Abstract:
An orthopedic cutting tool for reshaping the end of a femur is described. The cutting tool comprises three separate cutting blades that are positioned within different locations within a housing to reshape the end of the femur to thus receive a femur head prosthetic. The cutting tool forms the reshaped femur end in one cutting motion.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. provisional application Ser. No. 61/811,453, filed Apr. 12, 2013. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the art of orthopedic cutting devices, more particularly, to an orthopedic cutting device designed to remove bone and tissue from a femur. 
     BACKGROUND OF THE INVENTION 
     Hip arthroplasty involves removing a diseased hip joint and replacing it with an artificial joint. In one procedure, commonly referred to as a total hip replacement, the head of the femur is removed and a femoral stem having a femoral head prosthesis end is positioned within the end of the bone. The femoral head is received within a prosthetic cup positioned within the acetabulum. While it has been shown that total hip replacement surgery is effective for some patients, a total hip replacement surgical procedure may cause neuromuscular damage. Furthermore, removing the end of the femur may cause bleeding problems, infection, or other complications that are not desirable. 
     Therefore, an alternative hip replacement surgical procedure was developed in which the head of the femur is resurfaced, as opposed to being removed in a total hip replacement surgery, to receive a femoral head prosthetic. 
     Since the head of the femur is not removed, the femur resurfacing procedure may be better suited for some patients in which removal of the end of the femur may cause complications or restrict future mobility. 
     During a hip resurfacing procedure, the head of a femur  10  is reshaped to receive a femoral head prosthetic (not shown). Historically, the procedure utilizes three separate cutting tools to reshape the head of the femur  10  into a desired form as shown in  FIG. 4 . In a first step, a sleeve cutter  12 , an example of which is illustrated in  FIG. 1 , is used to form a cylindrical shape at the head of the femur  10 . After the cylindrical shape has been formed using the sleeve cutter  12 , a plan cutter  14 , an example of which is illustrated in  FIG. 2 , is used to create a planar surface at the proximal end of the femur  10 . Finally, a chamfer cutter  16 , an example of which is illustrated in  FIG. 3 , is used to impart a chamfered surface on the head of the femur  10 . The resultant reshaped femur, shown in  FIG. 4 , is now ready to receive a femoral head prosthetic that is positioned over the end of the reshaped femur  10 . 
     Use of the three separate cutters  12 ,  14 ,  16  during this bone reshaping procedure is not ideal. Each cutting tool requires proper positioning and alignment with respect to the bone  10  to ensure proper fit and function of the femoral head prosthesis. Utilization of three separate cutting tools creates an inherent risk that the tools might not be properly positioned and aligned with respect to the cut created by the prior tool. Therefore, there is a possibility that the head of the femur might not be properly shaped for proper positioning of the femoral head prosthetic. For example, these traditional cutting tools generally require the use of a handle to interface the cutting tool with a drive shaft that imparts rotation to the cutting blade. This interface between the handle and the cutting tool may not be secure. Therefore, because the handle may not be adequately positioned and secured to the cutting tool, the cutting surface of the tool may be askew from its proper position or the cutting surface may shift during use. Therefore, possible misalignment between the handle and the cutting instrument may result in an improperly shaped femur. 
     In addition, a slight misalignment in positioning the cutting surface of the cutting tool to the bone by the surgeon of any one of the three prior art cutting tools, could also result in an improperly shaped femur, thereby leading to poor positioning of the femoral head prosthesis. In either case, an improperly fit femoral head prosthesis may negatively affect patient mobility and also require that the patient undergo additional surgical procedures to correct the misalignment. 
     The cutting tool of the present invention addresses these deficiencies by providing a tool that is capable of reshaping the head of the femur in one cutting motion at one time. That is in contrast to using three separate tools of the prior art. According to the present invention, the desired form of the reshaped femur ( FIG. 4 ) is obtained by incorporating different cutting blades into one tool. Therefore, the possibility of incorrectly reshaping the end of the femur as a result of misalignment of the cutting blades to the bone is reduced. As a result, the possibility of an improperly fit femoral head prosthesis is minimized and patient mobility is improved. 
     SUMMARY OF THE INVENTION 
     Thus, a new orthopedic cutting tool designed to cut and reshape the head of a femur to receive a femoral head prosthetic is provided. The cutting tool of the present invention comprises a housing in which three different cutting blades, namely a first or post forming blade, a second or chamfer blade, and a third or plan cutting blade, are positioned therewithin. 
     Specifically, the three different cutting blades of the present invention are securely received within two separate housing segments, a first housing segment and a second housing segment that are connected to each other. The first and second housing segments are positioned with respect to each other such that the three separate cutting blades are positioned at differing depths within the instrument to reshape the head of a femur into a desired cylindrical form. 
     The first housing segment is of a cylindrical form comprising an annular sidewall designed to be fit over the end of a bone. The first or post cutting blade is preferably positioned within the sidewall of the first housing segment. In a preferred embodiment, a plurality of first blades is positioned within the distal end of the sidewall of the first housing segment. Each of the first blades is bent at a rake angle so that when they are rotated, the cutting edges reshape the head of the femur into a cylindrical shape. 
     The second or chamfer cutting blade is also positioned within the first housing segment. The second blade extends outwardly from within the cavity formed by the annular sidewall of the first housing segment. The second blade is bent at a rake angle and a chamfer angle. The angular orientation of the cutting edge of the second blade, defined by its rake and chamfer angles, enables the second blade to form a chamfered surface at the distal end of the cylindrical post formed at the end of a bone. 
     The second housing segment resides proximate of the first housing segment along a longitudinal axis. The second housing segment comprises a platform that extends longitudinally from a second base. The first and second housing segments are preferably joined together in a keyed relationship in which the platform which extends from the distal end of the second housing segment is received within an opening of the first housing segment. The third blade is received and secured within a slot that extends through at least a portion of the platform of the second housing segment. The third blade is orientated to cut a planar surface at the proximal end of a femur. 
     Rotation of the cutting instrument of the present invention against a bone causes the end of the bone to be shaped into the desired multi-faceted form shown in  FIG. 4 . Thus, unlike the prior art, the femoral head is reshaped into a desired form in a single cutting motion at one time. Since all the cutting blades are incorporated into one tool, the possibility of causing prosthesis misalignment is reduced, thereby improving patient outcomes and patient mobility. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a prior art sleeve cutter  12  used to reshape the end of a bone. 
         FIG. 2  is a perspective view of an embodiment of a prior art plan cutter  14  used to reshape the end of a bone. 
         FIG. 3  is a perspective view of an embodiment of a prior art chamfer cutter  16  used to reshape the end of a bone. 
         FIG. 4  illustrates a perspective view of the head of a femur having been reshaped to a desired form. 
         FIG. 5  shows a perspective view of an embodiment of the bone cutter of the present invention. 
         FIG. 5A  illustrates a cross-sectional view of the bone cutter shown in  FIG. 1 . 
         FIG. 6  shows a perspective view of an embodiment of the housing segments that comprise the bone cutter of the present invention. 
         FIGS. 7 and 7A  illustrate perspective views of an embodiment of the first housing segment of the bone cutter. 
         FIG. 7B  shows an end view taken from the distal end of the first housing segment illustrated in  FIGS. 7 and 7A . 
         FIG. 8  illustrates an embodiment of the first housing segment in which a plurality of first cutting blades have been positioned therewithin. 
         FIG. 8A  is a cross sectional view of an embodiment of the first housing segment in which the first and second cutting blades have been positioned therewithin. 
         FIGS. 9 and 9A  illustrate an embodiment of the second housing segment of the bone cutter of the present invention. 
         FIG. 9B  is a cross-sectional view of the second housing segment shown in  FIG. 9 . 
         FIG. 9C  shows an end view taken from the distal end of the second housing segment shown in  FIG. 9 . 
         FIG. 10  illustrates a perspective view of an embodiment of the first cutting blade. 
         FIG. 11  is a perspective view of an embodiment of the second cutting blade. 
         FIG. 11A  is a side view taken from the first sidewall of the second cutting blade shown in  FIG. 11 . 
         FIGS. 11B and 11C  are additional perspective views of the second cutting blade shown in  FIG. 11 . 
         FIG. 12  illustrates a perspective view of an embodiment of the third cutting blade. 
         FIG. 13  is a cross-sectional view of the bone cutter of the present invention cutting the end of a bone. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Now turning to the figures,  FIGS. 5, 5A, 6 and 13  illustrate an embodiment of a bone cutter  20  of the present invention. As shown, the bone cutter comprises a bone cutter proximal end  22  that extends to a bone cutter distal end  24  along a longitudinal axis A-A. As illustrated, the bone cutter  20  of the present invention comprises a housing  26  that is designed to hold and secure a plurality of cutting blades that are used to cut and reshape the end of a bone  10 , more specifically a femur ( FIG. 4 ). 
     In an embodiment, the housing  26  comprises a first housing segment  28  that is connected to a second housing segment  30 . The first housing segment  28  comprises a first blade holder proximal end  32  that extends along longitudinal axis A-A to a first housing segment distal end  34 . The second housing segment  30  comprises a second housing segment proximal end  36  that extends along longitudinal axis A-A to a second housing segment distal end  38 . A shaft portion  40  having spaced apart proximal and distal shaft ends  42 ,  44  extends in a proximal direction along longitudinal axis A-A from the second blade holder segment proximal end  36 . As shown in  FIG. 6 , the first housing segment  28  is positioned distal of the second housing segment  30 , the distal end  38  of the second housing segment positioned in contact with the proximal end  32  of the first housing segment  28 . 
     In a preferred embodiment, a first blade or post cutting blade  46  and a second or chamfer blade  48  are held and secured by the first housing segment  28 . A third or plan blade  50  is held and secured by the second housing segment  30 . Thus, by connecting the first and second blade housing segments  28 ,  30  together, all three blades  46 ,  48 , and  50  work in concert to form the head of a femur  10  into the desired shape as illustrated in  FIG. 4 . 
       FIGS. 7, 7A, 7B, 8 and 8A  illustrate an embodiment of the first housing segment  28  of the present invention. As shown, the first housing segment  28  is preferably of a cylindrical form having a first housing segment annular sidewall  52  that extends distally along longitudinal axis A-A from a first housing segment base  54 . In a preferred embodiment, the sidewall  52  has an exterior sidewall surface  56  that extends to an interior sidewall surface  58 . A sidewall thickness  60  resides therebetween. The annular sidewall  52  of the first housing segment  28  defines a cavity  62  which is intended to be positioned over the femur end. As shown in  FIGS. 7 and 8A , the sidewall thickness  60  extends about perpendicular to longitudinal axis A-A. The interior sidewall surface  58  of the first housing segment  28  defines an inner diameter  64 . In a preferred embodiment, the inner diameter  64  ranges from about 1 cm to about 15 cm. Since the inner diameter  64  defines the spacing and arrangement of the first cutting blades  46  which provide the cylindrical shape to the femur  10 , the inner diameter  64  of the first housing segment  28  should be dimensioned accordingly. 
     As illustrated in  FIGS. 5A, 7A, 7B, 8, and 8A , an opening  66  extends lengthwise along longitudinal axis A-A through a thickness  68  of the base  54  of the first housing segment  28 . The opening  66  preferably provides a space for at least a portion of the second blade holder  30  to extend therethrough. In addition, the opening  66  provides a space for a guide rod  70  ( FIG. 13 ) to extend therethrough. 
     In a preferred embodiment, the opening  66  provides a keyed interface within which the second housing segment  30  is received. As shown in  FIG. 7B , which illustrates an end view of the first housing segment  28 , the opening  66  is preferably constructed having a cross-section, oriented perpendicular with respect to longitudinal axis A-A, that enables the second housing segment  30  to mate and engage therewithin. Once joined, rotation of the second housing segment  30  imparts a rotational torque to the first housing segment  28 . 
     In a preferred embodiment, as illustrated in  FIG. 7B , the opening  66  of the base  54  of the first housing segment  28  comprises a cross-section, oriented perpendicular to longitudinal axis A-A, that is of a multi-sided polygon geometric shape, such as a triangle, a rectangular, a star, or octagon. This preferred embodiment enables the distal end  38  of the second housing segment  30 , having a corresponding geometric shape, to mate and reside therewithin. In a preferred embodiment, an exterior sidewall or plurality of sidewalls of the second housing segment  30  is in physical contact with an interior surface  72  of the first housing segment opening  66  forming an interference fit therebetween. This interference relationship is preferred so that torque transfer between the blade holder segments  28 ,  30  is maximized. 
     As illustrated in  FIGS. 5, 5A, 6, 7, 7A, 8 and 8A , at least one sidewall slot  74  extends through a portion of the thickness  60  of the sidewall  52  of the first housing segment  28 . In a preferred embodiment, a plurality of sidewall slots  74 , spaced apart from each other, reside about the perimeter of the distal end  34  of the first housing segment  28 . The sidewall slot  74  is designed and dimensioned to receive and secure the first cutting blade  46  therewithin. Preferably, one sidewall slot  74  receives one first cutting blade  46 . As shown, the sidewall slot  74  extends through the distal end  34  of the first blade holder  28 . The sidewall slot  74  comprises a slot length  76  that extends about parallel to longitudinal axis A-A. In a preferred embodiment, the sidewall slot length  76  extends at least partially through a height  78  of the annular sidewall  52  to a point proximal of the distal end  34  of the first blade holder  28 . The sidewall slot  74  of the first housing segment  28  also comprises a slot width  80  that extends about perpendicular to longitudinal axis A-A. In a preferred embodiment, the slot length  76  and slot width  80  are dimensioned to securely hold the proximal end of the first blade  46  therewithin. In addition, the sidewall slot  74  of the fist housing segment  28  comprises a slot depth  82  that preferably extends through the entire thickness  60  of the sidewall  52 . In a preferred embodiment, the length  76  of the sidewall slot  74  may extend from about 0.5 cm to about 5 cm. The width  80  of the sidewall slot  74  may extend from about 1 cm to about 10 cm. 
     As shown in  FIGS. 7A and 7B , in addition to the sidewall slot  74 , the first blade holder segment  28  comprises a base slot  84 . In an embodiment, the base slot  84  extends through a top surface  86  of the base  54  of the first blade holder  28  and at least partially through the base thickness therewithin. In a preferred embodiment, the second blade  48  is received by the base slot  84  which holds and secures the blade therewithin. At least one base slot  84  is formed within the base  54  of the first housing segment  28 . In a preferred embodiment, the base slot  84  comprises a base slot length  88  that extends at least partially through the thickness  66  of the base  54  parallel to longitudinal axis A-A. Alternatively, the length  88  of the base slot  84  may extend through the entire thickness  68  of the base  54  of the first housing segment  28 . In addition, the base slot  84  comprises a base slot width  90  that extends about perpendicular to longitudinal axis A-A. In a preferred embodiment, the length  88  and/or the width  90  of the base slot  84  ranges from about 0.5 cm to about 5 cm. 
     In an embodiment, the first housing segment  28  may also comprise at least a throughbore  92  that extends through the thickness of the base along longitudinal axis A-A. The throughbore  92  provides an opening through which a fastener  94 , such as a screw, a bolt or a rivet can be positioned therewithin to thereby join the first and second blade holder segments  28 ,  30  together. In an alternative embodiment, the first and second housing segments  28 ,  30  may be joined together using an adhesive or they may be welded together. 
       FIGS. 9-9C  illustrate an embodiment of the second housing segment  30  of the present invention. As shown in the embodiment the shaft portion  40  and the second blade holder  30  are constructed of a one piece body. However, in an alternative embodiment, the shaft  40  and the second housing segment  30  may be constructed as two separate bodies that are connected together. In this case, the distal end  44  of the shaft  40  would be connected to the proximal end  36  of the second housing segment  30 . 
     As shown in  FIGS. 9-9C , the second housing segment  30  comprises a blade holding platform  96  that extends distally along longitudinal axis A-A from a second base  98  of the second blade holder  30 . Specifically, the blade holding platform  96  comprises a platform thickness  100  that extends distally from an end surface  102  ( FIG. 9B ). The thickness  100  of the platform  96  of the second base  98  extends parallel to longitudinal axis A-A. As shown in  FIGS. 9 and 9B , the distal end  38  of the second housing segment  30 , which engages the first housing segment  28 , preferably comprises at least two platforms  96 A,  96 B that are spaced apart diametrically opposite from each other. 
     In a preferred embodiment, each of the platforms  96 A,  96 B comprises opposed first and second platform sidewalls  104 ,  106  that extend and meet opposed third and fourth platform sidewalls  108 ,  110 . The first and second platform sidewalls  104 ,  106  are oriented perpendicular to the third and fourth platform sidewalls  108 ,  110 . In a preferred embodiment, each of the platforms  96 A,  96 B are positioned so that the platform thickness  100  extends outwardly from the end surface  102  of the second base  98 . In addition, each of the platforms  96 A,  96 B is designed to reside within a second base perimeter  112  ( FIG. 9C ) defined by the cross-sectional area of the distal end  38  of the second base  98 . Furthermore, these platforms  96 A,  96 B are designed to at least partially extend through the opening  66  of the first base  54  of the first housing segment  28  to secure the second housing segment  30  therewithin. Therefore, it is preferred that the platforms  96 A,  96 B are positioned spaced from each other such that they fit through the aperture of the first base opening  66  of the first housing segment  28 . In a preferred embodiment, shown in  FIG. 9 , the opposed third  108  and fourth  110  sidewalls of the platform  96  comprise planar surfaces. In a preferred embodiment, the planar surface of the third and fourth platform sidewalls  108 ,  110  are designed to contact the interior sidewall surface  72  of the opening  66  so that torque transferred between the second blade holder segment  30  and the first blade holder segment  28  occurs in unison. 
     In a preferred embodiment, each of the platforms  96 A,  96 B and the second base  98  may share a sidewall. As shown in the example of  FIGS. 9 and 9B , platform  96 A is positioned such that the first sidewall  104  and an exterior sidewall  114  of the second base  98  form one continuous sidewall. 
     As shown in  FIGS. 9, 9A, and 9B  a platform slot  116  at least partially extends through the thickness  100  of at least one of the platforms  96 A,  96 B. In an embodiment, the platform slot  116  may comprise a slot length  118  that extends longitudinally through an end surface  120  of the platform  96 A,  96 B and through at least a portion of the thickness  100  of the platform  96 A,  96 B to a position proximal of the distal end of the platform  96 A,  96 B. 
     The platform slot  116  is dimensioned so that the third cutter blade  50  is received and securely positioned therewithin. The platform slot  116  comprises a platform slot width  121  that extends at least partially through a width of the platform  96 A,  96 B ( FIG. 9 ). In a preferred embodiment, the length  118  of the platform slot  116  may extend through the thickness  100  of the platform  96 A,  96 B and through a portion of a thickness  122  of the base  98  of the second blade holder  30 . The slot  116  is oriented such that the platform slot length  118  is positioned parallel to longitudinal axis A-A and the platform slot width  121  is positioned perpendicular to the longitudinal axis A-A. 
     As illustrated in  FIGS. 9, 9B and 9C , an inlet  124  extends through the distal end surface  102  of the second base  98  of the second blade holder  30  in a proximal direction parallel to longitudinal axis A-A. The inlet  124 , which preferably lies co-axial the longitudinal axis A-A, provides a space in which the guide rod  70  may extend. In a preferred embodiment, the inlet  124  extends through the thickness  122  of the base  98  and through at least a portion of the thickness within the shaft  40 . In a preferred embodiment, a proximal end  126  of the inlet  124  resides within the shaft  40  between the proximal and distal shaft ends  42 ,  44 . 
     In a preferred embodiment, both the first and second blade housing segments  28 ,  30  are composed of a biocompatible material. In a preferred embodiment, the housing segments  28 , may be composed of a polymeric material such as acroylonitirile butadiene styrene (ABS), polyarylamide, polyetheretherketone (PEEK), and combinations thereof. Alternatively, the first and second blade holder segments  28 ,  30  may be comprised of a metallic material, examples of which include, but are not limited, to stainless steel, MP35N, titanium, and combinations thereof. 
     In addition, as shown in  FIG. 9C , the second blade holder segment  30  may comprise at least one second blade holder throughbore  128  which extends longitudinally through the second base  98  of the second holder  30 . In a preferred embodiment, the second blade holder throughbore  128  is designed to provide an opening for the fastener  94  that connects the second blade holder  30  to the first holder  28 . 
       FIG. 10  illustrates an enlarged view of an embodiment of the first blade  46 . As shown, the first blade  46  comprises a first blade proximal end  130  spaced from a first blade distal end  132 . More specifically, the first blade  46  comprises a first blade holder engagement portion  134  located at the proximal end  130  of the blade  46  and that extends to a first blade cutting portion  136  that resides at the distal end  132  of the first blade  46 . As illustrated in  FIGS. 5, 5A and 6 , the first blade engagement portion  134  is preferably positioned within the sidewall slot  74  of the first blade holder  28 . 
     In a preferred embodiment, the first blade  46  comprises a first sidewall  138  having a first exterior surface  140  that is spaced from a second sidewall  142  having a second exterior surface  144 . A first blade thickness  146  extends therebetween. As illustrated in  FIG. 10 , an imaginary line B-B extends parallel to the opposed first and second sidewalls  138 ,  142  through the thickness  146  of the blade engagement portion  134 . In a preferred embodiment, imaginary line B-B extends substantially through the middle of the thickness  146  between the opposed first and second sidewalls  138 ,  142 , thereby bisecting the thickness  146  of the first blade  46  within the first blade holder engagement portion  134 . In addition, the first blade  46  comprises opposed third and fourth sidewalls  148 ,  150  having respective third and fourth exterior surfaces  152 ,  154  that are oriented perpendicular to the opposed first and second sidewalls  138 ,  142 . A first blade width  156  extends between the third and fourth sidewalls  148 ,  150 . Preferably, the first and second exterior surfaces  140 ,  144  may be planar having a knurled surface particularly within the blade holder engagement portion. This preferred construction of the blade engagement portion  134  helps ensure a secure fit within the sidewall slot  74  of the first housing segment  28 . 
     The cutting portion  136  of the first blade  46  extends distally from the first blade engagement portion  134  to a first blade distal end sidewall  158  having a distal end surface  160 . The distal end of the first sidewall  138  extends and meets the distal end sidewall  158  at a first blade cutting edge  162 . The distal end of the second sidewall  142  extends and meets the distal end sidewall  158  at a first blade trailing edge  164 . In a preferred embodiment, the first blade cutting edge  162  is oriented perpendicular to the line B-B. In addition, the first blade distal end sidewall  158  is also oriented perpendicular to the line B-B. At the proximal end  130  of the first blade  46 , the proximal end of the first and second sidewalls  138 ,  142  extend and meet at a first blade proximal end sidewall  166  having a first blade proximal end surface  168 . 
     As illustrated in  FIG. 10 , the cutting portion  136  of the first cutting blade  46  is preferably bent at an angle away from the line B-B. More specifically, the cutting portion  136  of the first cutting blade  46  is bent at a rake angle α. The rake angle α of the cutting portion  136  of the first blade  46  is defined by the angle that extends between imaginary line C-C and line B-B. As shown in  FIG. 10 , imaginary line C-C is coincident a first side edge  170  that is formed at the meeting of the first sidewall  138  and the third sidewall  148  within the cutting portion  136 . As shown, imaginary line C-C extends through a first intersection point  171  where the first cutting edge  162  and the third sidewall  170  meet. In a preferred embodiment, the rake angle α ranges from about 50 to about 40°. The perpendicular orientation of the first cutting edge  162  with respect to line B-B in addition to the rake angle α that efficiently removes bone material from the end of the femur so that the post  268  and platform surface  270  illustrated in  FIG. 4  are formed. 
     As shown in  FIGS. 5, 5A and 6 , each of the first blades  46  are positioned within their respective sidewall slot  74  of the first housing segment  28 . In a preferred embodiment, the blade holder engagement portion  134  is positioned within the slot  74  so that the line B-B is positioned about parallel with longitudinal axis A-A. In addition, when positioned within the slot  74 , the cutting edge  162  of the first blade  46  is positioned about perpendicular to longitudinal axis A-A. 
       FIG. 11  illustrates a magnified view of an embodiment of the second blade  48 . The second blade  48 , also referred to as a chamfer blade, is designed to impart a chamfered edge  272  to the proximal end of the cylindrically reshaped femur as illustrated in  FIG. 4 . As shown, the second blade comprises a proximal end  172  that extends to a distal end  174 . More specifically, the second blade  48  comprises a second blade holder engagement portion  176  that extends to a second blade cutting portion  178 . As illustrated in  FIG. 5A , the second blade engagement portion  176  is preferably positioned within the first base slot  84  of the first blade holder  98 . 
     In a preferred embodiment, the second blade  48  comprises a first sidewall  180  having a first exterior surface  182  that is spaced from a second sidewall  184  having a second exterior surface  186 . A second blade thickness  188  extends therebetween. As illustrated in  FIGS. 11, 11B and 11C , an imaginary line D-D extends parallel to the first and second sidewalls  180 ,  184  through the thickness  188  of the blade engagement portion  176 , and about mid-way through the thickness  188  of the second blade  48  within the second blade holder engagement portion  176 . In addition, the second blade  48  comprises opposed third and fourth sidewalls  190 ,  192  having respective third and fourth exterior surfaces  194 ,  196  that are oriented perpendicular to the opposed first and second sidewalls  180 ,  184 . A second blade width  198  extends between the third and fourth sidewalls  190 ,  192 . Preferably, the first and second exterior surfaces  182 ,  186  may be planar having a knurled surface particularly within the blade holder engagement portion. This preferred construction of the blade engagement portion  176  helps ensure a secure fit within the base slot  84  of the first blade holder  28 . 
     The cutting portion  178  of the second blade  48  extends distally from the second blade holder engagement portion  176  to a second blade distal end sidewall  200  having a distal end surface  202 . The distal end of the first sidewall  180  extends and meets the distal end sidewall  200  at a second blade cutting edge  204 . The distal end of the second sidewall  184  extends and meets the distal end sidewall  200  at a second blade trailing edge  206 . At the proximal end  172  of the second cutting blade  48 , the proximal end of the first and second sidewalls  180 ,  184  extend and meet at a second blade proximal end sidewall  208  having a second blade proximal end surface  210 . 
     As shown in  FIGS. 11 and 11A , a first imaginary line E-E lies coincident along the second blade cutting edge  204  extending widthwise across the blade  48 . In addition, a second imaginary line F-F oriented perpendicular to the line D-D, extends through a second intersection point  212  that resides at the intersection of the distal end of a second blade first edge  214  and the second blade cutting edge  204 . The first edge  214  defined by the intersection of the first sidewall  180  and the third sidewall  190  of the second blade  48 . Furthermore, a third imaginary line G-G is shown that is coincident the first edge  214  of the second cutting blade  48  that extends through the second intersection point  212  that resides at the distal end of the second blade  48 . 
     As illustrated in  FIGS. 11, 11B, and 11C , in a preferred embodiment, the cutting portion  178  of the second cutting blade  48  is preferably bent at an angle away from the line D-D. More specifically, the cutting portion  178  of the second cutting blade  48  is bent at a second rake angle φ. The second rake angle φ is defined by the angle that extends between the third imaginary line G-G and line D-D. In a preferred embodiment, the second rake angle φ ranges from about 50 to about 40°. 
     In addition, the second cutting blade  48  further comprises a chamfer angle ω. In a preferred embodiment, illustrated in.  FIG. 11 , the chamfer angle ω is defined as the angle that extends between imaginary line E-E and imaginary line F-F. In a preferred embodiment, the chamfer angle ω ranges from about 5° to about 40°. The chamfer angle ω is designed to impart a chamfer at the distal end of the femur  10 . The second cutting blade  48  is designed so that the chamfer angle ω of the second blade  48  creates a chamfered surface  272  ( FIG. 4 ) at the end of the reshaped cylindrical end of the femur that is angled at the same angular degree as the chamfer angle ω of the second cutting blade  48 . 
     As shown in  FIG. 8A , each of the second blades  48  are positioned within their respective base slot  84  of the first blade holder  28 . In a preferred embodiment, the blade holder engagement portion  176  of the second cutting blade  48  is positioned within the slot  84  so that the line D-D is positioned about parallel with longitudinal axis A-A. 
       FIG. 12  illustrates an enlarged view of an embodiment of the third blade  50 . As shown, the third blade  50  comprises a third blade proximal end  216  spaced from a third blade distal end  218 . More specifically, the third blade  50  comprises a third blade holder engagement portion  220  located at the proximal end  216  of the blade  50  that extends to a third blade cutting portion  222  that resides at the third blade distal end  218 . As illustrated in  FIG. 9A , the third blade engagement portion  220  is preferably positioned within the platform slot  116  of the second blade holder  30 . 
     In a preferred embodiment, the third blade  50  comprises a first sidewall  224  having a first exterior surface  226  that is spaced from a second sidewall  228  having a second exterior surface  230 . A third blade thickness  232  extends therebetween. As illustrated in  FIG. 12 , an imaginary line H-H extends parallel to the first and second sidewalls  224 ,  228  through the thickness  232  of the blade engagement portion  220 , thereby bisecting the thickness  232  of the holder engagement portion  220  of the third blade  50 . In addition, the third blade  50  comprises opposed third and fourth sidewalls  234 ,  236  having respective third and fourth exterior surfaces  238 ,  240  that are oriented perpendicular to the opposed first and second sidewalls  224 ,  228 . A width  242  extends between the third and fourth sidewalls  234 ,  236  of the third blade  50 . Preferably, the first and second exterior surfaces  226 ,  230  may be planar having a knurled surface, particularly within the blade holder engagement portion  220 . This preferred construction of the blade engagement portion  220  of the third blade  50  helps ensure a secure fit within the platform slot  116  of the second blade holder  30 . 
     The cutting portion  222  of the third blade  50  extends distally from the third blade holder engagement portion  220  to a third blade distal end sidewall  244  having a distal end surface  246 . The distal end of the first sidewall  224  of the third blade  50  extends and meets the third blade distal end sidewall  244  at a third blade cutting edge  248 . The distal end of the second sidewall  228  extends and meets the distal end sidewall  244  at a third blade trailing edge  249 . In a preferred embodiment, the third blade cutting edge  248  is oriented perpendicular to the line H-H. In addition, the third blade distal end sidewall  244  also resides perpendicular to the line H-H. In a preferred embodiment, the proximal end of the first and second sidewalls  224 ,  228  extend and meet at a third blade proximal end sidewall  252  having a third blade proximal end surface  254 . 
     As illustrated in  FIG. 12 , the cutting portion  222  of the third cutting blade  50  is preferably bent at an angle away from the line H-H. More specifically, the cutting portion  222  of the third cutting blade  50  is bent at a third rake angle δ. The third rake angle δ of the third blade  50  is defined by the angle that extends between imaginary line I-I and line H-H. As shown in  FIG. 12 , imaginary line I-I is coincident a first side edge  256  of the third blade  50  that is formed at the meeting of the first sidewall  224  and the third sidewall  234  that extends through intersection point  258  where the third cutting edge  248  and the third sidewall  234  meet. In a preferred embodiment, the third rake angle δ ranges from about 50 to about 40°. 
     As shown in  FIG. 9A , each of the third blades  50  are positioned within their respective platform slot  116  of the second blade holder  30 . In a preferred embodiment, the blade holder engagement portion  220  of the third cutting blade  50  is positioned within the platform slot  116  so that the line H-H is positioned about parallel with longitudinal axis A-A. In addition, when positioned within the slot  116 , the cutting edge  248  of the third blade  50  is preferably positioned about perpendicular to longitudinal axis A-A. 
     Referring back to  FIG. 5A , when the cutting blades  46 ,  48 , and  50  are properly positioned within the housing  26  of the cutting tool  20  of the present invention, the first cutting edge  162  of the first cutting blade  46  resides distal of the second and third cutting edges  204 ,  248  of the second and third blades  48 ,  50  respectively. As shown, the first cutting edge  162  extends beyond the distal end  34  of the first blade holder  28 . In addition, the second cutting edge  204  of the second blade  48  resides distal of the third cutting edge  248  of the third blade  50  within the cavity  62  of the first blade holder segment  28 . 
     As previously discussed,  FIG. 4  illustrates a desired shape  250  of the reshaped femur  10  that is ready to receive a femoral head prosthesis. As shown, the end of the femur has been reshaped to comprise a post  260  having a proximal post end  262  that extends to a distal post end  264  that is designed to receive a femoral head prosthesis (not shown). Specifically, the femoral head prosthesis is designed to be positioned over and secured to the post  260 . As illustrated, the post  260  comprises a cylindrical portion  266  having a cylindrical sidewall  268  that extends outwardly from a bone platform surface  270 . The bone platform surface  270  preferably comprises a planar surface to ensure proper fit of the femoral head prosthesis (not shown). In addition, the post  260  comprises a chamfer portion  272  that resides at the distal end of the post  260 . 
     As illustrated in  FIG. 13 , in a preferred embodiment, the first cutting edge  162  of the first cutting blade  46  of the present invention forms the cylindrically shaped post  260  and planar surfaced bone platform  270 . The second cutting edge  204  of the second or chamfer blade  48  imparts the chamfered surface  272  located at the distal end  264  of the post  260 . Lastly, the third cutting edge  248  of the third or plane cutting blade  50  imparts a planar surface  274  that resides at the distal end  264  of the post  260  of the reshaped femur  10 . 
     Rotation of the first blade holder  28  along with the first and second blades  46 ,  48  shape the end of a femur  10  into the form of a post  260  in one cutting event or procedure. As the cutting tool  20  of the present invention is rotated against the end of the bone, all three blades  46 ,  48 ,  50  cut their respective portions of the femur at the same time. In other words, the first blade  46  forms the sidewall of the post end  260 , the second blade  48  forms the chamfered surface  272  at the distal post end  264  and the third blade  50  forms the planar surface  274  at the distal end of the femur. 
     While the preferred embodiments of the cutting device and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.