent vertebrae by locking the screws  13  onto the transverse processes T, T′ which are relatively strong. So, the vertebrae may be stably fixed ready for a proper fusion. 
     By the aid of the oblique fixing holes for fixing screws  13  along axis X 1  or X 2 , the fixation plate of the present invention will be firmly secured with the adjacent vertebrae latitudinally (X 1 , X 1 ) and longitudinally (X 2 , X 2 ) ( FIG. 4 ), thereby enhancing a firm, stable, and reliable fixation of the vertebrae on the fixation plate for well protecting the spinal cord and nerve.