Abstract:
A glenoid component for securement to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus includes a body having a first surface configured to contact the glenoid surface of the scapula and a second surface configured to receive the head portion of the humerus. The glenoid component also includes an interruption such as a buttress extending from the body. The interruption is configured to be received in a like-configured notch formed in the glenoid surface of the scapula. The interruption helps prevent movement of the glenoid component relative to the glenoid surface of the scapula after implant. The body also may include anchoring extending from the body for penetrating the glenoid surface of the scapula so as to help secure the body to the glenoid surface of the scapula. The glenoid component is used in one application to help correct bone defects and in another application for wear. A method of securing the glenoid component to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus is also disclosed.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to a glenoid component, and more particularly to an augmented glenoid component and associated method for securing the augmented glenoid component to a glenoid surface of a scapula. 
     BACKGROUND OF THE INVENTION 
     During the lifetime of a patient, it may be necessary to perform a total shoulder replacement procedure on the patient as a result of, for example, disease or trauma. In a total shoulder replacement procedure, a humeral component having a head portion is utilized to replace the natural head portion of the arm bone or humerus. The humeral component typically has an elongated intramedullary stem which is utilized to secure the humeral component to the patient&#39;s humerus. In such a total shoulder replacement procedure, the natural glenoid surface of the scapula is resurfaced or otherwise replaced with a glenoid component that provides a bearing surface for the head portion of the humeral component. 
     As alluded to above, the need for a shoulder replacement procedure may be created by the presence of any one of a number of conditions. One such condition is the deterioration of the patient&#39;s scapula in the area proximate to the glenoid surface as a result of, for example, glenohumeral arthritis. In such a condition, the erosion of the patient&#39;s scapula is generally observed posteriorly on the glenoid surface. Such erosion of the scapula renders treatment difficult, if not impossible, with a conventional glenoid prosthesis. 
     In order to treat a condition in which a portion of the scapula has been eroded, a number of glenoid prostheses have heretofore been designed. Such glenoid prostheses, known generally as augmented glenoid prostheses, have a posterior edge that is thicker than the corresponding anterior edge. In FIG. 1A, a heretofore-designed augmented glenoid component  100  is shown. The glenoid component  100  has a metallic backing component  102  and plastic insert  104 . The thickness of the metallic backing component  102  gradually increases from an anterior edge  106  to a posterior edge  108  thereof thereby creating a relatively smooth, arcuate-shaped medial surface  110  from which a number of posts or pegs  112  extend. 
     The design of the augmented glenoid component  100 , however, has a number of associated drawbacks. For example, the relatively smooth, arcuate-shaped medial surface  110  may over time lead to loosening of the augmented glenoid component  100 , thereby potentially necessitating additional surgical procedures to replace or reseat the component  100 . Further, due to the configuration of the medial surface  110 , a relatively high shear load is created along the implant-to-bone interface when the component  100  is implanted. The presence of a high shear load along the implant-to-bone interface tends to also cause loosening of the component  100  over a period of time. Post-operative loosening is the largest cause of failures of implanted glenoid components. 
     In FIG. 1B another heretofore-designed augmented glenoid component  100   a  is shown. The glenoid component  100   a  has a single component plastic body  102   a . The thickness of the plastic body  102   a  gradually increases from an anterior edge  106   a  to a posterior edge  108   a  thereof thereby creating a relatively smooth, arcuate-shaped medial surface  110   a  from which a number of posts or pegs  112   a  extend. The design of this augmented glenoid component  100   a , however, suffers from at least the same drawbacks as the glenoid component  100 . 
     In FIG. 1C another heretofore-designed augmented glenoid component  100   b  is shown. The glenoid component  100   b  also has a single component plastic body  102   b . The thickness of the plastic body  102   b  gradually increases from an anterior edge  106   b  to a posterior edge  108   b  thereof thereby creating a relatively smooth medial surface  110   b  from which a keel  114  extends. The design of this augmented glenoid component  100   b , however, suffers from at least the same drawbacks as the glenoid components  100  and  100   a.    
     What is needed therefore is an augmented glenoid component that overcomes one or more of the above-mentioned drawbacks. What is further needed is an augmented glenoid component that is less susceptible to postoperative loosening relative to heretofore designed glenoid components. 
     SUMMARY OF THE INVENTION 
     The subject invention is a glenoid component and associated method for securement thereof to a glenoid surface of a scapula. Particularly, the subject invention is an augmented glenoid component and associated method for securement thereof to a glenoid surface of a scapula. More particularly, the subject invention is an augmented glenoid component having an interruption or the like and an associated method for securement of the augmented glenoid component to a glenoid surface of a scapula. 
     In one form, the interruption is defined by a buttress, step, shoulder, ledge, interface or the like that extends from a surface of a component body that defines at least a portion of the present augmented glenoid component. The body may also include anchoring. In one form, the anchoring of the body may comprise one or more anchors. An anchor may extend entirely from the surface of the body, entirely from the interruption, or from both the interruption and the surface (i.e. straddling). 
     In accordance with an embodiment of the subject invention, there is provided an augmented glenoid component for securement to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component includes a body and a buttress. The body has a first body surface configured to contact the glenoid surface of the scapula, and a second body surface configured to be contacted by the head portion of the humerus. The buttress is formed in the first body surface of the body. 
     In accordance with another embodiment of the subject invention, there is provided an augmented glenoid component for securement to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component includes a body, medial surface on the body, a humerus surface on the body, an interruption, and anchoring. The medial surface is configured to contact the glenoid surface of the scapula. The humerus surface is configured to be contacted by the head portion of the humerus. The interruption extends from the medial surface and defines a first interruption surface positioned relative to the medial surface at an angle θ in which 45°≦θ≦135°, and a second interruption surface positioned relative to a line parallel to the first body surface an angle φ in which 0°≦φ≦90°. 
     In accordance with a further embodiment of the subject invention, there is provided a method of securing an augmented glenoid component to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component has: (i) a body having: (a) a first body surface configured to contact the glenoid surface of the scapula, and (b) a second body surface configured to be contacted by the head portion of the humerus; and (ii) a buttress extending from the first body surface. The method includes the steps of (a) forming a buttress-shaped recess in the glenoid surface of the scapula; and (b) securing the augmented glenoid component to the glenoid surface of the scapula such that: (i) the first body surface is positioned in contact with the glenoid surface of the scapula, and (ii) the buttress is positioned in the step-shaped recess. 
     In all embodiments, the present augmented glenoid component provides good stabilization after implant. Further, the present augmented glenoid component converts normal high shear loads into compressive loading thereby reducing stress on the glenoid component. The present augmented glenoid component may be used to correct bone defects or wear. 
     It is therefore an object of the subject invention to provide a new and useful augmented glenoid component. 
     It is moreover an object of the subject invention to provide an improved augmented glenoid component. 
     It is a further object of the subject invention to provide a new and useful method of securing an augmented glenoid component to a glenoid surface of a scapula. 
     It is also an object of the subject invention to provide an improved method of securing an augmented glenoid component to a glenoid surface of a scapula. 
     It is yet another object of the subject invention to provide an augmented glenoid component and method of securing the same to a glenoid surface of a scapula that is less susceptible to post-operative loosening relative to heretofore designed glenoid components and methods of implanting the same. 
     The above and other objects, features, and advantages of the subject invention will become apparent from the following description and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a side sectional view of a prior art augmented glenoid component; 
     FIG. 1B is a side sectional view of another prior art augmented glenoid component; 
     FIG. 1C is a side sectional view of another prior art augmented glenoid component; 
     FIG. 2 is an exploded perspective view showing an augmented glenoid component that incorporates the features of the subject invention positioned between a prepared glenoid surface of a left scapula and a humeral component; 
     FIG. 3 is a bottom, right-angled perspective view of an embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 4 is a bottom, left-angled perspective view of the augmented glenoid component of FIG. 3; 
     FIG. 5 is a front plan view of the augmented glenoid component of FIG. 3; 
     FIG. 6 is a bottom plan view of the augmented glenoid component of FIG. 3; 
     FIG. 7 is a side plan view of the augmented glenoid component of FIG. 3; 
     FIG. 8 is a front plan view of another embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 9 is a bottom plan view of the augmented glenoid component of FIG. 8; 
     FIG. 10 is a side plan view of the augmented glenoid component of FIG. 8; 
     FIG. 11 is a bottom, right-angled perspective view of the augmented glenoid component of FIG. 8; 
     FIG. 12 is a bottom, right-angled perspective view of another embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 13 is a bottom, right-angled rear perspective view of the augmented glenoid component of FIG. 12; 
     FIG. 14 is a side plan view of the augmented glenoid component of FIG. 12; 
     FIG. 15 is a bottom plan view of the augmented glenoid component of FIG. 12; 
     FIG. 16 is a side plan view of the augmented glenoid component of FIG. 12; 
     FIG. 17 is a side plan view of an other embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 18 is a side plan view of another embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 19 is a bottom plan view of the augmented glenoid component of FIG. 18; 
     FIG. 20 is a side plan view of the augmented glenoid component of FIG. 18; 
     FIG. 21 is a bottom, right-angled perspective view of the augmented glenoid component of FIG. 18; 
     FIG. 22 is an exploded side view of a two-part embodiment of an augmented glenoid component in accordance with the present principles showing a backing member as one part thereof in cross-section; 
     FIG. 23 is a bottom plan view of the backing member of FIG. 22 taken along line  23 — 23  thereof, as viewed in the direction of the arrows; 
     FIG. 24 is a top plan view of the backing member of FIG. 22 taken along line  24 — 24  thereof, as viewed in the direction of the arrows; 
     FIG. 25 is a cross-sectional view of the backing member of FIG. 24 taken along line  25 — 25  thereof, as viewed in the direction of the arrows; 
     FIG. 26 is a bottom plan view of another embodiment of an augmented glenoid component in accordance with the present principles; 
     FIG. 27 is a bottom plan view of another embodiment of an augmented glenoid component in accordance with the present principles; and 
     FIG. 28 is a perspective view of a scapula having been prepared for securement of an augmented glenoid component in accordance with the present principles. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Like reference characters tend to indicate like parts throughout the several views. 
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein by described in detail. It should be understood, however, that there is no intent to limit the invention 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. 
     Referring now to FIG. 2, there is shown a general augmented glenoid component  10  in accordance with the present principles located between a glenoid surface  12  of a left scapula  14  and a humeral component  16 . The augmented glenoid component  10  is representative of ail embodiments of augmented glenoid components described herein. The humeral component  16  has been implanted or otherwise secured to a humerus  18 . As shall be discussed below in greater detail, the glenoid component  10  is configured to be secured to the glenoid surface  12  of the scapula  14  with or without the use of bone cement in order to replace the natural glenoid surface  12  during a total shoulder replacement procedure. In such a manner, the augmented glenoid component  10  functions as a “replacement” bearing surface  44  for receiving a head portion (a prosthetic head portion) of the humerus  18  (as shown, a prosthetic head portion  20  attached to a stem  17  of the prosthetic humeral component  16  implanted in the humerus  18 ). A surface  46  of the augmented glenoid component contacts the glenoid surface  12 . 
     In FIG. 2, the glenoid surface  12  has been prepared to receive the augmented glenoid component  10 . Particularly, a notch  13  has been removed from the glenoid surface  12  to correspond in configuration to the augmented glenoid component  10 . Additionally, a plurality of bores  15  have been prepared in the glenoid surface  12 . The bores  15  are configured to receive anchors or anchoring of the augmented glenoid component  10  as discussed below. 
     Referring to FIGS. 3-7, there is shown an embodiment of the general glenoid component  10  shown in FIG.  2 . The augmented glenoid component  10  includes a body  22  having a concave surface  26  on one end thereof. The concave surface  26  of the body  22  provides a smooth bearing surface for the head portion  20  of the humeral component  16  implanted into the humerus  18 . As such, the concave surface  26  is configured with the same or greater curvature (with respect to the concavity thereof) as the curvature (with respect to the convexity thereof) of the head portion  20 . 
     The body  22  includes an interruption in the form of a buttress, step, ledge or the like  24  on or from a body or medial surface  32  that defines a top surface  28  and a side surface  30 . The top surface  28  is preferably substantially flat, but may be rounded or convex. The side surface  30  extends from the medial surface  32  to the top surface  28 . The medial surface  32  is preferably rounded or convex as best seen in FIG. 5 but may be flat. The side surface  30  is shown substantially perpendicular to the top surface  28  and the medial surface  32 . The side surface  30 , however, may be angled relative to both surfaces  28  and  32  within an angle of 45° to 135°, inclusive. 
     The augmented glenoid component  10  also includes an anchor peg  34 . The anchor peg  34  extends essentially perpendicular to the body surface  32 . The anchor peg  34  includes a rounded head  36  that provides easier insertion into a hole or bore that has been drilled or otherwise formed in the glenoid surface  12  of the scapula  14 . While not necessary, the glenoid component  10  is shown to include a plurality of stabilizing posts or pegs  38 . Two pegs  38  are shown extending substantially perpendicular to the medial surface  32 , while two pegs  38  are shown extending substantially perpendicular to the top surface  28 . The length of the pegs  38  is preferably less than the length of the anchor peg  34 . As well, the length of the pegs  38 , regardless of position, are preferably essentially the same length relative to the replacement bearing surface  46 , or of the ending length. The stabilizing pegs  38  are received into a number of respective stabilizing holes  15  (see FIG. 2) that are drilled or otherwise formed or prepared in the glenoid surface  12  of the scapula  14 . 
     Although it is contemplated that the anchor peg  34  and/or any one or all of the stabilizing pegs  38  may be embodied as separate components that are secured to the body  22 , the anchor peg  34  and any stabilizing pegs are preferably integrally formed with one another and the body  22 . In one exemplary embodiment, the body  22 , the anchor peg  34 , and the stabilizing pegs  38  are integrally molded using a polymeric material such as polyethylene or ultra-high molecular weight polypropylene (UHMWPE). As well, the augmented glenoid component  10  may be formed of a plastic, a ceramic, or a composite material. Examples of these materials include a polyethylene, alumina, zirconia, and alumina/zirconia composite or composite material. 
     The buttress  24  extends a height or length relative to the body surface  32  that is preferably less than the length of the anchor peg  34 . It should be appreciated that the length or height of the buttress may be longer or shorter depending on design choices as well as outer configuration and/or size. 
     The anchor peg  34  is herein shown in the figures to include two rings  40 . However, it should be appreciated that the anchor peg  34  may be embodied to include any number of rings or no rings at all. For example, the anchor peg  34  may be embodied to include only a single (i.e. one) ring  40 . In addition, although each of the rings  40  is herein shown in the figures to possess the same sized outer diameter, it should be appreciated that other ring or ring-like configurations such as fins (see FIG. 17) are also contemplated for use with the augmented glenoid component  10 . For example, the rings  40  may be provided in a tapered configuration in which the respective outer diameters of the rings  40  gradually increases from the distal end of the anchor peg  34  to the proximal end portion of the anchor peg  34  (i.e. the ring positioned on the distal end of the anchor peg  34  has a smaller diameter relative to the ring positioned on the proximal end of the anchor peg  34 ). In such a configuration, an anchor hole drilled in the scapula  14  would be drilled in a similarly tapered manner so as to provide a corresponding sidewall configuration for engagement by the rings  40 . 
     Although it is contemplated that the rings  40  may be embodied as separate components that are secured to the anchor peg  34 , the rings  40  are preferably integrally formed with the anchor peg  34 . Consistent with that described above, in one exemplary embodiment, the rings  40  are integrally molded with the anchor peg  34  (and hence also integrally molded with the body  22  and the stabilizing pegs  38  of the glenoid component  10   a ). 
     The rings  40  may be configured to slightly deform in a cementless application (or in oversize holes for cementless applications) when the anchor peg  34  is inserted into an anchor hole. This is caused when the rings  40  are advanced into the anchor hole since it is preferably drilled so as to have a diameter which is slightly larger than the diameter of a shaft portion  35  of the anchor peg  34 , yet smaller than the outer diameter of the rings  40  thereby causing deformation of the rings  40  upon contact with the sidewalls of an anchor hole as the rings  40  are “forced” into the anchor hole. Such deformation of the rings  40  allows the rings  40  to secure the glenoid component  10   a  to the scapula  14  by providing resistance to removal or “pull out” of the anchor peg  34  from the anchor hole much in the same way that the threads of a screw provide resistance to pull out of the screw from the material into which it is driven. In addition, over a period of time subsequent to securement of the augmented glenoid component  10  to the scapula  14 , bone tissue or other types of tissue will grow into the spaces between the rings  40  thereby providing further resistance to pull out of the anchor peg  34  from the anchor hole. 
     Such a configuration of the rings  40  and/or the buttress  24  as described above eliminates the need for the use of bone cement to secure the augmented glenoid component  10  to the glenoid surface  12  of the scapula  14  thereby reducing the complexity of a typical total shoulder replacement procedure along with eliminating any potential shortcomings associated with the use of bone cement. In particular, the above-described configuration of the buttress  24  provides a glenoid component  10  that “locks” into place upon insertion into the glenoid component  10  in the scapula  14 . It is contemplated, however, that bone cement may be used if desired. 
     The stabilizing pegs  38  are not necessary but are preferably provided to help prevent rotation or other types of movement of the body  22  of the augmented glenoid component  10  in addition to the buttress  24  relative to the scapula  14  once the glenoid component  10  has been secured to the glenoid surface  12 . The distal end of each of the stabilizing pegs  38  has a conical tip  39 . The conical tip  39  functions as a “lead in” to facilitate insertion of the stabilizing pegs  38  into respective stabilizing holes drilled in the glenoid surface  12  of the scapula  14 . 
     The stabilizing pegs  38  may be arranged in any orientation on the body  22  that fits the needs of an embodiment herein of an augmented glenoid component. In addition, it should be appreciated that any number of stabilizing pegs  38  may be utilized to fit the needs of a given augmented glenoid component. In particular, although the augmented glenoid component  10  is described herein as having four stabilizing pegs, and has significant advantages thereby in the present invention, it should be appreciated that the augmented glenoid component  10  may be alternatively embodied to include none or any number of stabilizing pegs  38 . 
     Referring now to FIGS. 8-11 there is shown another embodiment of an augmented glenoid component that is generally designated  10   a . The augmented glenoid component  10   a  includes a body  50  having a concave surface  52  on one end thereof. The concave surface  52  of the body  50  provides a smooth bearing surface for the head portion  20  of the humeral component  16  implanted into the humerus  18 . As such, the concave surface  52  is configured with the same or greater curvature (with respect to the concavity thereof) as the curvature (with respect to the convexity thereof) of the head portion  20 . 
     The body  50  includes an interruption in the form of a buttress, step, ledge or the like  54  on or from a medial or body surface  60  that defines a top surface  56  and a side surface  58 . The top surface  56  is preferably substantially flat, but may be rounded or convex. The side surface  58  extends from the medial surface  60  to the top surface  56 . The medial surface  60  is preferably rounded or convex as best seen in FIG. 8 but may be flat. The side surface  58  is shown substantially perpendicular to the top surface  56  and the medial surface  60 . The side surface  58 , however, may be angled relative to both surfaces  56  and  60  within an angle of 45° to 135°, inclusive. 
     The augmented glenoid component  10   a  also includes a keel  62 . The keel  62  extends essentially perpendicular to the body surface  60 . The keel  62  includes a tapered end  64  that provides easier insertion into a like-configured hole that has been drilled or otherwise formed or prepared in the glenoid surface  12  of the scapula  14 . 
     Although it is contemplated that the keel  62  may be embodied as a separate component that is secured to the body  50 , the keel  62  is preferably integrally formed with the body  50 . In one exemplary embodiment, the body  50  and the keel  62  are integrally molded using a polymeric material such a polyethylene or an ultra-high molecular weight polypropylene (UHMWPE). As well, the glenoid component  10   a  may be formed of a plastic, a ceramic, or a composite material. Examples of these materials include a polyethylene, alumina, zirconia, and alumina/zirconia composite or composite material. 
     The buttress  54  extends a height or length relative to the medial surface  60  that is preferably less than the keel  62 . It should be appreciated that the length or height of the buttress  54  may be longer or shorter depending on design choices. It should also be appreciated that the augmented glenoid component  10   a  does not show any stabilizing pegs. However, the augmented glenoid component  10   a  may include stabilizing pegs that may extend from the top surface  56  of the buttress  54 . 
     Referring to FIGS. 12-16, there is depicted another embodiment of an augmented glenoid component, generally designated  10   b . The augmented glenoid component  10   b  includes generally the same features and/or components as the augmented glenoid component  10  of FIGS. 3-7. In this embodiment, however, the anchor peg  34  extends from both the buttress  24  and the medial surface  32 . Stated in another way, the anchor peg  34  straddles the buttress  24  and the medial surface  32 . Additionally, the augmented glenoid component  10   b  has three (3) pegs  38 . One of the pegs  38  extends from the medial surface  32 . Another one of the pegs  38  extends from the buttress. Another one of the pegs  38  straddles the buttress  24  and the medial surface  32 . 
     FIG. 17 depicts yet another embodiment of an augmented glenoid component, generally designated  10   c . The augmented glenoid component  10   c  is essentially the same as the augmented glenoid component  10   b  of FIGS. 12-16, with the exception of the anchor peg  34 . The anchor peg  34  of the augmented glenoid component  10   c  includes a plurality of radial fins or the like  66 . The fins  66  are deformable. This allows the anchor peg  34  to fit into an anchor bore in the glenoid surface  12  of the scapula  14 , but aid in preventing the easy removal thereof. 
     Referring to FIGS. 18-20, there is depicted another embodiment of an augmented glenoid component, generally designated  10   d . The augmented glenoid component  10   d  is generally the same as the augmented glenoid component  10   a  of FIGS. 8-11. In this embodiment, however, the keel  62  straddles the buttress  54  and the medial surface  60 . The keel  62  is thus essentially centered on the medial surface  60  of the body  52 . 
     Referring now to FIGS. 22-25, there is depicted another embodiment of an augmented glenoid component generally designated  10   c . The augmented glenoid component  10   c  is formed of two pieces or components, namely a backing member  70  and a backing member insert  72 . The backing member  70  is adapted to be affixed or mounted to the glenoid surface  12  of the scapula  14 , while the backing member insert  72  is adapted to be attached to the backing member  70 . 
     The backing member  72  is preferably formed of a plastic, a ceramic, or a composite. Examples of these materials may be a polyethylene, alumina, zirconia, and alumina/zirconia composite or composite material. The backing member  70  is preferably formed of a metal, a ceramic, a composite, or a biological material. Examples of a biological material of the backing member  70  are bone, bone graft, or bone substitute material. Examples of a metal of the backing member  70  are titanium alloy, cobalt alloy, cobalt chromium, or stainless steel alloy. An example of ceramic of the backing member  70  includes alumina, zirconia or an alumina/zirconia composite ceramic. An example of the composite of the backing member  70  includes a carbon fiber/PEEK composite. 
     The backing member insert  70  includes a body  74  having a concave surface  76  on one end thereof. The concave surface  76  of the body  70  provides a smooth bearing surface for the head portion  20  of the humeral component  16  implanted into the humerus  18 . As such, the concave surface  76  is configured with the same or greater curvature (with respect to the concavity thereof) as the curvature (with respect to the convexity thereof) of the head portion  20 . The backing member insert  72  also includes a peripheral slot  78  that is adapted to allow the backing member insert  72  to be received and held by the backing member  70  in a manner as described below. 
     The backing member  70  has a body  80  having an interruption formed as a buttress, step, ledge or the like  86  that defines a top surface  90  and a side surface  88 . The top surface  90  is preferably substantially flat, but may be rounded or convex. The side surface  88  extends from a body surface  92  to the top surface  90 . The body surface  92  is preferably rounded or convex as best seen in FIG.  25 . The side surface  88  is shown substantially perpendicular to the top surface  90  and the body surface  92 . The side surface  88 , however, may be angled relative to both surfaces  90  and  92  within an angle of 45° to 135°, inclusive. 
     As best seen in FIG. 25, the backing member  70  includes a horseshoe-shaped rim  84  that defines a horseshoe-shaped slot  82 . The rim  84  and slot  82  cooperate/are adapted to slidingly receive the backing member insert  72 . In particular, a portion  75  of the backing member insert  72  is received in the slot  82  while the rim  84  engages the slot  78  of the backing member  72 . It should be appreciated that the backing member  70  is first affixed to the scapula  14  before the backing member insert  72  is attached thereto. As explained in greater detail below, the backing member  70  is affixed to the scapula  14  via fasteners. Of course, other types of connectors may be used for the backing member  70  and the backing member insert  72 . 
     The backing member  70  also includes a plurality of bores  94  each of which is adapted to allow a screw, nail, or other fastener to extend therethrough. In this manner, the backing member  70  is secured to the glenoid area  12  of the scapula  14 . The backing member  70  is shown with three bores  94  through the buttress  86 , and three bores  94  through the body surface  92 . It should be appreciated that the backing member  70  may contain more or less bores, in various places. Preferably, the middle two bores are substantially perpendicular to the buttress top surface  90 , while the outer bores are angled outwardly. Such configuration provides a secure attachment of the backing member  70  to the glenoid surface  12  of the scapula  14 . 
     Referring to FIG. 26, there is shown another embodiment of a backing member, generally designated  120 , in like kind to the backing member  70  of FIGS. 22-25. The backing member  120  includes a body  122  having a horseshoe-shaped slot  124  surrounded by a horseshoe-shaped rim  126 . The slot  124  and rim  126  are configured to receive a backing member insert (not shown) in like kind to the backing member insert  72  of FIG.  22 . 
     In accordance with an aspect of the present invention, the backing member  120  has a buttress  128  that covers approximately one-half of the body  122  or of a medial surface  132 . The buttress  128  defines a side surface  129  that is preferably essentially perpendicular to a preferably, but not necessarily, convex or rounded medial surface  132 . The side surface  129 , however, may be within an angle of 45° to 135°, inclusive (i.e. the side surface defines an angle θ, wherein 45°≦θ≦135°, with respect to the medial surface  132 ). The buttress  128  also includes a plurality of bores  130 . The bores  130  are configured to allow fasteners to extend therethrough and capture the ends thereof in order to affix the body  122  onto the glenoid surface  12  of the scapula  14 . The backing member  120  further includes a keel  134  in like kind to the keel  62  of FIGS. 8-11 and FIGS. 18-21. The keel  134  extends substantially perpendicular from the medial surface  132  and the buttress  128  in a straddling manner. 
     FIG. 27 provides another alternative embodiment of the backing member  120 . In particular, the backing member  120   a  of FIG. 27 includes many of the same features as the backing member  120  with the exception of the keel  134 . Rather than a keel, the backing member  120   a  includes an anchor peg or post  136  in like kind to the post  34  of FIGS. 3-7. The anchor peg  136  is preferably configured in the same manner as the anchor peg  34  and extends substantially perpendicular to the medial surface  132   a  and the buttress  128   a  in a straddling manner. In addition, the backing member  120   a  includes a pair of stabilizing posts or pegs  138  in like kind to the stabilizing posts  38  of FIGS. 3-7. In the present case, however, one stabilizing post  38  extends outwardly from the medial surface  132   a , while another stabilizing post  38  straddles the buttress  128   a  and the medial surface  132   a . The backing member  120   a  further includes a bore  130   a  extending through the buttress  128   a.    
     USE OF THE PRESENT INVENTION 
     The augmented glenoid component  10  of the present invention is utilized in the performance of a total shoulder replacement procedure in order to provide an artificial bearing surface for the head portion of the humerus with or without the use of bone cement. Referring to FIG. 28, there is depicted a left scapula  14  in which an augmented glenoid component  10  will be affixed. 
     In particular, an anchor hole  152  and stabilizing holes are drilled or otherwise formed in the glenoid surface  12  of the scapula  14  by use of a suitable drilling tool (as represented by the drill bit  150 ). For those augmented glenoid components having a keel or other type or style of main anchor or stabilizer, a complementary recess is formed in the glenoid surface  12 . It should be appreciated that a drill guide or pattern (not shown) may be utilized to properly position and align the holes on the glenoid surface of the scapula  14 . Further, the anchor hole  152  is drilled to accommodate the anchor peg of the glenoid component, or a keel (in which case the “hole” is shaped to accept the configuration of the keel). Alternatively, various holes may be formed in the scapula  14  to accommodate fasteners rather than pegs, when utilizing a two-part glenoid component having a backing member. 
     In addition to any holes to accommodate pegs and/or a keel, a notch  154  is formed to accommodate the buttress of the glenoid component. This may be accomplished utilizing an appropriate saw, reamer, router or the like. Typically, the notch  154  is formed at a posterior location of the glenoid surface  12  of the scapula  14 . 
     Once any holes and the notch  154  have been formed in the glenoid surface  12  of the scapula  14 , the glenoid component  10  is secured to the scapula  14 . In particular, the glenoid component  10  is oriented such that the buttress is received in the notch  154  and any anchor peg, keel, and/or stabilizing pegs are received in the respective holes (or in the case of fasteners, that the holes in the backing member are oriented over the holes in the scapula). Thereafter, the glenoid component  10  is advanced toward the glenoid surface  12 . 
     Hence, insertion of the buttress into the notch  154  retains the body of the glenoid component  10  into contact with the glenoid surface  12  of the scapula  14 . Moreover, insertion of the anchor peg, keel and/or stabilizing pegs into corresponding holes in the manner described above prevents rotation or other types of movement of the body of the glenoid component  10  relative to the glenoid surface  12  of the scapula  14 . 
     Once the glenoid component  10  has been secured to the glenoid surface  12  of the scapula  14  in the manner described, the concave surface  26  of the body  22  of the glenoid component  10  provides a bearing surface for receiving the head portion  20  of the humeral component  16  implanted in the humerus  18 . In such a manner, the concave surface  26  of the body portion  22  functions as a suitable artificial replacement for the natural glenoid surface  12  of the scapula  14 . 
     While the invention 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 the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 
     There are a plurality of advantages of the present invention arising from the various features of the glenoid component described herein. It will be noted that alternative embodiments of the glenoid component of the present invention 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 a glenoid component that incorporate one or more of the features of the present invention and fall within the sprit and scope of the present invention as defined by the appended claims. 
     For example, the embodiment of one bearing component in accordance with the concepts of the present invention has herein been described in regard to the glenoid component  10 . However, it should be appreciated that the concepts of the present invention may also be incorporated into an acetabular, patellar, femoral, humeral, tibial, ulnar, radial, wrist, and/or ankle component for a prosthetic joint assembly.