Abstract:
The present invention relates to a thoracic spine posterior transpedicular screw finder that guides a drilling device quickly to the exact position for drilling purpose onto vertebra, secures the drilling process and prevents it from deviation in spinal instrumentation with the transpedicular fixation of spinal operation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    At present, posterior instrumentation with transpedicular screws or hooks system is common in spinal surgery. To perform a posterior spinal instrumentation, the fixation process is made by inserting a vertebral screw which is called ‘transpedicular screw’ through the pedicle into the body, or a hook into the lamina. The former is usually used in lumbar spinal surgery, while the latter in thoracic spinal surgery. The fixation and strength is best while inserting a transpedicular screw through the pedicle into the body, but at the present, it is uncommon used in the thoracic spinal surgery for higher difficult technology. The new innovation provides specially designed tools for the operator to insert the thoracic spine transpedicular screw correctly, safely and easily, instead of the less effective hooks.  
           [0002]    The transpedicular screws are mainly used in the lumbar vertebral surgery, while the inlet for the vertebral screw is easily to identify by referent anatomy and the space of the pedicle is sufficient for the vertebral screw. While in the thoracic spinal surgery, the referent anatomy is not clear enough to find correct position exactly for transpedicular screw and the space of the pedicle for the vertebral screw is guarded, most surgeons choose the safer method with lamina or pedicle hooks onto the thoracic vertebra  19 . But the result is less satisfactory due to less fixation strength and more complications, such as dislodgement of the hooks. Because of the poorer fixation of a hook, the result is less satisfactory. Therefore, in order for better result, there still are some highly skilled physicians who are still willing to use transpedicular screws in the thoracic spinal surgery.  
           [0003]    The conventional method for identification for a thoracic pedicle screw inlet was mainly determined by the anatomical landmarkings. The anatomical landmarkings for identification of the thoracic spine transpedicular screw inlet is not clear enough, even a skillful surgeon could not determine the pedicle screw inlet precisely. Even a little error could result in catastrophic complications. This is why transpedicular screw is not widely used in thoracic spine surgery. By our new innovations, transpedicular screws could be inserted easily and safely in the thoracic spinal surgery, and provide better stability as compared with conventional thoracic spinal hooks system.  
         SUMMARY OF THE INVENTION  
         [0004]    Therefore, the inventor has devoted in research to seek improvement on the shortcomings of the conventional method, for application of thoracic transpedicular screw and after extended research, has come up with the present invention. The primary objective of the invention is to provide a posterior transpedicular screw finder that is capable of speedily and exactly guide a device to find the inlet for vertebral screw correctly and avoid any deviation, comprising a locating unit, a rod body and a grip part. Of which, the locating unit has a recess with its opening facing forward at the bottom thereof, forming a locating block that extends forward at a bottom thereof, the front of the locating block having a locating fork with an arched inside. The front of the locating unit has a duct at its front, the center of the duct being located on a line extending from a center of the locating fork. The rod body extends outwardly from one side of the locating unit and bent upwards to become an “L” shape, at its end being a grip part that can be gripped by a user, thereby the locating fork can be mounted onto the pedicle of the vertebra to prevent the duct of the locating unit from sliding left and right. The recess mounted onto the bottom of the lamina of the thoracic vertebra keeps the duct of the locating unit from moving up and down. By mounting the arch on the inside of the locating fork onto the pedicle of the thoracic vertebra, it will automatically guide and locate the center position of the pedicle, so that it is automatically positioned on the center line of the locating groove, and relatively the center point of the duct positioned on top of the lamina falls onto the center position of the pedicle, thereby when the drilling device is inserted into the drill hole of the duct, it will drill a positioning hole squarely on top of the pedicle to facilitate inserting of the steel screw, thereby achieve the efficiency of speedy and precise guidance, locating and avoid deviation during drilling process.  
           [0005]    For better understanding of the characteristics and technical contents of the present invention, please refer to the following description and drawings.  
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0006]    [0006]FIG. 1 is a perspective view of a conventional posterior thoracic vertebral instrumentation.  
         [0007]    [0007]FIG. 2 is a section view for the approach of a conventional posterior thoracic vertebral instrumentation.  
         [0008]    [0008]FIG. 3 is a section view of a conventional posterior thoracic vertebral instrumentation at the drilling with a steel screw.  
         [0009]    [0009]FIG. 4 is a perspective view of the present invention.  
         [0010]    [0010]FIG. 5 is a view for the approach of the invention when positioned on a thoracic vertebra.  
         [0011]    [0011]FIG. 6 is a view for the approach of the invention positioned on a thoracic vertebra with the drilling device for insertion.  
         [0012]    [0012]FIG. 7 is a section view of the invention positioned on a thoracic vertebra with the drilling device for insertion.  
         [0013]    [0013]FIG. 8 is a view of the invention in application when viewed from another angle.  
     
    
     BRIEF DESCRIPTION OF NUMERALS  
       [0014]    [0014]                                                               19   thoracic vertebra (e)   10   thoracic vertebral body           11   lamina   12   pedicle           13   vertebral cavity   14   rib           29   drilling device   20   drill bit           21   drill rod   22   handle           39   spinal column drill locator   30   locating unit           31   recess   32   locating block           33   locating fork   34   ducts           35   rod body   36   grip part           49   steel screw                        
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0015]    Please refer to FIG. 4 that illustrates a posterior transpedicular screw finder  39 , comprising a locating unit  30 , a rod body  35  and a grip part  36 , wherein the locating unit  30  has a recess  31  opening to the front on a lower part thereof, so that its bottom part is shaped to protrude forward as a locating block  32 . At the front part of the locating block  32  is a locating fork  33 . At the front of the locating unit  30  is a duct  34  that accommodates the insertion of a drilling device  29 . The center of the duck  34  is positioned on a line extending from the center of the locating fork  33 . The rod body  35  extends outwardly from one side of the locating unit  30  and bends upwards to become an “L” shape, on its end is a grip part  36  that can be gripped by a user. Thereby, the locating fork  33  is mounted on a pedicle of a thoracic vertebra, and the duct can be speedily and accurately guide the drilling device into a drilling position, which is properly secured by the engagement of the locating fork  33  and the recess  31  onto the pedicle  12  and a lamina  11  of a vertebra. As shown in FIGS. 5 through 8, when the locating fork  33  of the locating unit  30  of the invention is mounted on the pedicle  12  on a thoracic vertebra body  10 , the locating unit  30  is prevented from dislocating to its left or right side. Meanwhile, when the recess  31  is mounted to the bottom part of the lamina  11  of a thoracic vertebra  19 , the locating unit  30  is also prevented from sliding up or down. Furthermore, when the arch of the locating fork  33  is pushed against the pedicle  12  of the thoracic vertebra  19 , it will automatically lead to locate the center position of the pedicle  12 , and automatically position the pedicle  12  on the centerline of the locating fork  33 . In relation to that, the duct  34  at the front of the locating unit  30  is then positioned at the top of the center of the pedicle  12  of the lamina  11 . Thereby, when the drilling device  29  is inserted inside the duct  34  to drill a hole, it will drill a position hole at a correct angle right on top of the pedicle  12 , to facilitate the insertion of a steel screw  49  in the exact position.  
         [0016]    Due to unique structural design of the invention, there are characteristics in application as follows:  
         [0017]    1. Excellent locating: Since the invention relies on the arch on the inside of the locating fork  33  to automatically guide and locate the center position of the pedicle  12  and automatically position it on a center line of the locating fork  33  when the locating fork  33  is pressed against the pedicle  12  of the thoracic vertebra  19 , and relatively, the duct  34  at the front of the locating unit  30  is positioned on a center extended line of the locating fork  33 , therefore it is capable of promptly locating the optimum positioning spot. Furthermore, the locating fork  33  of the locating unit  30  is mounted onto the pedicle  12  of the thoracic vertebral body  10  to limit the locating unit  30  from misalignment. Meanwhile, the recess  31  is also mounted onto the bottom of the lamina  11  of the thoracic vertebra  19  to limit the locating unit  30  from up and down movement, therefore, the drilling device  29  can be inserted for drilling a hole on the thoracic vertebra  19 , to achieve a better locating effect.  
         [0018]    2. Simplified and speedy application and operation: Using the locating fork  33  of the locating unit  30  to promptly locate the center position of the pedicle  12 , and using the locating fork  33  and recess  31  of the locating unit  30  to effectively engage in position, the drilling device  29  can be correctly aligned with the top of the center of the pedicle  12  of the thoracic vertebra  19 , to drill a hole in the exact position, so that the steel screw  49  is squarely screwed into the pedicle  12  without harming other part. Therefore, the frequency of X-ray radiation and examination can be greatly reduced to minimize bad effects on human body. And, due to its significantly shortening of time involved in the process, all possible risks can be minimized in the operation.  
         [0019]    To sum up, the sophisticated design of the invention has contributed to the aforementioned characteristics and applicability, and since similar products have never been seen or used in public, this application is filed.