Acetabular prosthesis

Abstract

Acetabular prosthesis (10) comprising an acetabular cup (12) having a through-opening configured to receive both an iliac stem (11) and a safety cap (13).

Description

Technical Field

[0001] The present invention relates to a wide acetabular artificial device used to restore the correct function of the hip joint when, for example, the patient's pelvis exhibits significant bone deformities or cavities of natural origin due to, for example, osteoarthritis, tumors, dysplasia, and / or of artificial origin caused by, for example, the removal of a previous artificial implant.

Background Art

[0002] A wide acetabular artificial device is generally formed by a wide acetabular cup configured to be stably attached to the patient's wide acetabulum. To ensure correct attachment, the wide acetabular cup can be associated with a stem that is inserted into the iliac canal of the pelvis. In some cases, this stem can be attached to the patient's sacrum as an alternative or addition to fixation within the iliac canal. Regardless of where the fixation is performed, this type of stem is referred to herein and hereinafter as an "iliac stem".

[0003] There are known wide acetabular artificial devices having an iliac stem made in a single body with a wide acetabular cup, or an iliac stem that can be coupled to the outer surface of the wide acetabular cup by threaded attachment means before inserting the cup and the stem into the patient's wide acetabular cavity.

[0004] The disadvantages of artificial devices having a wide acetabular cup with an integrated or pre-assembled stem are that they have significant mass and overall dimensions that complicate the surgery.

[0005] Another disadvantage of the aforementioned artificial devices having a stem integrated on or pre-mounted on the wide acetabular cup is that the position of the wide acetabular cup during surgery may be different from the position initially planned by the surgeon, and thus, regardless of whether it is integrated on or rigidly clamped to the wide acetabular cup, the iliac stem may also be incorrectly positioned, that is, in a bone portion with low bone density.

[0006] It is also known that acetabular prostheses allow the iliac stem to be inserted from the inside, i.e., the concave side, of the acetabular cup after the acetabular cup has been inserted into the patient's acetabular cavity.

[0007] A drawback of these acetabular prostheses is that the iliac stem cannot be screwed into the acetabular cup because the rotation of the stem can induce axial twisting of the tissue present in the iliac canal, risking loss of contact between the prosthesis and the anatomical structure.

[0008] Another drawback of these acetabular prostheses is that screwing the iliac stem into the iliac canal can cause pelvic fractures.

[0009] Therefore, currently, iliac stems that can be inserted from the inside of the acetabular cup are attached to the acetabular cup only by a flat head contact and secured by compression with a safety or locking screw. However, these stems do not guarantee a stable attachment because the displacement of the stem along its axis is not unfavorably restricted. Therefore, this type of stem may move during use, potentially causing pain and serious injury to the patient.

[0010] Another known solution for stably mounting an acetabular cup within a patient's acetabulum is the use of a locking screw having a first threaded profile that can be mounted within an anatomical structure, either as an alternative to or in addition to the iliac stem, and a second threaded profile that can be mounted on the threaded seat of the acetabular cup.

[0011] The locking screw is inserted into the patient's anatomical structure downstream of the acetabular cup position. This allows the acetabular cup to be inserted first, followed by the locking screw, resulting in the "pack closure" of the acetabular cup and acetabulum.

[0012] Unfortunately, this solution does not allow for adjustment of the position of the locking screw axis relative to the axis of the corresponding hole present in the acetabular cup, and therefore cannot achieve proper integration with the acetabulum or / or correctly trigger the bone integration phenomenon.

[0013] International Publication No. 2010 / 072604 describes a stabilizing element for prosthetic joints that can be aligned in multiple axes.

[0014] International Publication No. 2009 / 081346 describes an acetabular prosthesis comprising a cup that can be inserted into the corresponding acetabulum and a cup mounting screw that can be engaged by screwing into a portion of the pelvic bone.

[0015] The German Patent Application Publication No. 19542116 describes a device for attaching an implant to bone.

[0016] U.S. Patent No. 5,888,204 describes an acetabular cup having a multi-axis locking screw for securing the cup to a desired bone site.

[0017] Therefore, it is necessary to complete an acetabular prosthesis that can overcome at least one of the shortcomings of state-of-the-art technology. [Overview of the project] [Problems that the invention aims to solve]

[0018] One object of the present invention, addressing a technical problem the applicant seeks to solve, is to provide an acetabular prosthesis of the type having an iliac stem that can be inserted from the inside of the acetabular cup, wherein the connection between the iliac stem and the acetabular cup is achieved without preventing axial displacement of the stem and without applying torsion / rotation to the stem itself.

[0019] Specifically, one objective of the present invention is to prevent axial displacement of the stem relative to the acetabular cup following confirmation of the mutual axial connection by a surgeon.

[0020] Another object of the present invention is to provide an acetabular prosthesis in which the axis of the stem can be oriented at an angle with respect to the acetabular cup before the mutual axial coupling is determined.

[0021] The applicant has devised, tested, and embodied the present invention in order to overcome the shortcomings of state-of-the-art technology and to obtain these and other purposes and advantages. [Means for solving the problem]

[0022] The present invention is described and characterized by the independent claims. Dependent claims describe other features of the present invention or variations of the main idea of ​​the present invention.

[0023] In accordance with the above objectives and achieving considerable advantages compared to the state of the prior art, and in order to solve the technical problems disclosed above in a novel and unique manner, the acetabular prosthesis according to the present invention comprises an acetabular cup having a through-opening configured to receive both an iliac stem and a safety element, i.e., a safety cap. The iliac stem, acetabular cup, and safety cap form the acetabular prosthesis.

[0024] According to one aspect of the present invention, the iliac stem has a first end, the first end provided with both a first coupling portion adapted to be housed in a first coupling seat defined in an opening, and a contact surface to which a safety cap can abut, the safety cap being adapted to be housed in a second coupling seat defined in an opening.

[0025] This provides at least the advantage of allowing the iliac stem to be inserted from the inside of the acetabular cup, downstream of the correct position of the acetabular cup within the patient's acetabular cavity. Furthermore, the presence of the safety cap prevents torsional stress on the stem, as the pressure on the contact surface of the stem causes the iliac stem at the first joint seat to close in the pack.

[0026] According to a modification, the first coupling seat portion and the first coupling portion can have a frustoconical shape that fits. The conical coupling between the first coupling portion and the first coupling seat portion enables unique axial positioning between the iliac stem and the acetabular cup.

[0027] According to another aspect of this modification, the abutment surface of the iliac stem is at least partially flat, and the safety cap can abut against it with its substantially flat contact surface. This configuration of the contact between the safety cap and the iliac stem enables the orientation of the iliac stem along a single axis, regardless of the spherical or conical coupling between the stem and the acetabular cup.

[0028] According to another aspect of the present invention, the first coupling seat portion and the first coupling portion can have at least a partially spherical shape that fits. The spherical coupling between the first coupling portion and the coupling seat portion can enable "multi-axis" positioning, that is, positioning along a plurality of axes between the iliac stem and the acetabular cup, before the stem is clamped against the acetabular cup by the safety cap.

[0029] This aspect of the present invention advantageously enables the iliac stem to be inserted into the optimal position inside the iliac canal, that is, within the zone having a greater bone density, even when the acetabular cup is firmly attached but in a position different from that initially planned by the surgeon.

[0030] According to another aspect of the present invention, the first end of the iliac stem has a concave receiving portion configured to receive a fitting central protrusion that protrudes from the contact surface of the safety cap.

[0031] According to another aspect of the present invention, the receiving portion can have a frustoconical shape, and the central protrusion can be at least partially spherical or frustoconical.

[0032] In the modified version, the receiving portion may have at least a partially spherical shape, and the central projection may have a corresponding at least partially spherical shape.

[0033] Advantageously, if the safety cap has a central projection, "multiaxial" positioning between the iliac stem and the acetabular cup is permitted only if the receiving portion has a truncated conical shape and the central projection has at least a partially spherical shape, or if both the receiving portion and the central projection have at least a partially spherical shape, taking into account the spherical connection between the iliac stem and the acetabular cup.

[0034] According to another aspect of the present invention, in order to establish a threaded connection between two components, the second connecting seat is provided with a threaded segment, and the safety cap is provided with a corresponding peripheral threaded segment. Thus, it is clear that the torsional action involves only the acetabular cup and the safety cap, while the pressure action on the iliac stem is axial only.

[0035] Some embodiments of the present invention also relate to an iliac stem for an acetabular prosthesis, having a first end, the first end being provided with both a first connecting portion having a truncated cone or at least partially spherical shape, and an anterior contact surface, from which a concave receiving portion unfolds inward, the concave receiving portion having a truncated cone or at least partially spherical shape.

[0036] These and other aspects, features, and advantages of the present invention will become apparent from the following description of some embodiments, which are given as non-limiting examples with reference to the accompanying drawings. [Brief explanation of the drawing]

[0037] [Figure 1] This is a schematic diagram illustrating the use of the acetabular prosthesis device according to the present invention. [Figure 2] Figure 1 is an enlarged partial cross-sectional view of several embodiments of acetabular prostheses. [Figure 3] Figure 1 is an enlarged partial cross-sectional view of several embodiments of acetabular prostheses. [Figure 4] Figure 1 is an enlarged partial cross-sectional view of several embodiments of acetabular prostheses. [Figure 5] Figure 1 is an enlarged partial cross-sectional view of several embodiments of acetabular prostheses. [Figure 6] Figure 1 is an enlarged partial cross-sectional view of several embodiments of acetabular prostheses. [Modes for carrying out the invention]

[0038] It should be made clear that the expressions and terminology used herein, as well as the figures in the accompanying drawings, also have the sole function of better illustrating and describing the present invention in relation to how it is described, and their purpose is to provide non-limiting examples of the present invention itself, since the scope of protection is defined by the claims.

[0039] For ease of understanding, the same reference numerals are used to identify the same common elements in the drawings, where possible. It is understood that elements and features of one embodiment can be conveniently combined or incorporated into other embodiments without further explanation.

[0040] Referring to Figure 1, the acetabular prosthesis device 10 comprises an acetabular cup 12 stably mounted in the patient's acetabulum and an iliac stem 11 inserted into the iliac canal of the patient's pelvis. The device 10 also includes a safety cap 13, as shown in Figures 2 to 6, configured to secure the axial connection between the iliac stem 11 and the acetabular cup 12.

[0041] For example, the iliac stem 11 has a cylindrical shape. However, those skilled in the art will understand that the shape of the iliac stem 11 is not limited to a cylindrical shape and may have one or more conical segments and / or one or more attachment tabs on its sides.

[0042] The iliac stem 11 can be made of a metallic material, preferably titanium or an alloy thereof.

[0043] According to possible embodiments, the iliac stem 11 can be completely or partially coated with a layer of titanium pores and / or hydroxyapatite to promote bone integration.

[0044] The iliac stem 11 unfolds along the longitudinal axis X and has a first end, i.e., the head 14, and a second end on the opposite side, i.e., the tip 15, the latter of which is shown in Figure 1.

[0045] The first end 14 is fitted to connect to the acetabular cup 12 and to cooperate with the safety cap 13, while the second end 15 is the "first insertion" portion of the iliac stem 11 into the patient's iliac canal.

[0046] The first end 14 has a first coupling portion 16 that is adapted to connect to a first coupling seat 17 that is present in the acetabular cup 12.

[0047] According to some embodiments, the first coupling portion 16 has a conical / truncated cone shape (Figures 2 and 3). Correspondingly, the first coupling seat portion 17 also has a fitting conical / truncated cone shape.

[0048] The conical joint between the first joint portion 16 and the first joint seat portion 17 allows for unambiguous axial positioning between the iliac stem 11 and the acetabular cup 12. In other words, the longitudinal axis X of the iliac stem 11 coincides with the surrounding axis that defines the first joint portion 16 and the first joint seat portion 17.

[0049] The taper of the first joint portion 16 and the first joint seat portion 17 may be slightly different to improve axial coupling due to interference (Figure 3).

[0050] According to other embodiments shown in Figures 4 to 6, the first coupling portion 16 has at least a partially spherical shape. Correspondingly, the first coupling seat portion 17 also has at least a partially spherical shape to fit into.

[0051] In the examples shown in Figures 4 and 5, the first end 14 of the iliac stem 11 is configured to articulate flexion in a manner that allows it to be angled and oriented at the first joint seat 17.

[0052] The spherical joint between the first joint portion 16 and the first joint seat portion 17 allows for "multi-axis" positioning, i.e., positioning along multiple axes between the iliac stem 11 and the acetabular cup 12. In this case, in practice, tilting or orientation of the iliac stem 11 within the first joint seat portion 17 is permitted before the position is blocked by the safety cap 13, as described below.

[0053] According to some embodiments, the first end 14 of the iliac stem 11 has a front contact surface 18 to which the safety cap 13 can abut (Figure 2).

[0054] According to some embodiments, the contact surface 18 may be at least partially flat. In this case, multi-axis adjustment is not permitted because the contact of the safety cap 13 with respect to the contact surface 18 determines the unique positioning, regardless of whether the joint between the iliac stem 11 and the acetabular cup 12 is conical or spherical.

[0055] Advantageously, the cavity 19 is created within the body of the iliac stem 11, extending along the longitudinal axis X toward the second end 15. The cavity 19 may be provided with a threaded segment 25. The cavity 19 is configured to receive a surgical impactor and guide it to move and position the iliac stem 11 during surgery.

[0056] According to some embodiments, the first end 14 of the iliac stem 11 may have a hollow receiving portion 20 having a concave structure that unfolds inside the body of the iliac stem 11.

[0057] The receiving portion 20 starts from the contact surface 18 and unfolds around the longitudinal axis X. The receiving portion 20 substantially forms an extension of the contact surface 18.

[0058] The receiving portion 20 is located upstream of the cavity 19 within the inlet zone of the first end portion 14.

[0059] The receiving portion 20 is configured to cooperate with the safety cap 13, and in particular to receive the central projection 24 of the safety cap 13, as will be described in more detail below.

[0060] According to some embodiments, the receiving portion 20 can have a spherical or hemispherical shape (Figures 2 to 5), or it can have a truncated cone shape coaxial with the body of the iliac stem 11 (Figure 6).

[0061] The iliac stem 11 is restrained within the first joint seat 17 by a safety cap 13, which is configured to prevent axial displacement of the iliac stem 11 relative to the acetabular cup 12.

[0062] The safety cap 13 is inserted into the second joint seat 22 of the acetabular cup 12 and is configured to translate axially toward the first end 14 of the iliac stem 11.

[0063] The second coupling seat portion 22 has, for example, a cylindrical shape that fits with the shape of the safety cap 13.

[0064] The first joint seat 17, together with the second joint seat 22, defines an opening through the hemispherical wall that defines the acetabular cup 12. Advantageously, the first joint seat 17 and the second joint seat 22 can be fabricated entirely within the thickness of the hemispherical wall.

[0065] According to one embodiment, the second joint seat 22 of the acetabular cup 12 may have a threaded segment 26 to allow the safety cap 13 inside the second joint seat 22 to be axially translated toward the iliac stem 11 by screwing it in, and the safety cap 13 may be provided with a corresponding peripheral threaded segment 23.

[0066] According to some embodiments, the second coupling seat 22 may, advantageously, have a self-locking type "female" thread.

[0067] The safety cap 13 is provided with a contact surface 21 that is at least partially flat.

[0068] The contact surface 21 faces the abutment surface 18 or the receiving portion 20 in order to "pack-tighten" the iliac stem 11 against the first joint seat portion 17 during use, restrain the iliac stem 11 in a predetermined position, and prevent its axial displacement.

[0069] According to some embodiments, the contact surface 21 is perfectly flat (Figure 2).

[0070] According to other embodiments, the contact surface 21 may, advantageously, have a central projection 24 that can come into contact with the receiving portion 20 of the iliac stem 11 during use (Figures 3 to 6). A portion of the flat or inclined contact surface, arranged annularly around the central projection 24, remains away from the contact surface 18 of the iliac stem 11, creating a gap or clearance to allow for angular orientation of the iliac stem 11.

[0071] The central projection 24 may have a hemispherical shape. In this case, the receiving portion 20 may have at least a partially spherical shape (Figures 2 and 4). Alternatively, the receiving portion 20 may have a truncated cone shape (Figures 3 and 5). This connection configuration between the safety cap 13 and the iliac stem 11 allows the iliac stem 11 to be oriented at an angle (multiaxial).

[0072] According to the embodiment shown in Figure 5, the first end 14 of the iliac stem 11 is at least partially spherical and fits with a first joint portion 16 that is at least partially spherical. The iliac stem 11 can be advantageously oriented at an angle with respect to the axis defining the first joint portion 16 and the first joint seat 17 in order to provide the surgeon with the most correct positioning of the iliac stem 11 during use.

[0073] Furthermore, the receiving portion 20 of the embodiment shown in Figure 5 is conically cut while the safety cap 13 has a central projection 24. This combination advantageously allows the safety cap 13 at the second connecting portion 22 to be packed against the iliac stem 11 regardless of the position of the iliac stem 11 with respect to the axis defining the first connecting portion 16 and the first connecting portion 17. At least the partial sphericity of the central projection 24 allows for maximizing the contact surface with the truncated conical receiving portion 20, and thus increases the tightening of the safety cap 13.

[0074] In a modified version, the central projection 24 may have a truncated cone shape (Figure 6). In this case, the receiving portion 20 may have a truncated cone shape to fit into. This connection configuration between the safety cap 13 and the iliac stem 11 does not allow the iliac stem 11 to be oriented at an angle.

[0075] By screwing on the safety cap 13, the central projection 24 tightly fastens the iliac stem 11 to the first joint seat 17 of the acetabular cup 12, restraining it in place and preventing axial displacement.

[0076] The multiaxial nature between the iliac stem 11 and the acetabular cup 12 advantageously allows for a wide range of versatility for the surgeon during surgery. For example, if the surgeon can ensure that the acetabular cup 12 is properly mounted in the planned position and orientation, the surgeon can insert the iliac stem 11 into the first joint seat 17 of the acetabular cup 12 such that the longitudinal axis X of the iliac stem 11 coincides with the axis defining the first joint portion 16 and the first joint seat 17.

[0077] The surgeon can clamp the iliac stem 11 along the same axis by an embodiment of the safety cap 13 according to the present invention, which determines unique positioning regardless of the spherical connection between the iliac stem 11 and the acetabular cup 12, for example, a safety cap 13 having a truncated conical projection as shown in Figure 6, as a non-limiting example.

[0078] Alternatively, if the surgeon securely mounts the acetabular cup 12 in a position and / or orientation different from the originally planned position and / or orientation, the surgeon can change the angular position of the iliac stem 11 relative to the first joint seat 17 of the acetabular cup 12 and clamp the iliac stem 11 to an angular position identified by an embodiment of the safety cap 13 according to the present invention that allows for multiaxiality (for example, a safety cap 13 having at least a partially spherical projection, as shown in the example in Figure 5, for example, as a purely non-limiting example).

[0079] This makes it clear that modifications and / or additions to the components can be made to the acetabular prosthesis 10 as described herein, without departing from the field and scope of the present invention as defined by the claims.

[0080] Furthermore, although the present invention has been described with reference to several specific examples, it will be apparent to those skilled in the art that other equivalent forms of acetabular prostheses can be achieved, having the features described in the claims and therefore all falling within the field of protection defined thereby.

[0081] In the following claims, the sole purpose of the references in parentheses is to facilitate their reading, and they should not be considered limiting factors with respect to the field of protection defined by the claims. [Explanation of symbols]

[0082] 10. Acetabular prosthesis 11. Iliac stem 12 acetabular cup 13 Safety cap 14 Head, first end 15. Tip, second end 16 First joint 17 First joint seat 18 Front contact surface 19 Cavity 20 Receptor part 21 Contact surface 22 Second connecting seat 23 Peripheral threaded segment 24 Central protrusion 25 Threaded Segment 26 Threaded segment

Claims

1. Acetabular prosthesis (10), Acetabular prosthesis (10) comprising an acetabular cup (12) provided with a through-opening configured to receive both an iliac stem (11) and a safety cap (13), wherein the iliac stem (11) has a first end (14) the first end (14) provided with both a first coupling portion (16) adapted to be accommodated in a first coupling seat (17) defined in the through-opening, and a contact surface (18) to which the safety cap (13) can abut, the safety cap (13) adapted to be accommodated in a second coupling seat (22) defined in the through-opening, and the first coupling seat (17) and the first coupling portion (16) having a truncated conical shape for fitting.

2. The acetabular prosthesis (10) according to claim 1, characterized in that the first connecting seat (17) and the first connecting portion (16) are configured to define a mutual conical joint that defines the unique axial positioning between the iliac stem (11) and the acetabular cup (12).

3. The acetabular prosthesis (10) according to claim 1 or 2, characterized in that the first end (14) of the iliac stem (11) has a concave receiving portion (20) configured to receive a central projection (24) that protrudes from the contact surface (21) of the safety cap (13).

4. The acetabular prosthesis (10) according to claim 3, characterized in that the receiving portion (20) has a truncated cone shape.

5. The acetabular prosthesis (10) according to claim 3, characterized in that the receiving portion (20) has at least a partially spherical shape.

6. The acetabular prosthesis (10) according to any one of claims 3 to 5, characterized in that the central projection (24) has a truncated cone shape.

7. The acetabular prosthesis (10) according to any one of claims 3 to 5, characterized in that the central protrusion (24) has at least a partially spherical shape.

8. The acetabular prosthesis (10) according to any one of claims 1 to 7, characterized in that, in order to secure the screw connection, the second connecting seat (22) is provided with a threaded segment (26), and the safety cap (13) is provided with a corresponding peripheral threaded segment (23).

9. Iliac stem (11) for an acetabular prosthesis (10) according to any one of claims 1 to 8, wherein the iliac stem (11) has a first end (14), the first end (14) is provided with both a first connecting portion (16) having a truncated cone shape and an anterior contact surface (18), and a concave receiving portion (20) unfolds inward from the anterior contact surface (18), the concave receiving portion (20) having a fitted truncated cone shape.

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