Reinforcement element for a knee prosthesis

Abstract

To provide a reinforcement element for a prosthesis, particularly a knee prosthesis.SOLUTION: A reinforcement element (100) comprises a metal body (101) of a substantially truncated conical shape. The metal body is configured to be inserted into a bone extremity, and has an outer surface comprising a metal trabecular surface (102). The metal body is hollow with an axial through-cavity (104) defining a plurality of substantially annular transversal sections. The metal body is inclined in a direction of inclination, so as to define at least one eccentricity between a first transversal section at a first end of the axial through-cavity and a second transversal section at a second end of the axial through-cavity.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reinforcing element for a prosthesis comprising a substantially frustoconical metal body configured to be inserted into an epiphysis.

[0002] The present invention is particularly useful in surgical interventions for knee prosthesis implantation, and the following description refers to this specific field of application in order to simplify the explanation.

[0003] Generally, the present invention does not exclude the possibility of being applied to other types of surgical interventions for implanting prostheses into epiphyses.

Background Art

[0004] In orthopedic surgery for implanting a prosthesis, the bone seat may typically receive the application of a reinforcing element applied within a housing that has been milled into the bone having a desired contour.

[0005] As used herein, the term "reinforcing element" means a prosthetic element that can fill or replace a bone portion that has been cut or deteriorated due to an existing medical condition or implantation, and can further be connected to a further prosthetic joint element to provide a stable implantation.

[0006] The use of reinforcing elements is particularly common when the cancellous portion of the bone is not capable of supporting the prosthesis itself, particularly in the case of knee or hip prostheses.

[0007] Typically, the reinforcing element is a substantially conical or frustoconical component made of metal.

[0008] For example, a knee prosthesis typically includes a femoral component fixed to the distal end of the femur and a tibial component fixed to the proximal end of the tibia. In that case, both a reinforcing element for the end of the femur and a reinforcing element for the end of the tibia can be provided.

[0009] WO 2015 / 145348 relates to a multilayer reinforcing element for a prosthesis, comprising a frustoconical body having an axially through cavity open at both ends and an annular part. The body includes an outer part of a metal stud material.

[0010] US 2019 / 070008 relates to a reinforcing element for a prosthesis, comprising a hollow sleeve having an internal channel across the hollow sleeve. The hollow sleeve comprises one or more hinge joints configured to compress the channel and reduce the circumference and width of the hollow sleeve. The body is made of a metal material without a stud part.

[0011] A difficulty arising in the prior art is that known reinforcing elements cannot accurately correspond to the anatomical structure of the bone, and thus the performance of the implanted prosthesis is insufficient.

[0012] In particular, since both the tibia and the femur have an asymmetric elongated configuration, known reinforcing elements cannot conform to the specific tibial or femoral anatomical structure of a patient.

[0013] Furthermore, the prior art has problems regarding the insertion or removal of the reinforcing element in each bone seat, which involves surgical complexity or difficulty.

[0014] A general object of the present invention is to provide a surgeon with a reinforcing element that solves some of the drawbacks of the prior art.

[0015] A further object of the present invention is to enable the reinforcing element to better adapt to the specific bone anatomical structure.

[0016] A further object of the present invention is to provide a reinforcement element that is particularly suitable for the specific tibia or femur anatomical structure of a patient.

[0017] A further object of the present invention is to provide a reinforcement element that is more efficient during insertion or removal at each bone seat. SUMMARY OF THE INVENTION

[0018] The solution underlying the present invention is to provide a reinforcement element for a prosthesis having a generally frustoconical metal body configured to be inserted into a bone end and having an axially penetrating cavity. The metal body has a plurality of annular portions defined along the axially penetrating cavity, which are stacked eccentrically so as to define the overall inclination of the metal body. The configuration of the metal body enables better adaptation to the specific bone anatomical structure, particularly for femur or tibia applications. Further, a metal stud surface, preferably obtained integrally and seamlessly with the metal body, may be provided to further improve embedding and attachment to the bone seat.

[0019] Based on such a solution, a reinforcement element for a prosthesis, particularly for a knee prosthesis, is provided, comprising a generally frustoconical metal body. The metal body is configured to be inserted into a bone end. The metal body preferably has an outer surface including a metal stud surface. The metal body is hollow and has an axially penetrating cavity defining a plurality of generally annular cross-sections. Further, the metal body is inclined in the direction of inclination so as to define at least one eccentricity between a first cross-section at a first end of the axially penetrating portion and a second cross-section at a second end of the axially penetrating cavity.

[0020] Thereby, a reinforcement element is provided that is particularly suitable for a specific asymmetric bone anatomical structure and is particularly advantageous when applying the reinforcement element to the end of the tibia or femur.

[0021] The reinforcing element for the prosthesis is also defined as having a substantially frustoconical metal body with an axially penetrating cavity and including a metal stud surface. Preferably, the reinforcing element further comprises a plurality of through slits that are open from the first end to the intermediate portion of the metal body. Such slits are configured for radial compression of the metal body. Thus, the circumference of the substantially annular cross-section of the metal body is locally reduced.

[0022] As a result, as an advantage, a reinforcing element that is more efficient during insertion and embedding is provided, radial compression of the metal body becomes possible, press-fitting into the bone is increased, and along with the increase in press-fitting into the bone, the pressure of the stud surface on the bone also increases. Thus, bone growth is promoted to ensure a stable long-term connection.

[0023] The reinforcing element according to the present invention has the advantage of improving both the primary stability and the secondary stability of embedding. The primary stability is something that can be quickly observed during the intervention and is actually a mechanical wedge. The secondary stability, instead, is obtained by bone bonding. Bone bonding is improved by the presence of primary stability, the presence of the stud structure or appropriate porosity, and the presence of compressive forces or press-fitting that promote bone growth.

[0024] Furthermore, specific features of the reinforcing element that are particularly efficient when applied to the ends of the tibia or femur are provided, and these are illustrated in detail below.

[0025] Further features and advantages of the present invention will become apparent from the following detailed description provided for illustrative and non-limiting purposes, and from the claims that form an essential part of this description.

Brief Description of the Drawings

[0026]

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[0027] In different figures, similar elements are denoted by similar reference numerals.

[0028] The technical drawings shown in the figures should be understood as being purely illustrative and are not necessarily drawn to a fixed scale and do not necessarily have the same scale as each other.

[0029] Figure 1 shows a perspective view of a first embodiment of a reinforcing element 100 for a prosthesis according to the present invention. The reinforcing element 100 of this example is an element for application to the femur in combination with a knee prosthesis.

[0030] The reinforcing element 100 includes a substantially frustoconical metal body 101 configured to be inserted into the end of the femur. Preferably, the metal body 101 is made of titanium or its alloy for biomedical applications.

[0031] Generally, the metal body comprises a wall, which will be further described, having a substantially constant thickness.

[0032] The metal body 101 has an outer surface including a metal trabecular surface 102. Preferably, the metal trabecular surface 102 is integrally and seamlessly obtained with the metal body 101 by a co-manufacturing procedure, for example, an EBM (Electron Beam Melting) technique. In fact, the co-manufacturing procedure makes it possible to provide a metal trabecular surface without an interface so as to avoid the risk of peeling of the trabecular part of the metal body.

[0033] The metal body 101 preferably has a smooth edge 103 on the outer surface surrounding the metal trabecular surface 102 on one or more sides, preferably on all sides.

[0034] The metal body 101 is hollow and has an axial through-cavity 104 that defines a plurality of substantially annular transversal sections, the configuration of which will be further described.

[0035] Figure 2 shows a front view of the reinforcement element 100 for a prosthesis, where two identical symmetric side walls with the same inclination are shown.

[0036] Figure 3 shows a side cross-sectional view of the reinforcement element 100 for a prosthesis with respect to cross-section III-III of Figure 2.

[0037] The metal body 101 is inclined in the inclination direction, in this case towards the right of the figure, so as to define an eccentricity between a first tranversal section at a first end 105 of the axial through-cavity 104 and a second tranversal section at a second end 106 of the axial through-cavity 104.

[0038] In particular, the axial through-cavity 104 has a longitudinal axis 107 that is inclined in the inclination direction with respect to the vertical axis of the metal body 101. The vertical axis, not shown in the figure for the sake of brevity, is perpendicular to one of the first or second tranversal sections at each of the ends 105 or 106.

[0039] The metal body 101 comprises a front wall 108 that extends in the inclination direction and a rear wall 109 that faces the front wall 108 and extends away from the inclination direction.

[0040] The front wall 108 has an inclination with respect to the vertical axis, and this inclination is smaller than the inclination of the rear wall 109.

[0041] In other words, the profile of the metal body 101 tapers towards the first end 105, and a front asymmetry can be visually recognized in the cross-section.

[0042] Figure 4 shows a side view of the reinforcement element 100 for a prosthesis, where some features already discussed in relation to Figure 3 are pointed out.

[0043] Figure 5 shows a front cross-sectional view of the reinforcement element 100 for a prosthesis, taken along section V-V of Figure 4.

[0044] In this embodiment, considering the direction transverse to the inclination direction shown in Figure 3, instead, it is understood how the longitudinal axis 107 of the axially penetrating cavity 104 is not inclined with respect to the longitudinal axis of the metal body 101.

[0045] The reinforcement element 100 further comprises a plurality of through-slits 110 in the metal body 101, which are open from the first end 105 to an intermediate part on the metal body 101.

[0046] These slits 110 are configured for radial compression of the metal body 101, and in particular, to facilitate insertion into the femoral canal, locally reducing the circumference of the substantially annular cross-section constituting the metal body 101 during insertion of the reinforcement element 100 and increasing the press-fit towards the bone part.

[0047] In particular, with respect to application to the femur, the first cross-section at the end 105 is smaller in size compared to the second cross-section at the end 106 so as to facilitate insertion of the metal body 101 into the end of the femur.

[0048] Preferably, each of the through-slits 110 opens towards the first end 105 and terminates at a respective enlarged circular hole 111 in the intermediate part of the metal body 101. Thereby, the enlarged circular holes 111 are configured to improve the local mechanical resistance of the metal body.

[0049] FIG. 6 shows a bottom view of the reinforcement element 100 for a prosthesis. In this drawing, it can be understood that the eccentricity 112 results in a difference between the first transverse (in this case, circular) cross-section at the first end 105 of the axial through-cavity 104 and the second transverse (in this case, circular) cross-section at the second end 106.

[0050] FIG. 7 shows a front view of the reinforcement element 100 for a prosthesis having a geometric representation related to the metal body 101.

[0051] In particular, the conicity 113 of the symmetric side walls is between 6° and 10° overall, more preferably equal to 8.5°.

[0052] FIG. 8 shows a side view of the reinforcement element 100 for a prosthesis having a geometric representation related to the metal body 101.

[0053] In an example of the reinforcement element 100, the front wall 108 is vertical and has an inclination of 0° with respect to the vertical. Generally, the inclination of the front wall 108 with respect to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.

[0054] In an example of the reinforcement element 100, the rear wall 108 has an inclination 114 of 8.5° with respect to the vertical. Generally, the inclination of the rear wall 108 with respect to the longitudinal axis is configured between 6° and 10°.

[0055] FIG. 9 shows a perspective view of a second embodiment of the reinforcement element 200 for a prosthesis according to the present invention. The reinforcement element 200 of this example is an element for application to the femur in combination with a knee prosthesis.

[0056] The reinforcement element 200 comprises a substantially frustoconical metal body 201 configured to be inserted into the end of the femur. Preferably, the metal body 201 is made of titanium or its alloy for biomedical applications.

[0057] The metal body 201 has an outer surface including a metal stud surface 202. Preferably, the metal stud surface 202 is directly applied to the metal body 201 in an integral and seamless manner by a co-manufacturing process, for example, by an EBM (electron beam machining) technique.

[0058] The metal body 201 preferably has a smooth edge 203 on the outer surface surrounding the metal stud surface 202 on one or more sides, preferably on all sides.

[0059] The metal body 201 is hollow and has an axially extending cavity 204 defining a plurality of substantially annular cross-sections. Its configuration will be further described.

[0060] FIG. 10 shows a front view of a reinforcement element 200 for a prosthesis. Here, it is clear that a pair of bicondylar supports 220a and 220b are arranged side by side on the metal body 201.

[0061] The bicondylar supports 220a and 220b project from the end cross-section of the metal body 201, and each has a tapered body that spreads away from the metal body 201.

[0062] Preferably, the bicondylar supports 220a and 220b also have an outer surface including a metal stud surface, which is made integrally and seamlessly with the bicondylar supports 220a and 220b.

[0063] In the reinforcement element 200, the dual condyle supports 220a and 220b also perform a supporting function for the femoral condyles when the bone defect extends to the femoral condyles. The choice between the embodiment 100 without the dual condyle supports of the reinforcement element and the embodiment 200 including the dual condyle supports of the reinforcement element may depend on, for example, the location and extent of the bone defect. For example, when removing the implant piece having a stem, bone defects in the femur often occur along the channel. Therefore, it is preferable to use the reinforcement element 100 according to the first embodiment. In contrast, in the case of advanced bone degeneration, a situation may occur where the femoral condyles do not provide sufficient support for the prosthesis, and in order to obtain greater reinforcement of the region, it is preferable to use the reinforcement element 200 according to the second embodiment.

[0064] Preferably, the metal body comprises a smooth edge 203 on the outer surface that at least partially surrounds the metal stud surface 202, preferably also the metal stud surfaces of the dual condyle supports 220a and 220b.

[0065] FIG. 11 shows a side cross-sectional view of the reinforcement element 200 for a prosthesis with respect to the cross-section XI-XI of FIG. 10.

[0066] The metal body 201 is inclined in the inclined direction, in this case to the right in the figure, so as to define an eccentricity between the first cross-section at the first end 205 of the axially penetrating cavity 204 and the second cross-section at the second end 206 of the axially penetrating cavity 204.

[0067] In particular, the axially penetrating cavity 204 has a longitudinal axis 207 that is inclined in the inclined direction with respect to the longitudinal axis of the metal body 201. The longitudinal axis, which is not shown in the figure for the sake of brevity, is perpendicular to one of the first cross-section or the second cross-section at each of the ends 205 or 206.

[0068] The metal body 201 comprises a front wall 208 extending in the inclined direction and a rear wall 209 facing the front wall 208 and extending away from the inclined direction.

[0069] The front wall 208 has an inclination with respect to the vertical axis, and the inclination is smaller than that of the rear wall 209.

[0070] In other words, the profile of the metal body 201 tapers towards the first end 205, and a front asymmetry can be visually recognized in the cross section.

[0071] In fact, an eccentricity between the first cross section at the first end 205 of the axially penetrating cavity 204 and the second cross section at the second end 206 can be inferred.

[0072] FIG. 12 shows a side view of the reinforcement element 200 for the prosthesis, where some features already discussed in relation to FIG. 11 are pointed out.

[0073] FIG. 13 shows a front cross-sectional view of the reinforcement element 200 for the prosthesis with respect to the section XIII-XIII of FIG. 12.

[0074] The reinforcement element 200 further comprises a plurality of through slits 210 in the metal body 201, which open from the first end 205 to the middle part of the metal body 201.

[0075] These slits 210 are configured for the radial compression of the metal body 201. In particular, they facilitate the insertion into the femoral canal, locally reduce the circumference of the substantially annular cross section constituting the metal body 201 during the insertion of the reinforcement element 200, and increase the press fit towards the bone part.

[0076] In particular, with respect to the application to the femur, the first cross section at the end 205 is smaller in size compared to the second cross section at the end 206 so as to facilitate the insertion of the metal body 201 into the end of the femur.

[0077] Preferably, each of the through slits 210 opens towards the first end 205 and terminates at a respective enlarged circular hole 211 in the middle part of the metal body 201. Thereby, the enlarged circular body 211 is configured to improve the local mechanical resistance of the metal body.

[0078] In the reinforcement element 200 for application to the femur, the first cross-section at the end 205 is smaller in size than the second cross-section at the end 206. A pair of bicondylar supports 220a, 220b arranged side by side protrude precisely from the second cross-section and are thus in a distal position when the reinforcement element is implanted into the respective femoral canal.

[0079] FIG. 14 shows a front view of the reinforcement element 200 for a prosthesis having a geometric representation related to the metal body 201.

[0080] In particular, the concavity 213 of the side wall is between 6° and 10° in total, and more preferably equal to 8.5°, as in the example of the reinforcement element 200.

[0081] So as to be visible, the second cross-section at the end 206 is further inclined in a second inclination direction in a plane transverse to the inclination direction of the longitudinal axis 207. In that sense, the metal body 201 has an inclined surface at the end 206 that is different from the inclined surface at the end 205, creating an overall asymmetry of the reinforcement element 201 not only in the previously considered front inclination direction but also in the transverse inclination direction of the entire metal body 201, as visible in FIG. 14.

[0082] Furthermore, the pair of bicondylar supports 220a and 220b extend by the same height 221 from the second end 206, thereby defining a pair of asymmetric bicondylar supports 220a and 220b.

[0083] In light of the overall asymmetry of the reinforcement element 200, it is clear that different solutions must be provided for the left and right femurs.

[0084] FIG. 15 shows a side view of the reinforcement element 200 for a prosthesis having a geometric representation related to the metal body 201.

[0085] In the example of the reinforcement element 200, the front wall 208 is vertical and has an inclination of 0° with respect to the vertical. Generally, the inclination of the front wall 208 with respect to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.

[0086] In the example of the reinforcement element 200, the rear wall 209 has an inclination 214 of 8.5° with respect to the vertical. Generally, the inclination of the rear wall 209 with respect to the longitudinal axis is configured between 6° and 10°.

[0087] FIG. 16 shows a perspective view of a third embodiment of a reinforcement element 300 for a prosthesis according to the present invention. The reinforcement element 300 of this example is an element for application to the tibia in combination with a knee prosthesis.

[0088] The reinforcement element 300 includes a substantially frustoconical metal body 301 configured to be inserted into the end of the tibia. Preferably, the metal body 301 is made of titanium or its alloy for biomedical applications.

[0089] The metal body 301 has an outer surface including a metal stud surface 302, and preferably, the metal stud surface 302 is directly applied to the metal body 301 by an integral and seamless co-manufacturing process, for example, by EBM (electron beam machining) technology.

[0090] The metal body 301 preferably has a smooth edge 303 on the outer surface surrounding the metal stud surface 302 on one or more sides, preferably on all sides.

[0091] The metal body 301 is hollow and has an axial through cavity 304 defining a plurality of substantially annular cross-sections, and its configuration will be further described.

[0092] Naturally similar, the metal body 301 is similar in shape to a corolla with two opposing petals removed.

[0093] FIG. 17 shows a front view of the reinforcement element 300 for a prosthesis, where the same two symmetric side walls with the same inclination and configuration are shown.

[0094] Figure 18 shows a side cross-sectional view of a reinforcing element 300 for a prosthesis, taken along the cross-section XVIII-XVIII of FIG. 17.

[0095] The metal body 301 is inclined in an inclined direction, in this case to the right in the figure, so as to define an eccentricity between a first cross-section at a first end 305 of the axially penetrating cavity 304 and a second cross-section at a second end 306 of the axially penetrating cavity 304.

[0096] In particular, the axially penetrating cavity 304 has a longitudinal axis 307 that is inclined in the inclined direction with respect to the longitudinal axis of the metal body 301. The longitudinal axis, not shown in the figure for simplicity, is perpendicular to one of the first cross-section or the second cross-section at the end 305 or 306.

[0097] The metal body 301 includes a front wall 308 that extends in the inclined direction and a rear wall 309 that faces the front wall 308 and extends away from the inclined direction.

[0098] The front wall 308 has an inclination with respect to the longitudinal axis that is smaller than the inclination of the rear wall 309.

[0099] In other words, the profile of the metal body 301 tapers towards the second end 306, and a front asymmetry can be visually recognized in the cross-section.

[0100] Figure 19 shows a side view of the reinforcing element 300 for a prosthesis, where some features already discussed in relation to FIG. 18 are pointed out.

[0101] Regarding the application to the tibia, it can be seen that the first cross-section at the end 305 is larger in size than the second cross-section at the end 306 so as to facilitate the insertion of the above metal body into the end of the tibia.

[0102] The reinforcing element 300 is arranged side by side on the metal body 301 and further includes a pair of notches 320 that open from the first end 305 to the middle part on the metal body 301.

[0103] FIG. 20 shows a front cross-sectional view of the reinforcing element 300 for a prosthesis with respect to the cross-section XX-XX of FIG. 19.

[0104] In the present embodiment, considering the direction transverse to the inclination direction shown in FIG. 18, instead, it is understood how the longitudinal axis 307 of the axially penetrating cavity 304 is not inclined with respect to the longitudinal axis of the metal body 301.

[0105] FIG. 21 shows a front view of the reinforcing element 300 for a prosthesis having a geometric representation related to the metal body 301.

[0106] Preferably, the metal body 301 includes side walls 321 in the notches 320, and such side walls 321 have a curved shape and a concave shape with respect to the outside of the metal body 301, respectively, in order to reproduce the anatomical structure of the intermediate / lateral and posterior bones.

[0107] In particular, at each of the first end 305 and the second end 306, the overall concavity 313 of the symmetric side walls 321, measured with respect to the virtual straight line passing through the two edges of the metal body 301, is between 12° and 20° as a whole, and more preferably equal to 18°.

[0108] FIG. 22 shows a side view of the reinforcing element 300 for a prosthesis having a geometric representation related to the metal body 301.

[0109] In the example of the reinforcing element 300, the front wall 308 is close to vertical and has an inclination 315 equal to 2° with respect to the vertical. Generally, the inclination of the front wall 308 with respect to the longitudinal axis can be configured between 0° and 5°, and more preferably between 0° and 2°.

[0110] In the example of the reinforcement element 300, the rear wall 309 has an inclination of 16° with respect to the vertical. Generally, the inclination of the rear wall 309 with respect to the longitudinal axis is configured to be between 15° and 20°.

[0111] Preferably, the rear wall 309 further has a curved shape and a concave shape with respect to the outside of the metal body 301 in order to reproduce the anatomical structure of the posterior tibia.

[0112] FIG. 23 shows a plan view of the reinforcement element 300 for a prosthesis.

[0113] In this drawing, it can be understood that the eccentricity 312 results in an occurrence between the first cross-section (in this case, circular) at the first end 305 of the axial through-cavity 304 and the second cross-section (in this case, circular) at the second end 306.

[0114] FIG. 24 shows a perspective view of a fourth embodiment of the reinforcement element 400 for a prosthesis according to the present invention. The reinforcement element 400 of this example is an element for application to the tibia in combination with a knee prosthesis.

[0115] The reinforcement element 400 includes a generally frustoconical metal body 401 configured to be inserted into the end of the tibia. Preferably, the metal body 401 is made of titanium or its alloy for biomedical applications.

[0116] The metal body 401 has an outer surface including a metal stud surface 402, and preferably, the metal stud surface 402 is directly applied to the metal body 401 by a co-manufacturing procedure that is integral and seamless, for example, by EBM (electron beam machining) technology.

[0117] The metal body 401 preferably has a smooth edge 403 on the outer surface surrounding the metal stud surface 402 on one or more sides, preferably on all sides.

[0118] The metal body 401 is hollow and has an axial through-cavity 404 defining a plurality of generally annular cross-sections, and its configuration will be further described.

[0119] Figure 25 shows a front view of a reinforcement element 400 for a prosthesis, where two identical symmetric side walls 421 with the same inclination and configuration are shown.

[0120] Figure 26 shows a side cross-sectional view of the reinforcement element 400 for a prosthesis with respect to the section XVI-XVI of FIG. 25.

[0121] The metal body 401 is inclined in the inclined direction, in this case towards the right of the figure, so as to define at least one eccentricity between a first cross-section at the first end 405 of the axially penetrating cavity 404 and a second cross-section at the second end 406 of the axially penetrating cavity 404.

[0122] In particular, the axially penetrating cavity 404 has a longitudinal axis 407 inclined in the inclined direction with respect to the longitudinal axis of the metal body 401. The longitudinal axis, which is not shown in the figure for the sake of simplicity, is perpendicular to one of the first cross-section or the second cross-section at each of the ends 405 or 406.

[0123] The metal body 401 comprises a front wall 408 extending in the inclined direction and a rear wall 409 facing the front wall 408 and extending away from the inclined direction.

[0124] The front wall 408 has an inclination with respect to the longitudinal axis, and the inclination is smaller than that of the rear wall 409.

[0125] In other words, the profile of the metal body 401 tapers towards the second end 406, and a front asymmetry can be visually recognized in the cross-section.

[0126] Figure 27 shows a side view of the reinforcement element 400 for a prosthesis, where some features already discussed in relation to FIG. 26 are pointed out.

[0127] Regarding the application to the tibia, it can be seen that the first cross-section at the end 405 is larger in size than the second cross-section at the end 406 so as to facilitate the insertion of the above metal body into the end of the tibia.

[0128] The reinforcing element 400 further comprises a pair of notches 420 which are arranged side by side with respect to the metal body 401 and are open from the first end 405 to the intermediate portion on the metal body 401.

[0129] FIG. 28 shows a front cross-sectional view of the reinforcing element 400 for a prosthesis with respect to the cross-section XXVIII-XXVIII of FIG. 27.

[0130] In the present embodiment, considering the direction transverse to the inclination direction shown in FIG. 26, instead, it is understood how the longitudinal axis 407 of the axially penetrating cavity 404 is not inclined with respect to the longitudinal axis of the metal body 401.

[0131] FIG. 29 shows a plan view of the reinforcing element 400 for a prosthesis, where the first cross-section at the end 405 is bilobed annular, whereby it is understood that the outer surface of the metal body 401 tapers between the first cross-section and the second cross-section, as can be clearly seen in FIG. 24.

[0132] In a natural analogy, the metal body 401 is similar in shape to a corolla from which two opposing petals have been removed.

[0133] In this drawing, it is also possible to understand that a double eccentricity 412 occurs between the first cross-section (in this case, being bilobed and thus having two circumferential centers for its description) at the first end 405 of the axially penetrating cavity 404 and the second cross-section (in this case, circular with only one circumferential center) at the second end 406.

[0134] FIG. 30 shows a front view of the reinforcing element 400 for a prosthesis having a geometric representation related to the metal body 401.

[0135] Preferably, the metal body 401 has side walls 421 in the notch 420, and such side walls 421 have a curved shape and a concave shape respectively with respect to the outside of the metal body 401 in order to reproduce the anatomical structure of the intermediate / lateral and posterior bones.

[0136] In particular, the overall concave surface 413 of the lateral symmetric wall 421 is configured to be between 45° and 55° in total, more preferably equal to 50°.

[0137] FIG. 31 shows a side view of a reinforcement element 400 for a prosthesis having a geometric representation related to the metal body 401.

[0138] In an example of the reinforcement element 400, the front wall 408 is close to vertical and has an inclination 415 equal to 2° with respect to the vertical. Generally, the inclination of the front wall 408 with respect to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.

[0139] In an example of the reinforcement element 400, the rear wall 409 has an inclination of 19.4° with respect to the vertical. Generally, the inclination of the rear wall 409 with respect to the longitudinal axis is configured between 15° and 20°.

[0140] Preferably, the rear wall 409 further has a curved shape and a concave shape with respect to the outside of the metal body 401 in order to reproduce the anatomical structure of the posterior tibia.

[0141] FIGS. 32 and 33 show perspective views of respective deformations of a reinforcement element 400' for a prosthesis.

[0142] In this deformation, the reinforcement element 400' comprises a plurality of through slits 410 in the metal body that are open from a first end to an intermediate part of the metal body. The plurality of through slits 410 are configured for radial compression of the metal body, locally reducing the circumference during insertion of the reinforcement element 400' and increasing the press fit into the bone part. Preferably, each of the through slits 410 terminates in a respective enlarged circular hole 411.

[0143] Figure 34 shows an example of the application of the reinforcement element 200 for a prosthesis to the end of the femur.

[0144] Figure 35 shows an example of the application of the reinforcement element 300 for a prosthesis to the end of the tibia.

[0145] It is obvious that further implementations and modifications of the present invention are possible for those skilled in the art to meet occasional needs.

[0146] In particular, the specific features described with reference to the embodiments can also be applied to other embodiments described herein in their modified forms, provided there are no technical prejudices in this regard.

[0147] Therefore, the above embodiments should be understood as being provided for illustrative and non - limiting purposes.

Claims

**Claim 1**: A reinforcing element (100, 200, 400) for a knee prosthesis, wherein the reinforcing element (100, 200, 400) comprises a generally frustoconical metal body (101, 201, 401), the metal body being configured to be inserted into a bone end and having an outer surface including a metal stud surface (102, 202, 402). The metal body (101, 201, 401) is hollow and has an axially extending cavity (104, 204, 404) defining a plurality of generally annular cross-sections. The metal body (101, 201, 401) is inclined in an inclined direction so as to define at least one eccentricity (112, 412) between a first cross-section at a first end (105, 205, 405) of the axially extending cavity (104, 204, 404) and a second cross-section at a second end (106, 206, 406) of the axially extending cavity (104, 204, 404). The reinforcing element further comprises a plurality of through slits (110, 210, 410) in the metal body (101, 201, 401) that are open from the first end (105, 205, 405) to an intermediate portion on the metal body (101, 201, 401). The plurality of through slits (110, 210, 410) are configured for radial compression of the metal body (101, 201, 401), locally reducing the circumference of the generally annular cross-section during insertion of the reinforcing element (100, 200, 400) and increasing press-fitting into the bone portion. A reinforcing element (100, 200, 400) characterized thereby. **Claim 2** The axially extending cavity (104, 204, 404) has a longitudinal axis (107, 207, 407) inclined in the inclined direction with respect to the longitudinal axis of the metal body (101, 201, 401), the longitudinal axis being perpendicular to one of the first cross-section or the second cross-section. The reinforcing element according to claim 1. **Claim 3** The metal body (101, 201, 401) comprises a front wall (108, 208, 408) extending in the inclined direction, and further comprises a rear wall (109, 209, 409) facing the front wall (108, 208, 408) and extending away from the inclined direction. The front wall (108, 208, 408) has an inclination with respect to the longitudinal axis, and the inclination of the front wall is smaller than the inclination of the rear wall (109, 209, 409). The reinforcing element according to claim 2. **Claim 4** For application to the femur, the first cross-section (105, 205) is smaller in size than the second cross-section (106, 206) so as to facilitate insertion of the metal body (101, 201) into the end of the femur, the reinforcing element according to claim 1.

5. For application to the tibia, the first cross-section (405) is larger in size than the second cross-section (406) so as to facilitate insertion of the metal body (401) into the end of the tibia, the reinforcing element according to claim 1.

6. Each of the plurality of through slits (110, 210, 410) terminates at a respective enlarged circular hole (111, 211, 411) in the middle portion, and the enlarged circular holes (111, 211, 411) are configured to improve the local mechanical resistance of the metal body (101, 201, 401), the reinforcing element according to claim 1, 4, or 5.

7. For application to the femur, the first cross-section (205) is smaller in size than the second cross-section (206), and the reinforcing element further comprises a pair of bicondylar supports (220a, 220b) arranged side by side on the metal body (201), each of the bicondylar supports (220a, 220b) protruding from the second cross-section (206) and having a tapered body that spreads away from the metal body (201), the reinforcing element according to any one of claims 1 to 6.

8. The bicondylar supports (220a, 220b) have an outer surface including a metal stud surface that is integral and seamless with the bicondylar supports (220a, 220b), the reinforcing element according to claim 7.

9. The second cross-section (206) is inclined in a second inclined direction transverse to the inclined direction, and the pair of bicondylar supports (220a, 220b) extend by the same height (221) from the second cross-section (206), thereby defining a pair of asymmetric bicondylar supports (220a, 220b), the reinforcing element according to claim 7 or 8.

10. For application to the tibia, the first cross-section (405) is larger in size than the second cross-section (406), and the metal body (401) has side walls (421) that are curved and concave in shape respectively with respect to the outside of the metal body (401) in order to reproduce the anatomical structure of the middle / lateral and posterior bones, the reinforcing element according to any one of claims 1 to 6.

11. The reinforcing element according to claim 10, further comprising a pair of notches (420) arranged on the side wall (421) and opening from the first end (405) to an intermediate portion on the metal body (401).

12. The reinforcing element according to claim 10 or 11, wherein the first cross-section (405) is a bilobed annulus, the second cross-section (406) is a circular annulus, and the outer surface of the metal body (401) tapers between the first cross-section (405) and the second cross-section (406).

13. The reinforcing element according to any one of claims 1 to 12, wherein the metal body (101, 201, 401) comprises smooth edges (103, 203, 403) on the outer surface surrounding the metal stud surface (102, 202, 402).

14. The reinforcing element according to any one of claims 1 to 13, wherein the metal stud surface (102, 202, 402) is integrally and seamlessly formed with the metal body (101, 201, 401).

15. The reinforcing element according to any one of claims 1 to 14, wherein the metal body (101, 201, 401) comprises walls (108, 208, 408; 109, 209, 409; 421) having a substantially constant thickness.

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