Patent Publication Number: US-9402747-B2

Title: Femoral trial component

Description:
This application claims priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 13/731,575, which was filed on Dec. 31, 2012 and which claimed priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 13/530,239, which was filed on Jun. 22, 2012 and which claimed priority under 35 U.S.C. §119 to U.S. Patent Application No. 61/503,237, which was filed on Jun. 30, 2011. Each of these applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to orthopaedic surgical instruments and, more particularly, to surgical instruments used on a patient&#39;s femur. 
     BACKGROUND 
     Joint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. A typical knee prosthesis includes a tibial tray, a femoral component, and a polymer insert or bearing positioned between the tibial tray and the femoral component. Femoral components are designed to be attached to a surgically-prepared distal end of a patient&#39;s femur. Tibial trays are designed to be attached to a surgically-prepared proximal end of a patient&#39;s tibia. 
     To facilitate the replacement of the natural joint with the knee prosthesis, orthopaedic surgeons use a variety of orthopaedic surgical instruments such as, for example, prosthetic trial components, cutting blocks, drill guides, milling guides, and other surgical instruments. Prosthetic trial components, such as, for example, a femoral trial component and a tibial bearing trial component, are used to size and select the components of the knee prosthesis that will replace the patient&#39;s natural joint. A procedure that utilizes the trial components to size and select the components of the knee prosthesis is often referred to as a trial reduction. 
     SUMMARY 
     According to one aspect of the disclosure, an orthopaedic surgical instrument includes a polymeric femoral trial component configured to be coupled to a surgically-prepared distal end of a patient&#39;s femur. The femoral trial component includes an articular side having a posterior femoral condyle surface and a fixation side that is opposite the articular side. The fixation side has a plurality of ribs that extend in a direction away from the articular side so as to define a plurality of pockets therebetween. Each rib has an outer surface, and the outer surfaces of the ribs define a posterior fixation surface that extends generally in the superior/inferior direction and is configured to match the surgically-prepared distal end of the patient&#39;s femur. The femoral trial component also includes a plurality of teeth extending from the posterior fixation surface in a direction away from the articular side. Each tooth of the plurality of teeth has a pointed tip that defines a longitudinal axis of the tooth extending in the medial/lateral direction. 
     In some embodiments, each tooth of the plurality of teeth may have a triangular cross-section. In some embodiments, the plurality of teeth may include at least four teeth. 
     Additionally, in some embodiments, the polymeric femoral trial component may be formed as a molded integral component. In some embodiments, the outer surfaces of a number of the plurality of ribs may further define a distal fixation surface extending generally in the anterior/posterior direction and a posterior-chamfer fixation surface extending superiorly and posteriorly from the distal fixation surface to the posterior fixation surface. 
     In some embodiments, a second plurality of pockets may be defined in each of the distal fixation surface and the posterior-chamfer fixation surface between the plurality of ribs. In some embodiments, the femoral trial component may have an aperture defined in the distal fixation surface, and the aperture may extend from the fixation side to the articular side. 
     Additionally, in some embodiments, the femoral trial component may further include a lateral posterior condyle including the articular side and the fixation side that is opposite the articular side, and a medial posterior condyle. The medial posterior condyle may include a second articular side including a second posterior femoral condyle surface and a second fixation side that is opposite the second articular side. The second fixation side may have a second plurality of ribs that extend in a direction away from the second articular side so as to define a second plurality of pockets therebetween. Each rib may have an outer surface and the outer surfaces of the ribs may define a second posterior fixation surface that extends generally in the superior/inferior direction and is configured to match the surgically-prepared distal end of the patient&#39;s femur. The medial posterior condyle may also include a second plurality of teeth extending from the posterior fixation surface in a direction away from the second articular side. 
     In some embodiments, the femoral trial component may further have a medial side and a lateral side. The medial side may have at least one notch defined therein extending from the fixation side to the articular side, and the lateral side may have at least one notch defined therein extending from the fixation side to the articular side. 
     In some embodiments, the medial side may include two notches, and the lateral side may include two notches. 
     According to another aspect, an orthopaedic surgical instrument includes a polymeric femoral trial component configured to be coupled to a surgically-prepared distal end of a patient&#39;s femur. The femoral trial component includes an articular side having a posterior femoral condyle surface and a fixation side that is opposite the articular side. The fixation side has a planar posterior fixation surface that extends generally in the superior/inferior direction and is configured to match the surgically-prepared distal end of the patient&#39;s femur. A plurality of teeth extend from the planar posterior fixation surface in a direction away from the articular side. Each tooth has a pointed tip that defines a longitudinal axis of the tooth extending in the medial/lateral direction. 
     In some embodiments, a plurality of pockets may be defined in the planar posterior fixation surface between the plurality of teeth. 
     According to another aspect, an orthopaedic surgical instrument includes a polymeric femoral trial component configured to be coupled to a surgically-prepared distal end of a patient&#39;s femur. The femoral trial component has a medial side, a lateral side, an articular side including a posterior femoral condyle surface, and a fixation side that is opposite the articular side. The fixation side is configured to engage a posterior aspect of the surgically-prepared distal femur. The polymeric femoral trial component also includes a first notch extending from the fixation side to the articular side that is defined in the medial side, and a second notch extending from the fixation side to the articular side that is defined in the lateral side. 
     In some embodiments, the fixation side may include a plurality of ribs. Each rib may have an outer surface and the outer surfaces may define a posterior fixation surface extending generally in the superior/inferior direction that is configured to match the surgically-prepared distal end of the patient&#39;s femur. A plurality of teeth may extend from the posterior fixation surface in a direction away from the articular side. In some embodiments, the plurality of teeth may include at least four teeth. 
     Additionally, in some embodiments, each tooth of the plurality of teeth may have a pointed tip that defines a longitudinal axis of the tooth extending in the medial/lateral direction. In some embodiments, the femoral trial component may be formed as a molded integral component. In some embodiments, each tooth of the plurality of teeth may have a triangular cross-section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the following figures, in which: 
         FIG. 1  is a perspective view of an orthopaedic surgical instrument assembly; 
         FIG. 2  is an exploded perspective view of the orthopaedic surgical instrument assembly of  FIG. 1 ; 
         FIG. 3  is a perspective view of the femoral trial component of the orthopaedic surgical instrument assembly of  FIG. 1 ; 
         FIG. 4  is a sagittal cross sectional view of the femoral trial component of  FIGS. 1-3 ; 
         FIG. 5  is a bottom plan view of the femoral trial component of  FIGS. 1-4 ; 
         FIG. 6  is a perspective view of the femoral trial component of  FIGS. 1-5  positioned on a surgically-prepared distal end of a patient&#39;s femur; 
         FIG. 7  is a sagittal cross sectional view of the femoral trial component of  FIGS. 1-6  on the surgically-prepared distal end of the patient&#39;s femur; 
         FIG. 8  is a perspective view of the orthopaedic surgical instrument assembly of  FIG. 1  positioned on surgically-prepared ends of the patient&#39;s femur and tibia with the patient&#39;s knee in extension; and 
         FIG. 9  is a perspective view of the orthopaedic surgical instrument assembly of  FIG. 8  with the patient&#39;s knee in flexion. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, etcetera, may be used throughout the specification in reference to the orthopaedic implants and surgical instruments described herein as well as in reference to the patient&#39;s natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in the written description and claims is intended to be consistent with their well-understood meanings unless noted otherwise. 
     Referring to  FIGS. 1-4 , an orthopaedic surgical instrument assembly  10  is shown. The orthopaedic surgical instrument assembly  10  has a number of trial components  12 , including a femoral trial  14 , a tibial base trial  16 , and a tibial bearing trial  18 . The femoral trial  14  is configured to be secured to a surgically-prepared end of a patient&#39;s distal femur  20  (see  FIG. 6 ), whereas the tibial base trial  16  is configured to be secured to a surgically-prepared end of a patient&#39;s proximal tibia  22  (see  FIG. 8 ). 
     As shown in  FIG. 2 , the tibial base trial  16  includes a plate  30  having an opening  32  defined therein sized to receive a base insert  34 . The base insert  34  includes a body  36  having a number of fixation pins  38  extending away from a lower surface  40  of the body  36 . The base insert  34  also includes a post  42  extending away from an upper surface  44  of the body  36 . It should be appreciated that in other embodiments the fixation pins  38  may be omitted from base insert  34  or additional fixation pins  38  may be added. 
     The tibial bearing trial  18  is configured to assist the surgeon in selecting a prosthetic tibial bearing component of a typical knee prosthesis. The tibial bearing trial  18  is a multi-piece assembly that includes a bearing surface trial  46  and a shim  48 . The post  42  of the base insert  34  is received in an opening  50  defined in the shim  48  and an opening (not shown) defined in the lower surface of the bearing surface trial  46 . The bearing surface trial  46  includes a lateral articular surface  52  and a medial articular surface  54  positioned opposite the lower surface. In the illustrative embodiment, the bearing surface trial  46  is embodied as a fixed bearing trial and is fixed relative to the tibial base trial  16  (i.e., it is configured to not substantially rotate or move in the anterior/posterior direction or medial/lateral direction). In other embodiments, the bearing surface trial  46  may be a mobile bearing trial configured to rotate relative to the tibial base trial  16 . As shown in the illustrative embodiment, the tibial bearing trial  18  is a multi-piece assembly, but it should be appreciated that in other embodiments the tibial bearing trial  18  may be a single monolithic component. One example of a tibial bearing trial  18  is shown and described in co-pending U.S. Patent Application Ser. No. 61/503,300, entitled “TRIALING SYSTEM FOR A KNEE PROSTHESIS AND METHOD OF USE” by Thomas E. Wogoman et al., which is incorporated herein by reference. 
     The femoral trial  14  of the orthopaedic surgical instrument assembly  10  is configured to assist the surgeon in selecting a femoral prosthetic component, which will emulate the configuration of the patient&#39;s natural femoral condyles. As such, the femoral trial  14  includes a lateral condyle surface  56  and a medial condyle surface  58 , which may be shaped (i.e., curved) in a manner that approximates the condyles of the natural femur. The lateral condyle surface  56  and the medial condyle surface  58  are spaced apart from one another, thereby defining an intercondylar notch  60  therebetween. The articular surfaces  52 ,  54  of the tibial bearing trial  18  are configured to rotate with the lateral condyle surface  56  and the medial condyle surface  58 , respectively, of the femoral trial  14 . 
     As shown in  FIG. 3 , the lateral condyle surface  56  and the medial condyle surface  58  are formed in an articular side  62  of the femoral trial  14 . A fixation side  64 , which is the side of the femoral trial  14  that contacts the surgically-prepared distal femur of the patient, is opposite the articular side  62 . The fixation side  64  includes a plurality of ribs  66  that extend in a direction away from the articular side  62 . Each of the ribs  66  includes an outer surface  68 , and the outer surfaces  68  of the ribs  66  cooperate to define multiple surfaces of the fixation side  64 . Those surfaces, identified below as “fixation surfaces,” mate or match with planar surfaces surgically cut into the patient&#39;s femur, as discussed in greater detail below. 
     Although the femoral trial  14  is illustratively shown as a single integral or monolithic component, the trial  14  is characterized herein by a number of “regions” or “structures.” For example, the anterior structure of the femoral trial  14  is referred to herein as an anterior flange  70 . Moving along the femoral trial  14  from an anterior to posterior, the anterior flange  70  transitions to an anterior-chamfer region  72 , which transitions to a distal condylar region  74 . The distal condylar region  74  transitions to a posterior-chamfer region  76 . A pair of femoral condyles  78  forms the posterior structure of the femoral trial  14 . One of the femoral condyles  78  is medially positioned and the other laterally positioned when the femoral trial  14  is attached to the distal end of the patient&#39;s resected femur  20  depending on which knee is being replaced. 
     The outer surfaces  68  of the ribs  66  of each of the posterior femoral condyles  78  define a planar posterior fixation surface  82  on the fixation side  64 , with one of the posterior fixation surfaces  82  being the lateral fixation surface and the other medial fixation surface. Each posterior fixation surface  82  is positioned opposite a posterior condyle surface  84  on the articulation side  60 . As shown in  FIG. 4 , the posterior fixation surfaces  82  and the posterior condyle surfaces  84  extend generally in the superior/inferior direction. 
     The outer surfaces  68  of the ribs  66  of the distal condylar region  74  define a pair of planar distal fixation surfaces  86  (one being medially positioned, the other laterally positioned). Each of the distal fixation surfaces  86  is opposite a distal condyle surface  88 . As shown in  FIG. 3 , the distal fixation surfaces  86  extend generally in the anterior/posterior direction. 
     The distal condylar region  74  also includes a pair of apertures or through-holes  90 , one of which is positioned laterally while the other is positioned medially. Each through-hole  90  extends from an opening  92  defined in one of the distal fixation surfaces  86  to an opening  94  defined in the corresponding distal condyle surface  88 . Each through-hole  90  is sized to receive a surgical drill, as described in greater detail below. 
     The posterior-chamfer region  76  of the femoral trial  14  includes a pair of planar posterior-chamfer fixation surfaces  96  defined by the outer surfaces  68  of the ribs  66 , with one being medially positioned and the other laterally positioned. The lateral and medial posterior-chamfer fixation surfaces  96  extend superiorly and posteriorly from their respective lateral and medial distal fixation surfaces  86  to their respective posterior fixation surfaces  82 . Each of the posterior-chamfer fixation surfaces  96  is positioned opposite a posterior-chamfer condyle surface  98 . 
     Similarly, the anterior-chamfer region  72  includes a pair of planar anterior-chamfer fixation surfaces  100 . Each anterior-chamfer fixation surface  100  is positioned opposite an anterior-chamfer condyle surface  102 . The anterior-chamfer fixation surfaces  100  extend superiorly and anteriorly away from their respective lateral and medial distal fixation surfaces  86  to a planar anterior fixation surface  104  of the anterior flange  70 . The anterior fixation surface  104  is opposite an anterior condyle surface  106 , and, like the posterior fixation surfaces  82 , the anterior fixation surface  104  extends generally in the superior/inferior direction. 
     The plurality of ribs  66  define a plurality of pockets  108  in each of the fixation surfaces  82 ,  86 ,  96 ,  100 , and  104 . In the illustrative embodiment, the pockets  108  are separated such that none of the pockets are in fluid communication with each other. It should be appreciated that in other embodiments two or more pockets may be in communication with one another such that a single, continuous pocket is formed in the fixation side  72  of the femoral trial  14 . It will be appreciated that in other embodiments the pockets  108  may be omitted from one or more of the fixation surfaces. 
     The femoral trial  14  of the orthopaedic surgical instrument assembly  10  includes a plurality of teeth  110  that extend from each of the posterior fixation surfaces  82  in a direction away from the articular side  62 . The teeth  110  are configured to engage or grip the surgically-prepared distal end of the patient&#39;s femur  20  when the femoral trial  14  is coupled thereto. The illustrative teeth  110  extend parallel to each other in the medial/lateral direction. It should be appreciated that in other embodiments the teeth  110  may be angled relative to each other or arranged in various patterns on the posterior fixation surfaces  82 . Additionally, one or more of the teeth  110  may extend inferiorly/superiorly along the posterior fixation surface  82  in addition to, or instead of, extending medially/laterally as shown in  FIGS. 3-4 . It should also be appreciated that in other embodiments one or more teeth may be formed on any of the other surfaces  82 ,  86 ,  96 ,  100 , and  104  of the fixation side  64  of the femoral trial  14 . 
     As shown in  FIG. 4 , each tooth  110  has a triangular cross section when viewed in the sagittal plane. It should be appreciated that in other embodiments the teeth  110  may have a square cross section, rectangular cross section, dome-shaped cross section, or any other cross section suitable to engage the surgically-prepared distal end of the patient&#39;s femur  20 . Additionally, while the teeth  110  have the same cross section in the illustrative embodiment, it should be appreciated that in other embodiments each tooth  110  may have a unique cross section. 
     Each tooth  110  has a body  112  including a base  114  fixed to the posterior fixation surface  82  between one or more of the pockets  108 . The body  112  extends outwardly from the posterior fixation surface  82  to a tip  116 . The tip  116  defines a longitudinal axis  122  of each tooth  110  extending in the medial/lateral direction. The tip  116  of each body  112  is spaced apart from the posterior fixation surface  82  such that each tooth  110  has a height  120 . In the illustrative embodiment, the height  120  is approximately 0.38 millimeters. However, in other embodiments, the height  120  may be greater than that shown in the illustrative embodiment. Additionally, while each tooth  110  has the same height  120  in the illustrative embodiment, it should be appreciated that in other embodiments the height  120  of each tooth  110  may vary. 
     The femoral trial  14  also includes a pair of sidewalls  124 ,  126  that extend between the articular side  62  and the fixation side  64 , with one sidewall being medially positioned and the other laterally positioned depending on which knee is being replaced. As shown in  FIG. 5 , each of the sidewalls  124 ,  126  has a pair of notches  128 ,  130  defined therein. The notch  128  extends between the articular side  62  and the fixation side  64  of the distal condylar region  74  and has a base surface  132  that connects the distal fixation surface  86  to the distal condyle surface  88 . Similarly, the notch  130  extends between the articular side  62  and the fixation side  64  of the distal condylar region  74  and the anterior-chamfer region  72 . The notch  130  includes a base surface  134  that connects the distal fixation surface  86  to the distal condyle surface  88 , and a base surface  136  that connects the anterior-chamfer fixation surface  100  and the anterior-chamfer condyle surface  102 . In the illustrative embodiment, the notches  128 ,  130  extend inwardly approximately 1.75 millimeters from the sidewalls  124 ,  126 , respectively, to the base surfaces  132 ,  134 ,  136 . 
     The sidewalls  124 ,  126  define an outer edge  138  of the femoral trial  14  corresponding to a standard femoral prosthetic component size. The base surfaces  132 ,  134 ,  136  of the notches  128 ,  130  define another edge  140  of the femoral trial  14  corresponding to a standard, but more narrow, femoral prosthetic component size. As such, a single femoral trial  14  may be used to size multiple femoral prosthetic component sizes. It should be appreciated that in other embodiments one or more of the notches  128 ,  130  may be omitted from the femoral trial  14 . It should also be appreciated that in other embodiments the position of the notches  128 ,  130  along the sidewalls  124 ,  126  may vary such that, for example, the notches  130  are formed entirely in the distal condylar region  74 . 
     The femoral trial  14  is constructed from a polymeric material. In the illustrative embodiment, the polymeric material is a fifty percent glass-reinforced nylon. Another polymeric material that may be used is thirty percent glass-filled polyether ether ketone (PEEK) or polyethylene, such as ultrahigh molecular weight polyethylene (UHMWPE), although other biocompatible polymers may be used. The tibial bearing trial  18  may be constructed from a material, such as, for example, any of the polymeric materials described above, which permits smooth articulation between the tibial bearing trial  18  and the femoral trial  14 . The tibial base trial  16  and the base insert  34  may be constructed from a biocompatible metal, such as a cobalt chrome alloy; other materials, such as ceramics, may also be used. 
     Referring now to  FIGS. 6-9 , the orthopaedic surgical instrument assembly  10  is shown in use with the patient&#39;s bony anatomy. As shown in  FIG. 6 , a surgically-prepared distal end  200  of the patient&#39;s femur  20  includes a resected medial condyle  202  and a resected lateral condyle  204 . In use, the surgeon positions the femoral trial  14  over the distal end  200  of the patient&#39;s femur  20 . An impactor assembly  206  may be used to impact the femoral trial  14  into the distal end  200 . 
     To do so, an engagement end  208  of the impactor assembly  206  is positioned in contact with the articular side  62  of the femoral trial  14 , and force is applied to the impactor assembly  206  until the fixation side  64  of the femoral trial  14  contacts the resected medial condyle  202  and the resected lateral condyle  204 . Once the femoral trial  14  is properly positioned on the distal end  200  of the patient&#39;s femur  20 , the surgeon may remove the impactor assembly  206 . It should be appreciated that in other embodiments the surgeon may position the femoral trial  14  on the distal end  200  of the patient&#39;s femur  20  by hand without using the impactor assembly  206 . 
     When the femoral trial  14  is positioned on the distal end  200  of the patient&#39;s femur  20 , the sidewalls  124 ,  126  indicate where the outer edge of the standard femoral prosthetic component would be located on the resected medial condyle  202  and the resected lateral condyle  204 . Conversely, the base surfaces  132 ,  134 ,  136  of the notches  128 ,  130  in the femoral trial  14  indicate where the outer edge of the narrow femoral prosthetic component would be located. If the sidewalls  124 ,  126  extend beyond the resected medial condyle  202  and the resected lateral condyle  204  of the distal end  200  of the patient&#39;s femur  20 , the surgeon may select the narrow femoral prosthetic component for implantation. 
     The resected medial condyle  202  and the resected lateral condyle  204  of the patient&#39;s femur  20  include a number of resected surfaces  210 . As shown in  FIG. 7 , the resected surfaces  210  of each condyle  202 ,  204  include a posterior planar surface  212 , a distal planar surface  214 , and an anterior planar surface  216 . The resected surfaces  210  also include a posterior-chamfer planar surface  218  that extends superiorly and posteriorly from the distal planar surface  214  to the posterior planar surface  212  and an anterior-chamfer planar surface  220  that extends superiorly and anteriorly from the distal planar surface  214  to the anterior planar surface  216 . 
     When the femoral trial  14  is positioned on the distal end  200  of the patient&#39;s femur  20 , the anterior fixation surface  104  of the femoral trial  14  contacts the anterior planar surfaces  216  of the patient&#39;s femur  20  and the distal fixation surfaces  86  of the femoral trial  14  contacts the distal planar surfaces  214  of the patient&#39;s femur  20 . Similarly, posterior-chamfer fixation surface  96  of the femoral trial  14  contacts the posterior-chamfer planar surface  218  of the patient&#39;s femur  20 . The anterior-chamfer fixation surfaces  100  of the femoral trial  14  contacts the anterior-chamfer planar surfaces  220  of the patient&#39;s femur  20 . 
     Further, the posterior fixation surfaces  82  of the femoral trial  14  grip the posterior planar surfaces  212  of the patient&#39;s femur  20  when the femoral trial  14  is positioned thereon. As shown in  FIG. 7 , one or more of the teeth  110  of the lateral posterior fixation surface  82  engages with, or grips, the posterior planar surface  212  of the resected lateral condyle  204 . The engagement of the teeth  110  with the posterior planar surfaces  212  secures the femoral trial  14  to the distal end  200  of the patient&#39;s femur  20 . 
     In addition to positioning the femoral trial  14  on the distal end  200  of the patient&#39;s femur  20 , the surgeon may also position the tibial base trial  16  on a surgically-prepared proximal end  230  of the patient&#39;s tibia  22 . When the surgical instrument assembly  10  is fully installed, the tibial base trial  16  is secured to the surgically-prepared proximal end  230  of the patient&#39;s tibia  22 , as shown in  FIG. 8 . The tibial bearing trial  18 , including the bearing surface trial  46  and the shim  48 , are positioned over the post  42  of the base insert  34 . The lateral condyle surface  56  of the femoral trial  14  contacts the lateral articular surface  52  of the tibial bearing trial  18 , while the medial condyle surface  58  contacts the medial articular surface  54 . The surgeon may then evaluate the range of motion and stability of the knee with the surgical instrument assembly  10 . 
     As the range of motion is evaluated, the load on the femoral trial  14  translates posteriorly as the knee is moved from extension (see  FIG. 8 ) to flexion (see  FIG. 9 ). As the load moves posteriorly, the force normal to the posterior condyle surfaces  84  of the femoral trial  14  increases, thereby causing the teeth  110  of the posterior fixation surfaces  82  of the femoral trial  14  to further engage, or grip, the posterior planar surfaces  212  of the surgically-prepared distal end  200  of the patient&#39;s femur  20 . The engagement of one or more of the teeth  110  of the femoral trial  14  with the distal end  200  of the patient&#39;s femur  20  retains the femoral trial  14  on the patient&#39;s femur  20 . It should be appreciated that in other embodiments screws or other fasteners may be inserted through the through-holes  90  into the femur  20  to provide additional fixation. 
     While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims.