Glenoid Trial Implant for Reverse Total Shoulder Prosthesis

Abstract

The invention relates to a glenoid trial implant for reverse total shoulder prosthesis including a metaglene intended to be assembled in a stabilized and temporary manner inside the glenoid fossa of a patient who will receive surgery, and a glenosphere integrally assembled to the metaglene.

Claims

1. A glenoid trial implant for reverse total shoulder prosthesis, wherein it comprises: a metaglene having an axis of revolution (d1) and being intended to be assembled in a stabilized and temporary manner inside the glenoid fossa of a patient who will receive surgery, and a glenosphere having an axis of revolution (d2) and being integrally assembled to the metaglene and intended to be received inside a cupula of a humeral trial implant.

2. The glenoid trial implant according to claim 1, wherein the axes of revolution (d1, d2) of the metaglene and of the glenosphere coincide.

3. The glenoid trial implant according to claim 1, wherein the axes of revolution (d1, d2) of the metaglene and of the glenosphere intersect.

4. The glenoid trial implant according to claim 1, wherein the axes of revolution (d1, d2) of the metaglene and of the glenosphere are strictly parallel.

5. The glenoid trial implant according to claim 1, wherein the axes of revolution (d1, d2) of the metaglene and of the glenosphere are separated from each other by a distance of between 0.5 and 5 mm, preferably between 1 and 3 mm.

6. The glenoid trial implant according to claim 1, wherein the metaglene comprises a stop designed to act as a spacer between the glenosphere and the glenoid fossa when the trial implant is assembled inside the glenoid fossa, the thickness of said stop being less than or equal to 10 mm, preferably less than or equal to 6 mm.

7. The glenoid trial implant according to claim 1, wherein the metaglene and the glenosphere are made in one piece, forming a monoblock implant.

8. The glenoid trial implant according to claim 1, comprising means for assembling the metaglene and the glenosphere.

9. The glenoid trial implant according to claim 1, wherein the metaglene and/or the glenosphere are made from plastic polymer or stainless steel or titanium and an alloy of these materials.

10. A set comprising several glenoid trial implants according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] The invention will be better understood on reading the following description, given solely by way of example and with reference to the accompanying drawings in which:

[0037] FIG. 1 is a set of diagrammatic views showing the humoral and glenoid implants forming a reverse total shoulder prosthesis;

[0038] FIG. 2 is a set of diagrammatic views showing glenoid implants according to several variants of the invention;

[0039] FIG. 3 is a set of diagrammatic views showing glenoid implants according to several variants of the invention;

[0040] FIG. 4 is a set of diagrammatic views showing glenoid implants according to several variants of the invention.

DETAILED DESCRIPTION

[0041] FIGS. 1 to 4 show glenoid trial implants for reverse total shoulder prosthesis, designated by the general reference 1.

[0042] As shown on FIG. 1, the glenoid trial implant 1 according to the invention comprises a metaglene 3 having an axis of revolution d1 and being intended to be assembled in a stabilized and temporary manner inside the glenoid fossa (not shown) of a patient who will receive surgery. In the variants shown on the figures, the metaglene 3 is circular. The implant 1 also comprises a glenosphere 2 having an axis of revolution (d2) and being integrally assembled to the metaglene 3 and intended to be received inside a cupula 101 of a humeral trial implant 100. In the variants shown on the figures, the glenosphere 2 is more than a half-sphere.

[0043] Thus, the surgeon has a trial implant 1 that he/she can attach to the glenoid fossa in order to define, during the operation, the best position for the center of rotation of the shoulder joint. When such a position is reached, the surgeon can choose the final glenoid implant whose shape corresponds to the trial implant 1. Thus, the final implant is removed from its sterile packaging only when the surgeon is certain that it is the right implant to be used.

[0044] According to alternative embodiments of the invention shown on FIG. 2, the axes of revolution d1 and d2 of the metaglene 3 and of the glenosphere 2 coincide, which means that these two elements can be centered relative to each other. This configuration is particularly advantageous when there is no need to longitudinally lower the center of rotation of the shoulder joint (which corresponds to the axis of revolution d2 of the glenosphere 2).

[0045] Alternatively, as shown on FIGS. 3 and 4, the axes of revolution d1 and d2 of the metaglene 3 and of the glenosphere 2 are strictly parallel, which means that these two elements are offset relative to each other. According to the variants of the invention shown on FIG. 3, the metaglene 3 and the glenosphere 2 are longitudinally offset relative to each other, with respect to the patient's body, by a distance of 1 mm, thereby finally lowering the position of the center of rotation of the shoulder joint, which also lowers the humerus longitudinally. This tenses the deltoid muscle in a longitudinal direction. This offset also allows the metaglene to be positioned slightly higher or lower according to the patient's morphological characteristics. Such a variation also allows the center of rotation of the shoulder joint to be positioned in the most suitable location. According to the variants of the invention shown on FIG. 4, the axes of revolution d1 and d2 are separated by a distance of 3 mm, which means that the center of rotation of the joint can be lowered even further and therefore, finally, that a greater tension can be applied on the deltoid muscle.

[0046] The metaglene 3 comprises a stop 4 (visible on FIGS. 2 to 4) designed to act as a spacer between the glenosphere 2 and the glenoid fossa when the trial implant 1 is assembled inside the latter. As shown, the thickness of this stop 4 varies up to 6 mm. This variation in the thickness of the stop 4 allows lateralization of the center of rotation of the shoulder joint and, consequently, lateralization of the humerus once the shoulder prosthesis has been assembled. As a result, a greater tension is applied on the deltoid muscle in the lateral direction.

[0047] The deltoid muscle can therefore be tensed sufficiently so that it can operate from the first degrees of abduction as a replacement for the muscles forming the rotator cuff.

[0048] Lastly, the diameter of the glenosphere 2 of a glenoid trial implant 1 can also be varied to further offset its axis of revolution d2 (and therefore vary the center of rotation of the shoulder joint longitudinally and/or laterally). The diameter of such glenospheres 2 can vary between 30 and 44 mm.

[0049] The glenoid trial implant 1 can be monoblock, which means that the metaglene 3 and the glenosphere 2 are made in one piece and cannot be separated from each other.

[0050] Alternatively, the implant 1 comprises assembly means used to integrally attach the metaglene 3 and the glenosphere 2 so that they do not separate when the implant 1 is attached inside the glenoid fossa or when the surgeon performs tests during the operation. Such assembly means are known to those skilled in the art. As non-limiting examples, clips or a screw/nut combination, etc. can be used.

[0051] The surgeon can be provided with a set of several glenoid trial implants 1 according to different variants of the invention, in the form of a kit. The surgeon can therefore choose from all the possible variants of glenoid trial implants 1 required to best adjust the center of rotation of the shoulder joint according to the patient's morphological characteristics. Once the center of rotation of the shoulder joint has been placed in the right position, the surgeon only has to choose the final glenoid implant of shape identical to that of the glenoid trial implant 1 used to reach said position.

[0052] The invention is not limited to the embodiments described and other embodiments will be clearly apparent to those skilled in the art. In particular, glenospheres of diameters different from those mentioned can be used, or the metaglene can be further offset relative to the glenosphere.

LIST OF REFERENCES

[0053] 1: glenoid trial implant [0054] 2: glenosphere [0055] 3: metaglene [0056] 4: stop [0057] 100: humoral trial implant [0058] 101: cupula [0059] d1: axis of revolution of the metaglene [0060] d2: axis of revolution of the glenosphere