Glenoid Positioning Device

Abstract

A glenoid positioning device (100), particularly for Kirschner wires, is provided, comprising a hub (101) having a fiducial through-hole (110) and including three radially arranged housings (102a, 102b, 102c), and three sliding elements (103a, 103b, 103c) slidably housed within the three housings (102a, 102b, 102c), respectively, and configured to interact with the glenoid, the three sliding elements (103a, 103b, 103c) being configured to be radially extended or retracted to identify a circular area (2) of the glenoid.

Description

[Technical field]

[0001] The present invention relates to a glenoid positioning device, particularly for positioning a fiducial in the glenoid during shoulder prosthesis implantation surgery.

[0002] The present invention finds particular utility in both anatomical and reverse shoulder prosthetic implantation procedures, and the following description is made by way of exemplary disclosure with reference to this specific application.

[0003] Generally, the present invention can be used to find a central location within the glenoid cavity of the scapula and fix a fiducial thereto, such as, for example, a Kirschner wire, which can be used for further surgery during implantation of a shoulder prosthesis. [Background technology]

[0004] In the field of shoulder prostheses, the use of prostheses is widespread today, typically modular prostheses consisting of several elements that can be combined with each other to obtain an anatomical prosthesis or a reverse prosthesis and, in some cases, can be converted from an anatomical prosthesis to a reverse prosthesis.

[0005] Some commonly used prostheses involve the use of a glenoid anchor inserted into a pre-obtained hole substantially in the center of the glenoid. In the case of anatomic prostheses, a polyethylene insert is typically fixed to the glenoid anchor, whereas in the case of reverse prostheses, a convex glenoid articulating component called a glenosphere is typically fixed to the glenoid anchor.

[0006] The difficulty that arises is to accurately secure the appropriate anchor in the center of the glenoid so that the center of the prosthetic component connected to the appropriate anchor is aligned with the center of the glenoid.

[0007] In the prior art, there is in fact a problem of reproducibility of optimal positioning in the center of the glenoid cavity, which can compromise the effectiveness of the shoulder prosthesis.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS It is an object of the present invention to provide a glenoid positioning device having structural and functional features which overcome the cited shortcomings of the prior art.

[0009] A further object of the present invention is to enable correct positioning of fiducials, whether anatomical or reverse, such as Kirschner wires, which serve as guides for the implantation of the glenoid portion of a shoulder prosthesis.

[0010] A further object of the present invention is also to enable correct positioning of a fiducial in the center of the glenoid cavity of the scapula for better positioning of the shoulder prosthesis. Summary of the Invention

[0011] The solution underlying the present invention is to create a mechanical guide that allows the approximation of the glenoid cavity by three circumferential points while allowing the positioning of a fiducial in the center of the circumference thus identified, in particular for fixing the fiducial.

[0012] As an advantage, the present invention allows for a more reliable identification of the center of the glenoid cavity and allows for a more accurate and repeatable positioning of fiducials, for example constituted by Kirschner wires, used during implantation of a shoulder prosthesis.

[0013] Based on this solution, a glenoid positioning device is provided, comprising a hub having a reference through hole and including three radially arranged housings, and three slide elements slidably housed within the three housings respectively and configured to interact with the glenoid, the slide elements being configured to be radially extended or contracted to identify a circular area of ​​the glenoid.

[0014] The sliding elements are extended or retracted synchronously with one another, so that, when extended radially, the sliding elements advantageously pass the glenoid rim in the sagittal plane in the anterior-posterior direction and thus may provide a central reference with a variable radius at the circumference thus specified, in particular for fixing a reference, for example a Kirschner wire.

[0015] Preferably, the glenoid positioning device further comprises a central spindle axially associated with the hub and rotatable therein, and three connecting bars connecting each of the sliding elements to the central spindle, so that the three sliding elements are adapted to be radially extended or retracted by the action of the three connecting bars actuated by the rotation of said central spindle.

[0016] Thus, the three sliding elements allow for the identification of a circular area of ​​the glenoid cavity, and the central spindle is configured to identify the center of the circular area in order to position a reference in the center of the glenoid cavity of the scapula.As an advantage, therefore, it becomes possible to position a reference in the center of the glenoid cavity of the scapula in an accurate and repeatable manner.

[0017] Preferably, two slide elements are substantially opposed to one another and have protruding ends for externally gripping the glenoid portion of the scapula, and a third slide element, preferably transverse to the first two slide elements, provides a visual reference for verifying alignment of the glenoid with its own circumference.

[0018] Preferably, the hub and central spindle are provided with respective through holes that are axially aligned and configured for axial insertion of a datum, for example a Kirschner wire.

[0019] Advantageously, the hub and central spindle also comprise respective lateral access slots which, once the fiducials are correctly implanted, are alignable with one another to allow lateral withdrawal of the fiducial, e.g., Kirschner wire, i.e., removal of the glenoid positioning device from the fiducial positioned in the glenoid region. Advantageously, this allows the glenoid positioning device to be disconnected from the fiducial.

[0020] Further characteristics and advantages of the invention will become more apparent from the following detailed description, given for illustrative and non-limiting purposes, and from the claims, which form an integral part of this specification. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 shows a schematic lateral view of the scapula, with the glenoid cavity visible. [Diagram 2] 1 shows an exploded perspective view of an embodiment of a glenoid positioning device according to the present invention; [Diagram 3] FIG. 2 illustrates a cross-sectional side view of an embodiment of a glenoid positioning device according to the present invention in an assembled configuration. [Figure 4] 1 shows a perspective view of an embodiment of a glenoid positioning device according to the present invention in an open configuration. [Diagram 5] 5 illustrates a top view of the glenoid positioning device of FIG. 4. [Figure 6] 1 illustrates a perspective view of an embodiment of a glenoid positioning device of the present invention in a closed configuration. [Figure 7] 7 illustrates a top view of the glenoid positioning device of FIG. 6. [Figure 8] 1 shows a schematic side view of a scapula with a glenoid positioning device according to the present invention positioned therein. [Figure 9] FIG. 9 shows a frontal schematic view of the scapula of FIG. 8 with the Kirschner wire associated with the glenoid positioning device.

[0022] In the various drawings, like elements are designated with like reference numerals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Figure 1 shows a schematic lateral view of a scapula 1. Analysing the shape of the glenoid cavity of the scapula 1, it is possible to identify a circular area 2 in its lower part, defined as the glenoid "fossa" of the scapula and represented by a circumference 2.

[0024] As will become apparent below, the glenoid positioning device according to the invention makes it possible to accurately determine the center 3 of the glenoid fossa 2 in order to position fiducials, such as Kirschner wires, which are particularly useful as guides for the implantation of the anatomical structure or the glenoid part of a reverse shoulder prosthesis.

[0025] Usable fiducials for implantation in the glenoid 2 in conjunction with the glenoid positioning device of the present invention include, but are not limited to, Kirschner wires ("K-wires") or "Steinmann pins" or other types of "pins."

[0026] 2 shows a perspective view of an embodiment of a glenoid positioning device 100 in accordance with the present invention. The exemplary glenoid positioning device 100 is presented in an "exploded" view to more effectively display the elements, as well as the internal elements, of the glenoid positioning device 100. The glenoid positioning device 100 is also depicted and described in its assembled form.

[0027] The glenoid positioning device 100 comprises a hub 101 with fiducial through holes 110, described below, and including three housings 102a, 102b, and 102c radially disposed within the hub 101.

[0028] The glenoid positioning device 100 in turn includes three slide elements 103a, 103b, and 103c slidably housed within the three housings 102a, 102b, and 102c, respectively.

[0029] As will become clearer below, the three slide elements 103a, 103b, and 103c are configured to interact with the glenoid cavity during use of the glenoid positioning device 100.

[0030] The glenoid positioning device 100 further comprises a central spindle 104 axially associated with and rotatable within the hub 101. Preferably, the hub 101 further comprises a pin 105 configured to engage a radial groove 107 in the hub 104 to allow rotation of the central spindle 104 within the hub 101 but prevent translation of the central spindle 104 in the axial direction.

[0031] The glenoid positioning device 100 further comprises three connecting bars 108a, 108b and 108c connecting each of the three sliding elements 103a, 103b and 103c, respectively, to a respective seat formed on the central spindle 104.

[0032] Thus, in the glenoid positioning device 100, the three slide elements 103a, 103b, and 103c are configured to be radially extended or contracted to identify a circular region of the glenoid.

[0033] Thus, in particular, the three slide elements 103a, 103b and 103c are configured to be radially extended or contracted by the action of the three connecting bars 108a, 108b and 108c which are moved by the rotation of the central spindle 104.

[0034] Rotation of the central spindle 104 is preferably accomplished, during use, by a knob, not shown, associated with the glenoid positioning device 100.

[0035] FIG. 3 shows a cross-sectional side view of the glenoid positioning device 100 in an assembled configuration.

[0036] In this side view, it is possible to observe that the first and second slide elements 103a, 103b include respective protruding ends 109a, 109b configured to externally grip the glenoid portion of the scapula. In particular, the protruding ends 109a, 109b include internally machined or knurled inner surfaces configured to increase friction with bone surfaces during use of the glenoid positioning device 100, in a manner that will be described below.

[0037] FIG. 4 shows a perspective view of the glenoid positioning device 100 in an open configuration.

[0038] As can be seen in FIG. 4, the first slide element 103 a and the second slide element 103 b are substantially opposite each other, i.e. aligned on opposite sides relative to the hub 101 and the central spindle 104 .

[0039] The third slide element 103c is substantially transversely aligned with the first two slide elements 103a and 103b. As will be explained below, the third slide element 103c is specifically configured to provide a visual reference by its own end, and indeed the anatomical structure of the scapula makes it impossible to provide the third slide element 103c with a protruding end similar to the protruding ends 109a and 109b.

[0040] In this view it is possible to see that the three connecting bars 108a, 108b and 108c are connected by pins to the central spindle 104 and to the three sliding elements 103a, 103b and 103c, respectively, to form a triple rod crank type system.

[0041] In particular, the triple rod crank type system of the glenoid positioning device 100 is configured to extend, during rotation of the central spindle 104, in a first stage, the three sliding elements 103a, 103b, and 103b from a maximum closed position depicted in subsequent FIG. 6 to a maximum open position depicted in FIG. 4 discussed herein.

[0042] Furthermore, as described below, during rotation of the central spindle 104 in the opposite direction, the three slide elements 103a, 103b, and 103c are retracted to a further position, at least partially retracted, where they interact with the scapula during use.

[0043] FIG. 5 shows a top view of the glenoid positioning device 100.

[0044] In this view it is possible to observe that the hub 101 and the central spindle 104 are provided with respective reference through holes 110 axially aligned with one another, which are configured for the axial insertion of a reference, e.g., a Kirschner wire.

[0045] FIG. 6 shows a perspective view of the glenoid positioning device 100 in a closed configuration.

[0046] Comparing the drawing of FIG. 6 with that of FIG. 4, it can be observed that in the glenoid positioning device 100, the sliding elements 103a, 103b and 103c are configured to be extended or retracted.

[0047] FIG. 7 shows a top view of the glenoid positioning device 100.

[0048] Furthermore, by comparing the drawing of FIG. 5 with that of FIG. 7, it can be observed that in the glenoid positioning device 100, the slide elements 103a, 103b, and 103c are configured to be extended or retracted, with each end lying on the same circumference having a radius that is variable by rotation of the central spindle 104.

[0049] It can further be seen that the hub 101 and central spindle 104 are provided with respective lateral access slots 111 a and 111 b to the respective fiducial through holes 110 .

[0050] The side access slots 111 a and 111 b are aligned with one another due in particular to the angular position resulting from the rotation of the central spindle 104 .

[0051] The angular position is preferably the fully closed position of the glenoid positioning device 100 depicted in FIG. 7, allowing lateral withdrawal of a fiducial, such as a Kirschner wire, inserted into the axial fiducial through-hole 110.

[0052] In this manner, once the fiducial is centered and implanted in the glenoid cavity of the scapula, the glenoid positioning device 100 can be easily removed with a lateral movement.

[0053] FIG. 8 shows a schematic side view of a scapula 1 with the glenoid positioning device 100 positioned in an in-use position.

[0054] In accordance with what has already been described, in the glenoid positioning device 100, the three slide elements 103a, 103b and 103c are configured to identify a circular area 2 of the glenoid, while the central spindle 104 and the associated fiducial through hole 110 are configured to identify the centre 3 of the circular area 2, in particular for positioning a fiducial, e.g. a Kirschner wire, in the centre of the glenoid of the scapula.

[0055] For illustrative and non-limiting purposes, an example of the use of the glenoid positioning device 100 in accordance with the present invention will now be provided.

[0056] First, the glenoid positioning device 100 is positioned below the glenoid cavity.

[0057] Thereafter, via rotation of the central spindle 104, the sliding elements 103a, 103b, and 103c are radially extended until they pass the glenoid rim in the anterior-posterior plane.

[0058] Subsequently, while keeping the central spindle 104 rotating, the sliding elements 103a, 103b and 103c are radially contracted until contact between the inner portions of the ends 109a and 109b of the elements 103a and 103b and the glenoid rim is obtained in the widest region of the latter on the anterior-posterior sagittal plane.

[0059] In a next step, it was visually confirmed that the end of the slide element 103c was approximately positioned at the lowest point of the scapular glenoid cavity, thus identifying the three points required to determine the circumference 2 which identifies the scapular glenoid cavity.

[0060] Thus, a fiducial, in this example a Kirschner wire 4 , is inserted into the central spindle 104 using the fiducial through-hole 110 present therein and in the hub 101 .

[0061] Advantageously, the point at which the entry of the Kirschner wire 4 into the glenoid cavity occurs represents the centre 3 of the glenoid cavity of the scapula 1, which has been treated with the glenoid positioning device 100 described above.

[0062] When full closure of the device is obtained by further rotation of the central spindle 104, the lateral access slots 111a and 111b on both the hub 101 and the central spindle 104 are aligned with each other, thus allowing the glenoid positioning device 100 to be removed from the Kirschner wire 4 temporarily implanted in the glenoid by passing a fiducial, in this case a Kirschner wire 4, through the two aligned slots 111a and 111b.

[0063] Thus, the radial stroke of the sliding elements 103a, 103b, and 103c is such that when they are radially extended, they pass the glenoid rim in the sagittal plane in the anterior-posterior direction.

[0064] FIG. 9 shows a frontal schematic view of the scapula of FIG. 8 with a fiducial, e.g., a Kirschner wire, associated with the glenoid positioning device.

[0065] In accordance with what has been described above, the glenoid positioning device 100 is configured to identify the center of the glenoid cavity of the scapula for accurate and repeatable positioning of a fiducial, such as a Kirschner wire 4.

[0066] Using the solution of the present invention, the glenoid positioning device 100 identifies the glenoid center 3 with greater reliability, allowing more accurate and repeatable positioning of the fiducials formed by the Kirschner wire 4 used during shoulder prosthesis implantation.

[0067] The slide elements 103a, 103b and 103c make it possible to identify a circular area of ​​the glenoid cavity, and the central spindle 104 is configured to identify the center 3 of the circular area 2 for positioning of a reference in the center of the glenoid cavity of the scapula.

[0068] Advantageously, it is therefore possible to position the fiducial in the centre of the glenoid scapular cavity in an accurate and repeatable manner.

[0069] It is obvious that further implementations and modifications of the present invention are possible for those skilled in the art to meet foreseeing needs. Therefore, the above embodiments are intended to be provided for illustrative purposes, not for limiting purposes.

Claims

1. A glenoid positioning device (100), comprising: A hub (101) with a fiducial through hole (110) and including three radially arranged housings (102a, 102b, 102c); three slide elements (103a, 103b, 103c) slidably accommodated in the three housings (102a, 102b, 102c), respectively, the slide elements (103a, 103b, 103c) being configured to interact with a glenoid cavity; The glenoid positioning device (100), wherein the three slide elements (103a, 103b, 103c) are configured to be radially extended or contracted to identify a circular area (2) represented by a circumference within the glenoid cavity.

2. The glenoid positioning device (100) a central spindle (104) axially associated with said hub (101) and rotatable therein; three connecting bars (108a, 108b, 108c) respectively connecting each of the three sliding elements (103a, 103b, 103c) to the central spindle (104); 2. The glenoid positioning device (100) of claim 1, wherein the three sliding elements (103a, 103b, 103c) are configured to be radially extended or contracted by the action of the three connecting bars (108a, 108b, 108c) operated by rotation of the central spindle (104).

3. 3. The glenoid positioning device (100) of claim 2, wherein a first slide element (103a) and a second slide element (103b) of the three slide elements (103a, 103b, 103c) are substantially opposed to each other, and the first slide element (103a) and the second slide element (103b) include respective protruding ends (109a, 109b) configured to externally grip the glenoid portion of the scapula.

4. 4. The glenoid positioning device (100) of claim 3, wherein a third slide element (103c) of the three slide elements (103a, 103b, 103c) is aligned substantially transversely to the first slide element (103a) and the second slide element (103b), and the third slide element (103c) is configured to provide a visual reference at an end thereof.

5. The glenoid positioning device (100) of claim 3 or 4, wherein said protruding ends (109a, 109b) include an inner surface that is machined to increase friction with a bone surface.

6. The glenoid positioning device (100) of any one of claims 2 to 5, wherein the hub (101) and the central spindle (104) include respective datum through-holes (110) that are axially aligned and configured for axial insertion of a datum (4).

7. 7. The glenoid positioning device (100) of claim 6, wherein the hub (101) and the central spindle (104) are provided with respective lateral access slots (111a, 111b) to the through holes (110) of the respective datums, the lateral access slots (111a, 111b) being aligned with one another to allow removal of the glenoid positioning device (100) from the datum (4) positioned in the glenoid.

8. The glenoid positioning device (100) according to any one of claims 2 to 7, wherein the sliding elements (103a, 103b, 103c) are configured to be extended or retracted with their respective ends on the same circumference, the circumference having a radius that is variable by the rotation of the central spindle (104).

9. The glenoid positioning device (100) according to any one of claims 2 to 8, wherein the three connecting bars (108a, 108b, 108c) are respectively connected to the central spindle (104) and to the three sliding elements (103a, 103b, 103c) by pins, thus providing a triple rod crank type system.

10. 10. The glenoid positioning device (100) of claim 9, wherein the triple rod crank type system is configured to extend the three sliding elements (103a, 103b, 103c) from a maximum closed position to a maximum open position during the rotation of the central spindle (104) and to retract the three sliding elements (103a, 103b, 103c) to a further position, at least partially retracted, during a rotation of the central spindle (104) in the opposite direction.

11. The glenoid positioning device (100) of any one of claims 2 to 10, wherein the hub (101) further comprises a pin (105) configured to engage in a radial groove (107) of the central spindle (104) to allow rotation of the central spindle (104) and thus prevent axial movement of the central spindle (104).

12. The glenoid positioning device (100) according to any one of claims 2 to 11, wherein the central spindle (104) is configured to identify a center (3) of the circular area (2) for positioning a reference (4) in the center (3) of the glenoid cavity of the scapula.

13. The glenoid positioning device (100) of claim 12, wherein said datum (4) is a Kirschner wire.

14. A glenoid positioning device (100) as described in any one of claims 1 to 13, wherein the stroke of the three sliding elements (103a, 103b, 103c) is such that when extended radially, they pass through the glenoid rim in the anterior-posterior direction in the sagittal plane.

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