Abstract:
Various embodiments of orthopaedic implants which optimize the articular geometries of the implants. An exemplary implant may include a plurality of protrusions which provide an articulating surface and which create paths for fluid movement relative to the implant.

Description:
BACKGROUND 
       [0001]    1. Field of the Disclosure. 
         [0002]    The present disclosure relates to optimization of articular geometries of orthopaedic implants. 
         [0003]    2. Description of the Related Art 
         [0004]    Many prosthetic joints include components having articulating surfaces which articulate with each other or with natural anatomical structures. For example, a prosthetic knee joint may include a femoral component, a tibial component, and a meniscal component, each of which may include articulating surfaces which articulate with each other. The prosthetic knee joint may be formed as a mobile bearing prosthetic knee joint, i.e., the meniscal component may rotate relative to and articulate with the tibial component. In the mobile bearing prosthetic knee joint, the tibial component and the meniscal component may have a flat-on-flat mating engagement, i.e., the surface of the tibial component in articulating engagement with the meniscal component is a flat surface and the surface of the meniscal component in articulating engagement with the tibial component is also a flat surface. 
       SUMMARY 
       [0005]    The present disclosure provides various embodiments of orthopaedic implants which optimize the articular geometries of the implants. An exemplary implant may include a plurality of protrusions which provide an articulating surface and which create paths for fluid movement relative to the implant. 
         [0006]    In one form thereof, the present disclosure provides an orthopaedic implant including a body; and a plurality of macroscopic protrusions extending from the body, at least some of the protrusions defining articulating surface portions cooperating to define an articulating surface of the implant, wherein the articulating surface portions are substantially coplanar. 
         [0007]    In another form thereof, the present disclosure provides an orthopaedic implant including a body; and optimization means associated with the body for providing enhanced lubrication to the implant. 
         [0008]    In yet another form thereof, the present disclosure provides an orthopaedic implant including a body; and a plurality of substantially spherical protrusions extending from the body, at least some of the protrusions defining articulating surface portions cooperating to define an articulating surface of the implant. 
         [0009]    In still another form thereof, the present disclosure provides an orthopaedic implant including a body; and a plurality of protrusions extending from the body, at least some of the protrusions defining articulating surface portions cooperating to define an articulating surface of the implant, the protrusions defining a path through which fluid can flow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above-mentioned and other features of the disclosure, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a cross-sectional view of a prosthetic implant system including a first component and a second component according to an exemplary embodiment of the present disclosure; 
           [0012]      FIG. 2  is a bottom view of one of the components of  FIG. 1 ; and 
           [0013]      FIG. 3  is a top view of one of the components of  FIG. 1 . 
       
    
    
       [0014]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the disclosure and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0015]    Referring now to  FIG. 1 , prosthetic implant system  20  may include first component  22  and second component  24 . Second component  24  may include body  25  and mating surface  26  which may be substantially planar, e.g., surface  26  forms a substantially flat articulating surface with no macroscopic protrusions, i.e., surface  26  has only microscopic protrusions due to the inherent non-smooth microscopic nature of materials used to form second component  24 . First component  22  may include body  23  and surface  28 . Surface  28  may include a plurality of protrusions  30 . Protrusions  30  each may include contact surface  34  for articulating engagement with surface  26  of second component  24 . The raised portions of surface  28  including protrusions  30  define depressed areas  32 . Each contact surface  34  may define apex  34   a  which defines an area, point, or region of protrusion  30  furthest from depressed areas  32 . Depressed areas  32  may define paths or channels  36  between protrusions  30 . Surface  28  may include a plurality of microscopic protrusions and depressions due to fundamental characteristics of the materials used to form first component  22 , i.e., surface  28  is not perfectly smooth and may include a plurality of protrusions which are perceivable only with the aid of a microscope. Protrusions  30  are to be distinguished from such microscopic protrusions and extend a height H above a most depressed area of depressed areas  32 , i.e., protrusions  30  are macroscopic protrusions which are large enough to be perceived or examined by the unaided eye. In exemplary embodiments, height H may be as small as approximately 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5, or 3.0 mm or as large as approximately 6.0, 5.5, 5.0, 4.5, 4.0, or 3.5 mm. In one embodiment, channels  36  may define generally wedge-shaped openings, as illustrated in  FIG. 1 . In other embodiments, channels  36  may define a polygonal-shaped opening, a circular-shaped opening, or an elliptical-shaped opening. In an exemplary embodiment, channels  36  have a tapered cross-sectional area. In one embodiment, protrusions  30  may be formed to create discrete depressed areas  32  such as to define a plurality of discontinuous paths or channels  36 , e.g., paths or channels  36  form pockets. In an exemplary embodiment, depressed areas  32  form a continuous network of paths or channels  36  to further enhance fluid movement between first component  22  and second component  24 , as described below. 
         [0016]    In an exemplary embodiment, surfaces  34  of each protrusion  30  together define an articulating surface of first component  22 . As shown in  FIG. 1 , surfaces  34  are all substantially coplanar with respect to each other, i.e., surfaces  34  of each protrusion  30  are each substantially positioned in a single plane. For example, apexes  34   a  of surfaces  34  are all substantially coplanar. 
         [0017]    Channels  36  provide passageways or paths for fluid to move between protrusions  30 . Such fluid proximate the articulating surfaces of first component  22  and second component  24  enhances the amount of lubrication provided between first component  22  and second component  24  during articulation therebetween. The enhanced lubrication improves wear characteristics and properties of first component  22  and second component  24  by reducing the amount of wear imposed on each component. Furthermore, the geometry of protrusions  30  allows optimization of the amount of articulating contact area between first component  22  and second component  24  while maintaining channels  36  for flow of fluid lubricant therethrough. For example, the geometry of protrusions  30  provides a sufficient amount of surface contact between first component  22  and second component  24  while simultaneously providing enhanced lubrication therebetween. For example, contact surfaces  34  of protrusions  30  provide a substantial amount of contact between first component  22  and second component  24  such that articulation is not adversely affected during use of system  20 . In exemplary embodiments, contact surfaces  34  may define an articulating surface area percentage of surface  28  (where depressed areas  32  define the remainder of surface  28 ) of as small as approximately 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or as large as approximately 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, or 55%. The remainder of surface  28  defining depressed areas  32  provides the enhanced lubrication to the interface between first component  22  and second component  24 . Moreover, the enhanced lubrication reduces friction between first component  22  and second component  24  while still allowing rotation and movement therebetween with lower forces imposed on first component  22  and second component  24 . The reduced friction allows a more natural, i.e., non-prosthetic, movement within the joint, thereby allowing more normal rotations, movements, and kinematics of the components. 
         [0018]    As shown in  FIG. 2 , depressed area  32  may form a continuous, depressed region which surrounds each protrusion  30 . Each protrusion  30  may define a spherically-shaped dome. In other embodiments, each protrusion  30  may define other cross-sectional shapes, such as polygons and ellipses, with rounded contact surfaces  34 . Protrusions  30  may vary in size on surface  28  and may have cross-sectional diameters D defined proximate depressed area  32 . In exemplary embodiments, diameters D may be as small as approximately 0.2, 0.4, 0.6, 0.8, or 1.0 mm or as large as approximately 3.0, 2.5, 2.0, 1.8, 1.6, 1.4, or 1.2 mm. Also, protrusions  30   a  may be larger in cross-sectional size, i.e., protrusions  30   a  have a larger cross-sectional diameter than diameters D of protrusions  30 . Protrusions  30   a  may be positioned on surface  28  in a location which incurs the highest load levels on first component  22  during articulation with second component  24 . In an exemplary embodiment, multiple protrusions  30  and  30   a  carry the load imposed on first component  22  during articulation with second component  24 . In an alternative embodiment, depressed area  32  may be formed as a plurality of discontinuous regions, such as a plurality of spherical depressions formed in surface  28 . 
         [0019]    As shown in  FIG. 3 , first component  22  may include second surface  40 . In one embodiment, surface  40  is opposite surface  28  ( FIGS. 1 and 2 ). Second surface  40  may include a plurality of protrusions  42 . Protrusions  42  are substantially similar to protrusions  30 ,  30   a  ( FIGS. 1 and 2 ), described above, and each may include contact surface  44  for articulating engagement with a third component (not shown) of prosthetic implant system  20 . The raised portions of surface  40  including protrusions  42  define depressed areas  50 . Each contact surface  44  may define apex  44   a  which defines an area, point, or region of protrusion  42  furthest from depressed areas  50 . Depressed areas  50  may define paths or channels  52 , similar to channels  36  ( FIGS. 1 and 2 ), described above, between protrusions  42 . Surface  40  may include lateral/medial condyle surface  46  and lateral/medial condyle surface  48 . Similar to protrusions  30 ,  30   a  ( FIGS. 1 and 2 ), described above, protrusions  42  may be formed in varying cross-sectional sizes. Although depicted in  FIG. 3  positioned exclusively on surface  48  of first component  22 , protrusions  42  may extend across the entire surface  40  and also extend from surface  46 . Surfaces  44  of each protrusion  42  together define an articulating surface of first component  22 . 
         [0020]    Although shown in  FIG. 3  as positioned on a condylar mating surface of first component  22  which may have a slight curvature, surfaces  44  of each protrusion  42  are all substantially coplanar with respect to each other, i.e., surfaces  44  are each substantially positioned in a single plane. 
         [0021]    In an exemplary embodiment, system  20  is a prosthetic knee joint and first component  22  is formed as a meniscal or bearing component of the prosthetic knee joint, second component  24  is formed as a tibial component of the prosthetic knee joint, and the third component is formed as a femoral component of the prosthetic knee joint. Although described throughout the present disclosure as pertaining to a prosthetic knee joint, protrusions  30 ,  30   a ,  42  may be used on any orthopaedic implant which includes two components articulating against one another to reduce the wear and enhance the lubrication between the two components. Protrusions  30 ,  30   a ,  42  may also be used on any orthopaedic implant which includes a component which articulates against a natural anatomical structure to reduce the wear and enhance the lubrication between the component and the natural anatomical structure. 
         [0022]    In one embodiment, protrusions  30 ,  30   a ,  42  may be formed by a net shape molding process. In another embodiment, protrusions  30 ,  30   a ,  42  may be formed by removing a portion of body  23  to define channels  36 ,  52 . In yet another embodiment, protrusions  30 ,  30   a ,  42  may be formed by adding material to body  23  to create channels  36 ,  52 . 
         [0023]    In an alternative embodiment, protrusions  30  may be formed on second component  24  and first component  22  includes a substantially planar mating surface. 
         [0024]    While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.