Abstract:
Disclosed is a method of selecting a femoral prosthetic for implantation relative to a femur using a femoral sizing guide. An extension portion of the femoral sizing guide is placed adjacent to a posterior condyle surface of the femur. A stylus is located proximate to an interior condyle surface of the femur. A first actuator disposed between the extension portion and a base portion is moved to rotatably displace the extension portion with respect to the base portion until the stylus is centrally located on top of the interior condyle. A measurement of the femur is identified with the sizing guide based on a relative location of the stylus, the extension portion and the base portion. A femoral prosthesis is selected based on the measurement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/367,903 filed on Feb. 9, 2009, which is a continuation of U.S. patent application Ser. No. 10/730,456 filed on Dec. 8, 2003, issued on Feb. 10, 2009 as U.S. Pat. No. 7,488,324. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates generally to the alignment hardware used in a surgical procedure and, more particularly, to an alignment hardware used in the implantation of a femoral prosthesis. 
       BACKGROUND 
       [0003]    The implantation of knee prosthetics require the distal end of the femur to be prepared to receive a femoral component of the knee prosthetic. This preparation generally requires the resection of various surfaces of the femur to ensure the proper coupling of the knee prosthetic to the resected surfaces. Various guides are known to assist the surgeon in locating cutting blades used to resect the femur. 
         [0004]    The location and size of cuts to the femur generally correspond to internal surfaces within the femoral prosthetics. The location of the surfaces may change depending on the size of the prosthetics used. To this end, a femoral sizing guide is used to determine the size of the femoral prosthetic which will be implanted at the implantation site of the particular patient. 
         [0005]    Femoral knee prosthesis are made available in a range of standard sizes. A femoral sizing guide is used to assist the selection of a standard sized femoral knee prosthetic which will best fit the requirements of a particular implantation site. The size and orientation of the implant is a function of kinematic and biomechanical considerations. In this regard, the femoral sizing guide is used to measure the condyles of the patient&#39;s femur and specifies the proper location of guiding apertures within the femur. As such, it is necessary to provide a reliable femoral sizing guide which is configured to allow the surgeon to determine the size and proper orientation of the femoral implant. 
       SUMMARY 
       [0006]    Disclosed is a method of selecting a femoral prosthetic for implantation relative to a femur using a femoral sizing guide. An extension portion of the femoral sizing guide can be placed adjacent to a posterior condyle surface of the femur. A stylus can be located proximate to an interior condyle surface of the femur. A first actuator disposed between the extension portion and a base portion can be moved to rotatably displace the extension portion with respect to the base portion until the stylus is centrally located on top of the interior condyle. A measurement of the femur can be identified with the sizing guide based on a relative location of the stylus, the extension portion and the base portion. A femoral prosthesis can be selected based on the measurement. 
         [0007]    According to additional features, the stylus can be translated along an axis relative to the base portion. A superstructure associated with the stylus can be translated along the axis relative to the extension portion. Translating the stylus can include rotating a second actuator causing a threaded distal end of the second actuator to rotate within a threaded hole of the base portion. Moving the first actuator can include rotating a worm gear disposed between the extension portion and the base portion. Identifying the measurement can include identifying a first gradation of a plurality of indexing gradations provided on a worm gear mount of the worm gear. Identifying the measurement can further include identifying a second gradation of a series of gradations provided on the stylus. At least one retaining hole can be drilled into the femur while referencing drilling guides extending from the base portion. 
         [0008]    Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  represents a perspective view of the femoral sizing guide of the present disclosure; 
           [0011]      FIG. 2  represents a front view of the femoral sizing guide shown in  FIG. 1 ; 
           [0012]      FIG. 3  represents a femoral sizing guide shown in  FIG. 1  with the worm gear actuated; 
           [0013]      FIG. 4  is a cross-sectional view of the worm gear mechanism shown in  FIG. 2 ; 
           [0014]      FIG. 5  represents a side view of the femoral sizing guide measuring a plurality of insert sizes; 
           [0015]      FIG. 6  is a side view of the femoral sizing guide coupled to a resected femur; 
           [0016]      FIGS. 7 and 8  are exploded views of a femoral measurement guide according to another embodiment of the present disclosure; 
           [0017]      FIG. 9  is a modular adjustable foot portion shown in  FIG. 7 ; 
           [0018]      FIG. 10  is a base portion shown in  FIG. 7 ; and 
           [0019]      FIGS. 11 and 12  are modular superstructures shown in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. 
         [0021]    Referring generally to  FIGS. 1 and 2 , a femoral sizing guide  10  according to the teachings of the present disclosure is shown. The femoral sizing guide  10  is generally formed of an extension portion  12 , a base portion  14 , a superstructure portion  16  having a corresponding graduated stylus  18 , an actuator  20  disposed between the superstructure  16  and the base portion  14 , and a worm gear  22 . The femoral sizing guide  10  is configured to measure the size and general angular orientation of the condyles of a femur to allow a treating physician to interoperatively select a proper femoral prosthetic. 
         [0022]    The feet  25  of the extension portion  12  use the posterior sides of the condylar surfaces as a reference. As the surfaces of the condyles can be degraded due to natural causes, their ability to function as a reference surface and, therefore, indexing plane can be degraded. As such, adjustability of the feet  25  can assist in the alignment of the sizing guide. 
         [0023]    As best seen in  FIGS. 2 and 3 , the extension portion has a pair of feet  25  coupled to a central member  26 . The extension portion  12  is pivotally coupled to the base portion  14  at a central pivot point  28  through a pivot axis  30 . Further disposed between the extension portion  12  and the base portion  14  is a worm gear  22  which functions to rotate the extension portion  12  and corresponding feet  25  about the pivot axis  30  in a predetermined and repeatable fashion. The extension portion  12  further has a depending pin or flange  32  which defines a first portion of the worm gear  22 . 
         [0024]    The base portion  14  has a body  34  having a body pivot point  35  which corresponds to the pivot axis  30 . A body  34  defines a support flange  38  having a support flange track  40  which is configured to interface with a superstructure track  41 . Defined on a first side  35  of the body  34  is a threaded coupling portion  37 . The threaded coupling portion  37  is configured to be coupled to the actuator  20 . A second side  45  of the body  34  defines a worm gear mount  39 . The worm gear mount  39  defines an aperture  43  and further has a plurality of indexing gradations which will be used by a treating physician to determine the amount of rotation of the feet  25  with respect to the base portion  14  about pivot axis  30 . It should be noted that the pivot axis  30  is offset a predetermined distance from the transepicondylar axis of the femur. 
         [0025]    The superstructure  16  has a pair of depending side flanges  42  and  44  which define drilling guides  46  and  48 . The first depending side flange  42  further defines a coupling mechanism  50  which is shown in the form of an aperture to rotatably support and guide the second actuator  20 . The superstructure  16  further has a holding mechanism  52  which defines an indexed slot  54  which slidably receives the graduated stylus  18 . The holding mechanism  52  further defines a window  56  which displays graduations  58  of the graduated stylus  18 . 
         [0026]    As best seen in  FIG. 3 , the extension portion  12  can be rotated about the pivot axis  30  by the rotation of the first actuator or worm gear  22 . In this regard, the worm gear  22  defines an arcuate slot  60  which is rotatable about a gear pivot point  62 . The arcuate slot  60  slidably holds the fixed worm gear pin  32 . The rotation of the arcuate slot  60  about the coupling point  62  causes the rotation of the extension portion  12  with respect to the base portion  14 . Similarly, it causes rotation with respect to the superstructure  16  and the stylus  18 . The worm gear has a system of associated graduations which allow a treating physician to categorize the necessary rotation of the measurement guide about the central pivot axis  30 . 
         [0027]    The actuator  20  functions to translate the superstructure portion  16  with respect to the extension portion  12  or the base portion  14 . In this regard, the rotation of the actuator  20  causes a threaded distal end  64  of the actuator  20  to rotate within a threaded hole  66  in the coupling portion  37  of the base portion  14 . This causes the superstructure portion  16  and stylus  18  to translate in a second axis  67  away from or toward the base portion  14  and associated feet  25  of the extension portion  12 . The movement causes translation of the drill guides  46  and  48  with respect to the feet  25  and the resected femur. 
         [0028]      FIG. 4  represents a cross-sectional view of the worm gear  22 . As seen, the extension portion  12  has a depending pin  32  which interfaces with the arcuate slot  60  defined in a first rotating member  61 . The rotating member  61  and associated handle portion  63  are rotatably coupled to the worm gear mount  39  of the base portion  14 . The worm gear mount  39  has a plurality of gradations which indicate the relative rotations of the extension portion  12  with respect to the base portion  14  and associated superstructure  16 . 
         [0029]    Shown in  FIGS. 5 and 6 , the graduated stylus  18  rests against the anterior cortex of the femur at an anterior/posterior location. Angular adjustment of the extension portion  12  with respect to the base portion  14  is made by rotating the worm gear  22  and adjusting the actuator  20  so as to allow for the proper standard size femoral implant to be used. In this regard, the adjustments allow the surgeon to properly position the drilling guides  46  and  48  so as to allow a proper positioning of the guide holes (not shown). The holes drilled using the drilling guides  46  and  48  are used to position a cutting guide (not shown) which is used to make cuts to form surfaces which correspond to internal planar surfaces on the interior surface of the femoral prosthetic  80 . 
         [0030]    As shown in  FIGS. 3 ,  5 , and  6 , the feet  25  of the extension portion  12  are positioned adjacent to the posterior side of the femoral condyles. The location of the tip of the stylus  18  is adjusted by sliding the stylus  18  within the index slot  54  of the holding mechanism  52 . Further adjustment can be made by adjusting the position of the superstructure  16  with respect to the extension portion by rotating the actuator  20 . 
         [0031]    At this point, the worm gear  22  is rotated so as to centrally locate the tip of the stylus  18  on top of the interior condyle surface. The treating physician reads values from the graduated stylus  18 , actuator  20 , and indexed worm gear  22  to select the appropriate femoral prosthetic. A pair of retaining holes are then bore into the resected femur using the drilling guides  46  and  48 . 
         [0032]      FIGS. 7-12  represent a second embodiment of the present disclosure. Shown is a modular system which allows a treating physician to interoperatively assemble the femoral sizing guide  10   b . This allows the treating physician to use a rotatable foot portion  25   a  or a non-rotatable foot portion  25   b . Additionally, the treating physician can utilize varying types of superstructure  16   a  or  16   b.    
         [0033]      FIGS. 7 and 8  represent an exploded view of the femoral sizing guide  10   b  according to the teachings of a second embodiment of the disclosure. Shown is a base portion  14   a  which defines a coupling mechanism  82  for coupling either the first or second superstructure  16   a  or  16   b  to the top surface  84  of the base portion  14   a . As shown, the coupling mechanism can take the form of an aperture  86  defined in the top surface  84  which is configured to fixably receive a post  88  formed on the superstructure  16   a  or  16   b . The post  88  can optionally have a locking feature  90  which allows the post to be non-rotatably and yet releasably coupled to the base  14   a.    
         [0034]    Additionally, the base  14   a  defines a second coupling mechanism  90  which is configured to couple the base  14   a  to either one of the rotatable foot portion  25   a  or the non-rotatable foot portion  25   b . The coupling mechanism  90  is shown as an elliptical bore defined in the base  14   a . The elliptical bore  90  corresponds to an elliptical coupling structure defined on the foot portions  25   a  or  25   b.    
         [0035]    Components which are coupled to base portion  14   a  can be removed by releasing a spring loaded locking mechanism  92  defined on the elliptical structure on the foot portion  25   a . It is envisioned the spring loaded locking mechanism  92  can be positioned on the base  14   a.    
         [0036]    As shown in  FIGS. 7 ,  8 , and  10 , the base  14   a  is configured to allow translation of the drilling guides  46  and  48  with respect to the foot portion  25   a . Shown is a knob  94 , which is coupled to an internal gear (not shown) which causes the relative translation. It is envisioned that the actuator shown in  FIG. 1  can additionally be used to adjust the relative location of the superstructure portion  16  with respect to the foot portion  25   a.    
         [0037]    As best seen in  FIG. 9 , the adjustable foot portion  25   a  has a rotational mechanism which allows for rotation of the feet  25  with respect to the coupling mechanism  90 . In this regard, the adjustable foot portion  25   a  has an oval post  96 , about which the feet  25  are rotatably coupled. As described above with respect to the first embodiment, rotation of the worm gear  22  causes rotation of the feet with respect to the base portion  14   a.    
         [0038]      FIGS. 11 and 12  represent modular superstructure  16   a  and  16   b . The superstructures are configured to be adjusted in a fashion which allows the treating physician to measure anatomical features of a resected bone. The location of the tip of the stylus  18  can be measured by vertical and horizontal adjustment of the superstructure  16   b  or by angular movement shown in superstructure  16   a.    
         [0039]    The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.