MOBILE BEARING REVERSED HUMERAL IMPLANT

Abstract

An apparatus including a humeral tray (120) configured to be mounted to a proximal end of a humeral stem (100), and an insert (130) positioned on an outer surface of the humeral tray configured to articulate with a glenosphere (110); wherein the insert is not attached to the humeral tray such that the insert can articulate and move relative to the humeral tray.

Claims

1. An apparatus comprising: a humeral tray configured to be mounted to a proximal end of a humeral stem; and an insert positioned on an outer surface of the humeral tray configured to articulate with a glenosphere; wherein the insert is not attached to the humeral tray such that the insert can articulate and move relative to the humeral tray.

2. The apparatus of claim 1, wherein the humeral tray includes a concave articulation surface.

3. The apparatus of claim 2, wherein the humeral tray includes a constraint ridge located around a periphery of the humeral tray.

4. The apparatus of claim 3, wherein the insert is configured and sized so as to be constrained from moving past the constraint ridge.

5. The apparatus of claim 4, wherein the insert includes a circumferential groove around an outer periphery of the insert.

6. The apparatus of claim 4, wherein the insert has a height higher than a height of the constraint ridge.

7. The apparatus of claim 1, wherein the humeral tray includes a cut-out in a central surface of the humeral tray and wherein the insert includes a post extending from a bottom surface of the insert, wherein the post is configured to ride in the cut-out so as to prevent excessive motion of the insert relative to the humeral tray.

8. The apparatus of claim 1, wherein the insert includes a convex articulation surface for articulating with the humeral tray and a concave articulation surface for articulating with the glenosphere, wherein the convex articulation surface has a greater radius than the concave articulation surface.

9. A system comprising: a humeral stem configured to be implanted within a humerus: a glenosphere configured to be mounted on a scapula; a humeral tray mounted to a proximal end of the humeral stem; an insert positioned on an outer surface of the humeral tray configured to articulate with the glenosphere; wherein the insert is not attached to the humeral tray such that the insert can articulate and move relative to the humeral tray.

10. The system of claim 9, wherein the humeral tray includes a concave articulation surface.

11. The system of claim 10, wherein the humeral tray includes a constraint ridge located around a periphery of the humeral tray.

12. The system of claim 11, wherein the insert is configured and sized so as to be constrained from moving past the constraint ridge.

13. The system of claim 12, wherein the insert includes a circumferential groove around an outer periphery of the insert.

14. The system of claim 13, wherein the insert has a height higher than a height of the constraint ridge.

15. The system of claim 9, wherein the humeral tray includes a cut-out in a central surface of the humeral tray and wherein the insert includes a post extending from a bottom surface of the insert, wherein the post is configured to ride in the cut-out so as to prevent excessive motion of the insert relative to the humeral tray.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0028] FIG. 1 shows an implant system for a reverse shoulder arthroplasty, in accordance with one embodiment.

[0029] FIG. 2 shows top and side views of an insert for the reverse shoulder implant system, in accordance with one embodiment.

[0030] FIG. 3 shows top and side views of a humeral tray for the reverse shoulder implant system, in accordance with one embodiment.

[0031] FIG. 4 shows the reverse shoulder implant system with an arm at rest.

[0032] FIG. 5 shows the reverse shoulder implant system with an arm lifted.

[0033] FIG. 6 shows a side view of an insert, in accordance with one embodiment.

[0034] FIG. 7 shows a side view of an insert, in accordance with one embodiment.

[0035] FIG. 8 shows a side view of a humeral tray, in accordance with one embodiment.

[0036] FIG. 9 shows a method of improving a shoulder implant, in accordance with one embodiment.

DETAILED DESCRIPTION

[0037] As used herein, the following directional definitions apply. Anterior and posterior mean nearer the front or nearer the rear of the body, respectively, proximal and distal mean nearer to or further from the root of a structure, respectively, and medial and lateral mean nearer the sagittal plane or further from the sagittal plane, respectively. The sagittal plane is an imaginary vertical plane through the middle of the body that divides the body into right and left halves.

[0038] As noted above, reverse-type shoulder implant systems have been developed in which the conventional ball-and-socket configuration that replicates the natural anatomy of the shoulder is reversed, such that a concave recessed articulating component is provided at the proximal end of a humeral stem that articulates against a convex portion of a glenosphere of a glenoid component.

[0039] However, while the reverse-type shoulder design enables effective stabilization of the glenohumeral joint, it is often reported that the functional outcome is impaired and certain activities of daily living are no longer feasible. Therefore, current designs are often unable to give patients a full return to daily activities or offer the ability to perform subtle motions of the shoulder which are needed for a normal behavior of the glenohumeral joint.

[0040] The system described herein outlines a concept for an implant system, which is intended to enable a greater range of motion than offered with existing designs.

[0041] FIG. 1 shows an implant system for a reverse shoulder arthroplasty, in accordance with one embodiment. The system generally includes a humeral stem 100 configured to be implanted within a humerus 10, a glenosphere 110 configured to be mounted on a scapula 20, and having a curved outer surface 112, a humeral tray 120 mounted to a proximal end of the humeral stem 100, and an insert 130 positioned on an outer surface 122 of the humeral tray 120 and configured to articulate with the glenosphere 110. In this example, the insert 130 is not attached to the humeral tray 120 such that the insert 130 can articulate and move relative to the humeral tray 120. This can also be described that the insert 130 is “non-contained” relative to the humeral tray 120.

[0042] After implantation, the humeral tray 120 with the insert 130 can articulate about the glenosphere 112, such as to replicate the movement of the natural shoulder joint. The insert 130 is maintained in contact with the humeral tray 120 and the glenosphere 110 because of compressive loads across the joint, as well as conformity of the interface surfaces.

[0043] By having the insert be non-contained or not fixedly attached to the humeral tray 120 the insert 130 can travel along the humeral tray 120 during articulation. As will be further detailed below, this system allows the technical range of motion between the glenosphere 110 and the humeral stem 100 to be increased compared to a contained tray/insert concept where the humeral tray and insert do not move or articulate relative to each other. The extent of additional motion/freedom afforded with the present non-contained insert 130, as well as the resultant CCD angle, is based on the relative sizing of the insert and of the available space in the humeral tray.

[0044] Here, the humeral stem 100 can be sized or shaped or otherwise adapted to be fitted within a prepared proximal end canal of the humerus 10. In an example, the humeral stem 100 can be a metallic device anchored into the humeral canal of the humerus 10 using cement or a press-fit, for example.

[0045] The glenosphere 110 can be sized or shaped or otherwise configured to be mounted to a prepared surface of a patient's glenoid, such as via a plurality of screws.

[0046] FIG. 2 shows top and side views of the insert 130, in accordance with one embodiment; and FIG. 3 shows top and side views of the humeral tray 120.

[0047] In general, the insert 130 can be formed of a polymeric material, such as polyethylene and has a circular shape which is of a smaller diameter than the diameter of a concave articulation surface 122 of the humeral tray 124. The humeral tray 120 can be formed of a metallic material such as CoCr or a titanium alloy, for example, the humeral tray 120 includes the concave articulation surface 122 which receives the insert 130.

[0048] In this example, the humeral tray 120 can include a constraint ridge 124 located around a periphery of the humeral tray 120. The height of the constraint ridge 124 and the height of the insert 130 are chosen such that the insert 130 is constrained from moving past the constraint ridge 124. Moreover, the insert 130 can have a height higher than a height of the constraint ridge 124. This minimizes notching during articulation of the joint.

[0049] The insert 130 can include a convex articulation surface 132 for articulating with the humeral tray 120 and a concave articulation surface 134 for articulating with the glenosphere 110, wherein the convex articulation surface 132 has a greater radius than the concave articulation surface 134.

[0050] FIG. 4 shows the reverse shoulder implant system with an arm at rest; and FIG. 5 shows the reverse shoulder implant system with an arm lifted.

[0051] FIGS. 4 and 5 help shows the features of the present system. Here, due to the ability of the non-contained insert 130 to articulate and move with respect to its interface with the humeral tray 120, the CCD angle induced across the joint changes during motion.

[0052] For example, while the arm is resting at the side of the body (0° abduction) the resultant CCD angle would be relatively flatter (>150°) (FIG. 4), offering a high level of supero-inferior constraint. During abduction, the insert 130 can rotate with respect to both the glenosphere 110 and with respect to the humeral tray 120, reducing the CCD angle (≤135°) and offering a greater potential range of motion (FIG. 5).

[0053] Due to the ability of the non-contained insert 130 to articulate and move with respect to its interface with the humeral tray 120, the technical range of motion between the glenosphere 110 and the humeral stem 100 is increased compared to a contained tray/insert system. The extent of additional motion/freedom afforded with the non-contained insert 130, as well as the resultant CCD angle, is based on the relative sizing of the insert and of the available space in the humeral tray. Thus, different results can be provided by providing a smaller or larger insert 130 or humeral tray 120.

[0054] In the present system, beyond the additional technical range of motion that is afforded, there is expected to be additional scope for the patient to better perform activities of daily living due to the freedom to subtly alter the relative positions of the insert 130 and the humerus tray 120 during minor motions. These small motions, while constrained by the conformity of the articulations and bounded by the humeral tray 120, give the patient greater control over their ability to move the arm as they need it and account for the patient specific nature of glenohumeral rhythm.

[0055] FIG. 6 shows a side view of an insert 230, in accordance with one embodiment. In this example, the insert 230 can optionally include a circumferential groove 232 around an outer periphery of the insert 230. The groove 232 helps resist lift-off of the insert 230 from the humeral tray 120 at the extremes of insert 230 movement across the tray 120.

[0056] FIG. 7 shows a side view of an insert 250, in accordance with one embodiment; and FIG. 8 shows a side view of a humeral tray 320, in accordance with one embodiment. In this example, the humeral tray 320 can include a cut-out 322 in a central surface 330 of the humeral tray 320. The insert 250 can include a post 234 extending from a bottom surface of the insert 250. The post 234 is configured to ride in the cut-out 322 so as to prevent excessive motion of the insert 250 relative to the humeral tray 320.

[0057] FIG. 9 shows a method 400 of improving a shoulder implant, in accordance with one embodiment.

[0058] Method 400 includes mounting a humeral tray to a proximal end of a humeral stem (402). This can be done after the humeral stem is properly implanted in the humeral canal of the humerus. Method 400 further includes mounting a glenosphere to a scapula (404). As noted above, this can be accomplished in a variety of fashions, as by using a base plate, or a cement fit, or with screws or other fasteners. The method further includes positioning an insert (406) between the humeral tray and the glenosphere such that the insert articulates with both the humeral tray and the glenosphere. In the example method 400, the insert is not attached to the humeral tray such that the insert can articulate and move relative to the humeral tray.

[0059] In some options the method can include any of the other features discussed above such as the humeral tray including a constraint ridge located around a periphery of the humeral tray, and the insert having a height higher than a height of the constraint ridge.

[0060] The present system allows for better joint movement after a reverse-type shoulder implant. By providing the non-contained insert, the system allows patients find that the functional outcome is improved relative to a contained insert implant.

Additional Notes

[0061] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

[0062] All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0063] In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.