Modular reverse shoulder prosthesis

Abstract

A modular reverse shoulder prosthesis is provided, comprising a stem (110) including a tapered body (111) and a first annular housing (112), a tray (120) including a dome element (121) for insertion into the first annular housing (112) and further including a second annular housing (122), and a liner (130) including an engagement element (131) for at least partial insertion into the dome element (121) and further including an interface concave element (132) configured to couple with the second annular housing (122). The second annular housing (122) of the tray (120) is configured to support the interface concave element (132) and includes a raised edge (123) defining an overall contour having different height developments in at least diametrically opposed portions (123a; 123b) of the tray (120).

Description

[Technical field]

[0001] The present invention relates to a modular reverse shoulder prosthesis.

[0002] The present invention is particularly useful in reverse shoulder implant surgery, and the following description will refer to this specific application for ease of explanation.

[0003] Generally, it is not excluded that the invention can be applied to other types of artificial joints. [Background technology]

[0004] As is known, a total shoulder prosthesis provides a prosthetic glenoid component and a prosthetic humeral component which articulate with one another.

[0005] Two types of total shoulder prostheses are used in clinical practice.

[0006] The first type of prosthesis, called "anatomical," which was intended to replicate the natural anatomy of the glenohumeral joint, provides the humeral component with a convex end that articulates with a concave end of the glenoid component.

[0007] The second type of prosthesis, called "reverse," instead provides a convex glenoid component that articulates with a concave humeral component after resection of the humeral head, with reverse prostheses being preferred in critical situations of rotator cuff instability.

[0008] There are also "convertible" prostheses that allow the conversion of an anatomical prosthesis into a reverse prosthesis without the need to remove all of the implant components, yet advantageously maintain the original bone fixation.

[0009] Generally, when replacing the humeral head with a prosthesis, especially in the case of reverse-type prostheses, various elements should be provided that make it possible to obtain the desired overall inclination angle of the implant by matching the stems of the implant with the inserts, which allows to obtain a better joint mobility within the limitations imposed by the resection surface and the general condition of the patient's anatomy.

[0010] U.S. Patent Application Publication No. 2014 / 236304 relates to a modular reverse and convertible shoulder prosthesis including a distal stem, a reverse metaphysis, an angulatable reverse insert or liner, and a modular screw for connecting the reverse metaphysis with the distal stem.

[0011] WO 2014 / 067961 relates to a convertible reverse prosthesis implant including a humeral stem, an inversion tray, and a polyethylene reverse insert or liner. The reverse insert is provided in alternatives with different inclination angles, for example 7.5°, 12.5°, and 17.5°.

[0012] The difficulties encountered in the prior art are due to the fact that the size of the prosthesis, especially in the case of modular reverse prostheses, can lead to excessive tension of the surrounding tissues, which not only makes it difficult to reduce the prosthesis at the surgical site, but also leads to short- and medium-term consequences, among others, for example to unfavorable biomechanical configurations (suboptimally working muscle lines, overly tense muscles, etc.) or fractures (acromion fracture due to overstress). These sizes (and the relative consequences) are strictly related to the position of the concave surface relative to the resection surface of the humerus. In particular, the more the prosthesis design is of the "inlay" type, the more the lower point of the concave articular surface of the humerus is located below the resection surface. Conversely, the more the prosthesis design is of the "onlay" type, the more the lower point of the concave articular surface of the humerus is located above the resection surface. Especially in the case of modular prostheses, the design tends to be of the onlay type, since it is difficult to maintain the inferior point of the concave articular surface of the humerus in the area below the resection surface (metaphysis), a connection system between several modular components must in fact be provided, leaving little space available in said area to accommodate the concavity of the articular surface, and there are technical limitations related to the minimum thickness of the articular material.

[0013] Also, unlike radially symmetric liners, the onlay level can be even more pronounced in the case of liners with unique inclination angles; in fact, in order to ensure a minimum thickness to meet minimum mechanical strength requirements, inclined liners must have a higher lower concave point, and therefore a higher onlay level.

[0014] Thus, excessive onlay levels in reverse modular prostheses can impair the motion characteristics (rotation, extension, adduction) and generally reduce the performance of the implant, as discussed above.

[0015] On the other hand, lowering the onlay level is not easy, not only because of the reduction in space in the metaphysis, but also because of the thinning that can be observed in the liner itself, typically made of ultra-high molecular weight polyethylene (UHMWPE), due to the proximity of the interface of the concave liner to the resection surface. Even though the liner is supported by a metal tray, excessive thinning of the liner reduces its mechanical strength and therefore the overall performance of the implant and puts it at risk of failure under load.

[0016] A general object of the present invention is to provide surgeons with a shoulder prosthesis that overcomes the shortcomings of the prior art.

[0017] It is a further object of the present invention to limit or reduce the onlay level in liners of reverse-type modular prostheses.

[0018] It is a further object of the present invention to effectively allow for various correction angles of the liner of a reverse-type modular prosthesis.

[0019] It is a further object of the present invention to improve the motion characteristics of a shoulder prosthesis.

[0020] It is a further object of the present invention to improve the mechanical strength of the components of a shoulder prosthesis, particularly the polyethylene liner.

[0021] It is a further object of the present invention to have a modular prosthetic stem having improved features.

[0022] A further object of the present invention is to have a solution that can be applied to convertible modular prostheses with possible anatomical and reverse prosthesis configurations. Summary of the Invention

[0023] The solution underlying the present invention is to provide a modular shoulder prosthesis comprising a stem, a tray inserted into the stem, and a liner coupled to the tray, forming a reverse shoulder configuration.

[0024] The tray includes a raised edge that supports the mating concave elements of the liner, the raised edge being reduced in height on the side where the angled liner is thinner, thus forming an asymmetric tray with respect to the diametrically opposed portions.

[0025] This device allows the liner to be significantly lowered to the onlay level without affecting the minimum thickness of the liner and still providing sufficient support for the liner, especially at the full height of the raised edge.

[0026] Based on this solution, a modular reverse-type prosthetic shoulder joint is provided, comprising: a stem including a tapered body and a first annular housing; a tray including a dome element for insertion into the first annular housing and further including a second annular housing; and a liner including an engagement element for at least partial insertion into the dome element and further including a mating concave element configured to couple with the second annular housing.

[0027] The second annular housing of the tray includes a raised edge configured to support the mating concave element, the raised edge defining an overall contour having different height developments in at least diametrically opposed portions of said tray.

[0028] This produces a shoulder prosthesis system with great modularity and versatility, allowing the implantation of different liners with different correction angles. Larger correction angles also reduce the onlay level, i.e. the distance between the bone resection surface and the lower point of the interface of the concave liner inserted in the tray.

[0029] As an advantage, a reduced onlay level improves the mobility characteristics (rotation, extension, adduction) and the general performance of the prosthesis.

[0030] On the one hand, as an advantage, the overall contour of the tray edge, having different or asymmetric height developments, makes it possible to maintain sufficient thickness in each part of the liner itself, improving the mechanical strength of the liner and the entire prosthesis implant.

[0031] Further characteristics and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example, and from the claims, which form an integral part of this description. [Brief description of the drawings]

[0032] [Figure 1] 1 shows a three-dimensional exploded view of an embodiment of a modular reverse shoulder prosthesis in accordance with the present invention. [Diagram 2] 2 shows a cross-sectional view of the tray of FIG. 1. [Diagram 3] 2 shows a cross-section of an exploded view of the modular reverse shoulder prosthesis of FIG. 1; [Figure 4] 4 shows a cross-section similar to FIG. 3 of the assembled modular reverse shoulder prosthesis of FIG. 1; [Diagram 5] FIG. 2 shows a side view of the liner and tray assembly of FIG. 1. [Figure 6] 5 shows a cross section of FIG. [Figure 7] A detail of FIG. 6 is shown. [Figure 8] 4 shows the thickness of the liner for the solution according to the invention; [Figure 9] 4 shows the thickness of the liner in another example solution; [Figure 10] 2 shows a cross-sectional view of the liner and tray assembly of FIG. 1 in a vertical plane. [Figure 11] 2 shows a cross-sectional view of the liner and tray assembly of FIG. 1 in a vertical plane. [Figure 12]1 illustrates a further embodiment of a tray for a modular reverse shoulder prosthesis according to the present invention. [Figure 13] 1 illustrates a further embodiment of a tray for a modular reverse shoulder prosthesis according to the present invention. [Figure 14] 1 illustrates a three-dimensional exploded view of an alternative modular reverse shoulder prosthesis in accordance with the present invention. [Figure 15] 13 shows a cross-section of an exploded view of a further alternative modular reverse shoulder prosthesis. [Figure 16] 16 shows a cross-section similar to FIG. 15 of a further alternative assembly view of a modular reverse shoulder prosthesis; [Figure 17] FIG. 1 shows a three-dimensional view of an embodiment of a stem for a modular reverse shoulder prosthesis according to the present invention. [Figure 18] FIG. 18 shows a front view of the stem of FIG. 17. [Figure 19] FIG. 18 shows a side view of the stem of FIG. 17.

[0033] In the different drawings, similar elements are designated by similar reference numbers.

[0034] The technical drawings shown in the figures are for illustrative purposes only and are not necessarily drawn to scale or to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] FIG. 1 illustrates a three-dimensional exploded view of an embodiment of a modular reverse shoulder prosthesis 100 in accordance with the present invention.

[0036] The modular reverse shoulder prosthesis 100 includes a stem 110 that includes a tapered body 111 and a first annular housing 112 .

[0037] Preferably, the stem 110 further comprises a number of supports 113 connecting the tapered body 111 and the first annular housing 112 to one another and keeping them at an angle to one another. As will be comprehensively discussed below, the stem 110 falls into the "short stem" category of humeral prostheses that are particularly advantageous due to their reduced invasiveness and the reduced bone volume that they occupy, allowing for a reduction in the "stress shielding" phenomenon.

[0038] The modular reverse shoulder prosthesis 100 further comprises a tray 120 including a dome element 121 for insertion into the first annular housing 112 of the stem 110. The tray 120 further comprises a second annular housing 122.

[0039] The modular reverse shoulder prosthesis 100 comprises a liner 130 including an engagement element 131 configured for at least partial insertion into the dome element 121 of the tray 120. The liner 130 further comprises an interface concave element 132 configured to couple with the second annular housing 122 of the tray 120. In particular, the interface concave element 132 is configured for circumferential coupling with the second annular housing 122 of the tray 120.

[0040] Generally, the modular reverse shoulder prosthesis 100 allows for a high degree of modularity and versatility, as will be further described, and can accommodate a variety of liners 130 having a variety of correction angles.

[0041] The second annular housing 122 of the tray 120 also includes a raised edge 123 configured to support the mating concave element 132 of the liner 130 .

[0042] The tray 120 is made of a metallic material, preferably titanium or an alloy thereof. In particular, the tapered body 111 and the first annular housing 112, including the supports 113, are formed as a single piece within the stem 110.

[0043] Instead, the liner 130 is made of a plastic material, preferably polyethylene, and in particular ultra-high molecular weight polyethylene (UHMWPE).

[0044] FIG. 2 shows a cross-sectional view of the tray 120.

[0045] As described, the tray 120 includes a dome element 121 and a second annular housing 122. The second annular housing 122 includes a raised edge 123 (not visible in FIG. 2) configured to support a mating concave element 132 of the liner 130.

[0046] The raised edge 123 defines an overall contour having different height extensions at least in diametrically opposed portions 123a and 123b of the tray 120, as best seen in FIG.

[0047] FIG. 3 shows a side cross-sectional exploded view of the modular reverse shoulder prosthesis 100, showing the stem 110, tray 120, and liner 130 previously described.

[0048] Specifically, the tray 120 is assembled to the stem 110 by a conical connection between the dome element 121 and the first annular housing 112, and preferably by a further connection with a central safety screw 140. The liner 130 is assembled to the tray 120 by a snap engagement 150 acting between the engagement element 131 and an inner surface of the dome element 121. Also preferably, the liner 130 is assembled to the tray 120 by a further interference between the engagement element 131 and an inner surface of the dome element 121.

[0049] In this view of the modular reverse shoulder prosthesis 100, it can be seen that the general profile of the raised edge 123 comprises a first angled portion 123a configured to interlock with an angled surface 133a (not visible in the view section) of the articulating concave element 132. The first angled portion 123a has a reduced height development compared to a radially opposing second portion 123b of the raised edge 123.

[0050] 3, the dome element 121 is configured to be inserted into the first annular housing 112 along an insertion axis 10, and the engagement element 131 is configured to be inserted into the dome element 121 along the same insertion axis 10. When referring herein to the "height" or "height development" of the raised edge of the tray 120, the dimension of the raised edge evaluated along the insertion axis 10 is intended.

[0051] Generally, the raised edge 123 defines an overall contour having a height development, evaluated parallel to the insertion axis 10 , that is different in at least diametrically opposed portions 123 a and 123 b of the tray 120 .

[0052] Focusing on the first inclined portion 123a, it substantially comprises one semicircular half of the raised edge 123. In the other semicircular half of the raised edge 123, the overall contour comprises a flat portion 123b, which is radially opposite the first inclined portion 123a and has a greater height development compared to the first inclined portion 123a.

[0053] FIG. 4 shows a cross section similar to FIG. 3 of an assembled view of a modular reverse shoulder prosthesis 100.

[0054] In this view, it can be seen that the dome element 121 is configured to be inserted into the first annular housing 112 along an insertion axis 10, and that the engagement element 131 is likewise configured to be inserted into the dome element 121 along the same insertion axis 10, to form the modular structure of the modular reverse shoulder prosthesis 100. It is also noted that the second annular housing 122 is disposed substantially perpendicular to the insertion axis 10.

[0055] The mating concave element 132 of the liner 130 has an upper surface that lies substantially on the offset plane 11. The offset plane 11 is inclined at an offset angle relative to a plane perpendicular to the insertion axis 10. Instead, the tapered body 111 defines a stem main axis 12 that is angled relative to the insertion axis 10.

[0056] Generally, the stem 110 is configured to be implanted into the epiphysis of the humerus, while the liner 130 is configured to articulate with a respective spherical element, or glenosphere, of a reverse shoulder prosthesis.

[0057] In an alternative to the shoulder prosthesis, instead of the elements 120 and 130 already described, the stem 110 is further configured to be employed in a convertible prosthesis, in which case the first annular housing 112 is further adapted to accommodate the prosthesis elements according to the anatomical configuration.

[0058] FIG. 5 shows a side view of a partial prosthesis assembly including a liner 130 and a tray 120.

[0059] In this view, the raised edge 123 includes a plurality of notches 124 configured to interlock with a respective plurality of outer protrusions 134 on the mating concave element 132. It can thus be seen that the protrusions 134 and the notches 124 are configured to block relative rotation between the tray 120 and the liner 130.

[0060] Figure 6 shows cross section VI-VI of the assembly of Figure 5. As already explained, the raised edge 123 defines an overall profile having different height developments at least in diametrically opposed portions 123a and 123b of the tray 120, as can be seen in Figure 6.

[0061] In effect, by reducing the height of the raised edge 123, the tray 120 is made asymmetric in height, with the side 123a having a smaller development in height of the liner 130 due to the compensation angle provided. This modification allows the liner 130 to have a significantly lower onlay level, but without affecting the minimum thickness of the mating concave element 132, and still allowing sufficient support of the liner 130 by the highest portion 123b of the edge 123 of the tray 120.

[0062] Figure 7 shows a detail of figure 6. Here, the connection between the first portion 123a of the raised edge of the annular housing 122 and the respective surface 133a of the mating concave element 132 is better visible.

[0063] To clarify the effect of the invention, figures 8 and 9 show a comparison of the liner thickness according to the solution according to the invention and another example, with figure 8 showing the solution according to the invention and figure 9 showing another example, and a local enlargement of the part identified by the dashed line is also shown.

[0064] 8 shows a tray 120 and a liner 130, where the raised edges of the tray 120 define an overall profile having different height developments at least in diametrically opposed portions, and thus are asymmetric in height, where the minimum thickness 80 of the liner 130 between the concave surface and the interface with the tray 120 is, for example, 3.9923 mm.

[0065] In Fig. 9, a typical tray and a typical liner are shown having substantially the same diameter and size as those in the example of Fig. 8. However, in this case, the raised edges of the tray define an overall contour having the same height development at diametrically opposed portions and are therefore symmetrical in height. In this case, the minimum thickness 90 of the liner between the concave surface and the interface with the tray is, by way of example only, 1.6187 mm and is therefore considerably less than the minimum thickness 80 in the case of Fig. 8.

[0066] It is therefore clear that in the solution of the invention, for the same onlay level and in the presence of the same correction angle of the liner, there is no thinning of the thickness of the liner itself to the benefit of mechanical strength.

[0067] From another perspective, in the solution of the present invention, for the same minimum thickness of the liner and therefore for reasonably maintaining the mechanical strength properties of the liner, the onlay level can be lowered to the benefit of the functionality and effectiveness of the artificial joint.

[0068] 10 and 11 show respective cross-sectional views on mutually perpendicular planes of a subassembly comprised of the liner 130 and tray 120 already described, and further comprised of the central safety screw 140 and snap engagement 150 already described.

[0069] FIG. 12 illustrates a further embodiment of a tray 120' for a modular reverse shoulder prosthesis in accordance with the present invention.

[0070] In this alternative, the tray 120' still has an asymmetric raised edge 123', but has an annular housing 122' that has a flat, non-sloped configuration as in the raised edge 123 of the embodiment already described above, but that is subject to the minimum thickness of the liner associated therewith.

[0071] In particular, the overall profile of the raised edge 123' comprises a first planar portion 123a' that still has a smaller height development compared to a radially opposite second portion 123b of the raised edge 123'. In general, the overall profile of the raised edge 123' comprises a first planar portion 123a' that is configured to interlock with a respective planar surface (not visible in FIG. 12) of a mating concave element.

[0072] In this alternative with asymmetric raised edge 123' and first planar portion 123a', there is a larger minimum edge thickness while maintaining the same onlay level. This alternative is something of a trade-off with respect to the previous exemplary embodiment. Thus, this alternative takes the form of a liner with a smaller thickness compared to the angled version of the liner 130. This trade-off is acceptable as long as the minimum thickness required for the mechanical strength of the liner is met, thus limiting the correction angle of the liner.

[0073] It should also be considered that the protuberance of the raised edge 123' has proven beneficial in terms of liner restraint and stability compared to the raised edge 123. The asymmetrical flat raised edge 123' adds some material to the tray 120' where there is an interference connection and removes some material where there is an urging bevel for the insertion of the liner compared to the asymmetrical angled edge 123. It can therefore be said that the flat version of the asymmetrical tray 120' has more available surface for interference connection with the liner, making the assembly more stable.

[0074] FIG. 13 shows a cross-sectional view of a further embodiment of a tray 120'' for a modular reverse shoulder prosthesis in accordance with the present invention.

[0075] In this alternative, the tray 120" has an annular housing 122" with an asymmetric raised edge 123" that has a fully inclined configuration compared to the only partially inclined configuration of the raised edge 123 of the embodiment already described above.

[0076] In particular, the overall profile of the raised edge 123'' comprises a first inclined portion 123a'' having a smaller height development compared to a radially opposing second portion 123b'' which is still inclined.

[0077] This alternative of a tray 120" having a fully beveled raised edge 123" is also acceptable, so long as the minimum thickness required for the mechanical strength of the liner is met.

[0078] FIG. 14 illustrates a three-dimensional exploded view of an alternative modular reverse shoulder prosthesis 100' in accordance with the present invention.

[0079] The modular reverse shoulder prosthesis 100' includes the stem 110, tray 120'', and liner 130 previously described.

[0080] In this embodiment, the tray 120'' is assembled to the stem 110 by a conical connection between the dome element 121 and the first annular housing 112 and by a further connection with the modular pin 140b.

[0081] The modular pin 140b is preferably preassembled to the tray 120". As with the screw system 140 already described, the modular pin 140b makes it possible to facilitate and accelerate the insertion of the components in the operating room and also to accelerate the pull-out in case of a prosthesis revision, since it is sufficient to place a fork-shaped tool to adjust the pull-out of the tray 120" from the stem 110. Also, the pin 140b offers a lower resistance to axial pull-out compared to the screw 140, but the presence of an essentially compressive force at the shoulder still ensures adequate resistance to "lever-out", since only the conical connection contributes to the retention.

[0082] FIG. 15 shows a cross-section of an exploded view of a further alternative modular reverse shoulder prosthesis 100'', in which the already described stem 110, tray 120, liner 130, and modular pin 140b are shown.

[0083] Also in this embodiment, the modular pins 140b are preferably pre-assembled to the tray 120.

[0084] FIG. 16 shows a cross section similar to FIG. 15, but in an assembled view, of a modular reverse shoulder prosthesis 100″.

[0085] In this figure, it can be seen that the dome element 121 is configured to be inserted into the first annular housing 112 of the stem 110 by cooperation of the pin 140b to form the modular structure of the prosthesis 100".

[0086] FIG. 17 shows a three-dimensional view of an embodiment of a stem 110 for a modular reverse shoulder prosthesis in accordance with the present invention, FIG. 18 shows a front view of stem 110, and FIG. 19 shows a side view of stem 110.

[0087] The stem 110 for the modular reverse shoulder prosthesis comprises a tapered body 111 and a first annular housing 112 configured to receive the tray 120 for the other humeral components of the modular prosthesis, such as the liner 130 as previously described.

[0088] In implantation of a shoulder prosthesis, the stem 110 is configured to be implanted into the humeral epiphysis. The stem 110 is configured primarily for a modular reverse shoulder prosthesis, but also for a convertible prosthesis, where the first annular housing 112 is advantageously configured to accommodate modular anatomical prosthesis elements.

[0089] Preferably, the first annular housing 112 includes an external trabecular structure 201 configured to obtain better fixation with the humerus. The first annular housing 112 allows for load transfer to the humerus directly below the resection, thus helping to promote better metaphyseal type fixation.

[0090] The stem 110 further comprises a number of supports 113 that connect the tapered body 111 and the first annular housing 112 and keep them angled relative to one another. Notably, both the tapered body 111 and the first annular housing 112 and the number of supports 113 are made as a single piece within the stem 110.

[0091] Generally, the plurality of supports 113 is configured for fixation and stabilization of the prosthetic joint implant. More specifically, the plurality of supports 113 defines a finned portion connecting the tapered body 111 and the first annular housing 112, which in turn tapers at a region connecting with the tapered body 111. In particular, the plurality of supports 113 includes a first intermediate support 211, two front and rear supports 212a and 212b, and a lateral support 213. The plurality of supports 113 is configured to stabilize bending moments in addition to providing rotational stability to the stem 110.

[0092] Preferably, the configuration of the anterior and posterior supports 212a and 212b is curved according to the angle between the tapered body 111 and the first annular housing 112. This determines the curved implantation direction of the stem 110 and allows it to follow the mid-curvature of the humerus during the insertion process, better fitting the anatomy and thus facilitating the implantation process in the operating room.

[0093] Additionally, the undercut 20 of the stem 110 due to the angle between the tapered body 111 and the first annular housing 112 makes it possible to avoid excessive proximal bone removal due to insertion along the diaphyseal axis of the humerus.

[0094] In an alternative not shown, the two anterior and posterior supports can be straightened relative to the main axis of the stem to allow for the insertion of the implant into the axis of the diaphysis in a more intuitive and reproducible manner.

[0095] As an advantage, the gaps created between the supports 113 allow a larger lateral area of ​​the supports 211, 212a, 212b, and 213 to be exposed to the bone, improving the bending and torsional stability of the implant. Also, as an advantage, the gaps created between the supports 113 reduce the weight and volume of the entire implant and significantly reduce the amount of bone removed for implantation, which in turn reduces the filling factor (given by the ratio of the volume of bone removed from the prosthesis to the volume of bone without the prosthesis) and, as a result, is less invasive and reduces the risk of "stress shielding". Finally, the gaps created between the supports 113 allow access to the distal part of the prosthesis in case of revision interventions.

[0096] The distal portion of the stem 110 has a tapered body 111 with a substantially conical or frustoconical form with a circular cross-section, which provides additional stability to the implant, particularly in the immediate post-operative period when the bone has not yet integrated into the first annular housing 112.

[0097] More specifically, the substantially conical shape of the stem 110 helps convert axial translation into circumferential force, thus increasing the "press-fit" of the implant.

[0098] Preferably, the tapered body 111 comprises a polished end 202. The polished end 202, in addition to facilitating the insertion of the stem 110 during surgery, also makes it possible to avoid localized osseointegration, thus avoiding proximal bone resorption due to distal transfer of load and the resulting "stress shielding", and avoiding problems during implant revision procedures where it is difficult to access the distal part of the tapered body 111 to remove attached bone without being too invasive.

[0099] Finally, preferably, the stem 110 is symmetrical for implantation in both the left and right humerus, but it has a transverse average offset 21 between the stem main axis 12 and the center 22 of the first annular housing 112 that is configured to best replicate the offset anatomically present in the humerus.

[0100] It should be noted that because the stem 110 is a modular component separate from the tray 120 and liner 130 described above, it may be used in other alternative shoulder prostheses, both reverse and anatomical.

[0101] Moreover, it is obvious that further implementations and modifications of the present invention are possible for those skilled in the art to meet fortuitous needs.

[0102] Therefore, the above embodiments should be understood to be provided for illustrative and non-limiting purposes.

Claims

1. 1. A modular reverse shoulder prosthesis, comprising: a stem (110) including a tapered body (111) and a first annular housing (112); a tray (120) including a dome element (121) for insertion into said first annular housing (112) and further including a second annular housing (122); a liner (130) including an engagement element (131) for at least partial insertion into said dome element (121) and further including a mating concave element (132) configured to couple with said second annular housing (122); the second annular housing (122) of the tray (120) comprises a raised edge (123) configured to support the mating concave element (132); 1. A modular reverse shoulder prosthesis, wherein the raised edge (123) defines an overall contour having different height developments in at least diametrically opposed portions (123a; 123b) of the tray (120).

2. 2. The modular reverse shoulder prosthesis of claim 1, wherein the overall contour of the raised edge (123) comprises a first planar portion (123a') configured to interlock with a respective planar surface of the articulating concave element (132), the first planar portion (123a') having a smaller development in height than a diametrically opposed second portion (123b) of the raised edge.

3. 2. The modular reverse shoulder prosthesis of claim 1, wherein the overall profile of the raised edge (123) comprises a first inclined portion (123a; 123a'') configured to couple with a respective inclined surface (133a) of the articulating concave element (132), the first inclined portion (123a; 123a'') having a smaller height development than a diametrically opposed second portion (123b; 123b'') of the raised edge.

4. 4. The modular reverse shoulder prosthesis of claim 2 or 3, wherein the first portion (123a) substantially comprises one half of a semicircular shape of the raised edge (123).

5. 5. The modular reverse shoulder prosthesis according to claim 1, wherein the overall contour of the raised edge (123) comprises a flat portion (123b) radially opposite the first portion (123a; 123a') and having a greater height development compared to the first portion (123; 123a').

6. 6. The modular reverse shoulder prosthesis of claim 1, wherein the raised edge (123) comprises a plurality of notches (124) configured to interlock with a respective plurality of lateral protrusions (134) on the mating concave element (132) to block relative rotation of the tray (120) and the liner (130).

7. 7. The modular reverse shoulder prosthesis of claim 1, wherein the dome element (121) is configured to be inserted into the first annular housing (112) along an insertion axis (10), the engagement element (131) is configured to be inserted into the dome element (121) along the insertion axis (10), and the second annular housing (122) is disposed substantially perpendicular to the insertion axis (10).

8. 8. The modular reverse shoulder prosthesis of claim 7, wherein the articulating concave element (132) of the liner (130) has an upper surface that lies substantially on a correction surface (11), the correction surface (11) being inclined by a correction angle with respect to a plane perpendicular to the insertion axis (10).

9. 9. The modular reverse shoulder prosthesis of claim 7 or 8, wherein the tapered body (111) defines a stem main axis (12) that is angled relative to the insertion axis (10).

10. 10. The modular reverse shoulder prosthesis of claim 7, wherein the raised edge (123) defines the overall contour having a height variation, the height variation evaluated parallel to the insertion axis (10) being different in at least diametrically opposed portions (123a, 123b) of the tray (120).

11. 11. The modular reverse shoulder prosthesis of claim 1, wherein the tray (120) is assembled to the stem (110) by a conical connection between the dome element (121) and the first annular housing (112).

12. 12. The modular reverse shoulder prosthesis of claim 1, wherein the liner (130) is assembled to the tray (120) by a snap engagement (150) between the engagement element (131) and an inner surface of the dome element (121).

13. The modular reverse shoulder prosthesis of any one of claims 1 to 12, wherein the tray (120) is made of a metallic material and the liner (130) is made of a plastic material.

14. 14. The modular reverse shoulder prosthesis of claim 1, wherein the stem (110) further comprises a plurality of supports (113) connecting the tapered body (111) and the first annular housing (112) and maintaining them at an angle to each other.

15. 15. The modular reverse shoulder prosthesis of claim 14, wherein the plurality of supports (113) comprises a first intermediate support (211), two anterior and posterior supports (212a, 212b), and a lateral support (213).

16. 16. The modular reverse shoulder prosthesis of claim 15, wherein the anterior and posterior supports (212a, 212b) have a curved configuration according to an angle between the tapered body (111) and the first annular housing (112).

17. The modular reverse shoulder prosthesis of any one of claims 1 to 16, wherein the first annular housing (112) comprises an external trabecular structure (201).

18. 18. The modular reverse shoulder prosthesis of claim 1, wherein the stem (110) is configured to be implanted in the humeral epiphysis and the liner (130) is configured to articulate with a respective glenoid spherical element of a reverse shoulder prosthesis.

19. 19. The modular reverse shoulder prosthesis of claim 1, wherein the stem (110) is further configured for a convertible prosthesis and the first annular housing (112) is further adapted to accommodate a prosthetic element according to an anatomical configuration.

20. The modular reverse shoulder prosthesis of any one of claims 1 to 19, wherein the tapered body (111) has a substantially conical or frusto-conical form with a circular cross-section.

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