Abstract:
A kit for fixation of a fracture in a superior portion of a femoral bone, to minimize patient trauma by minimizing the incision during surgery, the kit having: a tube having a distal end and a proximal end, and a tube bore aligned with a longitudinal tube axis, the tube bore having a maximum internal dimension in a plane transverse to the tube axis; and a bone plate having a barrel portion with a barrel bore aligned with a barrel axis and a bone-engaging portion disposed at a selected angle to the barrel axis, the bone plate having an external dimension, in a plane transverse to the barrel axis, less than the maximum internal dimension of the tube bore.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to percutaneous bone fracture fixation in the superior portion of the femoral bone. 
       BACKGROUND OF THE ART 
       [0002]    Fixation of fractures in the superior portion of the femoral bone typically involves introducing a lag screw across the fracture and a bone plate to hold the lag screw and fracture in place. Bone screws pass through the bone plate and fix the plate to an intact portion of the bone. 
         [0003]    The prior art procedure typically requires a relatively large incision to be made down the hip and leg of the patient, in order to gain access to the femoral bone and introduce the fixation devices. Obese patients may require much larger incisions due to thicker fat layers. Such a large incision is associated with prolonged pain and hospital stay for the patient, as well as a greater possibility of developing other comorbidities. In addition, patients requiring treatment for such fractures are typically older less mobile adults with slower rates of healing. Thus, such a large incision will mean extensive pain and bed rest for the patient, causing a significant negative impact on the patient&#39;s quality of life, which may last for an extended period of time. 
         [0004]    Prior art devices have attempted to minimize this negative impact by providing smaller bone plates for treating a femoral fracture, such as disclosed in U.S. Application Publication 2004/0193162 and U.S. Pat. No. 2,397,545. While such devices might decrease the length of the necessary incision, a substantial incision is still required to access the bone, and perform the procedure. 
         [0005]    Percutaneous treatment in certain orthopedic procedures is generally preferred since the incision and accompanying recuperation are significantly lessened. These include the use of an access tube to percutaneously treat and introduce devices to the knee, as in U.S. Application Publication 2004/0243138, and the use of an access tube to remove orthopedic screws, as in U.S. Application Publication 2004/0158257. 
         [0006]    Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below. 
       DISCLOSURE OF THE INVENTION 
       [0007]    A first embodiment of the present invention provides a kit used for percutaneous fixation of a femoral fracture. In accordance with the first embodiment of the present invention, there is a kit for fixation of a fracture in a superior portion of a femoral bone, to minimize patient trauma by minimizing the incision during surgery, the kit having: a tube having a distal end and a proximal end, and a tube bore aligned with a longitudinal tube axis, the tube bore having a maximum internal dimension in a plane transverse to the tube axis; and a bone plate having a barrel portion with a barrel bore aligned with a barrel axis and a bone-engaging portion disposed at a selected angle to the barrel axis, the bone plate having an external dimension, in a plane transverse to the barrel axis, less than the maximum internal dimension of the tube bore. 
         [0008]    Preferably, the tube is small enough to be introduced into the patient through a minimal incision, and large enough to provide passage for devices commonly used to treat femoral fractures. 
         [0009]    Another embodiment of the invention provides a percutaneous method for fixation of a fracture in the superior portion of a femoral bone using a tube and a bone plate designed to pass through said tube, minimizing the size of an incision. 
         [0010]    Further aspects of the embodiments will become apparent upon reference to the accompanying drawings and description. 
     
     
       DESCRIPTION OF THE DRAWINGS 
         [0011]    In order that the invention may be readily understood, embodiments of the invention are illustrated by way of example in the accompanying drawings. 
           [0012]      FIG. 1  depicts a set of coaxial nested tubes to guide a central fastener or threaded wire being applied to a femoral bone. 
           [0013]      FIG. 2A  is an exploded perspective view of the tubes of  FIG. 1 . 
           [0014]      FIG. 2B  is an exploded perspective view of an alignment guide used with the largest tube. 
           [0015]      FIG. 3  depicts the alignment guide used to install parallel wire fasteners to a femoral bone. 
           [0016]      FIG. 4  depicts another embodiment of the tube having a handle grip showing a larger blind hole drilled about the central wire fastener. 
           [0017]      FIG. 5  is a perspective view of the tube of  FIG. 4 . 
           [0018]      FIG. 6  depicts a bone plate and fasteners being applied to the femoral bone. 
           [0019]      FIG. 7  is a close-up perspective view of the barrel of the bone plate with an optional keyed internal profile in alignment with a lag screw end having a matching keyed external profile to prevent rotation. 
           [0020]      FIG. 8  is a close-up side view of a cross-section of the inferior end of the bone plate, showing a bone screw fitting into the bone plate. 
           [0021]      FIG. 9  is a perspective view of elongate appendages and a view of the appendages introducing a medical substance sponge into a blind hole drilled in the femoral bone. 
           [0022]      FIG. 10  is a close-up view of the appendages of  FIG. 9  gripping the medical substance sponge. 
           [0023]      FIG. 11  is a cut-out of the appendages of  FIG. 10  along line  11 - 11  showing optional appendage protrusions. 
       
    
    
       [0024]    Further details of the invention and its advantages will be apparent from the detailed description included below. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]    The illustrated embodiment of the present invention is a kit including a tube  5 , a bone plate  26 , a lag screw  24 . Optionally a compression screw  37 , bone screws  35 , an alignment guide  13 , and elongate appendages  38  may be included. The details and use of these parts will be described below with reference to the drawings by way of example. 
         [0026]      FIG. 1  shows the present invention as applied to a patient  1  through an incision  2 , against the femoral bone  3 , which has a fracture  4  in the superior portion. The tube  5  may include a plurality of different sized nested and coaxial portions  10  and  11 . The distal end of the tube  5  is introduced to the bone  3  through the incision  2 , and is guided into position by loading the tube  5  over a conventional K-wire  12 . 
         [0027]    The incision  2  is small initially and accommodates only the smallest tube  11 . The incision  2  is then dilated to the size necessary for the procedure, by introducing tubes  10  and  5  of increasing size, as shown in  FIG. 1 , or by other means, such as an expanding tube, not shown. Regardless of the exact method, the tube  5  is introduced to the bone  3  to provide a passage sufficiently large to treat the fracture  4 , through a small incision  2  to minimize patient trauma. Further shown in  FIG. 1  is that tube  5  has a distal end  8  and a proximal end  9  seen more clearly in  FIG. 2 . 
         [0028]    In a preferred embodiment, dilation of the incision  2  is performed by telescoping tubes  5 ,  11 , and  10 , which are all cylindrical in the illustrations but need not be ,imited to this configuration.  FIG. 2  shows the telescoping tubes  5 ,  11  and  10  separately. Considering only the largest tube  5 , it can be seen that the distal end  8  is distinct from the proximal end  9  in that distal end  8  is angled relative to the longitudinal axis whereas the proximal end  9  is normal to the longitudinal axis. The distal end  8  is directed towards the bone  3 , and has an angle to aid in correctly directing the procedure. The tubes  5 ,  11  and  10  have differing inner and outer diameters to allow them to nest together. Each of the tubes  5 ,  11  and  10  has distinct distal ends  8  and proximal ends  9 , having the same angle on the distal end  8 . 
         [0029]    In a preferred embodiment, the smallest tube  11  has a length of 150 mm, inner diameter of 2.3 mm to fit over the K-wire  12 , and an outer diameter of 15 mm, such that the initial incision  2  causes minimal patient trauma. The middle tube  10  has a length of 150 mm, an inner diameter of 15 mm to fit over the smallest tube  11 , and an outer diameter of 30 mm. The largest tube  5  has a length of 150 mm, an inner diameter of 30 mm to fit over the middle tube, and an outer diameter of 40 mm. The distal end  8  of each tube has a preferred angle A ( FIG. 2 ) of 45°. It will be appreciated that tubes  10  and  11  are simply variations on tube  5  and are included in any description referring to tube  5 . 
         [0030]    As shown in  FIG. 2 , in the preferred embodiment, the middle tube  10  has a centered bore  6  and evenly spaced offset channels  7  circumferentially located about the bore  6 . There are preferably eight such channels  7 , each having an inner diameter of 2.8 mm, circumferentially located on a circle of diameter 20 mm to allow passage of other devices useful for the procedure. 
         [0031]    Also shown in  FIG. 2  is an alignment guide  13 , designed to fit into the largest tube  5 , and replacing the smaller tubes  10  and  11 . The alignment guide preferably has a length of 150 mm, a centered bore  14  with an inner diameter of 2.3 mm to fit over the K-wire  12 , and an outer diameter of 30 mm to fit inside the largest tube  5 . Because the alignment guide  13  replaces middle tube  10 , the alignment guide  13  also has offset channels  15 , shown here to have the same arrangement as on middle tube  10 , but other arrangements are possible. The alignment guide has distal end  16  and proximal end  17 , where the distal end  16  is directed towards the bone  3 . The distal end  16  of the alignment guide  13  is angled, but may differ from the angle on the tube  5 . In a preferred embodiment, the alignment guide  13  is angled at an angle A′ of 30°-40°, allowing a range of access orientations for performing the procedure. There may be a plurality of alignment guides, each providing a different angle at the distal end  16  or providing a different arrangement of the offset channels  15 . 
         [0032]      FIG. 3  shows how alignment guide  13  might be used with tube  5  in the procedure. A second K-wire  12   b  may be introduced to the bone  3  through one of the offset channels  15  on the alignment guide  13 . The alignment guide  13  can now be removed and the second K-wire  12   b  can be used to guide a derotation screw  18  ( FIG. 4 ) into the bone. A derotation screw  18  is commonly used to fix fractures in a femoral bone, and is commonly introduced at the end of the procedure. However, it will be appreciated by persons skilled in the art that the derotation screw  18  may be introduced near the start of the procedure, and may aid in fixing the fracture  4  by preventing motion in the fracture  4  in subsequent steps in the procedure. 
         [0033]    Once the incision  2  has been dilated and the derotation screw  18 , if using, has been introduced across the fracture  4 , an access tube  19  can be introduced over the largest tube  5 . It will be appreciated that the access tube  19  is simply another variation of tube  5  and is included in any description referring to the tube  5 . Tube  5  is removed from the access tube  19  along with other tubes  10 ,  11 , or alignment tube  13  if these are still in place, thus providing an open passage for introducing the lag screw  24 . The lag screw  24  preferably has a bone adhesion promotion coating on its outer surface, such as hydroxyapatite. A preferred embodiment of the access tube  19  has a handle  21  to aid in positioning the tube, a distal end  22  and a proximal end  23 . 
         [0034]    Details of the access tube  19  can be better appreciated in  FIG. 5 . A preferred embodiment of the access tube  19  has a length of 100-150 mm, an inner diameter of 40 mm to fit over the largest tube  5 , and a wall thickness of 1 mm, which maximizes the diameter of the access passage without significantly increasing the size of the incision  2 . The distal end  22  is angled at the same angle A as tubes  5 ,  10 , and  11 , the angle being 45° in the preferred embodiment. The handle  19  branches off from the proximal end  23  at a preferred angle of 60° to aid in positioning the access tube  19  and in holding it in place against the bone  3 . The access tube  19  is preferably made of a biocompatible, radiolucent material, such as an aluminum alloy. 
         [0035]    Once the access tube  19  is in place and the lag screw  24  has been introduced across the fracture  4 , bone plate  26  can be introduced to the bone  3 , as shown in  FIG. 6 . An elongated cylinder or rod, not shown, can be used to advance the bone plate  26  through the access tube  19  towards the bone. The bone plate  26  has a barrel portion  27  and a bone-engaging portion  29 . The bone-engaging portion has a bone-engaging medial side  31  and an opposite lateral side  32 . The bone-engaging portion also has a superior end  33  and an opposite inferior end  34 . In a preferred embodiment, the barrel portion  27  and the bone-engaging portion  29  form a selected angle of 135°, matching the angle on the access tube distal end  22 . There may be a plurality of bone plates  26  with selected angles ranging from 140°-150°, to match the angle on the alignment guide distal end  16 . In a preferred embodiment, the bone plate  26  is designed to pass through the access tube  19  when the axis of the barrel portion  27  is parallel to the longitudinal axis of the access tube  19 . Referring to  FIGS. 6 and 8 , the bone-engaging inferior end  34  has a rounded end and is beveled at angle A, matching the angle of the access tube  19 , to better allow bone plate  26  to pass through the access tube  19  without interference. 
         [0036]    As shown by the dotted oval in  FIG. 6 , the access tube  19  can be pivoted about its proximal end  23  in order to provide access to different locations on the bone  3  without having to increase the size of the incision  2 . This allows different areas of the bone plate  26  to be centered in the access tube  19 , for example to aid in fitting bone screws  35  into the screw holes  30 . 
         [0037]    In one embodiment, the barrel portion  27  is free to rotate about the lag screw  24 , to ease installation of the barrel  27  on the lag screw  24 , and ease passage of the bone plate  26  through the access tube  19 . However, the barrel portion  27  can also be designed to prevent rotation of the bone plate  26  about the lag screw  24 . This can be done for example by having a keyed internal profile  28  that is non-circular and matching the keyed outer profile of the lag screw  24 , as shown in  FIG. 7 . 
         [0038]    The bone plate  26  is introduced to the bone  3  and the barrel portion  27  is loaded over the lag screw  24 . The bone-engaging portion  29  is then attached to the bone  3  preferably using bone screws  35 . This attachment, as with all steps in the procedure, is performed percutaneously through a tube, such as access tube  19 . It will be appreciated by persons skilled in the art that the bone-engaging portion  29  can be attached to bone  3  using other fastening means, such as bone wires or bone staples, and that the bone plate  26  can be modified to be compatible with these other fastening means without deviating from the spirit of the present invention. In the preferred embodiment, the bone screws  35  fit into screw holes  30  on the bone plate  29 . The screw holes  30  may be tapered towards the medial side  31 , and may be threaded, as shown in  FIG. 8 . The bone screws  35  may also be threaded and tapered to match the screw holes  30 , to maximize attachment of the bone plate  29  to the bone  3  and prevent future loosening. 
         [0039]    A compression screw  37  can be introduced to compress the bone fracture as the barrel  33  of the bone plate  29  is drawn longitudinally towards the distal embedded end of the lag screw  24 , thus closing up fracture  4  even further. Once the fracture  4  is closed and stabilized, the access tube  19  can be removed from the patient  1  and the incision  2  can be closed. 
         [0040]    An optional step in the procedure is shown in  FIG. 9 . Elongate appendages  38  are used to introduce a medical substance  42 , shown here on a sponge carrier, into the blind hole drilled into the bone  3  to aid in fixation or healing of the fracture  4 . The medical substance  42  is introduced over the K-wire  12  after the bone  3  has been drilled but before the introduction of the lag screw  24 . 
         [0041]    As shown in greater detail in  FIG. 10 , the preferred embodiment, comprises two elongate appendages  38 . The appendages  38  each have a concave inner surface  39  and a convex outer surface  40  curved about their longitudinal axis.  FIG. 11  shows a cutout of one of the appendages  38  along line  11 - 11 . The cutout reveals the inner surface  39 , which preferably has protruding grips  41  to aid in gripping and pushing the medical substance  42 . The medical substance  42  may be an osteoinductive agent or any other medical substance introduced to the bone in a fracture fixation procedure. A medical substance  42  may also be introduced into the bone by other means through the access tube  19 . For example, an angiogenic biological or a bone cement may be injected into the bone to aid in fracture healing or fixation. 
         [0042]    Although the above description relates to a specific preferred embodiment as presently contemplated by the inventor, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.