Anchoring unit and prosthesis kit for fixing knee prosthesis components to the patient's leg bones.

Abstract

To provide an anchoring unit for a knee prosthesis component that can be removed during revision surgery in a time-efficient manner without putting stress on the bone. [Solution] The present invention relates to an anchoring unit 10 for fixing a knee prosthesis component 100 to the bone of the leg. The anchoring unit 10 comprises an anchoring sleeve 12 having a sleeve wall 14, the sleeve wall 14 defining a through-opening 16 designed to receive a prosthesis stem 102. The sleeve wall 14 has at least two wall portions 18 formed separately from each other and made of a physiologically non-degradable material, the wall portions connected to each other by at least one connector 20 made of a physiologically degradable material. The present invention also relates to a prosthesis kit.

Description

Technical Field

[0001] The present invention relates to the field of implant technology. In particular, the present invention relates to an anchoring unit for fixing a knee prosthesis component to the bone of a patient's leg, and a prosthesis kit.

Background Art

[0002] A knee prosthesis (also called a knee joint prosthesis) is a prosthesis that replaces the knee joint completely or partially. Usually, a knee prosthesis has two knee prosthesis components, namely a femoral prosthesis component and a tibial prosthesis component. The femoral prosthesis component is implanted in the femur, i.e., the thigh bone, and the tibial prosthesis component is implanted in the tibia, i.e., the shin bone. Such a knee prosthesis component usually has a prosthesis stem that carries the actual joint replacement part of the knee prosthesis component.

[0003] In case of bone defects, in addition to the actual knee prosthesis component, a sleeve-shaped anchoring unit is often used, which serves to fix the knee prosthesis component to the bone of the affected leg. Such a sleeve-shaped anchoring unit is also called a "cone". The cone is usually installed in the diaphyseal end region of the bone of the leg. For this reason, the outer contour of the cone often reproduces the diaphyseal end region of the tibia or femur, so that a good fit is obtained. The cone typically has a through-opening designed to accommodate the prosthesis stem of the knee prosthesis component. The knee prosthesis component arranged in this way can be attached to the cone using, for example, bone cement. The cone promotes the internal growth of the bone of the leg, thereby fixing the knee prosthesis component to the bone of the leg.

[0004] Such a cone is described, for example, in International Publication WO 2024 / 047127 A1.

Summary of the Invention

[0005] In certain situations, it is desirable to remove the internally grown knee prosthesis component along with the cone, a procedure also known as revision. Typically, the bone cement is removed first, followed by the removal of the knee prosthesis component and cone. Revision is performed, for example, when there is a bacterial infection in the area of ​​the cone or knee prosthesis component. The advantage of good osteointegration can be a disadvantage during revision because the internal growth of the leg bone into the cone makes its removal more difficult.

[0006] The present invention aims to provide an anchoring unit for a knee prosthesis component that can be removed during revision surgery in a time-efficient manner without putting stress on the bone. [Means for solving the problem]

[0007] A first aspect of this specification relates to an anchoring unit for fixing a knee prosthesis component to the bone of a patient's leg. The anchoring unit has an anchoring sleeve. In particular, since the anchoring unit is formed by the anchoring sleeve, the anchoring unit as a whole is sleeve-shaped. However, the anchoring unit may have one or more further parts in addition to the anchoring sleeve.

[0008] The anchoring sleeve has a sleeve wall that defines a through-opening. In particular, the sleeve wall is circumferentially closed so that the sleeve wall completely encloses the through-opening. However, the sleeve wall can also be interrupted circumferentially. The through-opening is designed to accommodate the prosthesis stem of a knee prosthesis component.

[0009] The sleeve wall has at least two wall sections formed separately from each other and made of a physiologically indestructible material. The wall sections are connected to each other by at least one connector made of a physiologically decomposable material. The connector holds the separately formed wall sections together. In particular, the two wall sections are connected to each other only by one or more connectors made of a physiologically decomposable material.

[0010] The inventors have recognized that the above objectives are achieved by an anchoring unit designed as described above. After implantation of the anchoring unit and associated knee prosthesis components, the physiologically decomposable material of the connection is decomposed by the body, and the connection between the wall portions provided by the connection is lost. After implantation, the sleeve wall is decomposed into several separate parts, which are preferably held together by bone cement. Upon removal of the bone cement, the wall portions exist in a separated form, thereby facilitating the removal of the anchoring unit, particularly the wall portions in their already separated state.

[0011] For the purposes of this disclosure, “physiologically biodegradable material” means a material that, after being implanted in the bone of the leg, is degraded by the body, particularly over several weeks to several months, such that the structural integrity of the portion made of the physiologically biodegradable material is gradually lost after implantation. Preferably, the physiologically biodegradable material is fully reabsorbable. Alternatively, only a portion of the physiologically biodegradable material may be reabsorbable. For example, the physiologically biodegradable material may also have a matrix of reabsorbable components in which non-reabsorbable particles are dispersed. Even such a mixed material will gradually lose its structural integrity as the matrix degrades, becoming a physiologically biodegradable material.

[0012] For the purposes of this disclosure, “physiologically indegradable material” means a material that does not decompose after implantation in the leg bone, or at best decomposes at a slow rate such that the structural integrity of the portion made of the physiologically indegradable material is permanently maintained after implantation.

[0013] The sleeve wall has at least two wall sections formed separately from each other and made of a physiologically indestructible material. More than two such wall sections may be provided. Preferably, the wall sections are the same shape.

[0014] The wall sections are connected to each other by at least one connector made of a physiologically biodegradable material. There may be two or more such connectors.

[0015] Preferably, at least two wall portions are held together by one or more connecting portions, and the wall portions are formed as separate parts. In particular, the separate parts are held together by only one or more connecting portions.

[0016] Preferably, the anchoring sleeve is conically tapered. Therefore, the cross-section of the anchoring sleeve decreases from the first longitudinal end to the second longitudinal end. Anchoring sleeves of this shape are particularly suitable for placement in the metaphysical region of the leg bones. The conically tapered anchoring sleeve can be designed symmetrically or asymmetrically. In a more preferred embodiment, the anchoring sleeve is cylindrical. The anchoring sleeve may have a first conically tapered longitudinal portion and a second cylindrical longitudinal portion.

[0017] Preferably, the sleeve wall has a structured surface on its outer surface in at least some areas. This can promote internal growth of the leg bone into the anchoring unit. The structured surface may have, for example, teeth, grooves, and / or lattice structures. A preferred lattice structure is known, for example, as a "structan surface". Preferably, each wall portion has a structured surface in at least some areas.

[0018] In some preferred embodiments, the wall portions are provided as wall segments of a sleeve wall that are offset from one another. In particular, the wall segments are offset from one another in the circumferential direction of the sleeve wall or in the longitudinal direction of the anchoring sleeve. The offset wall segments have the advantage of being easily accessible and therefore easily removable after the material of the connection portion has physiologically decomposed. Preferably, the wall segments are arranged without overlapping when viewed radially.

[0019] In some preferred embodiments, the wall sections are provided to be spaced apart from each other, and the connector is positioned in the space formed between the wall sections. After the material of the connector physiologically decomposes, a gap remains between the two wall sections. This improves the accessibility of the two wall sections, making their removal even easier. Preferably, the two wall sections are designed as wall segments of a sleeve wall that are offset from each other. Preferably, the wall sections and the connector are designed so that the outer surface of the connector is flush with the outer surface of the wall section. Such embodiments are facilitated by providing a gap and positioning the connector in that gap. The outer surface is the surface facing away from the through-opening. Preferably, the connector fills the space between the two wall sections. Preferably, the space is gap-like. Preferably, the connector is positioned only in the space formed between the wall sections. Thus, the connector does not protrude radially beyond the contour defined by the wall sections.

[0020] In some preferred embodiments, the wall portion is provided to be plate-like. In plate-like elements, the length and width of the element are significantly greater than its thickness. Thus, the plate-like element is substantially two-dimensional. Because the wall portion is designed to be plate-like, even after the connector has disassembled, the wall portion still effectively secures the knee prosthesis component to the leg bone. The plate-like wall portion is preferably curved. An anchoring sleeve having a curved wall portion can be more easily fitted into the metaphysical region of the leg bone.

[0021] In some preferred embodiments, the connecting portion is provided to be rod-shaped. In a rod-shaped element, the length of the element is significantly greater than its width and height. Thus, the rod-shaped element is substantially one-dimensional.

[0022] In some preferred embodiments, the wall portions are provided to be arranged side by side in the circumferential direction of the anchoring sleeve. The connecting portions preferably extend between the wall portions and in the longitudinal direction of the anchoring sleeve.

[0023] Preferably, a plurality of wall portions and a plurality of connecting portions are provided, and the wall portions and connecting portions together form a circumferentially closed sleeve wall, the wall portions are arranged side by side in the circumferential direction of the sleeve wall, and the connecting portions are always positioned between two adjacent wall portions, connecting the two wall portions to each other. Preferably, each wall portion extends along a circumferential angular interval of at least 30°. Preferably, each connecting portion extends along a circumferential angular interval of at most 10°.

[0024] In some preferred embodiments, at least one of the wall portions is provided to be connected to the connector by a shape-fitting connection. This achieves a mechanically robust connection between the wall portion and the connector.

[0025] In some preferred embodiments, at least one of the wall portions is provided to have a recess, and the connecting portion protrudes into the recess to form a shape-fitting connection. The recess may be formed on a circumferentially facing side of the wall portion. Preferably, the recess is filled by the connecting portion. Preferably, the recess is elongated and in the shape of, for example, a groove, channel, or furrow.

[0026] In some preferred embodiments, the recess is provided to have an undercut, and the connecting portion engages behind the undercut to form a shape-fit connection. Shape-fit connections of such design are particularly mechanically robust. Preferably, the connecting portion has a dovetail-shaped projection that protrudes into the recess and engages behind the undercut.

[0027] In some preferred embodiments, it is provided that a physiologically degradable material is designed to be deformable. As a result, the relative arrangement of the wall portions can be changed at least slightly, that is, by deforming the connecting portions. This has the advantage that it becomes easier to place the anchoring sleeve on the bone of the leg. Depending on the shape of the wall portions and the relative arrangement of the wall portions, for example, the length and / or diameter of the anchoring sleeve can be changed by deforming one or more connecting portions. Preferably, the physiologically degradable material is elastically deformable.

[0028] The physiologically non-degradable material is preferably a rigid body. For this reason, the wall portion is mechanically robust, but the wall portion itself cannot be deformed during the embedding of the anchoring sleeve.

[0029] In some preferred embodiments, the physiologically degradable material comprises a polymer material. A polymer material is a material containing macromolecules. Macromolecules are made from one repeating unit or a plurality of different repeating units.

[0030] Preferably, the polymer material is a protein material. Accordingly, the connecting portion is made from a protein material. Protein materials are particularly suitable in both their mechanical properties and their degradation behavior. The protein material can be a natural, especially plant or animal, or a synthetic protein material. Preferably, the physiologically degradable material has gelatin as a protein material. Gelatin is particularly suitable due to its good biocompatibility.

[0031] Preferably, the polymer material is a polyester material. Particularly preferably, the polyester material comprises poly-L-lactide (PPLLA), poly-lactide-co-glycolide (PLGA), and / or poly-D,L-lactide (PDLLA).

[0032] In some preferred embodiments, the physiologically biodegradable material is provided to comprise a physiologically biodegradable ceramic material. Particularly preferred, the physiologically biodegradable ceramic material comprises hydroxyapatite, α-tricalcium phosphate, and / or β-tricalcium phosphate.

[0033] In some preferred embodiments, the physiologically biodegradable material comprises a physiologically biodegradable metal or a physiologically biodegradable metal alloy. Preferred physiologically biodegradable metals include iron, zinc, and magnesium. Preferred physiologically biodegradable metal alloys are magnesium-containing metal alloys. Particularly preferred, the physiologically biodegradable material comprises a magnesium alloy containing zinc and calcium.

[0034] Mixtures of the physiologically biodegradable materials mentioned above are also possible. For example, physiologically biodegradable materials can be mixtures of polymer materials and ceramic materials.

[0035] In some preferred embodiments, the physiologically indestructible material is a metal or a metal alloy. Therefore, the wall is made of a metal or a metal alloy. Preferably, the physiologically indestructible material is titanium. Titanium is particularly preferred due to its high rigidity and good biocompatibility. Preferably, the wall is manufactured by an additive manufacturing process, particularly preferably by selective laser melting.

[0036] In some preferred embodiments, the sleeve wall is provided to have an inner surface, and at least one fixing anchor is formed on the inner surface and protrudes from the inner surface into the through-opening. As previously mentioned, the prosthesis stem is typically attached to the anchoring unit by bone cement, which is introduced into the through-opening, particularly between the sleeve wall and the prosthesis stem. Since the fixing anchor is formed from bone cement, particularly robust mechanical fixation is ensured. Preferably, each wall portion has at least one fixing anchor.

[0037] A second aspect of this specification relates to a prosthesis kit, comprising an anchoring unit designed as described above and a knee prosthesis component having a prosthesis stem that can be positioned in a through-opening of the anchoring unit. The prosthesis stem carries the actual joint replacement portion of the knee prosthesis component.

[0038] For the advantages that can be achieved with the prosthesis kit, please refer to the description of the anchoring unit. The features described in relation to the anchoring unit will help in further improving the prosthesis kit.

[0039] In some preferred embodiments, the prosthesis kit includes bone cement for attaching the knee prosthesis component to an anchoring unit. [Brief explanation of the drawing]

[0040] The present invention will be described in more detail below with reference to the drawings.

[0041] [Figure 1] Perspective view of an anchoring unit for fixing a knee prosthesis component to the leg bone.

[0042] [Figure 2] A cross-sectional view of an anchoring unit with a knee prosthesis component positioned inside.

[0043] [Figure 3] A diagram showing the details of the sleeve wall of the anchoring unit. [Modes for carrying out the invention]

[0044] Figure 1 is a perspective view of the anchoring unit 10. Figure 2 is a cross-sectional view of the anchoring unit 10, where the cross-section extends perpendicular to the longitudinal axis of the anchoring unit 10. Figure 3 shows a detailed cutout from Figure 2.

[0045] The anchoring unit 10 is used to fix the knee prosthesis component 100 to the bone of the patient's leg. Depending on the type of knee prosthesis component 100, the leg bone can be the femur or the tibia.

[0046] The anchoring unit 10 has an anchoring sleeve 12. In this case, the anchoring unit 10 is formed by the anchoring sleeve 12. Alternatively, the anchoring unit 10 may have one or more additional non-sleeve-like portions in addition to the anchoring sleeve 12.

[0047] The anchoring sleeve 12 has a sleeve wall 14 that defines a through-opening 16. In this case, the sleeve wall 14 is formed circumferentially, i.e., it closes circumferentially to the anchoring sleeve 12. The through-opening 16 is designed to receive the prosthesis stem 102 of the knee prosthesis component 100. The prosthesis stem 102, positioned in this manner, is shown by a dashed line in Figure 1. As can be seen from Figure 1, the prosthesis stem 102 protrudes axially through the anchoring sleeve 12. The portion of the knee prosthesis component 100 that simulates the knee joint is supported by the prosthesis stem 102, but is not shown for simplicity.

[0048] While the anchoring unit 10 and knee prosthesis component 100 are implanted into the leg bone, the prosthesis stem 102 can be attached to the anchoring sleeve 12 by bone cement 104. The bone cement 104 can fill the gap between the prosthesis stem 102 and the sleeve wall 14, as shown in Figure 2.

[0049] In this case, the anchoring sleeve 12 is tapered into a conical shape. An anchoring sleeve 12 of this shape is particularly suitable for placement in the metaphysical region of the leg bone. In this embodiment, as shown in Figure 2, the anchoring sleeve 12 has a circular cross-section.

[0050] The sleeve wall 14 has a plurality of wall sections 18 that are formed separately from each other. The wall sections 18 are made of a physiologically non-degradable material. In the exemplary embodiment shown in the figure, there are exactly four wall sections 18. However, a different number of wall sections 18 may be provided. In this exemplary embodiment, the wall sections 18 are the same shape.

[0051] The sleeve wall 14 further has a plurality of connecting parts 20. The separately formed wall sections 18 are connected to each other by the connecting parts 20. Thus, the connecting parts 20 hold the wall sections 18 together. The connecting parts 20 are made of a physiologically decomposable material. In the exemplary embodiment shown in the figure, just four connecting parts 20 are provided. However, a different number of connecting parts 20 may be provided. In this exemplary embodiment, the connecting parts 20 are the same shape.

[0052] After the anchoring unit 10 is implanted, the material of the connection 20 gradually decomposes physiologically. Such material decomposition can occur, for example, over several weeks to several months. As a result, the structural integrity of the connection 20 is lost, and the wall portion 18 eventually separates. In some cases, the separated wall portions 18 are held together by bone cement 104. The separation of the wall portions 18 after implantation has the advantage of facilitating the removal of the anchoring unit 10 in the event of subsequent replacement due to infection, for example.

[0053] In the exemplary embodiment shown in the figure, the wall portions 18 are wall segments of the sleeve wall 14, which are offset from each other. The wall portions 18 are arranged side by side in the circumferential direction of the anchoring sleeve 12, each extending along the entire length of the anchoring sleeve 12, i.e., from the first longitudinal end 22 of the anchoring sleeve 12 to the second longitudinal end 24 of the anchoring sleeve 12.

[0054] In this embodiment, the wall sections 18 are plate-shaped and extend along circumferential angular intervals of approximately 80°. Depending on the number of wall sections 18, other dimensions of the wall sections 18 can also be provided.

[0055] As can be seen from the figure, the wall sections 18 are spaced apart from each other, so there is always a gap-like space between two adjacent wall sections 18. The connecting section 20 is rod-shaped. One connecting section 20 is located in each space. In the exemplary embodiment shown in the figure, the connecting section 20 also extends along the entire length of the anchoring sleeve 12.

[0056] The wall portion 18 is connected to the connecting portion 20 by a shape-fit connection. The type of shape-fit connection will be explained below with reference to Figure 3. Figure 3 shows enlarged details of the wall portion 18 and the connecting portion 20.

[0057] As shown in Figure 3, the wall portion 18 has a recess 26. The recess 26 is formed on the side surface 28 of the wall portion 18 facing the circumferential direction of the sleeve wall 14. In this embodiment, the recess 26 is elongated and extends along the entire length of the side surface 28. The recess 26 has an undercut 30.

[0058] The connecting portion 20 protrudes into the recess 26, thereby forming a shape-fit connection. For this purpose, the connecting portion 20 has a dovetail-shaped projection 32 that engages with the rear of the undercut 30. In this embodiment, the projection 32 is elongated and extends along the entire length of the connecting portion 20.

[0059] As mentioned above, the wall portion 18 is made of a material that is physiologically indestructible. Preferably, the physiologically indestructible material is a metal or a metal alloy. Particularly preferably, the wall portion 18 is made of titanium, particularly by an additive manufacturing process.

[0060] As described above, the connector 20 is made of a physiologically biodegradable material. In this exemplary embodiment, the physiologically biodegradable material is a polymer material. More preferably, the polymer material comprises or consists of gelatin. Gelatin is particularly advantageous due to its biocompatibility, mechanical properties, and biodegradation behavior under physiological conditions.

[0061] However, other physiologically biodegradable polymer materials, such as polyester materials, are also possible.

[0062] Other preferred physiologically biodegradable materials include physiologically biodegradable ceramic materials and physiologically biodegradable metals or metal alloys.

[0063] In the figure, the outer surface 34 of the sleeve wall 14, i.e., the side facing away from the through-opening 16 of the sleeve wall 14, is shown as smooth. In contrast, it is preferable that the outer surface 34 has a structured surface in at least some areas. This can promote the internal growth of the leg bone into the anchoring unit 10. The structured surface may have, for example, teeth, grooves, and / or lattice structures. A preferred lattice structure is known, for example, as a "structan surface". Particularly preferable, each wall portion 18 has a structured surface in at least some areas.

[0064] As shown in Figures 2 and 3, several fixing anchors 38 are provided on the inner surface 36 of the sleeve wall 14, i.e., the side facing the through-opening 16 of the sleeve wall 14, and protrude from the inner surface 34 of the sleeve into the through-opening 16. The fixing anchors 38 are surrounded by the bone cement 104 when the bone cement 104 is filled, thereby reinforcing the connection between the bone cement 104 and the anchoring unit 10.

[0065] In this exemplary embodiment, each of the wall sections 18 has a fixing anchor 38. The fixing anchor 38 can extend along the entire length of the wall section 18. In this embodiment, the fixing anchor 38 extends only along a limited longitudinal portion of the wall section 18 and is therefore not visible in Figure 1.

Claims

1. An anchoring unit (10) for fixing a knee prosthesis component (100) to the bones of a patient's leg, particularly the femur or tibia, The anchoring unit (10) comprises an anchoring sleeve (12) having a sleeve wall (14), The sleeve wall (14) defines a through-opening (16) designed to receive the prosthesis stem (102) of the knee prosthesis component (100). The sleeve wall (14) has at least two wall portions (18) that are formed separately from each other and made of a physiologically non-degradable material. The wall portions (18) are connected to each other by at least one connector (20) made of a physiologically biodegradable material, forming an anchoring unit (10).

2. The anchoring unit (10) according to claim 1, characterized in that the wall portion (18) is a wall segment of the sleeve wall (14) that is offset from each other.

3. The wall portions (18) are arranged with space between them, The anchoring unit (10) according to claim 1 or 2, characterized in that the connecting portion (20) is arranged in a space formed between the wall portions (18), particularly in a gap-like space.

4. The wall portion (18) is plate-shaped, and / or The anchoring unit (10) according to any one of claims 1 to 3, characterized in that the connecting portion (20) is rod-shaped.

5. The anchoring unit (10) according to any one of claims 1 to 4, characterized in that the wall portion (18) is arranged side by side in the circumferential direction of the anchoring sleeve (12).

6. The anchoring unit (10) according to any one of claims 1 to 5, characterized in that at least one of the wall portions (18) is connected to the connecting portion (20) by a shape-fitting connection.

7. At least one of the wall portions (18) has a particularly elongated recess (26), The anchoring unit (10) according to claim 6, characterized in that the connecting portion (20) protrudes into the recess (26) to form the shape-fitting connection.

8. The recess (26) has an undercut (30), The anchoring unit (10) according to claim 7, characterized in that the connecting portion (20) engages with the rear of the undercut (30) to form the shape-fitting connection.

9. The anchoring unit (10) according to any one of claims 1 to 8, characterized in that the physiologically degradable material is designed to be deformable, particularly elastically deformable.

10. The anchoring unit (10) according to any one of claims 1 to 9, characterized in that the physiologically degradable material comprises a physiologically degradable polymer material, preferably a physiologically degradable protein material or a physiologically degradable polyester material, a physiologically degradable ceramic material, a physiologically degradable metal, and / or a physiologically degradable metal alloy.

11. The anchoring unit (10) according to any one of claims 1 to 10, characterized in that the physiologically indegradable material is a metal or a metal alloy, and in particular the physiologically indegradable material includes titanium.

12. The sleeve wall (14) has an inner surface (36), An anchoring unit (10) according to any one of claims 1 to 11, characterized in that at least one fixed anchor (38) is formed on the inner surface (36) and protrudes from the inner surface (36) into the through opening (38).

13. It is a prosthesis kit, An anchoring unit (10) according to any one of claims 1 to 12, A prosthesis kit comprising: a knee prosthesis component (100), particularly a femoral prosthesis component or a tibial prosthesis component, the knee prosthesis component (100) having a prosthesis stem (102) that can be positioned in the through-opening (16) of the anchoring unit (10).

14. The prosthesis kit according to claim 13, characterized in that the prosthesis kit includes bone cement (104) for attaching the knee prosthesis component (100) to the anchoring unit (10).

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