Abstract:
A method for treating fractures comprises positioning a bone fixation device along a bone and creating a first hole from an outer surface of the bone through a lateral cortex to a central portion thereof, the first hole corresponding to a position at which a first bone fixation element receiving opening is to be located when the bone fixation device is coupled to the bone in a desired orientation in combination with inserting and pushing a probe through the central portion of the bone until a tip of the probe contacts an interior structure of the bone providing resistance to penetration by the probe increased relative to the central portion of the bone and determining a first length of the portion of the probe extending into the bone via the first hole to select a desired length of a first bone fixation element to be inserted therethrough.

Description:
BACKGROUND  
       [0001]    Proximal humeral fractures are common in osteoporotic bone and may be fixed using a bone plate and a plurality of bone screws. For optimal fixation, the screw tip should be in close proximity to the far cortex. Determining a length of bone screw that should be used for fixing the plate to the humeral head, however, is a difficult process since the far cortex of the humeral head is often thin and weak. Currently, the length of screw is determined by pre-drilling a hole into the humeral head and inserting a standard depth gauge therein to measure a depth of the pre-drilled hole. The depth gauge in this process, however, is not guided so that the measured depth may be inaccurate, resulting in the use of an incorrect screw length. Studies have shown that the rate of screw tips penetrating into the joint is as high as 14%. 
       SUMMARY OF THE INVENTION 
       [0002]    The present invention is directed to a method for treating a fractures comprising positioning a bone fixation device along a bone, the bone fixation device including a first bone fixation element receiving opening and creating a first hole from an outer surface of the bone through a lateral cortex thereof to a central portion of the bone, the first hole corresponding to a position at which the first bone fixation element receiving opening is to be located when the bone fixation device is coupled to the bone in a desired orientation in combination with inserting a probe through the first hole and pushing the probe through the central portion of the bone until a tip of the probe contacts an interior structure of the bone providing resistance to penetration by the probe increased relative to the central portion of the bone and determining a first length of the portion of the probe extending into the bone via the first hole. A length of a length of a first bone fixation element to be inserted into the bone via the first bone fixation opening is then selected based on the first length of the portion of the probe extending into the bone via the first hole. 
         [0003]    The present invention is further directed to a system for treating bone comprising a bone fixation device extending from a proximal end to a distal end and including a first bone fixation receiving opening extending therethrough and a drill including a drill bit configured to drill a first hole from an outer surface of the bone through a lateral cortex thereof in a position at which the first bone fixation element receiving opening is to be located when the bone fixation device is coupled to the bone in a desired orientation in combination with a probe sized and shaped to be inserted through the first hole and into the bone, the probe including a blunt tip providing tactile feedback upon contact with interior structures of the bone and markings formed along a length of the probe indicating a first length of the probe from the blunt tip thereof. A first bone fixation element to be inserted into the bone via the first bone fixation opening has a first length selected to correspond to a length of a portion of the probe extending into the bone via the first hole. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  shows a perspective view of a system according to an exemplary embodiment of the present invention; 
           [0005]      FIG. 2  shows a top view of an exemplary bone plate according to the system of  FIG. 1 ; 
           [0006]      FIG. 3  shows a side view of the bone plate of  FIG. 2 ; 
           [0007]      FIG. 4  shows a perspective view of an exemplary aiming device and a bone plate according to the system of  FIG. 1 ; 
           [0008]      FIG. 5  shows a perspective view of the aiming device of  FIG. 4 ; 
           [0009]      FIG. 6  shows a side view of an exemplary guide sleeve according to the system of  FIG. 1 ; 
           [0010]      FIG. 7  shows a side view an exemplary drill tool according to the system of  FIG.1 ; 
           [0011]      FIG. 8  shows a side view of an exemplary probe according to the system of  FIG. 1 ; 
           [0012]      FIG. 9  shows a perspective view of the guide sleeve inserted into an opening of the aiming device of the system of  FIG. 1  according to an exemplary method of the present invention; 
           [0013]      FIG. 10  shows a perspective view of the drill tool inserted through the guide sleeve according to the method of  FIG. 9 ; 
           [0014]      FIG. 11  shows a perspective view of the probe inserted through the guide sleeve according to the method of  FIG. 9 ; 
           [0015]      FIG. 12  shows a perspective view of a bone fixation element inserted through the guide sleeve according to the method of  FIG. 9 ; 
           [0016]      FIG. 13  shows a perspective view of the bone plate fixed to a bone via bone fixation elements according to the method of  FIG. 9 ; 
           [0017]      FIG. 14  shows a top plan view of the bone plate and bone fixation elements of  FIG. 13 ; and 
           [0018]      FIG. 15  shows a perspective view of a system according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention relates to the treatment of bone fractures and, in particular, relates to a system and method for determining a length of a bone fixation element to be inserted into a head portion of a bone. Exemplary embodiments of the present invention describe a method of inserting a depth probe into the humeral head in a guided fashion to measure a length of screw that should be inserted therein. Although the exemplary embodiments specifically describe measuring a depth of a humeral head, it will be understood by those of skill in the art that the system and method of the present invention may be used to measure the depth of a head portion of any long bone. 
         [0020]    As shown in  FIGS. 1-6 , a system  100  for fixing a fracture according to an exemplary embodiment comprises a bone plate  104  which may be fixed to a bone  102  using a plurality of bone fixation elements  106 . The bone plate  104  may be sized and shaped to be positioned along a proximal humerus such that a proximal portion  112  of the bone plate  104  lies over a humeral head. Thus, a bone fixation element  106  may pass through a proximal opening  114  in the proximal portion  112  and into the head portion of the bone  102 . The system  100  further comprises an aiming device  108  and a guide sleeve  138  which may be used to guide a drill tool  110  and/or a probe  116  through the proximal opening  114  for measuring a depth of the head portion of the bone  102  so that a desired length for the bone fixation element  106  may be properly determined. Where the far cortex of the head portion of the bone  102  is thin and weak, there is a risk for the bone fixation element  106  to penetrate the far cortex of the bone  102  and extend into the joint. Thus, it is important for a surgeon or other user to accurately determine a length of the bone fixation element  106  that should be inserted into the proximal opening  114 . The drill tool  110  may be used to drill a hole through the lateral cortex of the head portion of the bone  102  to permit insertion of the probe  116  therethrough. The probe  116 , guided by the guide sleeve  138 , may then be inserted through the drilled hole to measure a depth of the head portion of the bone  102  so that a surgeon or other user may select a bone fixation element  106  having a length corresponding to the measured depth of the head portion of the bone  102 . 
         [0021]    As shown in  FIGS. 1-3 , the plate  104  extends longitudinally from a proximal end  118  to a distal end  120  such that the proximal portion  112  may be positioned over the head portion of the bone  102  while a distal portion  122  extends distally therefrom to lie over a portion of a length of the bone  102 . The plate  104  has a first surface  124  which, when the plate  104  is in an operative position along the bone  102 , faces away from the bone  102  and a second surface  126  which, when the plate  104  is in the operative position faces the bone  102 . The bone plate  104  includes a plurality of proximal openings  114  extending therethrough from the first surface  124  to the second surface  126  along the proximal portion  112  and distal openings  128  extending therethrough from the first surface  124  to the second surface  126  along a distal portion  122  of the bone plate  104 . Each of the proximal openings  114  defines a central axis extending through a center thereof and is sized and shaped to receive a bone fixation element  106  therethrough along its respective central axis. The distal openings  128  may be any of a variety of types of bone fixation receiving openings such as, for example, locking holes, tapered holes, compression holes, variable angle holes or combination holes or any combination of these types of holes. That is, as would be understood by those skilled in the art, to bone plate  104  may include more than one type of distal opening  128  configured to receive different types of distal fixation elements  168  (e.g., locking screw, cortex screw) therethrough. 
         [0022]    As shown in  FIGS. 4-5 , the aiming device  108  may be used to guide the drill tool  110  and the probe  116  through the proximal openings  114  along central axes thereof. A second surface  134  of the aiming device  108  is preferably sized and shaped to correspond to a size and contour of the first surface  124  of the proximal portion  112  of the bone plate  104  and may be configured to releasably coupled to the first surface  124  of the bone plate  104 . The aiming device  108  may be coupled to the bone plate  104  via, for example, an attaching screw  136 . For example, the attaching screw  136  may engage a hole in the aiming device  108  and a corresponding hole in the bone plate  104 . The aiming device  108  includes a plurality of aiming holes  130  extending therethrough from a first surface  132  which, when the aiming device  108  and the bone plate  104  are coupled, faces away from the bone plate  104 , to the second surface  134  which, when the aiming device  108  and the bone plate  104  are coupled, faces the bone plate  104 . In the coupled configuration, each of the aiming holes  130  corresponds to and aligns with a corresponding one of the proximal openings  114 . Thus, when the aiming device  108  and the bone plate  104  are coupled to one another, the central axes of the aiming holes  130  align with the central axes of the proximal openings  114 . As shown in  FIG. 5 , the aiming holes  130  may overlap one another so long as the central axes of the aiming holes  130  are co-axial with the central axes of the proximal openings  114 . Each of the aiming holes  130  is sized and shaped to receive the guide sleeve  138  therethrough. 
         [0023]    The guide sleeve  138 , as shown in  FIG. 6 , may be substantially tubular extending longitudinally from a first end  140  to a second end  142  and including a lumen  144  extending therethrough. The lumen  144  is sized and shaped to permit the drill  110  and/or the probe  116  to be received therein and guided into the bone  102  along the central axis of one of the proximal openings  114 . The first end  140  may be configured to engage an inner surface of the aiming hole  130 . For example, the first end  140  may include wings  164  separated from one another via a longitudinal slot and biased toward an open configuration in which an outer diameter of the first end  140  is greater than an inner diameter of the aiming holes  130 . Thus, when the first end  140  is inserted into an aiming hole  130 , the wings  164  are flexed toward one another providing a friction fit with the inner surface of the aiming hole  130 . 
         [0024]    As shown in  FIG. 7 , the drill tool  110  includes a drill bit  146  extending longitudinally from a first drilling end  148  including, for example, cutting flutes  155 , to a second end  150  configured for attachment to a drill (not shown). The drill bit  146  may have an outer diameter only slightly smaller than an inner diameter of the guide sleeve  138  so that the drill bit  146  is slidably guided therethrough. The drill bit  146  may also include a stop  152  along a length thereof to prevent the user from drilling beyond a predetermined depth (i.e., corresponding to a depth of an inner surface of a lateral cortex of the bone  102  on a side opposite the point of entry into the bone). The stop  152  may be configured as a shoulder at which a diameter of the drill bit  146  increases so that a diameter of a portion of the drill bit  146  extending from the stop  152  toward the first end  148  is smaller than a diameter of the drill bit  146  extending from the stop  152  toward the second end  150 . 
         [0025]    As shown in  FIG. 8 , the probe  116  includes a shaft portion  160  extending longitudinally from a first end  156  to a second end  158  attached to a handle  162  for moving the shaft portion  160  through the guide sleeve  138  and into the bone  102 . The first end  156  may include a blunt tip preventing damage to the bone and providing tactile feedback to the user regarding bone density. An outer diameter of the shaft portion  160  may be sized and shaped to be slidably accommodated within the lumen  144  of the guide sleeve  138 . The shaft portion  160  also includes markings  166  along a portion of a length thereof, indicating a distance from the first end  156 . Thus, as the probe  116  is inserted into the head portion of the bone  102 , the markings  166  indicate a length of the probe  116  inserted into the bone  102  and thus correspond to a depth through the head portion of the bone  102  to the cortex on the far side of the head portion. Thus, the depth measured via the markings  166  may be used to select a length of the bone fixation element  106  which will provide maximum purchase in the bone  102  without penetrating the cortex on the far side of the bone. Although the probe  116  is described as including markings  166  therealong, in another embodiment, the probe  116  may include other features for indicating a length of the probe  116  inserted into the bone  102 . For example, the probe  116  may include a display (e.g., digital) for showing the length of the probe  116  inserted into bone. In an alternative embodiment, the markings  166  may be similarly incorporated in the guide sleeve  138  so that the length of the probe  116  inserted into the bone may be determined via markings on the guide sleeve  138 . 
         [0026]      FIGS. 9-14  illustrate a technique by which a user (e.g., surgeon) may fix a fracture of the bone  102  using the bone plate  104 . The bone plate  104  is coupled to the aiming device  108  to ensure that the bone fixation elements  106  are properly inserted along the central axes of the proximal openings  114 . As described above, the aiming device  108  may be releasably coupled to the bone plate  104  via, for example, the attachment screw  136 . The fracture of the bone  102  is reduced and the bone plate  104 , and the attached aiming device  108  are positioned along the bone  102  (e.g., along the proximal humerus) and temporarily fixed thereto via a distal fixation element  168  inserted through the distal opening  128  in the distal portion  122  of the bone plate  104 . The guide sleeve  138  is then inserted into one of the aiming holes  130 , as shown in  FIG. 9 , so that a central axis of the lumen  1144  is co-axial with the central axis of the corresponding proximal opening  114 . 
         [0027]    Once the guide sleeve  138  has been properly positioned in the aiming hole  130 , a hole may be formed through the lateral cortex of the bone  102  using, for example, the drill bit  146  of the drill tool  110 . The drill but  146  may be inserted through the lumen  144 , as shown in  FIG. 10 , to drill through the lateral cortex of the bone  102  until the stop  152  abuts the bone  102  preventing the drill tool  110  from passing further into the bone once it has penetrated the lateral cortex on the near side of the bone  102 . The drill bit  146  is removed from the guide sleeve  138  so that the shaft  160  of the probe  116  may be inserted into the lumen  144 , as shown in  FIG. 11 , and carefully pushed through the humeral head of the bone  102  using the handle  162 . Guided by the guide sleeve  138 , the user continues to push the probe  116  through the bone  102  until the user feels via the blunt tip at the first end  156  the increased density indicating that the tip  156  of the probe  116  has contacted the far cortex. Once the far cortex has been detected, the user reads the markings  166  to determine the depth of the far cortex and uses this depth to select a bone fixation element  106  having a desired length. 
         [0028]    The selected bone fixation element  106  may then be inserted through the guide sleeve  138 , as shown in  FIG. 12 , into the proximal opening  114  and driven into the bone  102  using a driving tool, as will be understood by those of skill in the art. The steps described above may be repeated for each of the proximal openings  114  with a desired length of bone fixation element  106  selected for each of the proximal openings  114 . As shown in  FIGS. 13-14 , the bone fixation elements  106  should extend through the humeral head of the bone  102  so that the tips  170  of the bone fixation elements  106  are adjacent to the far cortex without penetrating the far cortex and, more importantly, to prevent any bone fixation element  106  from being inadvertently driven through the far cortex to project from the bone  102 . Once a desired length of bone fixation element  106  has been selected for each of the proximal openings  114  and the selected bone fixation elements  106  have been inserted therethrough, the aiming device  108  and the guide sleeve  138  are de-coupled from the bone plate  104 . It will be understood by those of skill in the art that once the fracture has been reduced as desired, additional bone fixation elements may be inserted through any of the remaining distal openings  128  to provide additional fixation. 
         [0029]    Although the method of the system  100  is specifically described with respect to the bone plate  104 , it is respectfully submitted that it would be understood by those of skill in the art that the method of the present invention may be used to fix a bone fracture using any of a variety of bone fixation devices. For example, as shown in  FIG. 15 , a system  200  may be used to fix a fracture of a bone  202  using an intramedullary nail or rod  204 , an aiming device  208 , a probe  216  and a guide sleeve  238 . The system  200  may be substantially similar to the system  100  and may be utilized in a substantially similar manner. The intramedullary rod  204  includes at least one opening for receiving a bone fixation element therethrough, the opening positioned within the head portion of the bone  202  when the intramedullary rod  204  is inserted into bone  202 . Thus, a user may select a length of the bone fixation element by measuring a depth of the head portion through the opening. The probe  216  and the guide sleeve  238  are substantially similar to the probe  116  and guide sleeve  138  of the system  100 , as described above. 
         [0030]    The intramedullary rod  204  is inserted through the medullary canal of the bone  202  and coupled to the aiming device  208  such that an aiming hole  230  of the aiming device  208  corresponds to and aligns with the opening of the intramedullary rod  204 . The guide sleeve  238 , which may be substantially similar to the guide sleeve  138  described above, is inserted through the aiming hole  230  so that a lumen of the guide sleeve  238  is coaxial with a central axis of the opening of the intramedullary rod  204 . Thus, as described above with respect to the system  100 , a hole may be formed through only the lateral cortex of the bone  202  using, for example, a drill, such that the probe  216  may be inserted therethrough, as described above with respect to the system  100 , to measure the depth of the far cortex head portion of the bone  202 . The measured depth may then be used to select a desired length of a bone fixation element to be inserted through the opening of the intramedullary rod  204 . 
         [0031]    It will be understood by those skilled in the art that various modifications and variations can be made in the structure and methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and the variations of this invention provided that they come within the scope of the appended claims and their equivalents.