Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/112,084, filed on Aug. 20, 2011, now U.S. Pat. No. x,xxx,xxx, which claims priority from U.S. Provisional Patent Application Ser. No. 61/346,976, filed May 21, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the art of orthopedic cutting tools, and more particularly, to a disposable cutter used for shaping and preparing the femoral bone for implant insertion. 
         [0004]    2. Prior Art 
         [0005]    Cutting tools used in orthopedic procedures are designed to cut bone and associated tissue matter. Specifically, cutters of the present invention are designed to cut and shape the end of a long bone such as a femur or humerus. Typically, the end of the long bone is cut and shaped for insertion of an implant. As such, these cutters are required to be sterile and sharp. Using a dull cutter generates heat that typically leads to tissue necrosis and results in undesireable patient outcomes. A non-sterile cutter blade typically results in an infected and damaged bone that may lead to other problems for the patient. 
         [0006]    Depicted in  FIGS. 1 and 1A  are images of a prior art bone cutter  10  designed to cut and shape the femoral head  12  of the femur  14 . As shown in the figures, the prior art cutter  10  is similar to that of a “hole saw” drill. These prior devices  10  generally comprise a hollow cylinder in which a series of cutting teeth slots  16  are formed within the cylinder wall thickness  18 . However, these prior devices  10  do not remove all the bone  14  required to properly fit an implant. Therefore, additional procedures are required to remove this extra bone material  22  and smooth the surface of the bone end  24 . 
         [0007]    As shown in  FIG. 1A , the prior cutter device  10  imparts a channel  20  within the end  24  of the bone  14 . This channel  20  and associated bone material  22  proximate the channel  20 , must be removed to properly fit the implant (not shown) on the end  24  of the bone  14 . Typically, hand tools such as rongeurs are used to remove this extra bone material  22 . 
         [0008]    Such a bone removal procedure makes it difficult to properly fit an implant over the end  24  of the bone  14 . The extra bone material  22  must be intricately removed to produce a smooth surface and ensure that the bone  14  is shaped to meet the exacting dimensions of the implant. If the implant is not properly fit over the end  24  of the bone  14 , undesirable implant wear or improper implant operation could result. 
         [0009]    In addition to the inefficient bone removal limitations, traditional bone cutters are typically reused multiple times. That is because of their high cost. Such multiple reuses require that the cutter be cleaned and sterilized before each use. Furthermore, over time, as these cutters are used and reused, they become dull, thus requiring resharpening. Therefore the blades of the cutter are required to be resharpened, cleaned and sterilized. However, these resharpening and sterilization processes add additional costs and increase the possibility of infection. In addition, resharpening tends to deform the dimensions of the cutter. These dimensional changes could adversly impact the optimal fit and function of the implant. Furthermore, there is a high likelihood that the cleaning and sterilization process may not remove all possible infection agents such as bacteria, machining lubricants, and the like. 
         [0010]    Accordingly, the present invention provides a cost effective single use bone cutter with a novel blade and assembly design that improves cutting efficiency. The enhanced bone cutting and shaping efficiencies of the present invention ensure proper implant fit and reduced implant wear. In addition, the improved bone cutting efficiencies afforded by the present invention, decrease procedural time and minimize patient trauma. Furthermore, the bone cutter of the present invention ensures proper cutter sharpness and cleanliness that promotes optimal patient outcomes. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a disposable bone cutter device comprising a cutter assembly and guide rod for orthopedic surgical applications. Specifically, the cutter device of the present invention is designed to re-shape the head of a femur for joint revision surgeries. 
         [0012]    The cutter assembly comprises a disposable housing and a series of insert blades or a cutter disc arranged in circumferential manner within the assembly. The series of insert, blades or cutter disc are preferably secured in the cutter assembly through an interference fit at a distal base portion of the cutter assembly. 
         [0013]    The housing comprises two cylinders that are joined together at a distal portion of the housing. In a preferred embodiment, a first cylinder is positioned such that its inner diameter circumferentially surrounds the outer diameter of a second cylinder. Both the first and second cylinders are positioned such that they share a common central longitudinal axis. A series of radial connectors loin the two cylinders together along the distal base portion of the assembly. In a preferred embodiment, these connectors may take the form of a bar or rod or alternativly be formed into a blade enclosure designed to secure and house the individual insert cutter blades. 
         [0014]    Furthermore, it is preferred that the distal base portion of the centrally located second cylinder is recessed or offset from the distal base of the first cylinder. This recess establishes an offset rim formed by the wall thickness of the first cylinder. The depth of the offset rim is determined by the gap between the distal base plane of the first cylilnder and the distal base plane of the second cylinder. The offset rim provides a barrier that prevents unintentional damage to nearby bone and/or tissue resulting from contact with the cutting surface of the insert blades or cutting disc. 
         [0015]    Located at the proximal end portion of the assembly, within the interior of the inner diameter of the centrally located second cylinder, is a boss. The boss comprises a central throughbore that is positioned such that the throughbore is coaxial with the common longitudinal axis. The throughbore of the boss provides an alignment aid to the axis of the desired cut. 
         [0016]    Another feature of the boss is that it acts as a “stop” to prevent overcutting of the bone. As will be explained in greater detail, the distal end of the boss comes into contact with the end of the bone thus preventing further advancement of the cutter. As such, the position of the boss preferably determines the depth of cut into the bone and prevents unintentional overcutting of the end of the bone. 
         [0017]    The boss is joined within the interior of the second cylinder through a series of rods which radially extend between the exterior wall surface of the boss and an interior wall surface of the inner diameter of the second cylinder. In addition, these rods serve as an interfacing feature by which the cylindrical cutter attaches to a handle or a motor that rotates the cutter in a clockwide or counterclockwise direction. In a preferred embodiment, the housing can be produced as a single component using an injection molding process. 
         [0018]    The insert blades are universal and can be manufactured to a minimal size to accommodate all sizes of the cutter. In a preferred embodiment, the series of individual cutter blades are secured within their respective blade enclosures. These blades are preferably of an “L” shape and are designed to provide a cutting edge that extends into the interior of the centrally located second cylinder. 
         [0019]    The cutter insert blades preferrably include a slot, residing within the surface that extends along the width of the blade. The slot is designed to interface with a post positioned within the blade enclosure. The interaction between the post and slot secures the insert blade therewithin. 
         [0020]    In this embodiment, the cylindrical cutter is assembled by pressing the insert blades into the blade enclosures of the assembly. The insert blades are designed such that they snap into the blade enclosure. This low cost production process, along with the economical production of the component parts, avoids the need for expensive machining and grinding operations that are common with the prior art. 
         [0021]    In an alternate embodiment, a cutter disc having a plurality of cutting teeth openings, resides within the distal base portion of the assembly. In a preferred embodiment, the cutting disc comprises an outer diameter, an inner diameter, and a planar surface therebetween. The plurality of cutting teeth are positioned at spaced intervals throughout the planar surface. 
         [0022]    In operation, the femoral head is first shaped to accept a replacement shell of an implant utilizing the present invention. The shaping of the femoral head is accomplished by first establishing an axis of cut on the femoral head. This axis is established by drilling a guide hole into the femoral head and placing a guide rod into the bone. This guide rod serves to align the axis of the cylindrical cutter to the axis of the intended cut. The cutter of the present invention is then attached to the handle—driver assembly and positioned over the guide rod by means of the hollow boss within the cylindrical cutter. The powered driver provides a means of rotating the cylindrical cutter and advancing the cutter against the femoral head. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  is a perspective view of a prior art bone cutter and bone. 
           [0024]      FIG. 1A  is a cross-sectional view of the prior art bone cutter and bone shown in  FIG. 1 . 
           [0025]      FIG. 2  is a perspective view of the cutter housing of the present invention. 
           [0026]      FIG. 3  is an alternate perspective view of the cutter housing of the present invention. 
           [0027]      FIG. 4  is a cross-sectional view of the cutter housing of the present invention. 
           [0028]      FIG. 5  is a perspective view of an embodiment of a cutter blade of the present invention. 
           [0029]      FIG. 6  is a side view of the embodiment of the cutter blade shown in  FIG. 5 . 
           [0030]      FIG. 7  is a perspective view of an alternate embodiment of a cutter blade of the present invention. 
           [0031]      FIG. 8  is a perspective view illustrating an assembly step of the present invention. 
           [0032]      FIG. 8A  is a perspective view illustrating a preferred embodiment of an assembled bone cutter assembly of the present invention. 
           [0033]      FIG. 9  is a perspective view of a preferred embodiment of a cutter disc of the present invention. 
           [0034]      FIG. 10  is a perspective view of the cutter disc and an alternative cutter housing embodiment of the present invention. 
           [0035]      FIG. 10A  is a perspective view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in  FIG. 10 . 
           [0036]      FIG. 10B  is a cross-sectional view of an assembled alternate embodiment of the bone cutter assembly of the present invention shown in  FIG. 10 . 
           [0037]      FIG. 11  is a cross-sectional view of an embodiment of the bone cutter of the present invention, being used to shape the end of a bone. 
           [0038]      FIG. 11A  is a cross-sectional view illustrating the shaped end of a bone after using the bone cutter of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    Now turning to the figures,  FIGS. 2-11A  illustrate embodiments of a bone cutter  30  of the present invention. In a preferred embodiment, the bone cutter  30  comprises a cutter housing  32 , cutter blades  34  or cutter disc  78 , and a guide rod  36  ( FIGS. 11 ,  11 A). 
         [0040]    As shown in  FIGS. 2-4 ,  8 ,  8 A, and  10 - 11 A, the cutter housing  32  preferably comprises two cylinders, a first cylinder  38  and a second cylinder  40  that are joined therebetween. In a preferred embodiment, the first cylinder  38  comprises a first cylinder inner diameter  42 , a first cylinder outer diameter  44 , and a first cylinder wall thickness  46  therebetween. The second cylinder  40  comprises a second cylinder inner diameter  48 , a second cylinder outer diameter  50 , and a second cylinder wall thickness  52  therebetween. 
         [0041]    In addition, the first cylinder  38  comprises a first cylinder height  54  extending from a first cylinder distal base portion  56  to a first cylinder proximal end portion  58 . In a preferred embodiment, the distal base portion  56  of the first cylinder  38  is co-planar with an imaginary first cylinder base plane BB ( FIG. 4 ). This imaginary base plane B-B preferably extends outwardly from the outer diameter  44  of the first cylinder base portion  56 . 
         [0042]    The second cylinder  40  comprises a second cylinder height  60  extending from a second cylinder distal base portion  62  to a second cylinder proximal end portion  64 . In a preferred embodiment, the distal base portion  62  of the second cylinder  40  is co-planar with an imaginary second cylinder base plane CC ( FIG. 4 ). This imaginary base plane CC preferably extends outwardly from the outer diameter  50  of the second cylinder base portion  62 . 
         [0043]    In a preferred embodiment, the first and second cylinders  38 ,  40  are joined such that the outer diameter  50  of the second cylinder  40  is positioned within the inner diameter  42  of the first cylinder  38 . The first and second cylinders  38 ,  40  are further positioned such that they are co-axial to a common central longitudinal axis A-A as shown in  FIGS. 2-4 ,  8 ,  8 A, and  10 - 11 A. 
         [0044]    In a preferred embodiment, the outer diameter  44  of the first cylinder  38  ranges from about 5 cm to about 10 cm, the inner diameter  42  of the first cylinder  38  ranges from about 4.5 cm to about 9.95 cm and the height  54  of the first cylinder  38  ranges from about 1 cm to about 4 cm. The wall thickness  46  of the first cylinder  38  preferably ranges from about 0.05 cm to about 0.5 cm. 
         [0045]    In a preferred embodiment, illustrated in  FIGS. 2-4 ,  8 ,  8 A, and  10 - 11 A, the height  60  of the centrally located second cylinder  40  is greater than that of the height  54  of the first cylinder  38 . Furthermore, the height  60  of the centrally located second cylinder  40  ranges from about 5 cm to about 10 cm. The outer diameter  50  of the second cylinder  40  ranges from about 3 cm to about 6 cm and the inner diameter  48  of the second cylinder  40  ranges from about 2 cm to about 6 cm. The wall thickness  52  of the second cylinder  40  ranges from about 0.05 cm to about 0.5 cm. 
         [0046]    The two cylinders  38 ,  40  are joined together by a connector  66  that interfaces between the two cylinders  38 ,  40  at a distal end portion  67  of the housing  32  as shown in  FIG. 10 . The connector  66  can be of many non-limiting forms such as a bar, a rod, a rectangle or a sphere such that one surface interfaces with the interior wall surface  68  of the inner diameter  42  of the first cylinder  38  and an opposite surface interfaces with the exterior wall surface  70  of the outer diameter  50  of the second cylinder  40 . In a preferred embodiment, a plurality of two or more connectors  66 , radially extend between the inner and outer diameters  42 , SO of the first and second cylinders  38 ,  40 , respectively, and join them therebetween as shown in  FIG. 10 . 
         [0047]    In a preferred embodiment, the connector  66  can be designed as a blade enclosure  72  such that individual insert blades  34  ( FIGS. 2-3 , and  8 - 8 A) are disposed therewithin. This preferred blade enclosure  72  embodiment, will be discussed in more detail. 
         [0048]    As shown in the embodiments illustrated in  FIGS. 3-4 ,  8 - 8 A, and  10 - 10 A, the housing  32  is preferably constructed such that an offset rim  74  is formed by a portion of the wall thickness  46  of the first cylinder  38 . The depth  76  of the offset rim  74  is defined by the distance between the first and second imaginary distal base planes B-B, C-C as shown in the cross sectional view of  FIG. 4 . In a preferred embodiment, the offset rim  74  preferably has a depth  76  that ranges from about 0.01 cm to about 0.05 cm. The offset rim  74  preferably extends around the perimeter of the first cylinder  38  at the distal base portion  56 . The thickness of the offset rim  74  is defined by the wall thickness  46  of the outer first cylinder  38 . 
         [0049]    The offset rim  74  is designed to prevent the cutter blades  34  or cutter disc  78  ( FIG. 9 ) from inadvertently damaging nearby bone or tissue, particularly preventing a proximal bone or tissue from being cut or nicked. However, it is contemplated that the housing  32  could be constructed such that the first and second imaginary planes B-B, CC are coplanar, therefore constructing a housing  32  without an offset rim  74 . 
         [0050]    It is preferred that both the first and second cylinders  38 ,  40  have a hollow interior  80 ,  82  within their respective inner diameters  42 ,  48 . Such a hollow interior  80 ,  82  allows for efficient removal of bone debris as the debris can freely flow through the cutter assembly  84  ( FIGS. 8 ,  8 A). It is also contemplated that such a housing  32 , could be constructed with a cylinder having a solid or partially solid interior. 
         [0051]    In a preferred embodiment shown in FIGS,  2 ,  4 ,  8 A, and  11 - 11 A, the cutter housing  32  has a boss  86  that is positioned within the inner diameter  48  of the second cylinder  40 . More specifically, the boss  86  is centrally positioned within the inner diameter  48  of the second cylinder  40 . In a preferred embodiment, the boss  86  comprises a throughbore  88 . The boss  86  is preferably further positioned within the inner diameter  48  of the second cylinder  40  such that the throughbore  88  is co-axially aligned with the central axis A-A of the housing  32  as shown in  FIGS. 2 ,  4 ,  8 A, and  11 - 11 A. 
         [0052]    In a preferred embodiment, illustrated in  FIG. 4 , the boss  86  is constructed with a distal planar edge  90 . This distal planar edge  90  is designed to act as a “stop” to prevent further advancement of the cutter  30  into the end  24  of the bone  14 . The boss  86  is preferably positioned with the interior  82  of the second cylinder  40  such that a cut depth  92  is defined between the distal planar edge  90  of the boss  86  and the imaginary second cylinder base plane C-C. It is contemplated that this distal planar edge  90  can be positioned anywhere within the interior  82  of the centrally located second cylinder  40  to establish an optimal cut depth  92  for a particular implant (not shown). In a preferred embodiment the cut depth  92  ranges from about 2 cm to about 10 cm. 
         [0053]    A plurality of bars  94  secure the boss  86  within the inner diameter  48  of the centrally located second cylinder  40 . A plurality of bars  94 , having a length  96  from about 4 cm to about 8 cm and a thickness  98  from about 0.5 cm to about 1 cm, fluidly extend from the interior wall surface  68  of the inner diameter  48  of the first cylinder  38  to the exterior wall, surface  70  of the outer diameter  50  of the second cylinder  40  within the proximal portion  64  of the housing  32 . It is preferred that a plurality of at least two bars  94 , connect the boss  86  within the interior  82  of the second cylinder  40 . 
         [0054]    It is preferred that the housing  32  be composed of a biocompatible material. In a preferred embodiment, the cutter housing  32  is composed of a biocompatible thermoplastic such as, but not limited to, Acrylonitrile Butadiene Styrene (ABS), Polyarylamide (PAA), or Polyetheretherketone (PEEK). 
         [0055]    Furthermore it is preferred that the series of cutter blades  34  are positioned in a radial fashion about the outer diameter  50  of the second cylinder  40  as illustrated in  FIGS. 8 and 8A . More specifically, these cutter insert blades  34  are positioned between the exterior surface  70  of the outer diameter  50  of the second cylinder  40  and the interior surface  68  of the inner diameter  42  of the first cylinder  38  at the distal base portion  56  of the housing  32 . 
         [0056]    Preferred embodiments of the cutter insert blade  34 ,  130  are shown in  FIGS. 5-7 . As illustrated, insert blades  34 ,  130  comprise a blade proximal portion  100  and a blade distal portion  102 . The widths  104 ,  106  of the proximal and distal portions  100 ,  102  are not necessarily equal. In a preferred embodiment, the width  106  of the distal portion  102  is greater than the width  104  of the proximal portion  100 . An insert blade cutting surface  108  preferably extends along the distal width  106  of the insert blade  34 ,  130 . In a preferred embodiment, when inserted into the bone cutter housing  32 , the plurality of these blade cutting surfaces  108  align to form an imaginary blade cutting surface plane DD ( FIG. 4 ). It is further preferred that this imaginary blade cutting surface plane D-D reside between the imaginary first and second cylinder planes B-B, C-C. 
         [0057]    As shown in  FIGS. 5 ,  7  and  8 A, the distal width  106  of the insert blade  34 ,  130  is greater than the proximal width  104  of the blade  34 ,  130 . This extra “width portion.” of the insert cutter blade  34 ,  130  is defined as the blade extension portion  110 . The blade extension portion  110  is designed such that when the cutter blade  34 ,  130  is inserted into the housing  32 , the extension portion  110  protrudes past the inner diameter  48  of the second cylinder  40  towards the interior  82  of the second cylinder  40  ( FIGS. 8 and 8A ). 
         [0058]    In addition, the blade extension portion  110  acts as a “free end”. This “free end” extension is designed to cut into the head  12  of the bone  14 . As such, this “free end” extension  110  defines a new diameter  112  of the bone head  12  as illustrated in  FIG. 11A . If such an extension  110  were not present, the interior wall  69  of the second cylinder  40  would prevent cutting of the bone  14 . In a preferred embodiment, the blade extension  110  has a width from about 0.05 cm to about 0.10 cm. 
         [0059]    As illustrated in  FIGS. 5 and 6 , a groove  114  is preferably formed within the surface  116  of the distal end portion  102  of the insert blade  34 . In a preferred embodiment, the groove  114  has a “V” shape. The groove  114  is designed to establish a rake angle θ of the insert blade  34 . The rake angle θ is defined as the intersection between the distal surface  120  of the “V” cut out portion  114  and a perpendicular line E-E to the cutting edge surface  108  as shown in  FIG. 6 . It is preferred that rake angle θ range from about 4° to about 30°. 
         [0060]    A relief angle φ, as illustrated in  FIG. 6 , is formed between the intersection of the distal end surface  124  of the blade  34  and a tangent line FF to the blade cutting edge  108 . It is preferred that the relief angle φ range from about 4° to about 20°. 
         [0061]    Each cutter blade  34 ,  130  is preferably positioned within the cutter blade enclosure  72  as shown in  FIGS. 8 and 8A . In a preferred embodiment, the insert blade  34 ,  130  is positioned in the housing  32  such that the proximal end portion  104  of the insert blade  34 ,  130  resides inside the blade enclosure  72  and the cutting surface  108  of the insert blade  34 ,  130  lies outside the blade enclosure  72 . Furthermore, it is preferred that the cutting surface  108  of the insert blade  34  lies parallel to an imaginary cutting plane D-D as shown in  FIG. 4 . As shown in  FIG. 4 , the imaginary cutting plane D-D lies between the first cylinder imaginary plane B-B and the second cylinder imaginary plane C-C. The blade extension  110  preferably is positioned towards the central axis A-A of the assembly  84 . 
         [0062]    In a preferred embodiment shown in  FIGS. 2 and 3 , each cutter blade enclosure  72  has a post  126  therewithin, The post  126  is preferably designed to snap-fit into a slot  128  within the proximal end portion  100  of the cutter blade  34  ( FIGS. 5 and 6 ). Once the post  126  snaps into the slot  128 , the insert blade  34  is locked within the cutter blade enclosure  72 . 
         [0063]    In an alternative embodiment, as shown in  FIG. 7 , the insert blade  130  can be designed without a groove  114  and slot  128 . In this embodiment, the cutting edge  108  is formed at the intersection of the side blade surface  116  and the distal end surface  124 . It is preferred that a portion of the surface  116  at the proximal end portion  100  of the insert blade  130  has a roughened finish  132 . This roughened surface finish portion  132  provides for a more secure fit when positioned within the blade enclosure  72 . 
         [0064]    In a preferred embodiment, insert blades  34 ,  130  are secured within the blade enclosure  72  with an induction bonding process. Alternatively, the insert blade  34 ,  130  can be secured by an alternate means not limited to adhesives, overmolding, press fitting, induction bonding, and the like. 
         [0065]    In an alternate embodiment, the cutting disc  78  is positioned at the distal end portion  67  of the housing  32 . The cutting disc  78  embodiment provides an additional means of bone removal which is illustrated in  FIGS. 9-10A . An embodiment of this alternate cutter assembly  146  is shown in  FIG. 10A . The assembly  146  of this embodiment comprises the housing  32  and the cutter disc  78 . 
         [0066]    The cutting disc  78  preferably comprises an outer disc diameter  134 , an inner disc diameter  136  and a planar surface  138  therebetween. The cutting disc  78  is positioned between the wall thickness  46  of the first cylinder  38  and the wall thickness  52  of the second cylinder  40  at the distal end portion  67 . More specifically, it is preferred that the cutting disc  78  be placed between the inner diameter  42  of the first cylinder  38  and the inner diameter  48  of the second cylinder  40  such that the planar surface  138  of the cutting disc  78  is parallel to the first and second cylinder imaginary planes B-B, C-C ( FIG. 10B ). 
         [0067]    Positioned throughout the surface  138  of the disc  78  are a series of openings  140 . These openings  140  are preferably positioned throughout the surface  138  of the disc  78  in a helical pattern. Protruding from the opening  140  is a cutting tooth  142 . The cutting teeth  142  are designed such that a cutting surface  144  is positioned outwardly from the planar surface  13 $ of the disc  78 . Alternately, the cutting surface  144  may protrude inwardly from the surface  13 $ of the disc  78 . In a preferred embodiment, these cutting surfaces  144  of the cutting teeth  142  align to form an imaginary cutting disc plane G-G. This imaginary plane G-G preferably resides between the first and second imaginary cylinder planes B-B, C-C ( FIG. 10B ). 
         [0068]    It is preferred that the cutter insert blades  34 ,  130  and the cutting disc  78  are composed of a biocompatible metal. In a preferred embodiment, such biocompatible metals include, but are not limited to, stainless steel, MP35N, titanium, and combinations thereof. It is most preferred that cutter blades  34 ,  130  and the cutting disc  78  are composed of a 300 series stainless steel. 
         [0069]    In a preferred embodiment, the cutter housing  32  is first molded from a biocompatible polymer as previously mentioned. After the housing  32  has been molded, the cutter blades  34 ,  130  or cutter disc  78  are then inserted in the distal base portion  67  of the housing  32 . As previously mentioned, an induction bonding process is preferably used to secure the cutter blades  34 ,  130  or cutter disc  78  to the molded assembly  84 ,  146 . Alternatively, adhesives, over-molding, press fitting, and the like may also be used. 
         [0070]    In this preferred bonding embodiment, electromagnetic current is used to heat the blades  34 ,  130  or blade disc  78 . Heat generated from the current, melts the surrounding assembly polymer material, causing the material to flow and engage the cutter blades  34 ,  130  or disc  78 . It is well known that alternative processes such as cross pinned engagements, direct insert molding, or ultrasonic insertion may also be used to strengthen the connection or act as a primary means to join the bone cutter  30  of the present invention. 
         [0071]      FIGS. 11 and 11A  illustrate the use of the bone cutter  30  of the present invention. Initially, a guide-hole  148  is drilled into the end  24  of a bone  14 . The guide rod  36  is placed into the guide-hole  148  and the cutter assembly  84 ,  146  is placed over the rod  36  as shown. In a preferred embodiment, the guide rod  36  is preferably positioned through the central axis AA of the bone cutter  30 . 
         [0072]    Once in place over the end  24  of the bone  14 , the cutter  30  is rotated in either a clockwise or counterclockwise direction. This rotational movement of the cutter  30 , removes bone material from the end  24  of the bone  14  with a smooth surface finish with a bone diameter  112  suitably sized for insertion of an implant (not shown). Once the bone head  12  is properly shaped, the cutter  30  and guide rod  36  are removed. An implant (not shown) is then positioned over the end  24  of the bone  14 . 
         [0073]    Now, it is therefore apparent that the present invention has many features and benefits among which are promoting proper implant fit, decreased procedural times and minimized patient trauma. While embodiments of the present invention have been described in detail, such is for the purpose of illustration, not limitation.

Technology Category: a