AU2012203752B2 - Polymer femoral trial component - Google Patents

Abstract

An orthopaedic surgical instrument including a femoral trial component configured to be coupled to a surgically-prepared distal end of a patient's femur. The femoral trial component has a fixation side configured to engage a posterior aspect of the surgically-prepared distal femur. 70 66 78g, 78 5662 72 586 Fig. 2

Description

AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INVENTION TITLE: POLYMER FEMORAL TRIAL COMPONENT The following statement is a full description of this invention, including the best method of performing it known to us:- 1 POLYMER FEMORAL TRIAL COMPONENT [0001] This application claims priority under 35 U.S.C. § 119 to U.S. Patent Application No. 61/503,247, which was filed on June 30, 2011 and is incorporated 5 herein by reference. FIELD OF THE INVENTION [0002] The present disclosure relates generally to orthopaedic surgical instruments and, more particularly, to surgical instruments used on a patient's femur. 10 BACKGROUND OF THE INVENTION [0003] 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 15 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's femur. Tibial trays are designed to be attached to a surgically-prepared proximal end of a patient's tibia. [0004] To facilitate the replacement of the natural joint with the knee prosthesis, 20 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's natural 25 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 [0005] In accordance with the present invention, therefor, there is provided An 30 orthopaedic surgical instrument, including a polymeric femoral trial component configured to be coupled to a surgically-prepared distal end of a patient's femur, the femoral trial component including: (i) an articular side including a posterior Document13 2 femoral condyle surface, (ii) a fixation side that is opposite the articular side, the fixation side including a planar posterior fixation surface that extends generally in a superior/inferior direction and is configured to match the surgically-prepared distal end of the patient's femur, and (iii) a plurality of teeth extending from the 5 planar posterior fixation surface in a direction away from the articular side, each tooth having a pointed tip that defines a longitudinal axis of the tooth extending in the medial/lateral direction. [0006] 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 10 at least four teeth. [0007] 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 15 direction and a posterior-chamfer fixation surface extending superiorly and posteriorly from the distal fixation surface to the posterior fixation surface. [0008] 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 20 may have an aperture defined in the distal fixation surface, and the aperture may extend from the fixation side to the articular side. [0009] 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 25 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 Dncumentl A 3 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'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. [0010] 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. [0011] In some embodiments, the medial side may include two notches, and the lateral side may include two notches. [0012] 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'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'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. [0013] In some embodiments, a plurality of pockets may be defined in the planar posterior fixation surface between the plurality of teeth. [0014] 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'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 4 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. [0015] 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'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. [0016] 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 [0017] The detailed description particularly refers to the following figures, in which: [0018] FIG. I is a perspective view of an orthopaedic surgical instrument assembly; [0019] FIG. 2 is an exploded perspective view of the orthopaedic surgical instrument assembly of FIG. I; [0020] FIG. 3 is a perspective view of the femoral trial component of the orthopaedic surgical instrument assembly of FIG. 1; [0021] FIG. 4 is a sagittal cross sectional view of the femoral trial component of FIGS. 1-3; 5 [0022] FIG. 5 is a bottom plan view of the femoral trial component of FIGS. 1-4; [0023] 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's femur; [0024] 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's femur; [0025] FIG. 8 is a perspective view of the orthopaedic surgical instrument assembly of FIG. 1 positioned on surgically-prepared ends of the patient's femur and tibia with the patient's knee in extension; and [0026] FIG. 9 is a perspective view of the orthopaedic surgical instrument assembly of FIG. 8 with the patient's knee in flexion. DETAILED DESCRIPTION OF THE DRAWINGS [0027] 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. [0028] 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'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.

6 [0029] 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'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's proximal tibia 22 (see FIG. 8). [0030] 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. [0031] 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 Serial No. 61/503,300, entitled "TRIALrNG SYSTEM FOR A KNEE PROSTHESIS AND METHOD OF USE" by Thomas E. Wogoman et al. (Attorney Docket No. 265280-210420, DEP6286USPSP), which is incorporated herein by reference.

7 [0032] 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'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. [0033] 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's femur, as discussed in greater detail below. [0034] 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's resected femur 20 depending on which knee is being replaced. [0035] 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 8 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. [0036] 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. [0037] 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. [0038] 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. [0039] 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 9 posterior fixation surfaces 82, the anterior fixation surface 104 extends generally in the superior/inferior direction. [0040] 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. [0041] The femoral trial 14 of the orthopaedic surgical instrument assembly 10 includes a plurality of teeth 1 10 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'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. [0042] 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'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.

10 [0043] Each tooth 1 10 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 1 10 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. [0044] 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. [0045] 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 11 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. [0046] 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. [0047] Referring now to FIGS. 6-9, the orthopaedic surgical instrument assembly 10 is shown in use with the patient's bony anatomy. As shown in FIG. 6, a surgically prepared distal end 200 of the patient'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's femur 20. An impactor assembly 206 may be used to impact the femoral trial 14 into the distal end 200. [0048] 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'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's femur 20 by hand without using the impactor assembly 206. [0049] When the femoral trial 14 is positioned on the distal end 200 of the patient'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 12 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's femur 20, the surgeon may select the narrow femoral prosthetic component for implantation. [0050] The resected medial condyle 202 and the resected lateral condyle 204 of the patient'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. [0051] When the femoral trial 14 is positioned on the distal end 200 of the patient's femur 20, the anterior fixation surface 104 of the femoral trial 14 contacts the anterior planar surfaces 216 of the patient's femur 20 and the distal fixation surfaces 86 of the femoral trial 14 contacts the distal planar surfaces 214 of the patient's femur 20. Similarly, posterior-chamfer fixation surface 96 of the femoral trial 14 contacts the posterior-chamfer planar surface 218 of the patient's femur 20. The anterior-chamfer fixation surfaces 98 of the femoral trial 14 contacts the anterior-chamfer planar surfaces 220 of the patient's femur 20. [0052] Further, the posterior fixation surfaces 82 of the femoral trial 14 grip the posterior planar surfaces 212 of the patient'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's femur 20.

13 [0053] In addition to positioning the femoral trial 14 on the distal end 200 of the patient's femur 20, the surgeon may also position the tibial base trial 16 on a surgically prepared proximal end 230 of the patient'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'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. [0054] 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's femur 20. The engagement of one or more of the teeth 1 10 of the femoral trial 14 with the distal end 200 of the patient's femur 20 retains the femoral trial 14 on the patient'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. [0055] 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. [0056] 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 14 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. [0057] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. [0058] The reference to any prior art in this specification is not and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia.

Claims (10)

1. An orthopaedic surgical instrument, including: a polymeric femoral trial component configured to be coupled to a surgically-prepared distal end of a patient's femur, the femoral trial component 5 including: (i) an articular side including a posterior femoral condyle surface, (ii) a fixation side that is opposite the articular side, the fixation side including a planar posterior fixation surface that extends generally in a superior/inferior direction and is configured to match the surgically-prepared 10 distal end of the patient's femur, and (iii) a plurality of teeth extending from the planar posterior fixation surface in a direction away from the articular side, each tooth having a pointed tip that defines a longitudinal axis of the tooth extending in the medial/lateral direction. 15

2. The orthopaedic surgical instrument of claim 1, wherein each tooth of the plurality of teeth has a triangular cross-section.

3. The orthopaedic surgical instrument of claim 1 or claim 2, wherein the 20 plurality of teeth include at least four teeth.

4. The orthopaedic surgical instrument of any one of claims 1 to 3, wherein the polymeric femoral trial component is formed as a molded integral component. 25

5. The orthopaedic instrument of any one of claims 1 to 4, wherein the fixation side has a plurality of ribs formed on it that extend in a direction away from the articular side so as to define a plurality of pockets between them, each rib having an outer surface, and the outer surfaces of the ribs defining a posterior fixation surface that extends generally in the superior/inferior direction. 30 16

6. The orthopaedic surgical instrument of any one of claims 1 to 5, wherein the outer surfaces of a number of the plurality of ribs further define (i) a distal fixation surface extending generally in an anterior/posterior direction, and (ii) a posterior-chamfer fixation surface extending superiorly and posteriorly from the 5 distal fixation surface to the posterior fixation surface.

7. The orthopaedic surgical instrument of claim 6, wherein a second plurality of pockets are defined in each of the distal fixation surface and the posterior-chamfer fixation surface between the plurality of ribs. 10

8. The orthopaedic surgical instrument of claim 6 or claim 7, wherein the femoral trial component has an aperture defined in the distal fixation surface, the aperture extending from the fixation side to the articular side. 15

9. The orthopaedic surgical instrument of any one of the preceding claims, wherein the femoral trial component further includes: a lateral posterior condyle including the articular side and the fixation side that is opposite the articular side, and a medial posterior condyle including 20 (i) a second articular side including a second posterior femoral condyle surface, (ii) a second fixation side that is opposite the second articular side, the second fixation side including 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 25 therebetween, each rib having an outer surface and the outer surfaces of the ribs defining a second posterior fixation surface that extends generally in a superior/inferior direction and is configured to match the surgically-prepared distal end of the patient's femur, and (iii) a second plurality of teeth extending from the posterior fixation 30 surface in a direction away from the second articular side. Document12 17

10. The orthopaedic surgical instrument of any one of the preceding claims, wherein the femoral trial component further has a medial side and a lateral side, the medial side having at least one notch defined therein extending from the fixation side to the articular side, and the lateral side having at least one notch 5 defined therein extending from the fixation side to the articular side. I1. The orthopaedic surgical instrument of claim 10, wherein the medial side includes two notches, and the lateral side includes two notches. 10 12. An orthopaedic surgical instrument, substantially as described herein with reference to the accompanying drawings. 2553493v1