Abstract:
An intervertebral filling includes a supporting body, a buffer layer covering the supporting body and at least two positioning pins, each positioning pin has a sharp end exposed out of the buffering layer, and the intervertebral filling uses this sharp ends of the positioning pins to stay in two adjacent spinal vertebrae end-plates. The supporting body is a little harder than the buffer layer and is used for sharing stress in the spine, providing a strong support. Consequently, the intervertebral filling of the present invention remains stably positioned between the two adjacent spinal vertebrae end-plates without undergoing displacement.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an intervertebral filling and, more particularly, to an intervertebral filling adapted for placement between any two adjacent spinal vertebrae end-plates in the human body.  
         [0003]     2. Description of the Related Art  
         [0004]     Human intervertebral discs between spinal vertebrae end-plates have an interesting mechanical structure. The intervertebral disc has a nucleus propulsus and an annulus fibrosus. The nucleus propulsus has a diameter of about 1.5 cm and is composed mainly of liquid. The annulus fibrosus has multiple layers and stabilizes the core. The intervertebral disc has the nature of a buffer for the human body, and helps to prevent damage to the spine.  
         [0005]     Due to various causes, such as moving heavy loads, inappropriate exercises, incorrect posture over long periods of time, pregnancies or back injuries, the spine in the human body may suffer herniated intervertebral disc problems; minor conditions may simply cause enlargement of the annulus fibrosus, but serious conditions can cause the annulus fibrosus to break and the nucleus propulsus to leak, thereby causing compression of the vertebral nerves, which is termed herniation of the intervertebral disc. This condition is very common among the elderly, and a medical solution involves performing an operation to install an artificial intervertebral disc. The following describes the structure of a prior art artificial intervertebral disc.  
         [0006]     Please refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is a schematic drawing of a prior art artificial disc.  FIG. 2  is a schematic drawing of the prior art artificial disc installed on spinal vertebrae. The prior art artificial intervertebral disc comprises a main body  10 . The main body  10  has a plurality of grooves  100 . A fillister  110  is formed on a spinal vertebra end-plate  11  matching the shape of the main body  10 . When the main body  10  is fixed in the fillister  110 , a plurality of grooves  100  need to be formed on the spinal vertebra end-plate  11  for newly grown bone, which increases the difficulty of the surgical operation. Moreover, the prior art artificial intervertebral disc is made of metal and rubs against the spinal vertebra end-plate  11  when the patient moves, which cause discomfort and deterioration of the spinal vertebra end-plate  11 .  
         [0007]     To improve comfort, U.S. Pat. No. 6,022,376, U.S. Pat. No. 5,824,093 and U.S. Pat. No. 5,674,295 disclose an artificial intervertebral disc having a main body  12  made of hydrogel and covered by a jacket  13  made of polyethylene. Please refer to  FIG. 3  and  FIG. 4 .  FIG. 3  is a schematic drawing of another prior art artificial disc.  FIG. 4  is a schematic drawing of another prior art artificial disc installed on spinal vertebrae. Two ends of the jacket  13  have a plurality of fastening members  14 . A spinal vertebra end-plate  15  has a plurality of corresponding holes (not shown) so the plurality of fastening members can be fastened in the holes on the spinal vertebra end-plate  15  to complete the artificial disc. Since this artificial disc is mainly made of hydrogel, it provides good elasticity and reduces stress on the spine. However, due to softness, the fastening member  14  does not provide a good locking effect, which can cause exposure and displacement of the artificial disc.  
         [0008]     Therefore, it is desirable to provide an artificial intervertebral disc to mitigate and/or obviate the aforementioned problems.  
       SUMMARY OF THE INVENTION  
       [0009]     A main objective of the present invention is to provide a comfortable and stable intervertebral filling, which is adapted for placement between any two adjacent spinal vertebrae end-plates in the human body.  
         [0010]     The intervertebral filling of the present invention includes a supporting body capable of being placed between two spinal vertebrae end-plates, and provides support between the two spinal vertebrae end-plates.  
         [0011]     A buffer layer covers the supporting body and providing a buffering effect between the two spinal vertebrae end-plates. The intervertebral filling also includes at least two positioning means. Each positioning means is fixed on the supporting body and mounted on a spinal vertebra end-plate to provide a positioning effect between the supporting body, the buffer layer and the spinal vertebra end-plates.  
         [0012]     The intervertebral filling of the present invention has three parts: the supporting body, the buffer layer and the positioning pins, and is adapted for placement between any two adjacent spinal vertebrae end-plates in the human body. The buffer layer is made of an elastic material so that the buffer layer does not cause inconvenience during movement of the patient, and does not suffer any wear or damage. The supporting body is a little harder than the buffer layer and is used for sharing stress in the spine, providing a strong support. The sharp ends of the positioning means can be inserted into the surface of the adjacent spinal vertebrae end-plates. Consequently, the intervertebral filling of the present invention remains stably positioned between the two adjacent spinal vertebrae end-plates without undergoing displacement.  
         [0013]     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a schematic drawing of a prior art artificial intervertebral disc.  
         [0015]      FIG. 2  is a schematic drawing of the prior art artificial intervertebral disc installed on spinal vertebrae.  
         [0016]      FIG. 3  is a schematic drawing of another prior art artificial intervertebral disc.  
         [0017]      FIG. 4  is a schematic drawing of another prior art artificial intervertebral disc installed on spinal vertebrae.  
         [0018]      FIG. 5  illustrates an intervertebral filling constructed according to a first preferred embodiment of the present invention.  
         [0019]      FIG. 6  is a cross-sectional view of the intervertebral filling shown in  FIG. 5 .  
         [0020]      FIG. 7  is a cross-sectional view of an intervertebral filling constructed according to a second preferred embodiment of the present invention.  
         [0021]      FIG. 8  is a schematic drawing showing the intervertebral filling shown in  FIG. 5  implanted between two spinal vertebrae end-plates in a human body.  
         [0022]      FIG. 9  is a schematic drawing showing the intervertebral filling shown in  FIG. 5  implanted between two spinal vertebrae end-plates under compression.  
         [0023]      FIG. 10  illustrates an intervertebral filling constructed according to a third preferred embodiment of the present invention.  
         [0024]      FIG. 11  illustrates an intervertebral filling constructed according to a fourth preferred embodiment of the present invention.  
         [0025]      FIG. 12  is a cross-sectional view of the intervertebral filling shown in  FIG. 11 .  
         [0026]      FIG. 13  is a schematic drawing showing an intervertebral filling constructed according to a fifth preferred embodiment of the present invention before being assembled.  
         [0027]      FIG. 14  is a schematic drawing showing the intervertebral filling shown in  FIG. 13  after being assembled.  
         [0028]      FIG. 15  is a schematic drawing showing the intervertebral filling shown in  FIG. 14  implanted between two spinal vertebrae end-plates.  
         [0029]      FIG. 16  is a schematic drawing showing an intervertebral filling constructed according to a sixth preferred embodiment of the present invention.  
         [0030]      FIG. 17  is a schematic drawing showing an intervertebral filling constructed according to a seventh preferred embodiment of the present invention.  
         [0031]      FIG. 18  is a schematic drawing showing an intervertebral filling constructed according to an eighth preferred embodiment of the present invention.  
         [0032]      FIG. 19  is a schematic drawing showing an intervertebral filling constructed according to a ninth preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     The present invention provides an intervertebral filling adapted for placement between any two adjacent spinal vertebrae end-plates in the human body, which has a simple design and that can be firmly mounted in the human body. The following description, in conjunction with the accompanying drawing, explains the present invention in detail.  
         [0034]     Please refer to  FIG. 5 ,  FIG. 6  and  FIG. 8 .  FIG. 5  illustrates an intervertebral filling according to a first preferred embodiment of the present invention.  FIG. 6  is a cross-sectional view of the intervertebral filling shown in  FIG. 5 . As shown in the drawings, the intervertebral filling of the present invention can be placed between any two adjacent spinal vertebrae end-plates  30   a ,  30   b  in the human body. During a surgical operation, the spinal vertebrae end-plates  30   a ,  30   b  can be held open with suitable tools, and the intervertebral filling can be placed between the spinal vertebrae end-plates  30   a ,  30   b  by tools that gently press upon upper and lower surfaces of the intervertebral filling. Subsequently, the tools separating the spinal vertebra end-plates  30   a ,  30   b  can be removed so that the spinal vertebrae end-plates  30   a ,  30   b  align with the intervertebral filling. A sharp end of two positioning pins  22   a ,  22   b  is respectively inserted into the surfaces of the spinal vertebra end-plates  30   a ,  30   b  to stabilize the spinal vertebra filling. The spinal vertebrae end-plates  30   a ,  30   b  may separately have at least one hole  300   a ,  300   b  (as shown in  FIG. 8 ) on their surfaces for placement of the positioning pins  22   a ,  22   b  of the intervertebral filling. Additionally, a groove may be formed on the spinal vertebrae end-plates  30   a ,  30   b  to allow the entrance of the positioning pins  22   a ,  22   b  of the intervertebral filling, so that the entire intervertebral filling can slide into the spine. However, such operations are a very well known technology involving many different methods, and no further description is required.  
         [0035]     The intervertebral filling comprises a buffer layer  21 , placed between the two adjacent spinal vertebrae end-plates  30   a ,  30   b  and providing a buffering effect between the two spinal vertebrae end-plates  30   a ,  30   b . This buffer layer  21  can be made of a soft plastic material or a hydrogel material that is flexible so that the buffer layer  21  does not cause any inconvenience during movement of the patient, and does not suffer any wear or damage. In this preferred embodiment, a concave groove  210  recessed perpendicularly to the direction of a center axis L of the support body (as shown in  FIG. 8 , and in the same direction as the spine) is formed on the peripheral surface of the buffer layer  21  to form a buffer area. With the groove  210 , when the two spinal vertebrae end-plates  30   a ,  30   b  are pressed towards each other due to pressure from the spine, the buffer layer  21  will not be pushed out of the spine. The thickness of the buffer layer  20  may have various designs according to the positions of the two spinal vertebrae end-plates  30   a ,  30   b  to provide suitable ergonomics and curve angles for the two spinal vertebrae end-plates  30   a ,  30   b.    
         [0036]     The intervertebral filling further comprises a supporting body  20 , which is covered by the buffer layer  21 . Preferably, the supporting body  20  is made of an elastic plastic material, but should be harder than the material of the buffer layer  21  to provide support between the two spinal vertebrae end-plates  30   a ,  30   b.    
         [0037]     The intervertebral filling also comprises at least two positioning pins  22   a ,  22   b . Ends of the positioning pins  22   a ,  22   b  are fixed on the two axial ends of the supporting body  20 , and two sharp ends of the positioning pins  22   a ,  22   b  protrude from the buffer layer  21  and may be inserted into two pre-formed holes  300   a ,  300   b  on the two spinal vertebrae end-plates  30   a ,  30   b . The two positioning pins  22   a ,  22   b  stabilize the supporting body  20  and the buffer layer  21  within the proper position between the two spinal vertebrae end-plates  30   a ,  30   b . Preferably, the two positioning pins  22   a ,  22   b  can be made of metal or a hard material (such as plastic) so as to be able to stick into the surfaces of the two spinal vertebrae end-plates  30   a ,  30   b  and provide support along the direction of the spine.  
         [0038]     In a second preferred embodiment, the supporting body  20  shown in  FIG. 5  may have a different design. Please refer to  FIG. 7 . An elastic structure  24  is placed between the two positioning pins  22   a ,  22   b  in this embodiment, and the bases  221   a ,  221   b  of the two positioning pins  22   a ,  22   b  and the elastic structure  24  are all covered by the buffer layer  21 . The elastic structure  24  provides support in the buffer layer  21  so that the two positioning pins  22   a ,  22   b  can also provide support along the axial direction; the elastic structure  24  is a compression spring, and can be of various types, such as spiral spring or disc spring. Additionally, the elastic structure  24  may be made of a metal or plastic material. This design can be an alternate for the supporting body  20  shown  FIG. 5 .  
         [0039]     With the above-mentioned structure, the present invention is stable between the two spinal vertebrae end-plates  30   a ,  30   b  and forms an artificial spinal disc. With the buffer layer  21 , the patient will feel more comfortable and have no directional limitations. The supporting body  20  with elastic material or the elastic structure  24  provides support, and the sharp ends of the two positioning pins  22   a ,  22   b  may be inserted into the holes  300   a ,  300   b  opened in the surface of the two spinal vertebrae end-plates  30   a ,  30   b . Therefore, when the present invention is mounted in the patient, it remains securely positioned when the patient moves, without dislocating. The intervertebral filling of the present invention is made of an elastic material, and so is easily placed in the patient in a surgical procedure that requires only a small incision. The best placement position may be in the neck vertebrae or any other vertebrae within the human spine, and therefore the positional placement of the invention should not be limited to particular regions within the spine.  
         [0040]     Please refer to  FIG. 9 .  FIG. 9  is a schematic drawing showing the present invention being compressed. As shown, the buffer layer  21  on the peripheral surface thereof has a groove  210  recessed toward the axial center L (as shown in  FIG. 8 , this is along the direction of the spine) of the supporting body  20  to form a buffer area, which ensures the buffer layer  21  is not squeezed out from between the two spinal vertebrae end-plates  30   a ,  30   b  when the intervertebral filling suffers an external axial force.  
         [0041]     Please refer to  FIG. 10 .  FIG. 10  illustrates a third preferred embodiment of the present invention. As shown in the drawing, there are three positioning pins  22   c ,  22   d ,  22   e  on the supporting body  20 , which can provide more stability to the entire intervertebral filling.  
         [0042]     Please refer to  FIG. 11  and  FIG. 12 .  FIG. 11  illustrates a fourth preferred embodiment of the present invention.  FIG. 12  is a cross-sectional drawing of the embodiment of the present invention shown in  FIG. 11 . In this embodiment of the present invention, the buffer layer  21  can be designed to have a shape (as indicated by the kidney shape shown in the drawing) conformal with the shape of the two spinal vertebrae end-plates  30   a ,  30   b , or the thickness of the buffer layer  21  can be varied to satisfy the different curvature requirements of the human spine.  
         [0043]     A fifth preferred embodiment is shown in  FIGS. 13, 14  and  15 , wherein the support body  20  is formed of a lower concave-up disk  20   b  having an upper concave-up surface  200   b , and an upper eye-shaped part  20   a  having a lower spherical surface  200   a , wherein the lower spherical surface  200   a  is received on the upper concave-up surface  200   b  to form a universal joint between the upper eye-shaped part  20   a  and lower concave-up disk  20   b . The support body  20  is embedded in an elastic buffer layer  21 , so that the upper eye-shaped part  20   a  and lower concave-up disk  20   b  are relatively movable to each other and the relative movement is confined by the elasticity of the buffer layer  21 . Two positioning pins  22   a ,  22   b  are formed on the two axial ends of the supporting body  20  with two sharp ends of the positioning pins  22   a ,  22   b  protruding from the buffer layer  21  which are to be inserted into the two spinal vertebrae end-plates  30   a ,  30   b . The buffer layer  21  has a groove  210  on the peripheral surface thereof to form a buffer area, which ensures the buffer layer  21  is not squeezed out from between the two spinal vertebrae end-plates  30   a ,  30   b  when the intervertebral filling suffers an external axial force. The materials of making the supporting body  20 , positioning pins  22   a ,  22   b , and buffer layer  21  are same as those described in the above preferred embodiments.  
         [0044]     An intervertebral filling constructed according to a sixth preferred embodiment of the present invention is shown in  FIG. 16 , which has a construction similar to the first embodiments shown in  FIGS. 5 and 6  except a major difference that a pair of position ring  22   c  having a sharp ridge are provided on the two axial ends of the supporting body  20  with the sharp ridge of the positioning ring  22   c  protruding from the buffer layer  21  to replace the position pins.  
         [0045]     An intervertebral filling constructed according to a seventh preferred embodiment of the present invention is shown in  FIG. 17 , which has a construction similar to the first embodiments shown in  FIGS. 5 and 6  except a major difference that a pair of toothed bars  22   d  having a plurality of teeth are provided on the two axial ends of the supporting body  20  with the sharp teeth of the toothed bar  22   d  protruding from the buffer layer  21  to replace the position pins.  
         [0046]     An intervertebral filling constructed according to an eighth preferred embodiment of the present invention is shown in  FIG. 18 , which has a construction similar to the first embodiments shown in  FIGS. 5 and 6  except a major difference that six positioning wedges  22   e  are provided on each one of the two axial ends of the supporting body  20  with the positioning wedges  22   e  protruding from the buffer layer  21  to replace the position pins.  
         [0047]     An intervertebral filling constructed according to a ninth preferred embodiment of the present invention is shown in  FIG. 19 , which has a construction similar to the first embodiments shown in  FIGS. 5 and 6  except a major difference that each one of the two axial ends of the supporting body  20  is provided with a corrugated surface with the sharp ridges  22   f  protruding from the buffer layer  21  to replace the position pins.  
         [0048]     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.