Abstract:
The present disclosure relates to a method for manufacturing an orthopedic implant. The method includes providing a blank adapted to be formed into an orthopedic implant, forging the blank to form an intermediate component, and bending the forged component to form a pre-finished component.

Description:
BACKGROUND 
       [0001]    1. Field of the Disclosure 
         [0002]    The present disclosure relates to a method for manufacturing an orthopedic implant and, particularly, to a method for manufacturing a femoral component of a knee joint prosthesis. 
         [0003]    2. Description of the Related Art 
         [0004]    Knee arthroplasty is used to partially or totally replace knee joints which have been damaged by trauma or disease such as arthritis. In total knee arthroplasty, the damaged surfaces of the knee joint are surgically removed and replaced with artificial surfaces. Particularly, the distal articulating surface of the femur is replaced by a prosthetic femoral component, and the proximal articulating surface of the tibia is replaced by a prosthetic tibial component, thereby providing a prosthetic knee joint. In bone-conserving surgical procedures where the femur is simply re-shaped rather than removed, resurfacing femoral components are used. Femoral components of knee joint prostheses are typically formed of a rigid metal and cast into the desired shapes which may have complex geometries. 
       SUMMARY 
       [0005]    One object of this disclosure is to provide a simple and economic method for manufacturing an orthopedic implant. 
         [0006]    Accordingly, the present disclosure provides a method that comprises: 
         [0000]    providing a blank adapted to be formed into the orthopedic implant; carrying out a forging operation on the blank so as to form an intermediate component; and carrying out a bending operation on the intermediate component so as to form a pre-finished component. 
         [0007]    To manufacture an orthopedic implant, the method of the present disclosure carries out the forging operation before the bending operation. Forging before bending has the advantage that topological features of the orthopedic implant such as cement pockets at an anchoring side of the orthopedic implant can be applied to the unbent blank and thus with easy access. In addition, a forged orthopedic implant has a high fatigue strength which is particularly beneficial to resurfacing implants. 
         [0008]    In one aspect, the intermediate component is of substantially planar shape. 
         [0009]    In another aspect, the pre-finished component has a shape substantially corresponding to the shape of the orthopedic implant. 
         [0010]    In yet another aspect, the forging operation includes forming the underlying geometrical structure of the orthopedic implant, particularly including at least one of lateral and medial condyle portions of a femoral component of a knee joint prosthesis. 
         [0011]    In still another aspect, the forging operation includes forming at least one depression in a first side of the blank. The depression is adapted to serve as a cement pocket in the orthopedic implant. The first side is adapted to serve as an anchoring side of the orthopedic implant adapted to be arranged at a resection surface of a bone. 
         [0012]    The shape and size of the depression in the intermediate component may be different from the shape and size of the cement pocket in the orthopedic implant. Therefore, the formation of the depression may be such that the effect of the bending operation on the shape and size of the depression is considered or accounted for. 
         [0013]    In yet another aspect, the bending operation includes forming a substantially rounded anchoring side of the orthopedic implant and/or the orthopedic implant has a substantially uniform thickness. 
         [0014]    In another exemplary aspect, the blank is a pre-forged blank. 
         [0015]    In a specific aspect, the forging operation is a die forging operation. 
         [0016]    In another specific aspect, the bending operation is a die bending operation. 
         [0017]    In yet another specific aspect, the method comprises at least one of: debarring, polishing, and cleaning the pre-finished component. 
         [0018]    In still another aspect, the blank and thus the orthopedic implant are formed from a material selected from: titanium and titanium alloy. 
         [0019]    In accordance with another embodiment of the invention, an orthopedic component made in accordance with the above-described method is provided. 
         [0020]    The present disclosure further relates to a method for implanting an orthopedic implant comprising preparing a bone to receive the orthopedic implant, and particularly to a method for implanting a femoral component of a knee joint prosthesis comprising preparing a femur to receive the femoral component. In one aspect, the bone is prepared such that it is substantially rounded when receiving the orthopaedic implant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the disclosure itself will be better understood by reference to the following description of an embodiment of the disclosure taken in conjunction with the accompanying drawings, wherein: 
           [0022]      FIG. 1  is a perspective view of a femur; 
           [0023]      FIG. 2  is a schematic representation of a forging operation on a blank; 
           [0024]      FIG. 3  is a perspective view of an intermediate component; 
           [0025]      FIG. 4  is a schematic representation of a bending operation on the intermediate component of  FIG. 3 ; 
           [0026]      FIG. 5  is a perspective view of a pre-finished component; and 
           [0027]      FIGS. 6   a, b  are cross-sectional views of femoral components of a knee joint prosthesis according the present disclosure and to the prior art, respectively. 
       
    
    
       [0028]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, identical reference numerals indicate the same or corresponding parts and features. 
       DETAILED DESCRIPTION 
       [0029]    Right femur  10  shown in  FIG. 1  includes lateral and medial condyles  12  and  14  which are in articulating contact to a tibia head (not shown) and facies patellaris  16  which is in articulating contact with a patella (not shown). A resurfacing femoral component of a knee joint prosthesis is adapted for attachment to a resected femur to replace lateral condyle  12 , medial condyle  14  and facies patellaris  16 . In partial knee arthroplasty, also called unicompartmental knee arthroplasty, only one of lateral condyle  12  and medial condyle  14  is replaced. 
         [0030]      FIGS. 2-5  show the manufacturing steps of a resurfacing femoral component. 
         [0031]    In a first step, as shown in  FIG. 2 , blank  18 , made of e.g. titanium, is provided. The blank  18  is pre-forged, which is to say it has a size and shape adapted to be formed into the final femoral component. 
         [0032]    In a second step, blank  18  is forged. Blank  18  is positioned between male and female die plates  20 ,  22  which are pressed against each other by a force F f  so as to form, either by cutting or a non-cutting deformation, a substantially planar intermediate component  24  ( FIG. 3 ). The male die plate  20  includes protrusions  26  so as to form depressions  58  in upper side  46  of intermediate component  24  which are adapted to serve as cement pockets in an anchoring side of the final femoral component. In general, male die plate  20  is adapted to form the topographic features of the final femoral component. Female die plate  22  comprises cavity  28  having a shape which pre-defines the overall (unbent or flattened) shape of the final femoral component and, particularly, of anterior portion  30 , distal portion  32  and lateral and medial condyle portions  34 ,  36  respectively. 
         [0033]    In a third step, as shown in  FIG. 4 , intermediate component  24  is bent by a force F b  so as to form a pre-finished component  38  ( FIG. 5 ). The bending is carried out by a bending die including punch  40  and die plate  42 . Pre-finished component  38  includes cement pockets  44  in anchoring side  48 , which correspond to depressions  58  provided in upper side  46  of intermediate component  24  ( FIG. 3 ). The size and shape of cement pockets  44  differ from the size and shape of depressions  58  as a result of the bending operation. This size difference may be considered and accounted for in the size and shape of protrusions  26  of the male die plate  20  of the forging die. When the femoral component  50  is anchored to the resected femur, cement pockets  44  are filled with bone cement. The cement may also be applied to regions of anchoring side  48  which have no cement pockets. 
         [0034]    Finally, pre-finished component  38  is subjected to finishing steps, such as polishing and cleaning, to form the final femoral component. Features of pre-finished component  38  are similar to the features of the final femoral component except for changes resulting from these finishing steps. 
         [0035]    As can be seen in  FIG. 6   a,  the bending operation or step includes forming anchoring side  48  of femoral component  50  such that it is substantially rounded and free of chamfers, because punch  40  is provided with a correspondingly rounded profile. Anchoring side  48  of femoral component  50  is adapted, such as through its shape and size, to directly contact the resected femur. 
         [0036]    As can be seen in  FIG. 6   b,  known femoral components  52  have an anchoring side  56  with two or more chamfers or angular seams  54  along the anterior-posterior direction. As a consequence, the thickness of non-chamfered femoral component  50  in the distal region of femoral component  50  may be smaller than the corresponding thickness of known femoral component  52 . In addition, the thickness of femoral component  50  is substantially constant along the anterior-posterior direction of femoral component  50 . 
         [0037]    Advantageously, formation of the cement pockets as part of the forging operation saves an additional drilling or milling step. For example, if cement pockets  44  are not formed in the forging operation as described above, a drilling or milling step would be necessary to form cement pockets. This step is complicated by restricted access to the anterior or posterior portions of the anchoring side of the femoral component, because the other portion is arranged oppositely to the accessed portion. 
         [0038]    While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           10  right femur 
           12  lateral condyle 
           14  medial condyle 
           16  facics patellaris 
           18  blank 
           20  male die plate 
           22  female die plate 
           24  intermediate component 
           26  protrusion 
           28  cavity 
           30  anterior portion 
           32  distal portion 
           34  lateral condyle portion 
           36  medial condyle portion 
           38  pre-finished component 
           40  punch 
           42  die plate 
           44  cement pocket 
           46  upper side 
           48  anchoring side 
           50  femoral component 
           52  femoral component 
           54  chamfer 
           56  anchoring side