Konus und Konus-Set

Abstract

The invention relates to a cone (10) for arrangement in a femoral or tibial bone cavity, comprising a conical hollow body (12) extending along a central axis (14) between a distal end (15) and a proximal end (16), wherein the conical hollow body has a larger cross-section at the distal end than at the proximal end, and wherein the hollow body at the proximal end has an annular end region (22) with a medial section (28) and a lateral section (30) diametrically opposite it, and with an anterior section (26) and a posterior section (32) diametrically opposite it. The invention further relates to a cone set.

Description

[0001] The invention relates to a cone for arrangement in a femoral or tibial bone cavity, comprising a conical hollow body which extends along a central axis between a distal end and a proximal end, wherein the conical hollow body has a larger cross-section at the distal end than at the proximal end, wherein the hollow body has an annular end region at the proximal end with a medial section and a diametrically opposite lateral section, and with an anterior section and a diametrically opposite posterior section.

[0002] A cone for placement in a femoral bone cavity, for example, serves to replace destroyed bone tissue in a femoral bone cavity and to reinforce the bone cavity. Such a cone also serves to accommodate the stem of a femoral component of a knee implant within its hollow space enclosed by the conical hollow body and to stabilize the femoral component. Finally, such a cone, with its conical outer surface, serves to provide an anchoring surface for the ingrowth of newly formed bone tissue, particularly in cases where direct anchoring with bone cement is not possible.

[0003] In principle, it is possible to provide a large number of cones that differ in size and geometry, allowing a cone to be selected during knee surgery that matches a specific type of damage to a femur or tibia bone and a specific stem size of a femur or tibia component. However, maintaining such a large number of cones is complex and expensive. It is also difficult for a surgeon to select the best-fitting cone from a large number of cones during surgery and under time pressure, or to test a preselected cone for optimal suitability.

[0004] Based on this, the present invention is based on the object of proposing a cone whose geometry allows the most flexible arrangement possible in a femoral or tibial bone cavity.

[0005] This task is solved by a cone of the type mentioned above in that a) a proximal boundary surface of the posterior section is offset from a proximal boundary surface of the anterior section, as seen from the proximal end of the hollow body, across a material recess in the direction of the distal end, and / or b) proximal boundary surfaces of at least the medial section and the lateral section - seen in a cross-section of the hollow body comprising the central axis - have an inclination and a proximal end of an outer surface of the hollow body facing outwards with respect to the central axis is offset along the central axis compared to a proximal end of an inner surface of the hollow body facing inwards with respect to the central axis.

[0006] The femoral cone according to the invention enables a comparatively deep insertion into a bone cavity, in particular into a femoral bone cavity. For this purpose, it is proposed to provide at least one free space at the proximal end of the hollow body, which can be occupied by remaining bone tissue and / or the cortex after insertion of the cone into the bone cavity. This comparatively free positioning of the cone within the bone cavity is accompanied by a correspondingly more flexible arrangement of the shaft, in particular of a femoral component, in the cavity of the hollow body.

[0007] In particular, it is proposed to provide a posterior material recess. This material recess prevents conflict, particularly with the cortex in the posterior femoral bone, which tapers sharply in this area.

[0008] An alternative or additional possibility for providing a clearance is for the proximal boundary surfaces of at least the medial section and the lateral section—as seen in a cross-section of the hollow body encompassing the central axis—to be inclined, and for a proximal end of an outer surface of the hollow body facing outward relative to the central axis to be offset along the central axis compared to a proximal end of an inner surface of the hollow body facing inward relative to the central axis. In this way, for example, an annular or annular-segment-shaped clearance can be provided in a radially outer region of the proximal end, which also makes it possible to insert the cone relatively deeply into the bone cavity, for example of a femur.

[0009] Preferably, the offset between the proximal boundary surface of the posterior section and the proximal boundary surface of the anterior section is at least 0.5 times the wall thickness of the hollow body and at most 1.5 times the wall thickness of the hollow body. In this way, a sufficiently large clearance can be created without compromising the stability of the hollow body of the cone.

[0010] It is further proposed that the proximal boundary surface of the posterior section be offset from the proximal end of the hollow body, compared to the proximal boundary surfaces of the medial section and the lateral section, toward the distal end across a material recess. In this way, anchoring surfaces for newly formed bone tissue can be provided at the medial section and the lateral section of the annular end region.

[0011] Preferably, the posterior section extends over an angular range relative to the central axis, the size of which is between 90° and 150°, preferably between 110° and 130°. These angular ranges create a sufficiently large clearance, particularly for the posterior cortex of the femur.

[0012] A conflict with the posterior cortex of the femur can be avoided in particular if outer surfaces of the medial section and the lateral section facing away from each other and pointing outwards with respect to the central axis are spaced apart from each other by a certain distance and if an extension of the posterior section parallel to this distance is at least 0.5 times and at most 0.93 times the distance.

[0013] It is particularly preferred if the hollow body is manufactured using additive manufacturing. This allows the hollow body to have a plurality of undercuts, which enable stable anchoring for newly formed bone tissue.

[0014] It is further preferred that the proximal boundary surface of the anterior section and / or the proximal boundary surface of the posterior section has or have an inclination corresponding to the inclination of the proximal boundary surfaces of the medial section and the lateral section. In particular, it is possible for the entire proximal boundary surface of the annular end region (optionally excluding the proximal boundary surface of the posterior section) to have the aforementioned inclination, thereby supporting a deep insertion of the cone, in particular into the bone cavity of the femur. Said inclination also has the advantage that bone cement applied in the region of a proximal boundary surface is pressed radially inwards towards the cavity of the hollow body when it rests against an additional cone, so that undesired escape of bone cement radially outwards can be avoided.The inclination is, for example, at least 5° and at most 30°, preferably at least 10° and at most 20°, in particular at least 12° and at most 17°.

[0015] The invention further relates to a cone set which comprises a cone as described above and furthermore an additional cone which can be stacked with such a cone, wherein at least one proximal boundary surface of the cone and at least one distal boundary surface of the additional cone are designed such that a bone cement layer arranged or arrangeable between these boundary surfaces widens in its cross section - viewed in the radial direction from the outside to the inside.

[0016] In particular, the distal boundary surface of the additional cone is provided with an inclination that is opposite to, or more pronounced than, the inclination of the cone. When a diaphyseal additional cone and a metaphyseal cone are pressed against each other in a stacked configuration before the bone cement hardens, an excess of unhardened bone cement, following the expansion of the cross-section between the boundary surfaces, escapes toward the interior of the hollow body and toward the shaft of a femoral or tibial component of a knee implant, supporting the stabilization of the femoral or tibial component.

[0017] The terms "proximal" and "distal" used in this application refer to the position of a cone for placement in a bone cavity of the lower end of the femur (the proximal end of the hollow body of the cone to be inserted faces the torso and has a smaller cross-section than a distal end of the hollow body of the cone following in the direction of insertion). For the purposes of this application, the position of a cone for placement in a bone cavity of the upper end of the tibia means that the end of the hollow body of the cone to be inserted faces away from the torso, but is nevertheless referred to as the "proximal end" in this application and has a smaller cross-section than the "distal end" of the hollow body of the cone following in the direction of insertion.This understanding in connection with a cone designed as a tibial cone also applies to an additional cone that can be used together with a tibial cone and also to all other features of this application to which one of the attributes “proximal” or “distal” is assigned.

[0018] Further features and advantages of the invention are the subject of the following description of preferred embodiments.

[0019] The drawing shows: Fig. 1 a perspective view of an embodiment of a cone designed as a femoral cone; Fig. 2 a schematic plan view of the cone according to Fig. 1; Fig. 3a a schematic vertical section of the cone according to Fig. 1; Fig. 3b shows a schematic vertical section of another embodiment of a cone; Fig. 4 a perspective view of an embodiment of a cone set, with a cone according to Fig. 1 and with an additional cone; Fig. 5 a vertical section of the additional cone according to Fig. 4.

[0020] An embodiment of a cone designed as a femoral cone is designated overall by reference numeral 10 in the drawing. The cone 10 has a conical hollow body 12 extending along a central axis 14 between a distal end 15 and a proximal end 16.

[0021] It is possible that the hollow body 12 is conical overall or, as in Fig. 1 and Fig. 4, has 15 intracondylar sections 18 and 20 at its distal end.

[0022] The hollow body 12 has at its proximal end 16 an annular end region 22 which extends around the central axis 14 and defines a cavity 24.

[0023] The end region 22 has a total of four sections that complement each other to form a circle along the circumference around the central axis 14, namely an anterior section 26, which borders a medial section 28 and a lateral section 30, wherein the medial section 28 and the lateral section 30 are diametrically opposite one another. The medial section 28 and lateral section 30, in turn, border a posterior section 32, which is diametrically opposite the anterior section 26.

[0024] In Fig. 2, the ring section surfaces, which form respective proximal boundary surfaces of the four sections of the end region 22, are designated by corresponding reference numerals. The proximal boundary surface of the anterior section 26 is designated by reference numeral 34. The medial section 28 has a proximal boundary surface 36. The lateral section 30 has a proximal boundary surface 38. The posterior section 32 has a proximal boundary surface 40. The proximal boundary surfaces 34, 36, and 38 (of the anterior section 26, the medial section 28, and the lateral section 30) are arranged together at the level of the proximal end 16. The proximal boundary surface 40 of the posterior section 32, however, is offset relative to the proximal boundary surfaces 34, 36 and 38 in the direction of the distal end 15, namely by an offset 42, see Fig. 1. In this way, the proximal boundary surface 40 of the posterior section 32 is offset across a material recess 44 in the direction of the distal end 15.

[0025] Relative to the central axis 14, the posterior section 40 extends over an angular range 46 (see Fig. 2), which is approximately 120°.

[0026] The hollow body 12 has a wall thickness 48 extending between an inner side and an outer side, which can, for example, correspond at least approximately to the height of the offset 42.

[0027] The respective outer surfaces of the medial section 28 and the lateral section 30 are in Fig. 2 with the reference numerals 50 and 52. These outer surfaces 50, 52 are spaced apart by a distance 54. An extension 56 of the posterior section 32 parallel to this distance 54 is, for example, approximately 0.7 times the distance 54.

[0028] Relative to an outer surface of the posterior section 32 designated by the reference numeral 58, the extension 56 is set back in the direction of the central axis 14. This setback is in Fig. 2 is designated by the reference numeral 60 and indicates a radial depth of the material recess 44, which enables a deeper insertion of the posterior section 32.

[0029] In addition to the material recess 44 described above or alternatively to a material recess 44 described above, it is possible that at least the proximal boundary surfaces 36 and 38 of the medial section 28 and the lateral section 30 have an inclination 66, see Fig. 3a. For example, the inclination 66 is such that, in a cross-section of the hollow body 12 encompassing the central axis 14, respective inner surfaces 62, 64 of the medial section 28 and the lateral section 30 extend from the distal end 15 to the proximal end 16. The respective outer surfaces 50, 52, which are spaced apart from each other across the wall thickness 48 of the hollow body 12, are offset in the direction of the distal end 15 with respect to the proximal ends of the inner surfaces 62, 64. The inclination 66 of at least the proximal boundary surfaces 36 and 38 - with respect to a plane perpendicular to the central axis 14 - is in particular between at least 12° and at most 17°.

[0030] In Fig. 4, a cone set 70 is shown, which is described above with reference to Fig. 1 to 3 and an additional cone 68 stackable with this cone. The additional cone 68 extends along an additional cone axis 72 between a distal end 74 and a proximal end 76.

[0031] The additional cone 68 has a hollow body 78 which defines a conical cavity 80. At its distal end 74, the additional cone 68 has a distal boundary surface 82 which preferably extends in a closed ring around the additional axis 72 and has a greater inclination 84 of, for example, 20° relative to the inclination 66 of the cone 10. This makes it possible to accommodate, in an annular disk-shaped space 86, see Fig. 4, to arrange a bone cement layer between the proximal end 16 of the cone 10 and the distal end 74 of the additional cone 68, wherein such a bone cement layer has a layer thickness that increases from the radially outside to the inside. This radially inwardly increasing layer thickness can be realized in particular by the proximal boundary surfaces 34, 36, and 38 of the cone 10 having an inclination 66 that is opposite to the inclination 84 of the additional cone 68, see Fig. 3b.

Claims

[1] Cone (10) for placement in a femoral or tibial bone cavity, comprising a conical hollow body (12) extending along a central axis (14) between a distal end (15) and a proximal end (16), wherein the conical hollow body (12) has a larger cross-section at the distal end (15) than at the proximal end (16), wherein the hollow body (12) has an annular end region (22) at the proximal end (16) with a medial section (28) and a diametrically opposite lateral section (30), and with an anterior section (26) and a diametrically opposite posterior section (32), characterized by , that a) a proximal boundary surface (40) of the posterior section (32) is offset from the proximal end (16) of the hollow body (12) in comparison to a proximal boundary surface (34) of the anterior section (26) across a material recess (44) in the direction of the distal end (15), and / or b) proximal boundary surfaces (36, 38) of at least the medial section (28) and the lateral section (30) - seen in a cross-section of the hollow body (12) comprising the central axis (14) - have an inclination (66) and a proximal end of an outer surface (50, 52) of the hollow body (12) pointing outwards with respect to the central axis (14) is offset compared to a proximal end of an inner surface (62, 64) of the hollow body (12) pointing inwards with respect to the central axis (14), as seen along the central axis (14). [2] Cone (10) according to claim 1, characterized bythat the offset (42) between the proximal boundary surface (40) of the posterior section (32) and the proximal boundary surface (34) of the anterior section (26) is at least 0.5 times a wall thickness (48) of the hollow body (12) and at most 1.5 times the wall thickness (48) of the hollow body (12). [3] Cone (10) according to one of the preceding claims, characterized by that the proximal boundary surface (40) of the posterior section (32) is also offset in comparison to proximal boundary surfaces (36, 38) of the medial section (28) and the lateral section (30) from the proximal end (16) of the hollow body (12) across the material recess (44) in the direction of the distal end (15). [4] Cone (10) according to one of the preceding claims, characterized bythat the posterior section (32) extends with respect to the central axis (14) over an angular range (46) whose size is between 90° and 150°, preferably between 110° and 130°. [5] Cone (10) according to one of the preceding claims, characterized by that outer surfaces (50, 52) of the medial section (28) and of the lateral section (30) facing away from one another and pointing outwards with respect to the central axis (14) are spaced apart from one another by a distance (54) and that an extension (56) of the posterior section (32) parallel to this distance (54) is at least 0.5 times and at most 0.93 times the distance (54). [6] Cone (10) according to one of the preceding claims, characterized by that the hollow body (12) is manufactured by additive manufacturing. [7] Cone (10) according to one of the preceding claims, characterized bythat the proximal boundary surface (34) of the anterior section (26) and / or the proximal boundary surface (40) of the posterior section (32) has or have an inclination corresponding to the inclination (66) of the proximal boundary surfaces (36, 38) of the medial section (28) and the lateral section (30). [8] Cone (10) according to one of the preceding claims, characterized by that the inclination (66) is at least 5° and at most 30°. [9] Cone (10) according to one of claims 1 to 7, characterized by that the inclination (66) is at least 10° and at most 20°. [10] Cone (10) according to one of claims 1 to 7, characterized by that the inclination (66) is at least 12° and at most 17°. [11] Cone set (70), comprising a cone (10) according to one of the preceding claims, further comprising an additional cone (68) stackable with the cone (10), wherein at least one proximal boundary surface (36, 38) of the cone (10) and at least one distal boundary surface (82) of the additional cone (68) are designed such that a bone cement layer arranged or arrangeable between these boundary surfaces (36, 38 and 82) widens in its cross section - viewed in the radial direction from the outside to the inside.

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