Abstract:
A fracture reduction assembly and method for insertion of the assembly through a surgical site in one embodiment includes a base portion including a bone contacting surface and an upper surface, a barrel with a first end portion connected to the bone contacting surface, the base portion and the barrel defining a bore extending through the barrel and the base portion and opening at the upper surface of the base portion, a screw portion including a shaft with a first diameter sized to fit within the bore and a threaded portion with a second diameter sized to not fit within the bore, wherein at least a portion of the shaft is positioned within the bore, and a retainer coupled with the shaft and having a third diameter sized to fit within a first portion of the bore but not within a second portion of the bore.

Description:
FIELD 
       [0001]    This application relates generally to the field of orthopaedics, and more specifically to appliances used in the reduction of bone fractures. 
       BACKGROUND 
       [0002]    Fractures of bones, such as a fracture of a femur at one or more locations adjacent the head and neck of the femur are comparatively common. Many fracture reduction devices have been proposed for the reduction of fractures of this type. Such reduction devices basically consist of an elongate lag screw which is threaded on one end to be threadably received in the head of the femur. The lag screw is secured at the other end to a plate to form a compression hip screw assembly. The plate may include a barrel through which the screw passes. The fracture reduction device may also include bone screws for securing the plate to the femur. 
         [0003]    The known reduction devices require that the lag screw first be inserted through an incision in a patient and into the canal of the femur. The lag screw is then advanced until the hip screw engages the head and/or neck of the femur proximal to the fracture site. The plate is then inserted through the incision and positioned over the lateral cortical wall of the shaft of the femur. At this time, the plate is assembled to the lag screw and the lag screw is tightened. When the lag screw is tightened, the head of the femur is forcibly compressed at the fracture line to the remainder of the femur. The screw may be permitted to slide in the barrel to place load on the fracture site under normal weight bearing. This sliding is known as sliding compression and promotes healing due to a phenomenon known as Wolff&#39;s law. Wolff&#39;s law teaches that load on the fracture site under normal weight bearing promotes healing and avoids atrophy of the fracture site. 
         [0004]    Functionally, some of these devices perform quite satisfactorily for many fractures of the femur. Thus, while these devices have application and advantages relative one to another, problems and concerns remain with these devices. For example, the necessity to sequentially implant multiple components and then fit the components together results in added surgical time. As surgical time increases, costs and risks to the patient also increase. 
         [0005]    Therefore, it would be advantageous to provide an improved hip screw assembly which is not only functional in providing the necessary stability and guidance in the reduction of the fracture, but can be efficiently, accurately and quickly implanted by the surgeon. 
       SUMMARY 
       [0006]    According to one embodiment of the present disclosure, there is provided A fracture reduction assembly and method for insertion of the assembly through a surgical site in one embodiment includes a base portion including a bone contacting surface and an upper surface, a barrel with a first end portion connected to the bone contacting surface, the base portion and the barrel defining a bore extending through the barrel and the base portion and opening at the upper surface of the base portion, a screw portion including a shaft with a first diameter sized to fit within the bore and a threaded portion with a second diameter sized to not fit within the bore, wherein at least a portion of the shaft is positioned within the bore, and a retainer coupled with the shaft and having a third diameter sized to fit within a first portion of the bore but not within a second portion of the bore. 
         [0007]    According to another embodiment of the present disclosure, a kit for a fracture reduction assembly for insertion through an incision in a patient includes at least one body including a bone contacting surface for contacting a bone and a barrel extending outwardly from the bone contacting surface of the body, at least one body defining a bore extending through the barrel and the at least one body along an axis, at least one screw portion configured to be slidingly restrained within the bore in a first direction along the axis by a threaded portion positioned outwardly of the barrel, and at least one restraining member configured to couple with the at least one screw portion to slidingly restrain the at least one screw portion within the bore in a second direction along the axis. 
         [0008]    According to yet another embodiment of the present disclosure there is provided a method of implanting a fracture reduction assembly including making an incision in the skin of a patient, preparing a bone to receive the fracture reduction assembly, assembling the fracture reduction assembly, inserting the assembled fracture reduction assembly through the incision, embedding a screw portion of the fracture reduction assembly in a first portion of the prepared bone, and affixing a plate portion of the fracture reduction assembly to a second portion of the prepared bone. 
         [0009]    Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in connection with the accompanying drawings, in which: 
           [0011]      FIG. 1  depicts an exploded perspective view of a fracture reduction assembly incorporating principles of the invention; 
           [0012]      FIG. 2  depicts a side plan view of the assembled fracture reduction assembly of  FIG. 1 ; 
           [0013]      FIG. 3  depicts a top plan view of the assembled fracture reduction assembly of  FIG. 1 ; 
           [0014]      FIG. 4  depicts a side cross sectional view of the base portion of the fracture reduction assembly of  FIG. 1 ; 
           [0015]      FIG. 5  depicts a side cross sectional view of the screw portion of the fracture reduction assembly of  FIG. 1 ; 
           [0016]      FIG. 6  depicts a side cross sectional view of the retainer of the fracture reduction assembly of  FIG. 1 ; 
           [0017]      FIG. 7  depicts a side cross sectional view of the base portion of the fracture reduction assembly of  FIG. 1  aligned with the screw portion of the fracture reduction assembly of  FIG. 1 ; 
           [0018]      FIG. 8  depicts a side cross sectional view of the screw portion of the fracture reduction assembly of  FIG. 1  inserted into the barrel of the base portion of the fracture reduction assembly of  FIG. 1  such that a portion of the shaft of the screw portion extends above the plate portion, and the retainer of the fracture reduction assembly of  FIG. 1  aligned with the portion of the shaft; 
           [0019]      FIG. 9  depicts a partial cross sectional view of the retainer of  FIG. 8  contacting the outer surface of the shaft as the shaft is inserted into the retainer, thereby causing the retainer to flex outwardly; 
           [0020]      FIG. 10  depicts a partial cross sectional view of the retainer of  FIG. 8  after flexing inwardly to couple with a coupling member of the shaft, and positioned above the base portion; 
           [0021]      FIG. 11  depicts a side cross sectional view of the fracture reduction assembly of  FIG. 1  wherein the threaded section of the screw portion is larger than the diameter of the bore entrance and the retainer is located within an upper portion of the bore; 
           [0022]      FIG. 12  depicts a partial side cross sectional view of the fracture reduction assembly of  FIG. 1  showing the diameter of the coupled retainer to be smaller than the portion of the bore located upwardly from a protuberance at the mouth of the bore and larger than the diameter of the bore defined by the protuberance, and also showing the clearance between the retainer and the bore to be less than the extent of the retainer located within the coupling member of the shaft; 
           [0023]      FIG. 13  depicts a fractured femur that has been prepared to receive an assembled fracture reduction assembly through an incision in accordance with principles of the invention; 
           [0024]      FIG. 14  depicts the fractured femur of  FIG. 13  after the fracture reduction assembly has been inserted through the incision and the screw portion has been embedded in the head of the femur; 
           [0025]      FIG. 15  depicts a side plan view of the locking member of  FIG. 1  that may be used to clamp the screw portion and the retainer of  FIG. 1  so as to rotationally lock the screw portion with respect to the base portion while allowing axial movement of the screw portion within the barrel; 
           [0026]      FIG. 16  depicts an end perspective view of the locking member of  FIG. 15 ; 
           [0027]      FIG. 17  depicts the locking member of  FIG. 15  with one hexagonal portion inserted within the hexagonal portion of the screw portion and a second hexagonal portion inserted within a hexagonal portion of the retainer; 
           [0028]      FIG. 18  depicts the locking member of  FIG. 15  with one hexagonal portion inserted within the hexagonal portion of the screw portion and a second hexagonal portion inserted within a hexagonal portion of the retainer, and a threaded member threaded into the threaded portion of the screw portion; 
           [0029]      FIG. 19  depicts the fracture reduction assembly of  FIG. 1  fully implanted on the femur of  FIG. 14 ; 
           [0030]      FIGS. 20 and 21  depict an alternative embodiment of a fracture reduction assembly incorporating a base with an extended proximal portion providing a second hole for receiving a second bone fastener; 
           [0031]      FIG. 22  depicts a side cross sectional view of the base portion of the fracture reduction assembly of  FIGS. 20 and 21 ; 
           [0032]      FIG. 23  depicts a side perspective view of a bone fastener that may be inserted through the second hole of the fracture reduction assembly of  FIGS. 20 and 21 ; and 
           [0033]      FIG. 24  depicts the fracture reduction assembly of  FIGS. 20 and 21  attached to a fractured femur with the threaded portion of the screw portion embedded in the head of the femur along with the threaded portion of the bone fastener of  FIG. 23 . 
       
    
    
       [0034]    Corresponding reference characters indicate corresponding parts throughout the several views. Like reference characters tend to indicate like parts throughout the several views. 
       DETAILED DESCRIPTION 
       [0035]    Embodiments of the present invention and the advantages thereof are best understood by referring to the following descriptions and drawings, wherein like numerals are used for like and corresponding parts of the drawings. 
         [0036]    A fracture reduction assembly  100  is shown in  FIGS. 1-3 . The fracture reduction assembly  100  includes a base portion  102 , a screw portion  104 , a retaining sleeve  106 , and a locking member  108 . Screws  110  and  112  are also shown in  FIG. 1 . The foregoing components may be made of any suitable durable material and may be made, for example, of a titanium alloy, a stainless steel alloy, or a cobalt chromium alloy. If desired, all of the components may be made of the same material. 
         [0037]    The base portion  102 , also shown in  FIG. 4 , includes a plate  114  and a barrel  116  which extends outwardly and medially from the plate  114 . The plate  114  includes a bone contacting surface  118  and an outer surface  120 . A threaded hole  122  is located on a distal portion  124  of the plate  114  and extends from the outer surface  120  to the bone contacting surface  118 . 
         [0038]    A bore  126  is located between the distal portion  122  and a proximal portion  128  of the plate  108 . As shown in  FIG. 4 , the bore  126  extends from the outer surface  120  through the barrel  116 . The bore  126  includes an upper threaded portion  130 , a shoulder  132  and a guide slot  134 . The diameter of the bore  126  is reduced at the shoulder  132  while the guide slot  134  provides a portion of the bore  126  with an increased diameter. 
         [0039]    With reference to  FIG. 5 , the screw portion  104  includes a shaft portion  140  and a threaded portion  142 . In this embodiment, the screw portion  104  is thus in the form of a lag screw incorporating cancellous threads in the threaded portion  142 . A coupling member  144  is located at the upper portion of the shaft portion  140 . A bore  146  extends through the shaft portion  140  and the threaded portion  142 . A shoulder  148  separates an upper hexagonally shaped portion  150  of the bore  146  from a threaded portion  152 . A shoulder  154  separates the threaded portion  152  of the bore  146  from a lower portion  156 . 
         [0040]    The retaining sleeve  106  which is shown in  FIGS. 1 and 6  includes an upper hexagonally shaped bore  160  which is separated from a lower bore  162  by a shoulder  164 . A coupling member  166  is located at the lower portion of the lower bore  162  and a guide member  168  extends along the outer surface of the retaining sleeve  106 . 
         [0041]    The assembly of the foregoing components to form the fracture reduction assembly  100  may be performed by the manufacturer and the assembly  100  packaged in a sterile container for later implantation into the patient. Alternatively, the components can be assembled in the surgery room prior to implantation. In either event, the screw portion  104  is initially aligned with the barrel  116  of the base portion  102  as shown in  FIG. 7 . The shaft portion  140  is sized to have a diameter that is slightly less than the diameter of the bore  126  defined by the smaller diameter of the shoulder  132 . In alternative embodiments, shapes other than circular shapes may be used so long as the shaft fits within the bore. The shaft portion  140  is then moved in the direction of the arrow  170  of  FIG. 7  and inserted into the bore  126 . 
         [0042]    The threads of the threaded portion  142  define a diameter that is larger than the smaller diameter of the shoulder  132 . Accordingly, movement of the screw portion  104  in the direction of the arrow  170  is restricted once the threaded portion  142  is adjacent to the barrel  116 . As shown in  FIG. 8 , however, the shaft portion  140  is sized such that the coupling member  144  is positioned outwardly of the bore  126  before the threaded portion  142  contacts the barrel  116 . Next, the retaining sleeve  106  is aligned with the shaft portion  140  which extends above the outer surface  120  of the plate  114 . As shown in  FIG. 8 , the retaining sleeve  106  is oriented such that the coupling member  166  is adjacent to the shaft portion  140 . 
         [0043]    Next, the retaining sleeve  106  is moved in the direction of the arrow  172  (see  FIG. 8 ) until the coupling member  166  contacts the shaft portion  140 . As shown in  FIG. 9 , the coupling member  166  defines a diameter which is less than the diameter of the shaft portion  140 . Accordingly, as additional force is applied in the direction of the arrow  172 , the coupling member  166  flexes radially outward as indicated by the arrows  163  of  FIG. 9 , thereby allowing additional movement of the retaining sleeve  106  onto the shaft portion  140 . Movement of the retaining sleeve  106  continues until the coupling member  166  is aligned with the coupling member  144  of the shaft portion  140 . 
         [0044]    The reduced diameter of the shaft portion  140  at the coupling member  144  allows the coupling member  166  to flex inwardly toward the original shape of the coupling member  166  as shown in  FIG. 10 . The diameter of the lower bore  162 , the shaft portion  140 , the coupling member  144  and the coupling member  166  are selected such that a tight fit is achieved between all of the components. Additionally, when the coupling members  144  and  166  are coupled, the end portion of the shaft portion  140  is adjacent to the shoulder  164 , restraining further movement of the restraining sleeve  106  onto the shaft portion  140 . 
         [0045]    Once the retaining sleeve  106  is positioned on the shaft portion  140 , the screw portion  104  is slidably coupled with the base portion  102 . Specifically, movement of the screw portion  104  outwardly of the base portion  102  in a direction above the outer surface  118  (to the left as viewed in  FIG. 10 ) is restrained by the threaded portion  142  abutting the barrel  114  (see  FIG. 8 ). Movement of the screw portion  104  in the direction of the arrow  174  from the position of  FIG. 10  is allowed by aligning the guide member  168  (see  FIG. 1 ) with the guide slot  134  (see  FIG. 4 ). The diameter of the restraining sleeve  106  at the guide member  168  is slightly less than the diameter of the bore  126  at the guide slot  134  and the diameter of the remainder of the restraining sleeve  106  is slightly less than the diameter of the remainder of the bore  126  defined by the smaller diameter of the shoulder  132 . Thus, the retaining sleeve  106  is allowed to move into the portion of the bore  126  between the threaded portion  130  and the shoulder  132  as shown in  FIG. 11 . 
         [0046]    As shown in  FIG. 12  the diameter of the retaining sleeve  106  is larger than the diameter of the bore  126  defined by the smaller diameter of the shoulder  132 . Accordingly, movement of the screw portion  104  outwardly of the barrel  116  in a direction away from the base  102  (to the right as viewed in  FIG. 12 ) is restrained by contact between the retaining sleeve  106  and the shoulder  132 . Thus, the screw portion  104  is slidably retained within the barrel  116 . The securing or retaining of the screw portion  104  in the barrel  116  provides a fracture reduction assembly  100  that may be surgically implanted as an assembly resulting in fewer steps in the surgical procedure than required for prior art lag screws which are implanted as individual components and assembled in vivo. 
         [0047]    By way of example,  FIG. 13  depicts a femur  10  with an intertrochanteric fracture  12  which separates the head  14  and neck  16  of the femur  10  from the shaft  18  of the femur  10 . The fracture  12  extends from a greater trochanter  20  to a lesser trochanter  22 . While the femur  10  and the intertrochanteric fracture  12  are used to describe a procedure incorporating the use of the fracture reduction assembly  100 , the fracture reduction assembly  100  may also be used with other bones and with fractures having different locations. 
         [0048]    After the fracture reduction assembly  100  has been assembled as described above, an incision  24  is made in the skin of the patient and the femur  10  is exposed in accordance with acceptable procedures. The femur  10  is then prepared to receive the fracture reduction assembly  100  by reducing the fracture  12  and drilling bores  26  and  28 . The bore  26  has a diameter corresponding to the diameter of the shaft portion  140  and extends from the end portion of the bore  28  into the neck  16  and/or head  14 . The bore  28  has a diameter corresponding to the diameter of the barrel  116 . The bore  28  extends from the surface of the femur  10  to a depth corresponding to the length of the barrel  116 . 
         [0049]    Next, the fracture reduction assembly  100  is inserted through the incision  24  in the direction of the arrow  176 . The screw portion  102  is inserted through the bore  28  and into the bore  26 . The threaded portion  142  of the screw portion  102  has a diameter that is larger than at least a portion of the bore  26 . Accordingly, the threaded portion  142  bites into the neck  16  and/or head  14  firmly engaging the femur  10  as shown in  FIG. 14 . 
         [0050]    Once the screw portion  142  is firmly engaged with the femur  10 , the base portion  102  is slid along the shaft portion  140  in the direction of the arrow  178  of  FIG. 14  into contact with the femur  10 . The bone contacting surface  118  of the base portion  102  is shaped for cooperation with the lateral aspect of the shaft  18 . Since the shaft  18  is generally cylindrical, the bone contacting surface  118  is generally concave in the horizontal plane to conform to the shaft  18 . The bone contacting surface  116  is slightly convex in the vertical plane to conform to the condylar portion of the femur  10 . Thus, the base portion  102  contacts a substantial portion of the femur  10  about the bore  28  as shown in  FIG. 14 . 
         [0051]    Next, the screw portion  104  is rotationally secured within the barrel  116  with the locking member  108 . The locking member  108 , shown in  FIGS. 15 and 16 , includes a housing  200  with an upper hexagonal portion  202  and a lower hexagonal portion  204 . A threaded member  206  is slidingly constrained within the housing  200 . The lower hexagonal portion  204  is formed complementary to the upper hexagonally shaped portion  150  of the bore  146  in the screw portion  104  and the upper hexagonal portion  202  is formed complementary to the hexagonally shaped upper bore  160  of the retaining sleeve  106 . 
         [0052]    Accordingly, the locking member  108  may be inserted into the hexagonally shaped portion  150  and the hexagonally shaped upper bore  160  as shown in  FIG. 17  thereby rotationally coupling the screw portion  104  and the retaining sleeve  106 . Because the retaining sleeve  106  is rotationally constrained by the coupling of the guide member  168  with the guide slot  134 , the screw portion  104  is also rotationally constrained. The locking member  108  is then axially coupled with the screw portion  104  and the retaining sleeve  106  by threading the threaded member  206  into the threaded portion  152  of the bore  146  as shown in  FIG. 18 . 
         [0053]    While the screw portion  104  is locked with respect to rotation, the screw portion  104  is axially movable with respect to the barrel  116 . So as to ensure that the retaining sleeve  106  does not back out of the bore  146 , the screw  110  is threaded with the upper threaded portion  130  of the base portion  102 . 
         [0054]    As shown in  FIG. 19 , the screw  110  may also be threaded into the threaded hole  122 . In this embodiment, the screw  110  includes a threaded head configured to lock in the threaded hole  122  and secure the base portion  102  to the lateral aspect or lateral cortex wall of the shaft  18 . In alternative embodiments, a non locking screw such as a cortical screw with a non threaded head may be used. A kit may include a variety of locking and non-locking screws of different lengths for use in the threaded hole  122 . 
         [0055]      FIG. 19  further shows the screw  112  engaged with the upper threaded portion  130  of the base portion  102 . The screw  112  thus restricts outward movement of the clamped screw portion  104  and retaining sleeve  106  which can move axially along the barrel  116 . 
         [0056]      FIGS. 20-21  depict a fracture reduction assembly  200 . The fracture reduction assembly  200  is substantially similar to the fracture reduction assembly  100  and includes a base  202  and a screw portion  204 . In one embodiment, the only difference between the fracture reduction assembly  200  and the fracture reduction assembly  100  is the configuration of the base  202 . With further reference to  FIG. 22 , the base portion  202  includes a plate  206  and a barrel  208 . A distal portion  210  of the plate  206  includes a threaded hole  212 . The plate  206  further includes a bone contacting surface  214  and an outer surface  216 . The barrel  208  and the distal portion  210  are similar to components discussed with reference to the fracture reduction assembly  100  and are not further described herein. 
         [0057]    A proximal portion  218  of the plate  206 , however, is configured to provide additional support to the lateral aspect of the greater trochanter. To this end, proximal portion  218  extends farther from the barrel  208  than the proximal portion  128  extends from the barrel  116  of the fracture reduction assembly  100 . This allows for an additional threaded hole  220  to be positioned proximally from the barrel  208 . In the embodiment of  FIG. 22 , the threaded hole  220  is oriented to define an axis  222  that is substantially parallel to the axis  224  defined by the barrel  208 . In alternative embodiments, the additional hole may be unthreaded. 
         [0058]    An anti-rotation screw  228  shown in  FIG. 23  may be used with the threaded hole  220 . The anti-rotation screw  228  includes tapered external threads formed on a head  230 . The threaded head  230  mates with tapered internal threads in the threaded hole  220  to lock the anti-rotation screw  228  to the plate  202 . The anti-rotation screw  228  further includes a shaft  232  and cancellous external threads  234  which engage cancellous bone in the head  44  of the femur  40 . In one embodiment, the screw  228  is a 6½ millimeter screw although screws of different sizes and lengths may be used. 
         [0059]    The orientation of the axes  222  and  224  allow a long screw such as the screw  228  to provide additional fixation with the neck and or head of a femur without contacting the screw portion  204 . By way of example, in  FIG. 24 , the fracture reduction assembly  200  is depicted mounted to a femur  40 . The femur  40  includes a fracture  42  separating the head  44  and the neck  46  from the shaft  48 . Both the screw portion  204  and the screw  228  extend across the fracture  42 , thereby providing additional fixation between the fracture reduction system  200  and the femur  40 . While the screw  228  is shown to have substantially the same length as the screw portion  204 , in alternative embodiments shorter screws or screws with non-threaded heads may be used. 
         [0060]    Although the present invention has been described with respect to certain preferred embodiments, it will be appreciated by those of skill in the art that other implementations and adaptations are possible. Moreover, there are advantages to individual advancements described herein that may be obtained without incorporating other aspects described above. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein.