Shoulder prosthesis

Abstract

A prosthesis may include a stem, a ball stud, an adaptor, and a head. The stem may include a longitudinal axis and a bore having a central axis that is angled relative to the longitudinal axis. The ball stud may include a cylindrical shaft and a ball end. The cylindrical shaft may be received in the bore of the stem. The adaptor may include a tapered outer surface and a ball socket rotatably receiving the ball end of the stud. The head may be rotatably supported by the adaptor and may include a semispherical articulating surface and a female taper rotatably receiving the tapered outer surface of the adaptor.

Claims

1. A joint prosthesis comprising: a stem having a stem longitudinal axis and a stem bore formed in a proximal face of the stem at an angle to the stem longitudinal axis; an adaptor including: a ball stud having a spherical section and a shank extending from the spherical section, the shank configured for insertion within the stem bore, the spherical section including a divided ball segment, an adaptor body having a central adaptor body axis and defining a cavity sized and shaped to receive the spherical section of the ball stud, the cavity having a central cavity axis that is offset from the central adaptor body axis, and a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion; and a head having a central head axis and defining a depression sized and shaped to receive the adaptor body, the head configured to be coupled to the adaptor body such that the central adaptor body axis is offset from the central head axis; wherein the head is adjustably positionable relative to the stem through rotation of the spherical section of the ball stud relative to the cavity of the adaptor body to set at least one of an angular inclination and version of the head with respect to the stem, and through rotation of the adaptor body relative to the head to set a radial offset of the head with respect to the stem; and wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the cavity thereby fixedly securing the adaptor body and the ball stud in a fixed relationship.

2. The joint prosthesis of claim 1, wherein the adaptor includes a plurality of indicia for indicating a degree of adjustment of the radial offset.

3. The joint prosthesis of claim 1, wherein the head includes a plurality of indicia for indicating alignment of the radial offset.

4. The joint prosthesis of claim 1, wherein the adaptor body has a male taper and the depression has a complementary female taper.

5. The joint prosthesis of claim 1, wherein the joint prosthesis is a shoulder prosthesis.

6. A joint prosthesis comprising: a stem having a longitudinal axis and a proximal face defining a stem bore, the stem configured to be inserted into a first bone; a head configured to articulate with a second bone or an implant component attached to the second bone, the head defining a head taper; an adaptor comprising a ring and a ball stud having a shank segment sized to be received in the stem bore, the ring defining an attachment aperture and having a tapered outer surface for securing the ring to the head via the head taper, the attachment aperture sized to receive the ball stud in a fixed orientation; and a plurality of indicia, including at least one indicator on the adaptor and a plurality of indicators on the head; wherein the head is positionable relative to the stem through rotation of the head about the adaptor for adjusting at least one of an angular inclination and a radial offset of the head, and wherein the indicia are configured for indicating a degree of adjustment of the at least one of the angular inclination and the radial offset; and a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion, wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the attachment aperture thereby fixedly securing the ring and the ball stud in the fixed orientation.

7. The joint prosthesis of claim 6, wherein when in an assembled state, an axis of rotation of the ball stud and a central axis of the ring are eccentric.

8. The joint prosthesis of claim 6, wherein when in an assembled state, a central axis of the stem bore and an axis of rotation of the ball stud are concentric.

9. The joint prosthesis of claim 6, wherein when in an assembled state, a central axis of the head and a central axis of the ring are eccentric.

10. The joint prosthesis of claim 6, wherein the joint prosthesis is a shoulder prosthesis.

11. A joint prosthesis comprising: a stem configured to be implanted in a first bone and defining a stem bore; a head having an articulation surface and an end surface defining a depression, the articulation surface configured to articulate with a second bone or an implant component connected to the second bone; an adaptor sized to be received in the depression and form a taper connection between the adaptor and the head, the adaptor further defining an aperture; a ball stud having a first end and a second end, the first end sized to be received in the aperture, the second end sized to be received in the stem bore; and a plurality of indicia, including a plurality of indicators on the adaptor and a plurality of indicators on the head; wherein the first end of the ball stud includes a spherical surface, wherein, when implanted, the head is positioned relative to the adaptor to define a radial offset of the head with respect to the adaptor, and the spherical surface of the ball stud is rotatable within the aperture to set an inclination angle of the head with respect to the stem, and wherein the indicia are configured for indicating a degree of adjustment of one or both of the radial offset and the inclination angle; and a fastener configured to be at least partially received within a bore of the ball stud, the fastener including a screw portion and a wedge portion, wherein as the screw portion is driven into the wedge portion during assembly, the wedge portion expands within the aperture thereby fixedly securing the adaptor and the ball stud in a fixed orientation.

12. The joint prosthesis of claim 11, wherein the spherical surface of the ball stud allows for adjustment of an angle formed between a central axis of the head and a central axis of a shank segment extending from the spherical surface of the ball stud.

13. The joint prosthesis of claim 11, wherein the aperture of the adaptor is offset with respect to a central axis of the adaptor, the adaptor having a cylindrical outer surface and the depression having an inner surface that is shaped complementary with the cylindrical outer surface such that the adaptor can be rotated in the depression to set the radial offset of the head with respect to the adaptor.

14. The joint prosthesis of claim 11, wherein the first bone is a humerus, and the second bone is a scapula.

15. The joint prosthesis of claim 11, wherein when in an assembled state, an axis of rotation of the ball stud and a central axis of the adaptor are eccentric.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present teachings in any way.

(2) FIG. 1 is an exploded front view of a modular shoulder prosthesis system in accordance with the present teachings;

(3) FIG. 2 is a normal view of the adapter and head components of the device illustrated in FIG. 1 shown in an assembled state;

(4) FIG. 3 is an exploded front view of an alternate embodiment of the modular shoulder prosthesis system illustrated in FIG. 1;

(5) FIG. 4 is a cross-sectional view of the adapter and head shown in FIG. 3 arranged to provide a maximum radial offset;

(6) FIG. 5 is a cross-sectional view of the adapter and head shown in FIG. 4 and arranged to provide a minimum radial offset;

(7) FIG. 6 is an exploded front view of a second alternative embodiment of a modular shoulder prosthesis system according to the present teachings;

(8) FIG. 7 is a normal view of the adapter and head illustrated in FIG. 6 shown in an assembled state;

(9) FIG. 8 is an alternate embodiment of the modular shoulder prosthesis system illustrated in FIG. 6;

(10) FIG. 9 is a partial cross-sectional view showing the adapter and head of FIG. 8 arranged to provide a maximum angular inclination;

(11) FIG. 10 is an illustration of the adapter and head similar to that shown in FIG. 9 and arranged to provide a minimum angular inclination;

(12) FIG. 11 is an exploded front view of a third alternative embodiment of a modular shoulder prosthesis system according to the present teachings;

(13) FIG. 12 is a normal view of the adaptor and head components of the device shown in FIG. 11 oriented in a first position; and

(14) FIG. 13 is a normal view similar to FIG. 12 with the components oriented in a second position.

DETAILED DESCRIPTION

(15) The following description is merely exemplary in nature and is not intended to limit the present teachings, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. Although the following description is related generally to a modular joint prosthesis system which provides adjustment of the radial offset and/or angular inclination of the head relative to the stem, it will be understood that the system as described and claimed herein can be used in any appropriate surgical procedure. Thus, it will be understood that the following discussions are not intended to limit the scope of the present teachings and claims herein.

(16) With reference now to FIG. 1, shoulder prosthesis 20 in accordance with the present teachings is illustrated to include a stem 22, an adapter 24 and a head 26. Stem 22 includes a rod portion 28 adapted to be received in the medullary canal of the humerus. A plurality of fins 30 are formed near the upper end of rod 28 for locating and fixing the stem within a humerus. A male taper 32 extends obtusely from rod 28 to provide a location for interconnecting stem 22 with adapter 24. Male taper 32 extends from stem 22 along axis 34. Stem 22 is of the type manufactured and sold by Biomet, Inc. as a component in its Bi-Angular Shoulder System.

(17) Adapter 24 is a generally cylindrical disc having a female taper 36 formed therein for receiving male taper 32 of stem 22. The outer surface 38 of adapter 24 defines a male taper. Female taper 36 is eccentrically located in adapter 24 such that central axis 34 of female taper 36 is not collinear with central axis 40 of adapter 24. Instead, central axis 40 is radially offset from central axis 34 by an amount indicated as r.sub.a.

(18) Head 26 includes a semispherical surface 42 defined about central axis 44. Bottom face 46 is formed opposite semispherical surface 42 and has a female taper 48 formed therein which is configured to receive adapter 24 along central axis 40. In this regard, female taper 48 is formed eccentrically within head 26 such that a radial offset r.sub.b exists between central axis 40 and central axis 44.

(19) As previously described, the eccentric relationship of central axes 34, 40 and 44 provide an arrangement whereby a relative rotational positioning of adapter 24 with respect to head 26 adjusts the radial offset within a given range. As best seen in FIG. 2, relative positioning of adapter 24 within female taper 48 of head 26 causes centroid 50 defined by female taper 36 to trace a helical path 52 relative to centroid 54 defined by central axis 40. Helical path 62 terminates at centroid 56 defined by central axis 34. A maximum radial offset is achieved when centroid 50 is located directly opposite centroid 56. Similarly, a minimum offset is achieved when centroid 50 aligns with centroid 56. In one example, the maximum radial offset is 10 mm and the minimum radial offset is 0 mm. However, one skilled in the art will recognize that the range of offset may be modified based on the design criteria for a given modular prosthesis system.

(20) With continuing reference to FIG. 2, the shoulder prosthesis 20 is provided with indicia 64 facilitating adjustment and alignment of the radial offset. Specifically indicia 60 includes a first set of indicators 62 formed on adapter 24 and a second set of indicators 64 formed on bottom face 46 of head 26. First and second indicators 62, 64 have a magnitude value associated therewith indicating the amount of radial offset. Furthermore, head indicators 64 include an enlarged arrowhead which indicate the direction of the radial offset. In this manner, indicia 60 provide a radial offset vector which may be utilized to precisely align adapter 24 and head 26 and achieve the desired radial offset.

(21) For example, as shown in FIG. 2, adapter indictor 62.10 associated with a 10 millimeter offset is aligned with head indictor 64.10 associated with 0,10 offset. Thus, the relative angular position of adapter 24 with respect to head 26 shown in FIG. 2 provides a 10 millimeter offset and the direction of the offset is indicated by arrowhead 64.10. The radial offset may be reduced by removing adapter 24 from head 26 rotating adapter 24 until indicia 60 are properly aligned and inserting adapter 24 into female taper 48 of head 26. For example, an offset of 4 millimeters would be obtained by aligning adapter indictor 62.4 with head indictors 64.4 at which point a 4 millimeter offset in the direction of arrowhead 64.4 would be achieved. In one example, a threaded through bore 66 may be formed in adapter 24 for receiving a threaded member to facilitate a disassembly of adapter 24 from head 26. In certain applications, a removeable plug (not shown) in the form of a bio-compatible cement or the like may be disposed in bore 66 to minimize joint fluid from entering the interface between the adapter 24 and the head 26 through the bore 66.

(22) With reference now to FIGS. 3 through 5, an alternate embodiment of the present teachings is illustrated in which the adapter has a first male taper adapted to engage the stem and a second male taper adapted to engage the head. With reference now to FIG. 3, stem 22 includes a rod portion 28 and a female taper 32 formed in the end opposite rod 28 which defines central axis 34. Stem 22 is of the type manufactured and sold by Biomet as a component of its Bio-Modular Shoulder System. Adapter 24 has a first male taper 36 adapted to be inserted into female taper 32 and a second male taper 38 formed along central axis 40. Head 26 includes a semispherical surface 42 defined about central axis 44. Bottom face 46 has a female taper 48 formed therein which is adapted to receive male taper 38 of adapter 24. Central axis 40 is offset from central axis 34 as indicated at r.sub.a and central axis 44 is offset from central axis 40 as indicated at r.sub.b. As in the first embodiment, relative rotational positioning of adapter 24 and head 26 provides an adjustable radial offset for shoulder prosthesis 20.

(23) With reference now to FIG. 4, central axis 34 of male taper 36 is located directly opposite central axis 44 of head 26 to provide a maximum radial offset. With reference now to FIG. 5, head 26 has been rotated 180 degrees relative to adapter 24 such that central axis 44 is collinear with central axis 34. In this orientation, a minimum radial offset is provided. Indicia similar to that described above with reference to FIG. 2 facilitates alignment of shoulder prosthesis 20.

(24) Based on the foregoing detailed description, one skilled in the art will readily recognize that one aspect of the present teachings is directed to an adapter and head having eccentric configurations such that a relative rotation therebetween provides an adjustable range of offset configuration.

(25) With reference now to FIGS. 6 through 10, a second alternative embodiment of the present teachings is illustrated which provides for adjustment of the angular inclination between the stem component and the head component in a manner similar to that described with reference to the radial offset. Specially, the shoulder prosthesis system 120 of the second alternative embodiment includes a stem 122, a head 124 having a first angular orientation and an adapter 126 interconnecting the stem 122 and the head 124 such that the adapter 126 has a second angular inclination. The adapter 124 is configured to be rotatably positionable with respect to the head 126 such that the angular inclination of the head 126 relative to the stem 122 may be adjusted.

(26) With specific reference to FIG. 6, shoulder prosthesis 120 includes stem 122 having rod 128 extending therefrom. A plurality of fins 130 are formed longitudinally along rod 128 parallel to central longitudinal axis A near the upper end of stem 122. A male taper 132 extends from rod 128 at an obtuse angle with respect to the central longitudinal axis A and defines a central axis 134.

(27) Adapter 124 is a generally cylindrical disc having a female taper 136 formed therein. The outer surface of adapter 124 defines a male taper 138. The central axis 140 of adapter 124 is configured at a first angular orientation with respect to central axis 134. Specifically, central axis 140 is defined by the angle at which female taper 130 is oriented relative to the bottom surface 125 of adapter 124. In one example, central axis 140 is disposed at a +5 degree angular inclination with respect to central axis 134.

(28) Head 126 includes a semispherical surface 142 and a flat bottom face 146 having a female taper 148 formed therein. Female taper 148 defines central axis 144 which is disposed at an angular inclination relative to a central axis 140. Specifically, central axis 144 is defined by the angle at which female taper 144 is oriented relative to bottom face 146. In one example, central axis 144 is disposed at a 5 degree angular inclination with respect to central axis 140.

(29) The relative rotational position of adapter 124 with respect to the head 126 defines the adjustment to the prosthesis inclination relative to central axis 34. For example, as illustrated in FIG. 6, adapter 126 provides a +5 degree inclination which is canceled by the 5 inclination provided in head 126. Thus, when adapter 124 and head 126 are assembled a net zero angular inclination is achieved. An angular adjustment may be provided by rotating adapter 124 relative to head 126 such that a net angular inclination is provided. For example, when adapter 124 is rotated clockwise 90 degrees, the angular inclination of central axis 140 combines with the angular inclination of central axis 144 to provide a +5 degree angular inclination of head 126 relative to central axis 134. Likewise, an additional 90 degree rotation of adapter 124 will provide an overall adjustment of +10 degrees in the angular inclination. In one example, a range of angular inclination is provided between 0 and 10. However, one skilled in the art will recognize that the range of angular inclination may be modified based on the design criteria for a given modular prosthesis system.

(30) With continuing reference to FIG. 7, adapter 124 and head 126 are provided with inclination indicia 160 which facilitates identification of the magnitude and direction of the angular inclination provided by shoulder prosthesis system 120. Specifically, angular indicia 160 includes a first indictor 162 on adapter 124 and a plurality of second indicators 164 provided on bottom face 146 of head 126. Adapter indicator 162 is an arrowhead which indicates the direction of the angular inclination. Head indicators 164 provide a magnitude of angular inclination as well as an alignment mark which cooperates with adapter indictor 162 to provide the angular inclination vector (i.e. magnitude and direction).

(31) With reference now to FIGS. 8 through 10, an alternate embodiment to the second alternative embodiment is illustrated in which the adapter has a first male taper adapted to engage the stem and a second male taper adapted to engage the head. With reference now to FIG. 8, stem 122 includes a rod portion 128 and a female taper 132 formed in the end opposite rod 128 which defines central axis 134. Adapter 124 has a first male taper 136 adapted to be inserted into female taper 132 and a second male taper 138 formed along central axis 140. Head 126 includes a semispherical surface 142 defined about central axis 144. Bottom face 146 has a female taper 148 formed therein which is adapted to receive male taper 138 of adapter 124. Central axis 140 is angularly inclined relative to central axis 34 and central axis 144 is angularly inclined relative to central axis 140. Relative rotational positioning of adapter 124 and head 126 provides an adjustable angular inclination for shoulder prosthesis 120.

(32) With reference now to FIG. 9, the angular inclination of central axis 134 of male taper 136 is complementary with the central axis 144 of head 26 to provide a maximum angular inclination. With reference now to FIG. 10, head 126 has been rotated 180 degrees relative to adapter 124 such that the angular inclination of central axis 144 is opposing central axis 134 to provide a minimum angular inclination.

(33) From the foregoing description of various embodiments, one skilled in the art will readily recognize that the present teachings are directed to a modular shoulder prosthesis in which the radial offset and/or the angular inclination (i.e. inversion and retroversion) of the head relative to the stem may be adjusted by relative rotational positioning of an adapter interdisposed between the stem and head components of the shoulder prosthesis. In this way, a range of radial offsets and/or angular inclinations may be provided without requiring numerous additional components. The various embodiments have discussed a radial offset adjustment or an angular inclination adjustment independently; however, one skilled in the art will readily recognize that a shoulder prosthesis system may incorporate both aspects of a radial and angular adjustment. Where a single adapter utilized to interconnect the stem and the head, an interrelationship exists between the radially offset adjustment and the angular inclination adjustment. In combination, a system could be employed which utilized two intermediate adapters such that the radial offset and angular inclination adjustment are isolated and thus independent. For example, the interface between a first adapter and a second adapter would provide the desired radial adjustment as described in particular reference to the first embodiment and the interface between the second adapter and the head would provide the angular inclination as described with reference to the second alternative embodiment. In such a system, each of the radial offset and angular inclination adjustments would be provided by a single interface, thereby minimizing the interrelation between both adjustments resulting from a single intermediate adapter.

(34) With reference now to FIGS. 11-13, a third alternative embodiment of the present teachings is illustrated which provides for adjustment of both the radial offset and the angular inclination. Specifically, the shoulder prosthesis 210 is provided and includes a stem 212, an adaptor 214 and a head 216. The stem 212 includes a longitudinal axis A along its length and further includes a rod portion 218 adapted to be received into the medullary canal of the humerus. A plurality of fins 220 are formed near the proximal end of the rod 218 for locating and fixing the stem 212 within the humerus whereby the proximal end of the rod 218 has a substantially larger body than that of the distal end and includes a proximal face 222 having a bore 224 formed therein along a central axis 226 for receiving the adaptor 214. The proximal face 222 extends from the stem 212 along axis 226 and provides a location for interconnecting the stem 212 with the adaptor 214. Further, the proximal face 222 provides sufficient clearance for angular and radial adjustments of the adaptor 214 and the head 216 as will be discussed in more detail below.

(35) The adaptor 214 is a generally cylindrical member including an outer ring 228 having a central axis 230 and a ball stud 232 rotatably connected to the ring 228. The ring 228 includes an attachment aperture 234 having a central axis 236 formed therethrough for rotatable engagement with the ball stud 232. The ring 228 further includes an outer surface having a male taper 238 for engagement with the head 216.

(36) The ball stud 232 includes a shank segment 233 for engagement with the bore 224 of the stem 212 and a divided ball segment 240 for attachment to attachment aperture 234 of the ring 228. The ball stud 232 further includes a second bore 242 formed therein for interaction with a fastener 244 for selectively securing the ring 228 to the ball stud 232 in a fixed orientation. Fastener 244 includes a wedge portion 254 and a set screw 256 as best shown in FIG. 11. Set screw 256 is received by a central bore of the wedge 254, whereby as the set screw 256 is driven into the wedge 254, the wedge 254 expands within the attachment aperture 234 of the ring 228 thereby securing the ring 228 and ball stud 232 in a fixed relationship. In this regard, the central axis 236 of the ball stud 232 is concentric with central axis 226 of the proximal face 222 and is received by the attachment aperture 234 such that the central axis 236 of the ball stud 232 is eccentric to the central axis 230 of the ring 228 as indicated by r.sub.a.

(37) The head 216 is rotatably supported by the adaptor 214 and includes a semispherical surface 246 defined about a central axis 248 adapted for mating engagement with the glenoid cavity of a scapula. The head 216 further includes a bottom surface 250 formed opposite the semispherical surface 246 having a female taper 252 for mating engagement with the male taper 238 of the ring 228. In this regard, the female taper 252 is received eccentrically within the head 216 such that a radial offset r.sub.b exists between the central axis 230 of the ring 228 and the central axis 248 of the head 216. While the present teachings disclose a head 216 for mating engagement with the glenoid cavity of a scapula, it is anticipated that the head 216 could also be received by a prosthetic device replacing a severely damaged glenoid cavity and should be considered within the scope of the present teachings.

(38) As previously described, the eccentric relationship of the central axes 230, 236 and 248 provides an arrangement whereby a relative rotational positioning of the adaptor 214 with respect to the head 216 or a relative rotational positioning of the adaptor 214 with respect to the ball stud 232 or a combination thereof adjusts the radial offset of the head 216 relative to the longitudinal axis A of the stem 212.

(39) With particular reference to FIG. 13, relative positioning of the head 216 to the longitudinal axis A of the stem 212 is accomplished by a first radial adjustment method. In the first radial adjustment method, the relative positioning of the ring 228 within the female taper 252 of the head 216 causes the central axis 248 of the head 216 to be rotated relative to the central axis 230 of the ring 228. The radial offset between the central axis 248 and the central axis 230 is again denoted by r.sub.b at its minimum and by r.sub.b at its maximum value. FIG. 2 further traces the movement of axis 248 from r.sub.b to r.sub.b as indicated by path 249, while each position along path 249 signifies a potential adjustment of the head 216 relative to the longitudinal axis A of the stem 212.

(40) With particular reference to FIGS. 12 and 13, relative positioning of the head 216 to the longitudinal axis A of the stem 212 is accomplished by a second radial adjustment method. In the second radial adjustment method, the relative positioning of the central axis 230 of the ring 228 and the central axis 236 of the ball stud 232 causes the central axis 248 of the head 216 to be rotated. Again, r.sub.a is used to designate the minimum offset between the central axis 230 of the ring 228 and the central axis 236 of the ball stud 232 while r.sub.a is used to designate the maximum offset. FIG. 3 further traces the movement of axis 248 from r.sub.a to r.sub.a as indicated by path 251, while each position along path 251 signifies a potential adjustment of the head 216 relative to the longitudinal axis A of the stem 212. For discussion purposes, the head 216 does not rotate relative to the ring 228 when making an adjustment of the ball stud 232 relative to the ring 228, but it should be understood that both adjustment methods could be used concurrently to achieve an overall desired radial offset of the head 216 relative to the longitudinal axis A of the stem 212.

(41) In addition to providing a radial offset, the shoulder prosthesis 210 further provides an angular adjustment of the head 216 relative to the longitudinal axis A of the stem 212 for both inversion and retroversion adjustments. As best shown in FIG. 3, the central axis 248 of the head 216 rotates about the central axis 236 of the ball stud 232, which is concentric with the central axis 226 of the first bore 224. As previously discussed, the divided ball segment 240 of the ball stud 232 rotatably supports the ring 228 while the ring 228 supports the head 216. By articulating either the head 216 or the ring 228, the ring 228 will rotate on the divided ball segment 240 of the ball stud 232, thereby providing the head 216 with an angular adjustment relative to the longitudinal axis A of the stem 212. For discussion purposes, the first and second radial adjustment methods are not utilized while making an angular adjustment of the head 216, however, it should be understood that both adjustment methods may be used concurrently with the angular adjustment method and with one another to achieve an overall desired angular and radial relationship of the head 216 relative to the longitudinal axis A of the stem 212.

(42) With continuing reference to FIGS. 12 and 13, the shoulder prosthesis is provided with indicia 260 facilitating adjustment and alignment of the radial offset. Specifically, indicia 260 includes a first set of indicators 262 formed on the ring 228 and a second set of indicators 264 formed on the bottom face 250 of the head 216. First and second indicators 262, 264 have a magnitude value associated therewith indicating the amount of radial offset. Furthermore, the head indicators 264 include an enlarged arrowhead which indicates the direction of the radial offset. In this manner, indicia 260 provide a radial offset vector which may be utilized to precisely align the adaptor 214 and the head 216 and achieve the desired radial offset.

(43) In reference to all of the above-described embodiments, various tapered surfaces have been referenced at interfaces between the stem, adapter and head. In one example, these tapered surfaces are configured as morse-type tapers which provide a self locking interface. While morse-type tapers are described herein, one skilled in the art will readily recognize that other means may be incorporated for providing a locking interface between the various components of the shoulder prosthesis system. In this regard, one or more interfaces may be interlocked with the use of an additional fastener to insure locking engagement therebetween.

(44) While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from the present teachings that features, elements and/or functions of one example can be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications can be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof. Therefore, it is intended that the present teachings not be limited to the particular examples illustrated by the drawings and described in the specification, but that the scope of the present teachings will include any embodiments falling within the foregoing description.