Abstract:
A fastener and plate assembly includes a plate including a hole having a first threaded lobe with a first axis and a second threaded lobe with a second axis. The second axis is offset relative to the first axis. The assembly also includes a threaded fastener received in one of the first threaded lobe and the second threaded lobe of the hole to install the threaded fastener in one of a first orientation and a second orientation, respectively.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/782,812 filed Mar. 14, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    During a surgical procedure, such as a bone fixation procedure that secures a fractured bone, a plate can be attached to bone with locking screws. The orientation of a locking screw is determined by a hole in the plate, resulting in only one orientation of the locking screw relative to the plate. 
       SUMMARY OF THE INVENTION 
       [0003]    A fastener and plate assembly includes a plate including a hole having a first threaded lobe with a first axis and a second threaded lobe with a second axis. The second axis is offset relative to the first axis. The assembly also includes a threaded fastener received in one of the first threaded lobe and the second threaded lobe of the hole to install the threaded fastener in one of a first orientation and a second orientation, respectively. 
         [0004]    A fastener and plate assembly includes a plate including a hole having a first threaded lobe with a first axis, a second threaded lobe with a second axis, and a third threaded lobe with a third axis. The second axis is offset relative to the first axis, and the third axis is offset relative to the first axis. The assembly includes a threaded fastener received in one of the first threaded lobe, the second threaded lobe and the third threaded lobe of the hole. Threads of the threaded fastener engage threads of one of the first threaded lobe, the second threaded lobe or the third threaded lobe for at least 180° around a central axis of the threaded fastener to install the threaded fastener in one of a first orientation, a second orientation, and a third orientation, respectively. 
         [0005]    A method of forming a hole in a plate includes the steps of forming a first base hole through a thickness of a plate and forming threads in the plate around the first base hole. The first base hole having a first axis. The method also includes the steps of forming a second base hole through the thickness of the plate that partially overlaps with the first base hole and forming threads in the plate around the second base hole. The second base hole has a second axis that is offset relative to the first axis. The method further includes the steps of receiving threads of a threaded fastener in one of the first base hole and the second base hole such that the threads of the threaded fastener engage the threads of the plate of one of the first base hole and the second base hole to install the threaded fastener in one of a first orientation and a second orientation, respectively. 
         [0006]    These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The various features and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0008]      FIG. 1  illustrates a plate including a plurality of threaded holes; 
           [0009]      FIG. 2  illustrates the forming of the first base hole; 
           [0010]      FIG. 3  illustrates the forming of the second base hole; 
           [0011]      FIG. 4  illustrates the forming of the third base hole; 
           [0012]      FIG. 5  illustrates a threaded hole of the plate of  FIG. 1 ; 
           [0013]      FIG. 6  illustrates a cross sectional view of the plate of  FIG. 1  taken along the line  6 - 6 ; 
           [0014]      FIG. 7  illustrates an enlarged view of a threaded hole of  FIG. 6 ; 
           [0015]      FIG. 8  illustrates a cross sectional view of the plate of  FIG. 1  taken along the line  8 - 8 ; 
           [0016]      FIG. 9  shows an enlarged view of a threaded hole of  FIG. 8 ; 
           [0017]      FIG. 10  illustrates a locking screw; 
           [0018]      FIG. 11  illustrates the locking screw installed relative to a first axis; 
           [0019]      FIG. 12  illustrates the locking screw installed relative to a second axis; 
           [0020]      FIG. 13  illustrates the locking screw installed relative to a third axis; and 
           [0021]      FIG. 14  illustrates several possible installation orientations of the locking screws. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]      FIG. 1  illustrates a plate  10  including a plurality of threaded holes  12 . Although 8 threaded holes  12  are illustrated, the plate  10  can include any number of threaded holes  12 . In one example, the plate  10  has a thickness T of approximately 3 mm. In one example, the plate  10  is made of carbon fiber or plastic. In another example, the plate  10  is made of metal. 
         [0023]    As shown in  FIG. 2 , a first base hole  13  (shown by two substantially parallel solid lines) is formed in the plate  10 . In one example, the first substantially circular base hole  13  is formed by drilling. The first substantially circular base hole  13  has a first longitudinal axis  18  that is substantially perpendicular to a plane defined by the plate  10 . 
         [0024]    As shown in  FIG. 3 , a second substantially circular base hole  20  (shown by two substantially parallel dashed lines) is then formed in the plate  10 . In one example, the second substantially circular base hole  20  is formed by drilling. The second substantially circular base hole  20  has a second longitudinal axis  22  that is angled about X° from the first longitudinal axis  18 . In one example, X° is about 0° to 20°. In one example, X° is about +12°. However, X can be any number. 
         [0025]    As the first substantially circular base hole  13  and the second substantially circular base hole  20  partially overlap, a single hole including two lobes is formed. The lobes are formed by areas where the first substantially circular base hole  13  and the second substantially circular base hole  20  do not overlap. The spacing of the second substantially circular base hole  20  relative to the first substantially circular base hole  13  is shown exaggerated in  FIG. 3  for illustrative purposes only. 
         [0026]    As shown in  FIG. 4 , a third substantially circular base hole  24  (shown by two substantially parallel dotted lines) is then formed in the plate  10 . In one example, the third substantially circular base hole  24  is formed by drilling. The third substantially circular base hole  24  has a third longitudinal axis  26  that is angled about Y° from the first longitudinal axis  18 . In one example, Y° is about 0° to −20°. In one example, Y° is about −12°. However, Y can be any number. 
         [0027]    As the hole with two lobes formed by the first substantially circular base hole  13  and the second substantially circular base hole  20  overlap with the third substantially circular base hole  24 , a single hole with three lobes is formed. The lobes are formed by areas where the first substantially circular base hole  13 , the second substantially circular base hole  20  and the third substantially circular base hole  24  do not overlap. The spacing of the third substantially circular base hole  24  relative to the first substantially circular base hole  13  is shown exaggerated in  FIG. 4  for illustrative purposes only. 
         [0028]    Each of the substantially circular base holes  13 ,  20  and  24  are then threaded to form the threaded hole  12 , as shown in  FIG. 5 . In one example, each of the substantially circular base holes  13 ,  20  and  24  is threaded by a thread whirling process. 
         [0029]    A threading instrument is inserted into the area created by the first substantially circular base hole  13  and aligned with the first longitudinal axis  18  to create a first thread  28  in the plate  10 , as shown in  FIGS. 6 and 7 . The threading instrument is inserted into the area created by the second substantially circular base hole  20  and aligned with the second longitudinal axis  22  to create a second thread  30  in the plate  10 , as shown in  FIGS. 8 and 9 . The threading instrument is inserted into the area created by the third substantially circular base hole  24  and aligned with the third longitudinal axis  26  to create a third thread  32  in the plate  10 . 
         [0030]    As shown in  FIG. 10 , a threaded fastener  34 , such as a locking screw, includes a threaded head  36  and a shaft  38  with a plurality of threads  40 . The threaded fastener  34  is received in the plate  10  and the bone  50  that is located under the plate  10  to secure the plate  10  to the bone  50 . In the above-described example, the threaded fastener  34  can be inserted in one of three orientations that each correspond to one of the holes  13 ,  20  and  24  including the threads  28 ,  30  and  32 , respectively. The threads  40  of the threaded fastener  34  engage one of the threads  28 ,  30  and  32  of one of the holes  13 ,  20  and  24 , respectively, of the threaded hole  12  at least 180° around a central axis Q of the threaded fastener  34  to secure the plate  10  to the bone  50 . 
         [0031]    As shown in  FIG. 11 , when the threaded fastener  34  is installed along the first longitudinal axis  18 , the threaded head  36  of the threaded fastener  34  engages the first thread  28  of the first hole  13  as shown in  FIG. 7  to secure the threaded fastener  34  in the first orientation to secure the plate  10  to the bone  50 . 
         [0032]    As shown in  FIG. 12 , when the threaded fastener  34  is installed along the second longitudinal axis  22 , the threaded head  36  of the threaded fastener  34  engages the second thread  30  of the second hole  20  as shown in  FIG. 9  to secure the threaded fastener  34  in the second orientation to secure the plate  10  to the bone  50 . 
         [0033]    As shown in  FIG. 13 , when the threaded fastener  34  is installed along the third longitudinal axis  26 , the threaded head  36  of the threaded fastener  34  engages the third thread  32  of the third hole  24  as shown in  FIG. 9  to secure the threaded fastener  34  in the third orientation to secure the plate  10  to the bone  50 . 
         [0034]      FIG. 14  illustrates the three possible orientations of the threaded fastener  34  relative to the plate  10 . The threaded fastener  34  can be installed in the plate  10  at variable angles along variable axes to secure the plate  10  to the bone  50 . The threaded fastener  34  allows for multiple threads of engagement. Additionally, cross threading or thread deformation is not required to achieve the variable angle locking. 
         [0035]    In the described example, the first longitudinal axis  18 , the second longitudinal axis  22  and the third longitudinal axis  26  are all in the same plane. However, the first longitudinal axis  18 , the second longitudinal axis  22  and the third longitudinal axis  26  can be in different planes and at different orientations relative to each other. This allows the threaded fastener  34  to be located at different orientations based on a patient&#39;s anatomy. Additionally, although a threaded hole  12  with three installation orientations is illustrated and described, the threaded hole  12  can include any number of lobes to define any number of possible orientations of the threaded fastener  34 . For example, the threaded hole  12  can include two lobes to allow for two different orientations of the threaded hole  12 . 
         [0036]    The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.