Modular glenoid prosthesis

0001The present invention relates generally to the field of orthopaedics, and more particularly, to an implant for use in arthroplasty.

0002During 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'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.

0003As 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'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'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.

0004Referring now to <figref idref="f0008">FIG. 4</figref> a prior art glenoid implant 1 is shown. Implant 1 includes a metal body to which a polyethylene glenoid bearing 3 is attached. A plurality of screws are used to secure the metal body to the glenoid. A central peg 5 may also be used to assist in securing the implant 1 to the glenoid.

0005Referring now to <figref idref="f0007">FIG. 3</figref> a prior art glenoid bearing is shown as plastic glenoid bearing 6. The plastic glenoid bearing 6 includes a body 7 from which a plurality of pegs 8 extend. The plastic glenoid bearing 6 may also include a central peg 9, which likewise extends from the body 7 of the plastic glenoid bearing 6.

0006Referring now to <figref idref="f0008">FIG. 4</figref>, a prior art glenoid bearing is shown as metal backed glenoid bearing 1. The metal backed glenoid 1 includes a metal backing 2 and a plastic bearing 3. Screws 4 are used to secure the metal backing 2. A central post 5 may also be used to secure the metal backing 2.

0007Total shoulder replacement surgery includes the replacement of the humeral component and the glenoid component. The glenoid component is often the cause for a need of a revision. The need of a revision for a glenoid component is often due to the loosening of the glenoid component. Although there are many potential causes for loosening, there are no adequate solutions to the problem.

0008Polyethylene glenoid components may wear and the polyethylene wear may lead to osteolysis and to aseptic wear loosening. Glenoid components have been provided which include a metal backing for fixation to the scapula and traditional snapped-in polyethylene components secured to the metal backed glenoid. These metal backed glenoids get better fixation, but tend to fail by polyethylene component disassociation from the metal backing. For a glenoid to be successful, the implant must be well fixed and the polyethylene must not disassociate itself from other components such as its metal backing.

0009<patcit id="pcit0001" dnum="EP0339530A"><text>EP-A-0339530</text></patcit> discusses an endoprosthesis for a joint. A joint pan part comprises a piece attached to a bone and an adaptation part. Two different adaptation parts are provided.

0010<patcit id="pcit0002" dnum="US20030055507A"><text>US-A-2003/0055507</text></patcit> discusses a modular prosthesis. The modular prosthesis comprises a base and a cap. The base has three stems that engage the glenoid cavity at defined holes adapted to receive the stems.

0011<patcit id="pcit0003" dnum="FR2776506"><text>FR-2776506</text></patcit> discusses a glenoid member of a prosthesis. It includes an anchor in the form of a central keel, a side lug with holes, joined by a screw inserted transversely through the bone.

0012<patcit id="pcit0004" dnum="FR2704747"><text>FR-2704747</text></patcit> relates to a support intended to receive a glenoid element. It is fixed in the glenoid cavity of the shoulder by diametrically arranged divergent screws in combination with a central, cylindrical and hollow stud.

0013<patcit id="pcit0005" dnum="US4550450A"><text>US-4550450</text></patcit> discusses a total shoulder prosthesis system. A glenoid articulator surface comprises a trapezoidal fixation keel.

0014In one aspect, the present invention provides a glenoid implant assembly as defined in appended claim 1 comprising: <ul id="ul0001" list-style="none" compact="compact"><li>a first component for attachment to the glenoid fossa of a scapula, said component defining an assembly face thereof; and</li><li>a second component removably secured to said first component, said second component including an assembly face thereof, the assembly face of said second component in close approximation to the assembly face of said first component said, second component attachable to said first component in a direction generally normal to the assembly faces; wherein the first component comprises an augmentation for replacing a void in the scapula caused by abnormal wear of the glenoid fossa.</li></ul>

0015The implant assembly of the invention can be used in a method for performing arthroplasty on a glenoid fossa of a scapula comprising the steps of: <ul id="ul0002" list-style="none" compact="compact"><li>providing a first glenoid component for attachment to the glenoid;</li><li>attaching the first glenoid component to the glenoid;</li><li>providing a second glenoid component for attachment to the first glenoid component; and</li><li>attaching the second glenoid component to the first glenoid component in a direction generally normal to the longitudinal axis of the first glenoid component.</li></ul>

0016The technical advantages of the present invention further include the ability to use the glenoid implant assembly of the present invention to correct defective glenoids with posterior erosion. According to the present invention a glenoid implant assembly is provided including a first component for attachment to the glenoid fossa of a scapula. The first component includes an augmentation or an additional portion for compensating for a void in the scapula. The glenoid implant assembly further includes a second component removeably secured to the first component. Thus the present invention provides for a glenoid implant assembly that can be used with posterior erosion.

0017The glenoid component of the invention is designed to have a portion that is used as a removable articular component, which is a standard component to be used with a total shoulder replacement system. The removable articular component may be selectively utilized with any of several fixation components. The components may be selected relative to specific applications for which they are intended. A fixation component of the glenoid prosthesis had a surface which interfaces with the supporting bony structure. The fixation components may be shaped relative to the specific condition.

0018The removable articular bearing component may have a composite structure including a molded metal back poly-bearing surface. The removable articular bearing component may engage the metal fixation component via a simple selectively releasable locking means. Such a selectively releasable locking means may be in the form for example a taper fit, for example a Morse taper.

0019Alternatively, the removable articulating bearing component may be replaced with a spherically convex component for use in reverse shoulder arthroplasty. This reverse shoulder spherical component may be reversibly locked to any of the fixation components.

0020The invention may permit a surgeon to implant a traditional anatomic prosthesis and later convert the traditional total shoulder replacement with a reverse shoulder if the patient's condition warrants it.

0021The modular glenoid prosthesis provided by the invention can include a replaceable moulded backed polyethylene component that can be reversibly locked into a metal fixation component. The metal fixation component may be of a standard type or may be designed to treat a more pathologic shoulder condition such as a posteriorly eroded glenoids or glenoids with other large bony defects.

0022The metal fixation component may have a feature, such as a taper, for example a Morse taper, for reversibly locking the metal fixation component to the polyethylene component. The locking feature may additionally be used with a convex spherical component for use with reverse shoulder prosthesis permitting a surgeon to implant a traditional anatomic implant and then later, as the patient's conditions warrant, convert the total shoulder arthroplasty to a reverse prosthesis or vice versa.

0023The articulating surface of the modular glenoid component of the present invention may be made of a polyethylene, for example an ultra-high molecular weight polyethylene, and may be made of a cross-linked polyethylene. The cross-linked, ultra-high, molecular weight polyethylene should provide decreased wear and thus permit a thinner glenoid be used. The polyethylene may be molded to a porous coated spherical surface and the porous coating may be, for example, sintered to a thin metal substrate. The substrate may have a feature on the opposite side of the porous coating designed for locking the component to mating feature on a metal fixation component. The metal fixation component and the metal backed polyethylene component provide an example of a molded metal backed poly-bearing component according to the present invention.

0024The bearing component of the present invention may be in the form of other embodiments that may include alternative materials such as metal or ceramic for the articulating surface. The metal fixation component may have a spherically shaped surface that conforms to the convex spherical shape of the polyethylene molded metal backed component. The fixation component may have a finite thickness and the opposite side of the component, the side that will interface with the bony surface of the scapula, may be porous coated for enhanced fixation. Screw holes may be positioned in the fixation component to permit good internal fixation. The bony interfacial surface may be conjured to fit several glenoid shapes. These shapes include glenoids that exhibit posterior erosion or other large defects. The metal fixation component may be porous coated or include other biologic factors to stimulate bone growth on the interfacial surface for enhanced fixation.

0025According to one embodiment of the present invention, there is provided a glenoid implant assembly. The assembly includes a first component for attachment to the glenoid fossa of a scapula. The component defines an assembly face of the component. The assembly also includes a second component removably secured to the first component. The second component includes an assembly face of the second component. The assembly face of the second component is in close approximation to the assembly face of the first component. The second component is attachable to the first component in a direction generally normal to the assembly faces.

0026According to another embodiment of the present invention there is provided a glenoid implant assembly. The glenoid implant assembly includes a first component for attachment to the glenoid fossa of a scapula. The first component defines an assembly face and attachment feature of the first component. The glenoid implant assembly also includes a second component removably secured to the first component. The second component includes an assembly face of the second component. The second component defines an attachment feature of the second component. The attachment feature of the second component adapted for attaching to the attachment feature of said first component in a direction generally normal to the assembly faces.

0027The technical advantages of the present invention include the ability to reduce problems with aseptic loosening of the glenoid. For example, according to one aspect of the present invention, a glenoid implant assembly is provided including a first component for attachment to the glenoid fossa of a scapula and a second component removably secured to the first component the second component is attachable to the first component in a direction generally normal to the assembly faces of the components. The portion of the first component for attachment to the glenoid fossa may include a surface, which assists in the prevention of the aseptic loosening of the glenoid. Thus the present invention provides for a reduction in the problem of aseptic loosening of glenoids.

0028The technical advantage of the present invention further include the ability of the present invention to reduce problems with the polyethylene bearing coming off the metal support. For example, according one aspect of the present invention, a glenoid implant assembly is provided including a first component for attachment to the glenoid fossa and a second component firmly secured to the first component. The second component is attached to the first component in a direction generally normal to the assembly faces of the first component and the second component. The polyethylene may be secured to the second component. The second component may include a feature on the context surface of the second component that engages the polyethylene to reduce the incidence of the polyethylene coming off of the second component. For example, the second component may include a porous or contoured surface with which the polyethylene may be inferenceably molded there to. Thus, the present invention provides for a reduction in the problems with the polyethylene component coming off of the metal support of the glenoid implant assembly.

0029The technical advantages of the present invention also include the replacement of the polyethylene without removal of the bone fixation of the glenoid component. For example, according to one aspect of the present invention, a glenoid component implant assembly is provided including a first component for attachment to the glenoid fossa and a second component removably secured to the first component. The second component is attachable to the first component in a direction generally normal to the assembly faces. The second component may include the polyethylene bearing connected to the second component. The second component including the polyethylene bearing may be removed from the second component and a second or replacement second component may be secured to the first component without removal of the bone fixation of the first component to the glenoid fossa of the scapula. Thus the present invention provides for the replacement of the polyethylene bearing without removal of the bone fixation of the glenoid implant assembly.

0030The technical advantages of the present invention include the ability of the glenoid implant assembly of the present invention to permit conversion to a reverse shoulder prosthesis. For example, according to one aspect of the present invention a glenoid implant assembly is provided including a first component for attachment to the glenoid fossa and a second component removably secured to the first component. The second component may be designed for a standard prosthesis. An alternative second component which is design for use with a reverse prosthesis may be replaced with the second component. Thus the present invention provides for the conversion of a glenoid implant assembly from a standard prosthesis to a reverse prosthesis.

0031The technical advantages of the present invention further include the ability to provide prosthetic components with improved materials without removal of the bone fixation of the glenoid implant assembly. For example, according to one aspect of the present invention a glenoid implant assembly is provided including a first component for attachment to the scapula and a second component removably attached to the first component. The second component may include a bearing surface which may be initially made of, for example, a polyethylene and may later replaced with a different, second component made of a different material, for example, a ceramics or a metal. Thus the present invention provides for replacement of the original articulating bearing material with a alternate material without removal of the bone fixation of the glenoid assembly.

0032Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: <ul id="ul0003" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a plan view partially in cross-section of a metal backed plastic articulating modular glenoid assembly with a tapered connection and a concave articulating surface given as an example, useful for understanding the present invention.</li><li><figref idref="f0002">FIG. 2</figref> is an exploded plan view of the metal backed plastic articulating modular glenoid assembly of <figref idref="f0001">FIG. 1</figref>;</li><li><figref idref="f0003">FIG. 2A</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with spaced apart components;</li><li><figref idref="f0004">FIG. 2B</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with a threaded connection;</li><li><figref idref="f0004">FIG. 2C</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with a press-fit connection;</li><li><figref idref="f0005">FIG.2D</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with a ribbed connection;</li><li><figref idref="f0005">FIG. 2E</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with a snap-fit connection;</li><li><figref idref="f0006">FIG. 2F</figref> is a plan view partially in cross-section of another example, useful for understanding the present invention in the form of a modular glenoid assembly with 2 connections;</li><li><figref idref="f0007">FIG. 3</figref> is a plan view partially in cross-section of an all plastic prior art glenoid component;</li><li><figref idref="f0008">FIG. 4</figref> is a plan view partially in cross-section of a metal backed prior art glenoid component;</li><li><figref idref="f0009">FIG. 5</figref> is a plan view partially in cross-section of the metal backed plastic articulating component of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref>;</li><li><figref idref="f0010">FIG. 6</figref> is a plan view partially in cross-section of a metal backed plastic articulating component of a modular glenoid assembly with a tapered connection and a convex articulating surface according to another example, useful for understanding the present invention;</li><li><figref idref="f0011">FIG. 7</figref> is a plan view partially in cross-section of the fixation component of the modular glenoid assembly 1 and 2;</li><li><figref idref="f0012">FIG. 8</figref> is a plan view partially in cross-section of a fixation component of a modular glenoid assembly with a tapered connection and with screw fixation for use with the articulation component of <figref idref="f0010">FIG. 6</figref> according to another example, useful for understanding the present invention;</li><li><figref idref="f0013">FIG. 9</figref> is a plan view partially in cross-section of a fixation component of a modular glenoid assembly with a tapered connection and with a posterior augmentation portion for use with the articulation component of <figref idref="f0010">FIG. 6</figref> according to the present invention;</li><li><figref idref="f0014">FIG. 9A</figref> is a bottom view of <figref idref="f0013">FIG. 9</figref>;</li><li><figref idref="f0014">FIG.9B</figref> is a bottom view of an elliptical modular glenoid assembly according to another embodiment of the present invention;</li><li><figref idref="f0015">FIG. 10</figref> is a plan view partially in cross-section of a fixation component of a modular glenoid assembly with a tapered connection and with a vault fixation portion and anti-rotation fins for use with the articulation component of <figref idref="f0010">FIG. 6</figref> according to another example, useful for understanding the present invention;</li><li><figref idref="f0016">FIG. 10A</figref> is a bottom view of <figref idref="f0015">FIG. 10</figref>;</li><li><figref idref="f0017">FIG. 11</figref> is a plan view of a series of components that may form a kit with the components partially in cross-section including three fixation components of a modular glenoid assembly with a tapered connection, with an augmentation and with a vault fixation portion and two articulation components of a modular glenoid assembly with a convex articulation surface and with a concave articulation surface; and</li><li><figref idref="f0018">FIG. 12</figref> is a flow chart of a method for performing total shoulder arthroplasty in using the modular glenoid assembly.</li></ul>

0033Referring to the drawings, <figref idref="f0001">FIG. 1</figref> shows a glenoid implant assembly 10 which includes a first component 12 for attachment to the glenoid fossa 14 of a scapula 16. First component 12 defines an assembly face 18.

0034The glenoid implant assembly 10 further includes a second component 20. The second component 20 as shown in <figref idref="f0001">FIG. 1</figref> is removeably secured to the first component 12. The second component 20 includes an assembly face 22. The assembly face 22 of the second component 20 is in close approximation to the assembly face 18 of the first component 12. The second component 20 is attachable to the first component 12 in the direction of arrows 24 in a direction generally normal to the first assembly face 18 and the second assembly face 22.

0035As shown in <figref idref="f0001">FIG. 1</figref>, the first component 12 includes an attachment feature 26. The second component 20 may likewise include an attachment feature 28. The attachment feature 26 of the first component 12 may cooperative with the attachment feature 28 of the second component 20 to secure the second component 20 to the first component 12.

0036Referring now to <figref idref="f0002">FIG. 2</figref>, the glenoid implant assembly 10 is shown disassembled. As shown in <figref idref="f0002">FIG. 2</figref>, the first component attachment feature 26 may be in the form of a female taper 26 and the second component attachment feature may be in the form of a male taper 28. The female taper 26 and the male taper 28 are preferably designed for intimate engagement therebetween. It should be appreciated that alternatively the first component attachment feature may be in the form of a male taper or have a generally conifrustical shape. Similarly, the second component attachment feature may be in the form of a female taper or have a cavity defining a generally conifrustical shape. Periphery 30 of the second component attachment feature 28 may define an included angle q therebetween. The angle q is selected to provide engagement between the first component attachment feature 26 and the second component attachment feature 28. The angle q may be selected to provide for a secure or self-locking connection between the first component 12 and the second component 20. For a typical material and surface finish the angle q may be, for example, from about 0° to 25°. To provide for a self-locking taper the angle θ may be determined by maintaining the formula: <maths id="math0001" num=""><math display="block"><mi>tan</mi><mfenced separators=""><mi mathvariant="normal">θ</mi><mo mathvariant="normal">/</mo><mn mathvariant="normal">2</mn></mfenced><mo mathvariant="normal">≥</mo><mi mathvariant="normal">m</mi></math><img file="EP1639967B1_D0001.tif" /></maths> where: <ul id="ul0004" list-style="none" compact="compact"><li>θ = the included angle of the taper</li><li>m=coefficient of friction of the surface of taper</li></ul>

0037Referring now to <figref idref="f0003">FIG. 2A</figref> an alternate example of the glenoid implant assembly useful for understanding the present invention is shown in glenoid assembly implant 10A. Glenoid implant assembly 10A is similar to the glenoid implant assembly 10 of <figref idref="f0002">FIG. 2</figref> except that the glenoid implant assembly 10A configured such that the assembly face 18A of the first component 12A is spaced from or not in contact with the assembly face 22 of the second component 20A. The second component 20A is separated from by the first component 12A simply by the connection of the first component attachment feature 26A to the second component attachment feature 28A.

0038Referring now to <figref idref="f0004">FIG. 2B</figref> an alternate example, useful for understanding the present invention is shown as glenoid implant assembly 10B. Glenoid implant assembly 10B of <figref idref="f0004">FIG. 2B</figref> is similar to the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> except that the glenoid implant assembly 10B of <figref idref="f0004">FIG. 2B</figref> includes a threaded connection of the first component 12B to the second component 20B of a threaded connection.

0039The glenoid implant assembly 10B is similar to the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> and includes a first component 12B, which is secured to second component 20B. The glenoid implant assembly 10B has an attachment feature different than that of the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref>.

0040For example and is shown in <figref idref="f0004">FIG. 2B</figref> the glenoid implant assembly 10B includes a first component attachment feature 26B in the form of a cavity defining internal threads which mates with a second component attachment feature 28B in the form of external threads. The external threads 28B of the second component 20B are threadably engagable with the internal threads 26B of the first component 12B.

0041Referring now to <figref idref="f0004">FIG. 2C</figref> another example, useful for understanding the present invention is shown as glenoid implant assembly 10C. Glenoid implant assembly 10C is similar to the glenoid implant 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> and includes a first component 12C, which is matingly fitted to the second component 20C. The glenoid implant assembly 10C is different from the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> in that the glenoid implant assembly 10C includes a first attachment feature 26C in the form of a generally cylindrical opening as well as a second attachment feature 28C extending from the second component 20C in the form of a cylindrical protrusion. The first component 12C is secured to the second component 20C by an interference fit between the cylindrical opening on cavity 26C and the cylindrical protrusion 28C.

0042Referring now to <figref idref="f0005">FIG. 2D</figref> another example, useful for understanding the present invention is shown as glenoid implant assembly 10D. The glenoid implant assembly 10D includes a first component 12D which is secureably fastened to the second component 20D. The glenoid implant assembly 10D is different from the glenoid implant assembly 10 of <figref idref="f0001 f0002 f0003 f0004 f0005 f0006">FIGS. 1 to 2</figref> in that the glenoid implant assembly 10D includes a first component attachment feature 26D in the form of an internal groove formed into a cavity on the first component 12D which cooperates with an external rib 28D formed on a protrusion extending from second component 20D. The external rib 28D matingly fits into the internal groove 26D.

0043Yet another example, useful for understanding the present invention is shown as glenoid implant assembly 10E. The glenoid implant assembly 10E is similar to the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref>. For example, and is shown in <figref idref="f0005">FIG. 2E</figref>, the glenoid implant assembly 10E includes a first component 12E which is matingly secured to a second component 20E.

0044The glenoid implant assembly 10E is different from the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> in that the glenoid implant assembly 10E includes a first component attachment feature 26E in the form of an internal notch formed in the first component 12E which matingly engages with an external lip 28E formed on a protrusion extending from second component 20E. The internal notch 26E mates with the external lip 28E to form a secure connection of the first component 12E to the second component 20E.

0045Referring now to <figref idref="f0006">FIG. 2F</figref> another example, useful for understanding the present invention is shown as glenoid implant assembly 10F. The glenoid implant assembly 10F is similar to the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> and includes a first component 12F which is matingly secured to a second component 20F. The glenoid implant assembly 10F of <figref idref="f0006">FIG. 2F</figref> is different from the glenoid implant assembly 10 of <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> in that the glenoid implant assembly 10F has a pair or two separate attachment features.

0046For example and as shown in <figref idref="f0006">FIG. 2F</figref> the glenoid implant assembly 10F includes a first external protrusion 28F as well as a second spaced apart external protrusion 29F. Both protrusion 28F and 29F extend from the second component 20F. The first external protrusion 28F mates with first internal cavity 26F formed in the first component 12F. Similarly, a second internal cavity 27F is formed on the first component 12F and mates with second external protrusion 29F. Centerlines 30F of 31F of protrusion 28F and 29F respectively may be parallel to each other and may be normal to or at arcuate angle to the first component 12F. The arcuate angle may assist in minimally invasive procedures.

0047Referring now to <figref idref="f0009">FIG. 5</figref> the second component 20 of the modular glenoid assembly 10 is shown in greater detail. This second component 20 may be made of any suitable durable material and may for example be made of a metal, a composite, a ceramic or a plastic. The second component 20 is preferably made from a material that may be sterilized by a currently available sterilizing technique such as gas plasma, gamma irradiation, ETO, or by autoclaving.

0048The second component 20 may be of a one piece or unitary design or may, as shown in <figref idref="f0009">FIG. 5</figref>, be modular or made of more than one component. If made of more than one component, the second component 20 may include a first portion 32 which may include the external taper connection 28 and a second portion 34 connected to the first portion 32. Since, as is shown in <figref idref="f0009">FIG. 5</figref>, the first portion 32 includes the tapered connection 28, the first component 32 is preferably made of a rigid material to obtain a secure tapered connection to the first component 12. For example and as shown in <figref idref="f0009">FIG. 5</figref>, the first portion 32 may be in the form of a metal backing.

0049The first portion 32 may be made of any suitable durable material for example a metal. If made of a metal the metal backing 32 may be made for example a cobalt chromium alloy, a stainless steel alloy, or a titanium alloy. Metal backing 32 includes the assembly face 22 as well as a connecting face 36 opposed to the assembly face 22.

0050The connecting face 36 may include a feature 38 on the connecting face 36 for enhancing the securing of the second portion 34 of the second component 20 to the first portion 32 of the second component 20. The feature 38 may, for example, be in the form of a roughened surface or may include a coating, for example, a porous coating such as that on products sold by DePuy Orthopaedics Inc under the trade mark Porocoat and as disclosed in <patcit id="pcit0006" dnum="US3855638A"><text>US-3855638</text></patcit>.

0051The second portion 34 of the second component 20 may, as shown in <figref idref="f0009">FIG. 5</figref>, be in the form of a plastic bearing. The plastic bearing 34 may include a connecting face 40 for contact with the first portion 32. The contacting face 40 cooperates with contacting face 36 of the first portion 32. The plastic bearing 34 may also include a concave articulating surface 42 for cooperation with the humeral component of a total shoulder joint. The plastic bearing 34 may be made of any suitable, durable material and may, as shown in <figref idref="f0009">FIG. 5</figref>, be made of an ultra- high molecular weight polyethylene. For example, the ultra-high molecular weight polyethylene may be a cross-linked, ultra-high molecular weight polyethylene. For example the plastic bearing 34 may be made of a material in the form used in products sold by DePuy Orthopaedics Inc under the trade mark Marathon and as disclosed in <patcit id="pcit0007" dnum="US6281264B"><text>US-6281264</text></patcit>.

0052The second component 20 of the modular glenoid assembly 10 may have any suitable shape to form a glenoid for cooperation with a humeral component to form a total shoulder. For example, the second component 20, as shown in <figref idref="f0009">FIG. 5</figref>, may include the first portion 32 with the assembly face 22 of the second component 20 in having a generally convex surface defined by a portion of a sphere. For example, as shown in <figref idref="f0009">FIG. 5</figref>, the assembly face 22 may be defined by a radius R1 extending from origin 44. Similarly the first portion 32 of the second component 20 may further be defined by the connecting face 36 having a generally concave surface. The concave connecting face 36 may be in the form of a portion of a sphere and be defined by a radius R2 extending from the origin 44.

0053Similarly, the concave articulating surface 42 of the second portion 34 of the second component 20 may have a concave shape as shown in <figref idref="f0009">FIG. 5</figref> and may be defined by a portion of a sphere. The concave articulating surface 42 may be, for example, and as is shown in <figref idref="f0009">FIG. 5</figref> be defined by a radius R3 extending from origin 44.

0054It should be appreciated that the second portion 34 of the second component 20 of the modular glenoid assembly 10 which forms the articulating surface of the glenoid assembly 10 may be made of any suitable material that is proven to work as an articulating surface for an artificial joint. For example the second portion 34 may be made of a plastic, a metal, a composite, or a ceramic. In fact, a feature of the invention is that the second component 20 may be removed from the first component 12 in such a way that the first component 12 may remain secured to the glenoid fossa in order that a alternate or a replacement articulating surface may be placed in the patient while the first component 12 remains secured to this glenoid fossa.

0055Referring now to <figref idref="f0011">FIG. 7</figref> the first component 12 of the modular glenoid assembly 10 is shown in greater detail. The first component 12 of the modular glenoid assembly 10 may, as shown in <figref idref="f0011">FIG. 7</figref>, be unitary or of a one-piece construction. Alternatively, it should be appreciated, that the second component 12 may be made of a multiple components or may be modular.

0056The first component 12 may be made of a suitable, durable material capable for providing support. For the second component 20 for example and is shown in <figref idref="f0011">FIG. 7</figref>, the first component 12 is made of a metal. If made of a metal, the first component 12 may be made of, for example, cobalt chromium alloy, a stainless steel alloy, or a titanium alloy. It should be appreciated that the first component 12 may be made of a ceramic, a composite, or a plastic. The first component 12 as shown in <figref idref="f0011">FIG. 7</figref> includes a glenoid surface 46 which is opposed to the assembly face 18 of the first component 12. The glenoid surface 46 fits against the glenoid fossa 14 of the scapula 16.

0057The glenoid surface 46 may, as is shown in <figref idref="f0011">FIG. 7</figref>, include a fixation feature 48 located on the glenoid surface 46. The fixation feature 48 may be in the form for example a roughened surface or an exterior coating. For example the fixation feature 48 may be in the form of a coating applied to the surface 46 and may for example be a porous coating. If a porous coating the fixation feature 48 may be for example a Porocoat Ò porous coating.

0058The first component 12 of the modular glenoid assembly 10 may have any suitable shape and may as shown in FIG. 17 include the glenoid surface 46 having a generally convex surface. For example the glenoid surface 46 may be in the form of a portion of a sphere and may be defined by a radius R4 extending from origin 50. Similarly, the first component 12 may include the assembly face 18 having a generally concave shape. The assembly face 18, as shown in <figref idref="f0011">FIG. 7</figref>, may be in the form of a portion of a sphere and may be defined by radius R5 extending from origin 50.

0059In order for the first component 12 to include the attachment feature 26 in the form of an internal taper the first component 12 may include a protrusion 52 extending outwardly from the glenoid surface 46. The protrusion 52 may have a shape generally similar to the internal taper attachment feature 26. It should be appreciated that the protrusion 52 may have any shape capable of accommodating the attachment feature 26 and that the protrusion 52 may assist in providing anchoring of the first component 12 into the glenoid.

0060According to the present invention and referring to <figref idref="f0010">FIG. 6</figref>, another example, useful for understanding the present invention is shown as modular glenoid assembly 100. The modular glenoid assembly 100 includes a first component 112 which may be similar or even identical to the first component 12 of the modular glenoid assembly 10 of <figref idref="f0001">FIG.S 1</figref> and <figref idref="f0002">2</figref>. The modular glenoid assembly 100 includes a second component 120, which is different than the second component 20 of <figref idref="f0009">FIG. 5</figref>.

0061For example and is shown in <figref idref="f0010">FIG. 6</figref> the second component 120 includes a first portion 132 in the form of for example a metal backing. The metal backing 132 is similar to the metal backing or first portion 32 of the second component 20 of <figref idref="f0009">FIG. 5</figref>. The metal backing 132 includes the assembly face 122 as well as the opposed connecting face 136. The metal backing 132 also includes the external tapered portion 128, which extends from the assembly face 122.

0062The second component 122 also includes a second portion 134. The second portion 134 like the second portion 34 of the second component 20 of <figref idref="f0009">FIG. 5</figref> is made of a material suitable for prosthetic articulation. For example, the second portion 134 may be made of, for example, a metal, a plastic, or a ceramic. For example, the second portion 134 may be made of a plastic for example ultra-high molecular weight polyethylene, for example, a cross-linked, ultra-high molecular weight polyethylene. The second portion 134 includes a connecting face 140 which mates with connecting face 136 of the first portion 132. The second portion 134 also defines a convex articulating surface 142.

0063The convex articulating surface 142 may be generally convex and may, for example, be in the form of a portion of a sphere. For example the articulating surface 142 may be defined by a radius R6 extending from origin 156. Generally the connecting face 140 may be generally convex and may be in the form of a portion of a sphere. For example the connecting face 140 may be defined by a radius R7 extending from origin 158.

0064Referring now to <figref idref="f0012">FIG. 8</figref>, another example, useful for understanding the present invention is shown as modular glenoid assembly 200. The modular glenoid assembly 200 includes a second component or articulation component (not shown) which may be similar or identical to the second component 20 of <figref idref="f0009">FIG. 5</figref>. The modular glenoid assembly 200 further includes a first component or fixation component 212 as shown in <figref idref="f0012">FIG. 8</figref>. The fixation component 212 is generally similar to the first component 12 of <figref idref="f0011">FIG. 7</figref> and includes a concave assembly face 218.

0065The assembly face 218 may be in the form of a portion of a sphere and may be defined by a radius R8 extending from origin 250. Similarly, the fixation component 212 may include a glenoid surface 246 which may be convex. The glenoid surface 246 may, as shown in <figref idref="f0012">FIG. 8</figref>, be in the form of a portion of a sphere and be defined by a radius R9 extending from origin 250. The fixation component 212 may include a female taper 226 formed in protrusion 252 extending from the glenoid surface 246 of the fixation component 212.

0066Unlike the first component 12 of <figref idref="f0011">FIG. 7</figref>, the fixation component 212 of <figref idref="f0012">FIG. 8</figref> includes a first opening 260 and a spaced apart second opening 262. The openings 260 and 262 extend through the fixation component 212 from the assembly face 218 through the glenoid surface 246. The openings 260 and 262 are adapted to receive fasteners for assisting in the securement of the fixation component 212 to the glenoid fossa 14 of the scapula 16.

0067For example as shown in <figref idref="f0012">FIG. 8</figref> the modular glenoid assembly 200 further includes a first screw 264 which matingly fits with the first opening 260 of the first component 212. The modular glenoid assembly 200 also includes a second screw 266 which mates with second opening 262 in the first component 212. First screw 264 includes a first screw head 268 for securing the screw 264 to the fixation component 212. The first screw 264 further includes first screw threads 270 formed on first screw shank 272. Generally the second screw 262 includes a second screw head 274 for securement to the fixation component 212. The second screw 266 also includes second screw threads 276 formed on second screw shank 278.

0068According to the present invention and referring to <figref idref="f0013">FIG. 9</figref> the present invention is shown as modular glenoid assembly 300. The modular glenoid assembly 300 includes an articulating component (not shown) similar to or identical to the articulating component or second component 20 of <figref idref="f0009">FIG. 5</figref>. The modular glenoid assembly 300 also includes the first fixation component 312.

0069The first component 312 is somewhat similar to the first component 12 the modular glenoid assembly 10 of <figref idref="f0011">FIG. 7</figref> and includes a glenoid surface 346 for placement against the glenoid fossa 14 of the scapula 16 as well as an opposed assembly face 318 opposed to the glenoid surface 346. The first component 312 further includes a protrusion 352 extending from the glenoid surface 346. An internal taper 326 is formed in a cavity formed in the protrusion 352.

0070Unlike the modular glenoid assembly 10 of <figref idref="f0011">FIG. 7</figref>, the modular glenoid assembly 300 of <figref idref="f0013">FIG. 9</figref> further includes a augmentation 380. The augmentation 380 may be an anterior augmentation or as shown in <figref idref="f0011">FIG. 7</figref> be in the form of a posterior augmentation. Posterior augmentation 380 may have any suitable shape and is provided to fill or replace a void caused by abnormal wear of the glenoid fossa 14. For example and as is shown in <figref idref="f0013">FIG. 9</figref>, the augmentation 380 is in the form of a protrusion extending downwardly from the glenoid surface 346. The augmentation 380 defines an opening 382 through the augmentation 380. The opening 382 is adapted for receiving a augmentation screw 384 for assisting in securing the fixation component 312 to the scapula 16. The augmentation screw 384 may be any suitable bone screw for example a cancellous screw or a cortical screw.

0071Referring now to <figref idref="f0014">FIG. 9A</figref>, the fixation component 312 of the modular glenoid assembly 300 is shown in greater detail. The fixation component 312 includes the posterior augmentation 380 assisting in providing support to a posteriorly eroded glenoid. The augmentation 380 may extend for 90° or for 180° as shown in phantom or any angle inbetween.

0072Referring now to <figref idref="f0014">FIG. 9B</figref> an elliptical modular glenoid assembly 300B is shown. The assembly 300B is similar to the assembly 300A of <figref idref="f0014">FIG. 9A</figref> except it is elliptical.

0073Referring now to <figref idref="f0015">FIG. 10</figref> another example, useful for understanding the present invention is shown as modular glenoid assembly 400. The modular glenoid assembly 400 is similar to the modular glenoid assembly 10 of <figref idref="f0001">FIG.S 1</figref> and <figref idref="f0002">2</figref> and includes an articulation component (not shown) similar to or identical to articulation component 20 of the modular glenoid assembly 10 of <figref idref="f0009">FIG. 5</figref>. The modular glenoid assembly 400 further includes a fixation component 412 which is somewhat similar to the fixation component 12 of <figref idref="f0011">FIG. 7</figref>. The first component 212 includes an assembly face 418 as well as an opposed glenoid surface 446. The fixation component 412 further includes an attachment feature 426.

0074Referring now to <figref idref="f0015">FIGS. 10</figref> and <figref idref="f0016">10A</figref>, the modular glenoid assembly 400 is different from the modular glenoid assembly 10 of <figref idref="f0001">FIG.S 1</figref>, <figref idref="f0002">2</figref>, <figref idref="f0009">5</figref> and <figref idref="f0011">7</figref> in that the modular glenoid assembly 400 further includes a vault fixation portion 480. The vault fixation portion 480 is used to provide for vault of internal scapula fixation for the modular glenoid assembly 400. The vault fixation portion 480 extends downwardly from the glenoid surface 446 of the fixation component 412. The vault fixation portion 480 may have any suitable shape and, as is shown in <figref idref="f0015">FIG. 10</figref>, may have a generally conifrustical shape. The vault fixation portion 480 may include a pair of spaced of apart anti-rotation fins 482. The anti-rotation fins 482 serve to securely position the fixation component 412 in the scapula 16. Vault fixation glenoid components are more fully described in <patcit id="pcit0008" dnum="US20040064189A"><text>US-A-2004/0064189</text></patcit>.

0075Referring now to <figref idref="f0017">FIG. 11</figref>, another embodiment of the present invention is shown as kit 500. The kit 500 includes a plurality of articulation components as well as a plurality of fixation components. As shown in <figref idref="f0017">FIG. 11</figref> the kit 500 includes a first articulation component, for example, articulation component 20. The articulation component 20 is shown in greater detail in <figref idref="f0009">FIG. 5</figref>. The kit 500 further includes a second articulation component 120. The second articulation component 120 is shown in greater detail in <figref idref="f0010">FIG. 6</figref>.

0076The kit 500 further includes a first fixation component 212. The first fixation component 212 more fully shown in <figref idref="f0011">FIG. 7</figref>. The kit 500 further includes a second fixation component, for example, component 312. The second fixation component 312 is shown in greater detail in <figref idref="f0013">FIG. 9</figref>.

0077The kit 500 may further include a third fixation component 412. The third fixation component 412 is shown in greater detail in <figref idref="f0015">FIG. 10</figref>.

0078It should be appreciated that the kit 500 may further include additional articulating components. For example, a third, fourth, or fifth or more articulation components (not shown). Similarly, the kit 500 may include additional fixation components, for example, a fourth fixation component, a fifth fixation component or additional fixation components (not shown).

0079It should be appreciated that the articulating components may have any suitable shape or size of their articulating surface. Similarly, it should be appreciated that the fixation components have any suitable size and shape of the glenoid surface for proper securement to the scapula. Further, it should be appreciated for the components of the glenoid kit 500 to be properly interchanged, the taper protrusions, for example, protrusions 28 of the articulating component 20, as well as, the tapered protrusion 128 of the second articulating component 120 preferably have identical sizes and shapes. Similarly, the internal taper 226 of the first fixation component, the internal taper 326 of the second fixation component as well as the internal taper 426 of the third fixation component 412 have similar sizes and shapes. Further the internal fixation component 226, 326, and 426 are preferably designed to matingly fitted the external components 28 and 128 of the articulating components 20 and 120.

0080Referring now to <figref idref="f0018">FIG. 12</figref>, a method 600 for performing shoulder surgery using the glenoid implant of the present invention is described. The method 600 further includes a first step 602 of providing a first glenoid component for attachment to the glenoid. The method 600 further includes a second step 604 of attaching the first glenoid component to the glenoid. The method 600 further includes a third step 606 of providing a second glenoid component to attachment to the first glenoid component. The method 600 further includes a fourth step 608 of attaching the second glenoid component to the first glenoid component in the direction generally normal to the longitudinal axis of the first glenoid component.