CONVERTIBLE TOTAL SHOULDER PROSTHESIS

Abstract

In some embodiments, disclosed is a glenohumeral implant with improved joint mobility. The implant can include a backing component; a neutral non-inclined bearing component on a concave side of the backing component, the bearing component made from a different material than the backing component and configured to touch a glenosphere having a center of rotation.

Claims

1. A shoulder implant with improved joint mobility, comprising: a backing component; a neutral non-inclined bearing component on a concave side of the backing component, the bearing component made from a different material than the backing component and configured to touch a glenosphere having a center of rotation, wherein the bearing component is substantially radially symmetrical; and a peg extending from the backing component and configured to be connected to a humeral stem; wherein the longitudinal axis of the peg of the backing component is offset from the center of rotation of the glenosphere, wherein the longitudinal axis of the backing component is aligned with the center of rotation of the glenosphere.

2. The shoulder implant of claim 1, wherein the backing component is inclined by an angle of between about 1.25 degrees and about 30 degrees with respect to a corresponding attachment surface of a humeral head.

3. The shoulder implant of claim 1, wherein the backing component is inclined by an angle of between about 2.5 degrees and about 12.5 degrees with respect to a corresponding attachment surface of a humeral head.

4. The shoulder implant of claim 1, wherein the glenoid implant when inserted into a patient does not change the center of rotation of the glenosphere.

5. The shoulder implant of claim 1, configured for anatomic positioning.

6. The shoulder implant of claim 1, configured for reverse positioning.

7. The shoulder implant of claim 1, wherein the bearing component has a depth of less than about 5.5 mm.

8. The shoulder implant of claim 1, wherein the bearing component has a depth of between about 3 mm and about 5 mm.

9. The shoulder implant of claim 1, wherein the bearing component comprises a plastic material.

10. The shoulder implant of claim 9, wherein the plastic material comprises polyethylene.

11. The shoulder implant of claim 1, wherein the backing component comprises a metal material.

12. The shoulder implant of claim 1, wherein the peg comprises a Morse taper.

13. The shoulder implant of claim 1, wherein at least a portion of an inferior-facing surface of the backing component configured to come in contact with a prepared humeral surface comprises an oval or elliptical cross-section, at least a portion of the inferior-facing surface of the bearing component comprises a circular cross-section, and at least a portion of the superior-facing surface of the backing component comprises a circular cross-section, the portion of the inferior-facing surface of the bearing component and the superior-facing surface of the backing component configured to snap or otherwise mate with each other.

14. A kit of shoulder implants, comprising a plurality of implants as in claim 1, wherein the plurality of implants comprises a first implant and a second implant, wherein the backing component of the first implant is inclined by a first angle, wherein the backing component of the second implant is inclined by a second angle different from the first angle, wherein the center of rotation of the glenosphere of the first implant and the second implant are in the same location.

15. A method of implanting a shoulder implant, comprising: reaming a cavity in the glenoid surface; sizing a first implant comprising a first angulation with respect to a stem, wherein the implant comprises a neutral bearing component and an inclined backing component comprising a first incline angle with respect to a corresponding attachment surface of a humeral head; sizing a second glenoid implant comprising a second angulation with respect to the stem, wherein the glenoid implant comprises a neutral bearing component and an inclined backing component comprising a second incline angle with respect to a corresponding attachment surface of a humeral head; implanting the second glenoid implant in the glenoid cavity; wherein the center of rotation of the glenosphere does not change between the first glenoid implant and the second glenoid implant, allowing for adjustment of version and inclination without changing the center of rotation.

16. A humeral prosthesis, comprising: a proximal end comprising at least three radially outwardly extending fins; a stem extending distally from the proximal end to a distal end, wherein the proximal end comprises a proximal end diameter defined by a circle contacting radial outward-most proximal tips of the at least three radially outwardly extending fins, wherein the distal end comprises a distal end diameter, wherein the proximal end diameter is between about 30 mm and about 50 mm, wherein the distal end diameter is between about 5 mm and about 6 mm, and wherein a ratio of the proximal end diameter and the distal end diameter is between about 5 and about 9.

17. The humeral prosthesis of claim 15, wherein the ratio is between about 5.5 and about 8.5.

18. The humeral prosthesis of claim 15, wherein the proximal end comprises a bowl-shaped concavity.

19. The humeral prosthesis of claim 15, comprising a central aperture in the proximal end configured to mate with a reverse component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a side perspective view of an embodiment of a convertible humeral prosthesis, according to some embodiments of the invention.

[0035] FIG. 2 is a bottom perspective view of the embodiment shown in FIG. 1;

[0036] FIG. 3 is a top view of the embodiment shown in FIG. 1 also showing an aperture in the center of the superior facing surface of the neck of the prosthesis and configured to be utilized as a reverse adapter for, in some cases, facilitating placement or removal of a spherical ball on the humeral head.

[0037] FIG. 4 is a side view of the embodiment shown in FIG. 1;

[0038] FIG. 5 is another side view of the embodiment shown in FIG. 1, also illustrating channel of the reverse adapter aperture extending within the neck and stem.

[0039] FIG. 6 is an inverted perspective view, also illustrating medial groove along the neck and stem of the prosthesis.

[0040] FIG. 7 is another perspective view of the prosthesis shown in FIG. 1.

[0041] FIG. 7A is a side perspective view of another embodiment of a convertible humeral prosthesis, according to some embodiments of the invention.

[0042] FIG. 7B is a bottom perspective view of the embodiment shown in FIG. 7A;

[0043] FIG. 7C is a top view of the embodiment shown in FIG. 7A also showing an aperture in the center of the superior facing surface of the neck of the prosthesis and configured to be utilized as a reverse adapter for, in some cases, facilitating placement or removal of a spherical ball on the humeral head.

[0044] FIG. 7D is a side view of the embodiment shown in FIG. 7A;

[0045] FIG. 7E is another side view of the embodiment shown in FIG. 7A, also illustrating channel of the reverse adapter aperture extending within the neck and stem.

[0046] FIG. 7F is an inverted perspective view, also illustrating medial groove along the neck and stem of the prosthesis.

[0047] FIG. 7G is another perspective view of the prosthesis shown in FIG. 7F.

[0048] FIGS. 8-11 illustrate various views of another embodiment of a humeral replacement prosthesis.

[0049] FIG. 12 is an illustration of one potential embodiment of the invention that depicts a conventional glenoid implant with an offset bearing component.

[0050] FIG. 13 is an illustration of one embodiment of the offset backing component allowing a 2.5 degree inclination.

[0051] FIG. 14 is an illustration of one embodiment of the offset backing component allowing a 7.5 degree inclination.

[0052] FIG. 15 illustrate the use of one embodiment of the offset backing component allowing a 12.5 degree inclination.

DETAILED DESCRIPTION

[0053] In particular, some embodiments of the invention are focused on advantageously exchanging the articular surface of the glenoid from a concave shape to a convex shape, without removing the components or interface having to do with fixation of the implant into the glenoid fossa, by utilizing a convertible humeral prosthesis.

[0054] In some embodiments, embodiments of the invention can be used or modified with use with particular advantages of using inset glenoid fixation technology in anatomic shoulder arthroplasty, such as described, for example, in U.S. Pat. No. 8,007,538 to Gunther, which is hereby incorporated by reference in its entirety. In some embodiments, an inset method includes identifying a patient having a glenoid surface; reaming a cavity into the glenoid surface; and inserting a glenoid implant having a body and a single, radially symmetric central peg oriented along a central axis of the implant, the body having a bearing surface on a peripheral edge thereof into the cavity, such that at least a portion of a peripheral edge of the body is inset with respect to the cavity and resides below the adjacent glenoid surface and the portion residing below the adjacent glenoid surface is circumferentially surrounded by cortical bone of the glenoid.

[0055] What is further described are methods by which the surgeon can achieve the use of the inset glenoid technology with an anatomic articulation, while after having the ability to convert the technology to a reverse articulation, without requiring removal the rigid fixation between the inset fixation and the scapula bone (in other words, allowing the rigid fixation support between the inset fixation and the scapula bone to remain in place during conversion from an anatomic to a reverse prosthesis).

[0056] FIGS. 1-7 illustrate various views of a humeral replacement prosthesis 100, according to some embodiments of the invention. The prosthesis 100 can optionally include a proximal ring element 102, such as a collar (which can be configured to be attached to a spherical ball head portion, not shown) with a peripheral edge 103 that can be annular such as circular as shown, with an inferior-facing surface that can be optionally recessed (including a convex or flat bowl-like shape) and include a cavity, or inline in other embodiments. The humeral prosthesis 100 can include a superior-facing surface 114 of the proximal end 106, and be concave and bowl-shaped as shown with the base and deepest portion of the bowl proximate the center of the superior facing surface 114 of the proximal end 106 such that there is a space 113 between the inferior-facing surface of the humeral head portion (not shown) and the superior-facing surface 114 of the proximal end 106 of the prosthesis 100. In some embodiments the depth of the bowl at the center of concave curvature is between about 3 mm and about 7 mm, such as between about 4 mm and about 6 mm deep, such as about 5 mm deep. The proximal end 106 of the prosthesis 100 can include spaced-apart flanges 107, such as three flanges 107 spaced equally apart, with vertices 111 of the flanges 107 extending radially outwardly while becoming narrower from the center of the proximal end 106 of the prosthesis 100. In some cases, a tri-flange design can provide for improved stability and rotation prevention, among other advantages. Extending distally from the proximal end 106 at an angle to the longitudinal axis of the proximal end/neck 106 is the stem 110 and distal end 108 of the prosthesis 100.

[0057] In some embodiments, the stem 110 and distal end 108 of the prosthesis has reduced thickness, e.g., tapering to no more than about 6 mm, 5.5 mm, 5 mm, 4.5 mm, 4 mm, or less in width dimension, such as between about 5.5 mm and about 6 mm, and ranges incorporating any two of the foregoing values, to advantageously reduce the quantity of native humerus bone needed to be removed, and allows for a stem 110 that is 3-4 mm or longer than a conventional stem 100 and allows for the majority of the fixation to occur in the proximal portion (e.g., neck 106) of the prosthesis. FIG. 1 is a side perspective view of an embodiment of the prosthesis; FIG. 2 is a bottom perspective view of the embodiment shown in FIG. 1; FIG. 3 is a top view of the embodiment shown in FIG. 1 also showing an aperture 120 in the center of the superior facing surface 114 of the neck 106 of the prosthesis and configured to be utilized as a reverse adapter for, in some cases, facilitating placement or removal of a spherical ball on the humeral head. FIG. 4 is a side view of the embodiment shown in FIG. 1; FIG. 5 is another side view of the embodiment shown in FIG. 1, also illustrating channel 124 of the reverse adapter aperture 120 extending within the neck 106 and stem 110. FIG. 6 is an inverted perspective view, also illustrating medial groove 126 along the neck 106 and stem 110 of the prosthesis 100. FIG. 7 is another perspective view of the prosthesis shown in FIG. 1.

[0058] FIGS. 7A-7G illustrate views of another embodiment of a humeral replacement prostheses somewhat similar to, and which can incorporate any number of features shown, for example in FIGS. 1-7. FIG. 7A illustrates a perspective view of the prosthesis 700 including optional proximal ring element 702, such as a collar, with a peripheral edge 703 that can be annular such as circular as shown, with an inferior-facing surface that can be optionally recessed (including a convex or flat bowl-like shape) and include a cavity, or inline in other embodiments. The humeral prosthesis 700 can include a superior-facing surface 714 of the proximal end 706, and be concave and bowl-shaped as shown with the base and deepest portion of the bowl proximate the center of the superior facing surface 714 of the proximal end 106 such that there is a space 713 between the inferior-facing surface of the humeral head portion (not shown) and the superior-facing surface 714 of the proximal end 706 of the prosthesis 700. The proximal end 706 of the prosthesis 700 can include spaced-apart flanges 707, such as three flanges 707 spaced equally apart, with vertices 711 of the flanges 707 extending radially outwardly while becoming narrower from the center of the proximal end 706 of the prosthesis 700. Extending distally from the proximal end 106 at an angle to the longitudinal axis of the proximal end/neck 706 is the stem 710 and distal end 708 of the prosthesis 700. Also illustrated is transition zone 747, of which proximal to that zone 747 the prosthesis 700 includes a porous coating, and distal to that zone 747 the prosthesis 700 does not include a porous coating. The coating could include, for example, a plasma spray, porous metal, hydroxyapatite, or other component which can facilitate cementless fixation to bone. However, cement fixation can be utilized in some embodiments.

[0059] FIG. 7A is a side perspective view of an embodiment of the prosthesis; FIG. 7B is a bottom perspective view of the embodiment shown in FIG. 7A; FIG. 7C is a top view of the embodiment shown in FIG. 7A also showing an aperture 120 in the center of the superior facing surface 114 of the neck 106 of the prosthesis and configured to be utilized as a reverse adapter for, in some cases, facilitating placement or removal of a spherical ball on the humeral head. FIG. 7D is a side view of the embodiment shown in FIG. 7A; FIG. 7E is another side view of the embodiment shown in FIG. 7A, also illustrating channel 124 of the reverse adapter aperture 120 extending within the neck 106 and stem 110. FIG. 7F is an inverted perspective view, also illustrating medial groove 126 along the neck 106 and stem 110 of the prosthesis 100. FIG. 7G is another perspective view of the prosthesis shown in FIG. 7.

[0060] FIGS. 8-11 illustrate various views of another embodiment of a humeral replacement prosthesis. FIG. 8 illustrates a humeral prosthesis that can be as described elsewhere herein, configured to be connected to a humeral head 801. FIG. 9 illustrates a perspective view of the humeral prosthesis 800, including stem 806, flanges 807, and adapter aperture 820 on the proximal end 806, as well as distal end 808. FIG. 10 illustrates a side view of the humeral prosthesis 800. FIG. 11 illustrates humeral head prosthesis 801 configured to be connected via projection 899 to the adapter aperture 820 of the humeral prosthesis 800, such as via press fit, threads, adhesive, or other techniques.

[0061] As shown, some potentially advantages of humeral implant configurations as described herein include that fixation is concentrated proximally, to conserve native bone. The prosthesis could be cemented, or cementless in some embodiments. The prosthesis geometry allows for ease of use, minimized surgical steps, and robust as errors can be readily absorbed. The prosthesis can also be convertible to reverse, which increases potentially for success and prevents or minimizing overstuffing. The prosthesis can also be advantageously inexpensive, logistically simple, and have minimal inventory requirements, as a diameter at or near the distal end of the stem can be constant, while the diameter at or near the proximal end of the stem can vary. For example, an operator could select a small number of humeral stem implants, e.g., with 34 mm, 38 mm, and 44 mm proximal diameters (which can be measured as the smallest circle that can encircle the proximal-most radially-outward end elements of the fins), all of which have the same distal-most diameter, such as about 5.5 mm or about 6 mm, or or no more than about 7 mm, 6.5 mm, 6 mm, 5.5 mm, 5 mm, or less, or ranges including any two of the foregoing values. In some embodiments, the proximal-most diameter can be between about 25 mm and about 50 mm, such as about 25, 30, 35, 40, 45, 50 mm, or ranges including any two of the foregoing values. In some embodiments, the humeral stem implants can have a ratio of proximal-most to distal-most diameter of the humeral stem of between about 5 and about 9, between about 5.5 and about 8.5, about 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 6.25, 6.5, 6.75, 7, 7.25, 7.5, 7.75, 8, 8.25, 8.5, 8.75, 9, 9.25, 9.5, 9.75, 10, or ranges including any two of the foregoing values. The ability to provide a set or array of humeral stem implants that a physician can choose from with varying proximal-most diameters, each with the same or substantially the same small distal-most diameter can be in contrast to conventional humeral stem prostheses, in which within a set of different humeral stem sizes, the distal-most diameter generally also increases as the proximal-most diameter increases. In some embodiments, the prosthesis is collarless. In some embodiments, the prosthesis has a total length of about or at least about 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, 56mm, 57 mm, 58 mm, 59 mm, 60 mm, 65 mm, 70 mm, or more, or ranges incorporating any two of the aforementioned values.

[0062] FIGS. 12-15 illustrate various views of several embodiments of components of a glenohumeral replacement prosthesis. FIG. 12 can be used to compare the effects of several different embodiments of the invention as depicted in FIGS. 13-15.

[0063] FIG. 12 depicts a conventional shoulder implant component embedded into the fossa of the scapula 201, such as the glenoid, or a humerus for example. FIG. 12, depicts an implant with an inclined, offset bearing component 204 (referring to the central axis of the bearing component being offset from the central axis of the backing component), with a backing component 205 which is aligned with center of rotation 208. The prosthetic is embedded on or within the bony cavity 203 comprises a bearing surface 204 embedded onto a backing component (e.g., a concave tray) 205. The bearing surface 204 lines the backing component 205 and can be made of any appropriate material, such as a non-metallic, biologically compatible material (e.g. polyethylene). The backing component connects to an elongated stem 207 that is embedded into the bone 202. The backing component 205 connects with the elongated stem 207 by a peg or keel (e.g. a morse taper) 206. In FIG. 12, the stem has neck shaft angle of about 132.5 degrees which is the angle created by intersection of the axis through the elongated stem 209 and the center of rotation 208. The backing component 205 is aligned with the axis of the fossa 210. Since the bearing component 204 is offset, the center of rotation 208 of the glenosphere 214 is medialized.

[0064] FIG. 13 illustrates a different embodiment wherein the inclination angle of the humerus angle is controllable exclusively by an offset backing component 211, while the bearing component is not offset. By offset, the peg 206 of the backing component 211 is positioned such that a first distance from the peg 206 to a first end of the offset backing component 211 is not equal to a second distance from the peg 206 to a second send of the offset backing component 211. In some embodiments, the first distance is at least about, about, or no more than about 5%, 10%, 15%, 20%, 25%, or more or less than the second distance, or ranges including any two of the foregoing values. This is in distinct contrast to FIG. 12 wherein the bearing component (e.g., polyethylene) is offset with respect to a central axis of the backing component. FIG. 13 shows the effect of a reverse articulation at 135 degrees using a backing component that provides a 2.5 degree incline 211 when attached to the elongated stem 207. The rotation 1 represents a rotation of 2.5 degrees about the axis of the glenoid fossa 210. When added to the angle , a reverse articulation of 135 degrees is achieved. Since the bearing component is not offset as in FIG. 12, the center of rotation of the glenosphere 215 remains constant, and is not medialized (or lateralized) away from the center of rotation 208. Also, the central axis 290 of the backing component 211 is offset from the central axis 208 of the peg.

[0065] FIG. 14 is similar to FIG. 13 with the exception that the angle of inclination of the backing component is different. FIG. 14 shows a desired 140 degree angle with a backing component providing a 7.5 degree incline 212 when attached to the elongated stem 207. The rotation 2 represents a rotation of 7.5 degrees about the axis of the glenoid fossa 210. When added to the angle , a reverse articulation of 140 degrees is achieved. Since the bearing component is not offset as in FIG. 12, the center of rotation of the glenosphere 215 is not medialized away from the center of rotation 208 and remains in the same position as it was in FIG. 13.

[0066] FIG. 15 illustrates a 145 degree angle with a backing component providing a 12.5 degree incline 213 when attached to the elongated stem 207. The rotation 3 represents a rotation of 12.5 degrees about the axis of the glenoid fossa 210. When added to the angle , a reverse articulation of 145 degrees is achieved. Since the bearing component is not offset as in FIG. 12, the center of rotation of the glenosphere 215 is not medialized away from the center of rotation 208 and remains in the same position as it was in FIG. 13 and FIG. 14.

[0067] In some embodiments of the invention, the inclination angles produced by the backing component above and beyond the neck shaft angle of the elongated stem may range from about 1.25, 2.5, 3.75, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35 degrees, or ranges including any two of the aforementioned values.

[0068] The native prepared surface of the humerus of which an inferior-facing surface of the backing component rests against after implementation generally has an oval or elliptical cross-section. In some embodiments, the inferior-facing surface of the backing component also has an oval or elliptical cross-section substantially matching that of the surface of the humeral bone. In some embodiments, at least a portion of the inferior facing surface of the bearing component (e.g., polyethylene component in some cases) has a circular cross-section, and is configured to snap into, or otherwise mate with a complementary portion of the superior-facing surface of the backing component, which can also have a circular cross-section.

[0069] Non-limiting potential advantages of the embodiments in FIG. 13-15 is observed by example when comparing FIG. 12 to FIG. 14. The depth of the backing component in FIGS. 13-15 can be about 5 mm, compared with about 7.5 mm with respect to the FIG. 12 embodiment where the bearing component is offset with respect to the center of rotation of the glenosphere, as well as the central axis of the backing component. In some embodiments, the depth of the backing component is less than about 6, 5.5, 5, 4.5, 4, 3.5, 3 mm or less, or ranges including any two of the aforementioned values. Changing the backing component angle in FIGS. 13-15, as opposed to changing the amount of polyethylene plastic or other material in the bearing component, results in an additional amount of space, such as about 2.5 mm or more or less of space formed in the bowl for rotation of the glenosphere. Therefore, in several of the embodiments presented, the joint is less stuffed and not overstuffed and can potentially have greater range of motion. Furthermore, a physician can select between a range of different backing components with varying inclination angles, while the bearing components are neutral (e.g., not inclined). As such, the inclination angle of the humerus can be controlled solely by selecting an appropriate backing component, and the center of rotation of the glenosphere remains constant irrespective of the potentially varying inclination angle of the backing component.

[0070] In some embodiments, a glenohumeral implant allowing for adjustable angles for anatomic or reverse arthroplasty is presented and comprises: a backing component; a bearing component on the concave side of the backing component, the bearing component made from a different material than the backing component; and a peg extending from the backing component. Further, in some embodiments the longitudinal axis of the backing component is offset from the center of rotation, but the center of rotation is not changed.

[0071] Various other modifications, adaptations, and alternative designs are of course possible in light of the above teachings. Therefore, it should be understood at this time that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein. It is contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments disclosed above may be made and still fall within one or more of the inventions. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an embodiment can be used in all other embodiments set forth herein. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above. Moreover, while the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various embodiments described and the appended claims. Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as insetting an implant into a glenoid cavity includes instructing the insetting of an implant into the glenoid cavity. The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as up to, at least, greater than, less than, between, and the like includes the number recited. Numbers preceded by a term such as approximately, about, and substantially as used herein include the recited numbers (e.g., about 10%=10%), and also represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms approximately, about, and substantially may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.