Augment element for prosthesis, in particular for knee prosthesis
The reinforcing element with a frusto-conical design and trabecular surface adapts to asymmetrical bone anatomy, improving stability and ease of insertion/removal by enhancing the press fit and encouraging bone integration, addressing the limitations of prior art.
Patent Information
- Application Number
- JP2025102656
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2020-07-06
- Filing Date
- 2025-06-18
- Publication Date
- 2025-09-02
AI Technical Summary
Existing reinforcing elements for prostheses, such as knee and hip implants, fail to accurately conform to the asymmetrical anatomy of the tibia and femur, leading to poor performance and surgical complications during insertion and removal.
A reinforcing element with a generally frusto-conical metal body featuring an axial through-cavity and eccentrically stacked annular portions, along with a metal trabecular surface, is designed to better fit specific bone anatomy. This element includes through slits for radial compression, enhancing the press fit and encouraging bone integration.
The solution provides improved primary stability through mechanical wedging and secondary stability via osseointegration, ensuring a stable, long-term connection by adapting to individual bone structures and facilitating easier insertion and removal.
Smart Images
Figure 2025128377000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a reinforcing element for a prosthesis comprising a metal body of generally frusto-conical shape adapted to be inserted into the epiphysis.
[0002] The present invention is particularly useful in surgical intervention for knee prosthesis implantation, and the following description will refer to this particular application for ease of explanation.
[0003] Generally, it is not excluded that the invention can be applied to other types of surgical interventions in which a prosthesis is implanted in the epiphysis. [Background technology]
[0004] In orthopedic surgery for the implantation of a prosthesis, the bone seat may be subjected to the application of a reinforcing element applied within a housing, typically milled into the bone with the desired contour.
[0005] For purposes of this specification, 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 pathology or implantation, and that can be connected to additional prosthetic articulating elements to provide stable implantation.
[0006] The use of reinforcing elements is particularly common when the cancellous portion of the bone is unable to support the prosthesis by itself, particularly in the case of knee or hip prostheses.
[0007] Typically, the reinforcing element is a substantially conical or frusto-conical shaped component made of metal.
[0008] For example, a knee prosthesis typically includes a femoral component secured to the distal end of the femur and a tibial component secured to the proximal end of the tibia, where both a reinforcement element for the distal end of the femur and a reinforcement element for the distal end of the tibia may be provided.
[0009] WO 2015 / 145348 relates to a multi-layer reinforcing element for a prosthesis, comprising a frusto-conical body having an axial through cavity open at both ends and an annular portion, the body comprising an outer portion of metal trabecular material.
[0010] U.S. Patent Application Publication No. 2019 / 070008 relates to a reinforcing element for a prosthesis, comprising a hollow sleeve having an internal channel traversing the hollow sleeve. The hollow sleeve includes one or more flexure joints configured to compress the channel and reduce the circumference and width of the hollow sleeve. The body is made of a metallic material without a trabecular portion.
[0011] A difficulty encountered in the prior art is that the known reinforcing elements are unable to accurately correspond to the anatomy of the bone, thus resulting in poor performance of the implanted prosthesis. WO 2013 / 134333 relates to a modular implant support structure system for femoral implants. The system includes a diaphyseal augment having a generally conical outer surface truncated at its proximal end by a proximal face and at its distal end by a distal face. The diaphyseal augment is integrally molded from a single piece of porous metallic material.
[0012] In particular, known reinforcing elements are unable to conform to a patient's specific tibial or femoral anatomy because both the tibia and femur have asymmetrical elongated configurations.
[0013] Furthermore, the prior art presents challenges regarding the insertion or removal of the reinforcing elements at the respective bone seats, which involves surgical complications or difficulties.
[0014] A general object of the present invention is to provide surgeons with a reinforcement element that overcomes some of the shortcomings of the prior art.
[0015] A further object of the present invention is to allow the reinforcing element to better adapt to specific bony anatomy.
[0016] It is a further object of the present invention to provide a reinforcing element that is particularly suited to a patient's specific tibial or femoral anatomy.
[0017] A further object of the present invention is to provide a reinforcing element that is more efficient during insertion or removal from its respective bony seat. Summary of the Invention
[0018] The invention is an augment for use in tibial applications for knee replacement according to the features of the appended claim 1. The solution underlying the present invention is to provide a reinforcing element for a prosthesis, which has a generally truncated metal body with an axial through-cavity, configured to be inserted into the epiphysis. The metal body has a plurality of annular portions defined along the axial through-cavity, which are eccentrically stacked to define the overall inclination of the metal body. The configuration of the metal body allows for a better adaptation to the specific bone anatomy, particularly in femoral or tibial applications. Furthermore, to further improve embedding and attachment to the bone seat, a metal trabecular surface can be provided, preferably integral and seamless with the metal body.
[0019] According to this solution, a reinforcing element for a prosthesis, particularly a knee prosthesis, is provided, comprising a generally frusto-conical metal body. The metal body is configured to be inserted into the epiphysis. The metal body preferably has an outer surface including a metal trabecular surface. The metal body is hollow, having an axial through-cavity defining a plurality of generally annular cross-sections. Furthermore, the metal body is inclined in an oblique direction to define at least one eccentricity between a first cross-section at a first end of the axial through-cavity and a second cross-section at a second end of the axial through-cavity.
[0020] This provides a reinforcing element that is particularly suited to specific asymmetric bone anatomy, and is particularly advantageous when the reinforcing element is applied to the distal end of the tibia or femur.
[0021] A reinforcing element for a prosthesis is also provided having a generally frustoconical metal body with an axially extending cavity and including a metal prism surface. Preferably, the reinforcing element further comprises a plurality of through slits extending from a first end to an intermediate portion of the metal body. Such slits are configured for radial compression of the metal body, thereby locally reducing the circumference of the generally annular cross section of the metal body.
[0022] This advantageously provides a reinforcing element that is more efficient during insertion and implantation, allows for radial compression of the metal body, increasing its press fit into the bone and, with increased press fit, increasing the pressure of the trabecular surface against the bone, thus encouraging bone in-growth to ensure a stable, long-term connection.
[0023] The reinforcing element according to the invention advantageously improves both the primary and secondary stability of the implant. Primary stability is what is immediately observable in the intervention and is in fact a mechanical wedge. Secondary stability is instead achieved by osseointegration. Osseointegration is improved by the presence of primary stability, the presence of trabecular structure or adequate porosity, and the presence of compressive forces or press-fits that encourage bone growth.
[0024] Furthermore, specific features of the reinforcing element that make it particularly effective when applied to the distal end of the tibia or femur are provided and are exemplified in detail below.
[0025] Further features and advantages of the invention will become apparent from the following detailed description, given for illustrative and non-limiting purposes, and from the claims, which form an integral part of this description. [Brief explanation of the drawings]
[0026] [Figure 1] FIG. 1 shows a perspective view of a first example of a reinforcing element for a prosthesis. [Figure 2] FIG. 2 shows a front view of a first example of a reinforcing element for a prosthesis. [Figure 3]FIG. 3 shows a side cross-sectional view of a first example of a reinforcing element for a prosthesis. [Figure 4] FIG. 4 shows a side view of a first example of a reinforcing element for a prosthesis. [Figure 5] FIG. 5 shows a front cross-sectional view of a first example of a reinforcing element for a prosthesis. [Figure 6] FIG. 6 shows a bottom view of a first example of a reinforcing element for a prosthesis. [Figure 7] FIG. 7 shows a front view of a first example of a reinforcing element for a prosthesis with further geometrical representations. [Figure 8] FIG. 8 shows a side view of a first example of a reinforcing element for a prosthesis with further geometrical representation. [Figure 9] FIG. 9 shows a perspective view of a first embodiment of a reinforcing element for a prosthesis according to the invention. [Figure 10] FIG. 10 shows a front view of a first embodiment of a reinforcing element for a prosthesis. [Figure 11] FIG. 11 shows a side cross-sectional view of a reinforcing element for a prosthesis. [Figure 12] FIG. 12 shows a side view of a first embodiment of a reinforcing element for a prosthesis. [Figure 13] FIG. 13 shows a front cross-sectional view of a first embodiment of a reinforcing element for a prosthesis. [Figure 14] FIG. 14 shows a front view of a first embodiment of a reinforcing element for a prosthesis with further geometrical indications. [Figure 15] FIG. 15 shows a side view of a first embodiment of a reinforcing element for a prosthesis with further geometrical indications. [Figure 16] FIG. 16 shows a perspective view of a second example of a reinforcing element for a prosthesis according to the invention. [Figure 17] FIG. 17 shows a front view of a second example of a reinforcing element for a prosthesis. [Figure 18] FIG. 18 shows a side cross-sectional view of a second example of a reinforcing element for a prosthesis. [Figure 19] FIG. 19 shows a side view of a second example of a reinforcing element for a prosthesis. [Figure 20] FIG. 20 shows a front cross-sectional view of a second example of a reinforcing element for a prosthesis. [Figure 21] FIG. 21 shows a front view of a second example of a reinforcing element for a prosthesis with further geometrical indications. [Figure 22] FIG. 22 shows a side view of a second example of a reinforcing element for a prosthesis with further geometrical indications. [Figure 23] FIG. 23 shows a plan view of a second example of a reinforcing element for a prosthesis. [Figure 24] FIG. 24 shows a perspective view of a third example of a reinforcing element for a prosthesis according to the invention. [Figure 25] FIG. 25 shows a front view of a third example of a reinforcing element for a prosthesis. [Figure 26] FIG. 26 shows a side cross-sectional view of a third example of a reinforcing element for a prosthesis. [Figure 27] FIG. 27 shows a side view of a third example of a reinforcing element for a prosthesis. [Figure 28] FIG. 28 shows a front cross-sectional view of a third example of a reinforcing element for a prosthesis. [Figure 29] FIG. 29 shows a plan view of a third example of a reinforcing element for a prosthesis. [Figure 30] FIG. 30 shows a front view of a third example of a reinforcing element for a prosthesis with further geometrical indications. [Figure 31] FIG. 31 shows a side view of a third example of a reinforcing element for a prosthesis with further geometrical representation. [Figure 32] FIG. 32 shows a perspective view of a third example variant of a reinforcing element for a prosthesis. [Figure 33] FIG. 33 shows a further perspective view of a variant of the third example of a reinforcing element for a prosthesis. [Figure 34] FIG. 34 shows the application of a first embodiment of a reinforcing element for a prosthesis to the distal end of the femur. [Figure 35] FIG. 35 shows the application of a second example of a reinforcing element for a prosthesis to the distal end of the tibia. DETAILED DESCRIPTION OF THE INVENTION
[0027] In the different figures, similar elements are designated by similar reference numerals.
[0028] The technical drawings shown in the figures are to be understood as purely illustrative and are not necessarily made to scale or to have the same scale as each other.
[0029] Figure 1 is , pu The first reinforcement element 100 for the prosthesis example The reinforcing element 100 in this example is an element for application to the femur in combination with a knee prosthesis.
[0030] The reinforcing element 100 comprises a generally frusto-conical metal body 101 adapted to be inserted into the distal end of the femur. Preferably, the metal body 101 is made of titanium or an alloy thereof for biomedical applications.
[0031] Generally, the metal body comprises a wall, as further described, having a substantially constant thickness.
[0032] The metal body 101 has an outer surface comprising a metal trabecular surface 102, which is preferably obtained integrally and seamlessly with the metal body 101 by a co-manufacturing procedure, for example an EBM (Electron Beam Machining) 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 delamination of the trabecular part of the metal body.
[0033] The metal body 101 preferably comprises a smooth edge 103 on its outer surface surrounding the metal prism 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 defining a plurality of generally annular transversal sections, the configuration of which will be further described.
[0035] FIG. 2 shows a front view of a reinforcing element 100 for a prosthesis, where the same two symmetrical side walls with the same slope are shown.
[0036] FIG. 3 shows a side cross-sectional view of a reinforcing element 100 for a prosthesis, according to section III-III of FIG.
[0037] The metal body 101 is angled in an oblique direction, in this case towards the right in the figure, to define an eccentricity between a first transverse section at a first end 105 of the axial through cavity 104 and a second transverse section at a second end 106 of the axial through cavity 104.
[0038] In particular, the axially through cavity 104 has a longitudinal axis 107 that is inclined at an angle relative to the vertical axis of the metal body 101. The vertical axis, which is not shown in the figures for simplicity, is perpendicular to one of the first or second transverse cross-sections at the ends 105 or 106, respectively.
[0039] The metal body 101 includes a front wall 108 extending in the inclined direction, and a rear wall 109 facing the front wall 108 and extending away from the inclined direction.
[0040] The front wall 108 has an inclination relative to the longitudinal axis that is less 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 the frontal asymmetry is visible in cross section.
[0042] FIG. 4 shows a side view of a reinforcing element 100 for a prosthesis, in which some features already discussed in relation to FIG. 3 are pointed out.
[0043] FIG. 5 shows a front cross-sectional view of a reinforcing element 100 for a prosthesis, with reference to section VV in FIG.
[0044] Book example Now, considering a direction transverse to the tilt direction shown in FIG. 3, it can be seen how the longitudinal axis 107 of the axial through cavity 104 is instead not tilted relative to the longitudinal axis of the metal body 101.
[0045] The reinforcing element 100 further comprises a plurality of through slits 110 in the metal body 101 , which open from the first end 105 to an intermediate portion on the metal body 101 .
[0046] These slits 110 are configured for radial compression of the metal body 101, in particular to facilitate insertion into the femoral cavity and to locally reduce the circumference of the approximately annular cross-section constituting the metal body 101 upon insertion of the reinforcing element 100, thereby increasing the press-fit towards the bone portion.
[0047] In particular, for femoral applications, the first cross section at end 105 is smaller in size than the second cross section at end 106 to facilitate insertion of body 101 into the distal end of the femur.
[0048] Preferably, each of the through slits 110 is open towards the first end 105 and terminates in a respective enlarged circular hole 111 in the middle part of the metal body 101. The enlarged circular holes 111 are thereby configured to improve the local mechanical resistance of the metal body.
[0049] 6 shows a bottom view of the reinforcing element 100 for the prosthesis. In this view, it is possible to see that an eccentricity 112 results between the first (in this case circular) cross section at the first end 105 and the second (in this case circular) cross section at the second end 106 of the axial through cavity 104.
[0050] FIG. 7 shows a front view of a reinforcing element 100 for a prosthesis with geometrical indications associated with the metal body 101.
[0051] In particular, the conicity 113 of the symmetric sidewalls is between 6° and 10° overall, and more preferably equal to 8.5°.
[0052] FIG. 8 shows a side view of a reinforcing element 100 for a prosthesis with geometrical indications associated with the metal body 101 .
[0053] In the example of the reinforcing element 100, the front wall 108 is vertical and has a 0° inclination relative to the vertical. Generally, the inclination of the front wall 108 relative to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.
[0054] In the example of the reinforcing element 100, the rear wall 108 has an inclination 114 of 8.5° relative to the vertical. Generally, the inclination of the rear wall 108 relative to the longitudinal axis is comprised between 6° and 10°.
[0055] FIG. 9 shows a first embodiment of a reinforcing element 200 for a prosthesis according to the invention. 1 1 shows a perspective view of an embodiment of a reinforcing element 200. The reinforcing element 200 in this example is an element for application to the femur in combination with a knee prosthesis.
[0056] The reinforcing element 200 comprises a generally frusto-conical metal body 201 adapted to be inserted into the distal end of the femur. Preferably, the metal body 201 is made of titanium or an alloy thereof for biomedical applications.
[0057] The metal body 201 has an outer surface including metal prism surfaces 202, which are preferably applied directly to the metal body 201 in an integral and seamless manner by a co-manufacturing procedure, for example by EBM (Electron Beam Machining) techniques.
[0058] The metal body 201 preferably comprises a smooth edge 203 on its outer surface surrounding the metal prism face 202 on one or more sides, preferably on all sides.
[0059] The metal body 201 is hollow and has a plurality of axially extending cavities 204 defining generally annular cross sections, the construction of which will be further described.
[0060] 10 shows a front view of a reinforcing element 200 for a prosthesis, where it is clear that a pair of bicondylar supports 220a and 220b are arranged side-by-side on the metal body 201.
[0061] Bicondylar supports 220 a and 220 b project from the distal cross section of body 201 , each comprising a tapered body that flares away from body 201 .
[0062] Preferably, the bicondylar supports 220a and 220b also have an outer surface that includes a metal trabecular surface that is integral and seamlessly made with the bicondylar supports 220a and 220b.
[0063] In the reinforcing element 200, the bicondylar supports 220a and 220b also provide support to the femoral condyles in case the bone defect extends to the femoral condyles. example 100 and a bicondylar support of the reinforcing element example The choice between 200 and 201 may depend, for example, on the location and extent of the bone defect. For example, when removing an implant with a stem, a defect in the femur often occurs along the channel. Therefore, the first exampleIt is preferable to use a reinforcement element 100 made of a tibial ligament. Conversely, in cases of advanced bone degeneration, situations may arise in which the femoral condyle does not provide sufficient support for the prosthesis, and in order to obtain a greater reinforcement of the area, a reinforcement element 100 made of a tibial ligament is used. 1 It is preferred to use a reinforcing element 200 according to the embodiment of
[0064] Preferably, the metal body comprises a smooth edge 203 on its outer surface which at least partially surrounds the metal prismatic surfaces 202, preferably also the metal prismatic surfaces of the bicondylar supports 220a and 220b.
[0065] FIG. 11 shows a side cross-sectional view of a reinforcing element 200 for a prosthesis, according to section XI-XI of FIG.
[0066] The metal body 201 is inclined in an oblique direction, in this case towards the right in the figure, to define an eccentricity between a first cross-section at a first end 205 of the axial through cavity 204 and a second cross-section at a second end 206 of the axial through cavity 204.
[0067] In particular, the axial through cavity 204 has a longitudinal axis 207 that is inclined in an oblique direction relative to the longitudinal axis of the metal body 201. The longitudinal axis, which is not shown in the figures for simplicity, is perpendicular to one of the first or second transverse planes at the ends 205 or 206, respectively.
[0068] The metal body 201 includes 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 relative to the longitudinal axis that is less than the inclination of the rear wall 209 .
[0070] In other words, the profile of the metal body 201 tapers towards the first end 205, and the frontal asymmetry is visible in cross section.
[0071] In fact, an eccentricity between the first cross-section at the first end 205 and the second cross-section at the second end 206 of the axial through cavity 204 can be inferred.
[0072] FIG. 12 shows a side view of a reinforcing element 200 for a prosthesis, in which some of the features already discussed in relation to FIG. 11 are pointed out.
[0073] FIG. 13 shows a front cross-sectional view of a reinforcing element 200 for a prosthesis, according to section XIII-XIII of FIG.
[0074] The reinforcing element 200 further comprises a plurality of through slits 210 in the metal body 201 , which open from the first end 205 to a middle portion of the metal body 201 .
[0075] These slits 210 are configured for radial compression of the metal body 201, in particular to facilitate insertion into the femoral cavity and to locally reduce the circumference of the approximately annular cross-section constituting the metal body 201 upon insertion of the reinforcing element 200, thereby increasing the press-fit towards the bone portion.
[0076] In particular, for femoral applications, the first cross section at end 205 is smaller in size than the second cross section at end 206 to facilitate insertion of body 201 into the distal end of the femur.
[0077] Preferably, each of the through slits 210 is open towards the first end 205 and terminates in a respective enlarged circular hole 211 in the middle part of the metal body 201. The enlarged circular bodies 211 are thereby configured to improve the local mechanical resistance of the metal body.
[0078] In the reinforcing 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 therefore in a distal position when the reinforcing element is implanted in the respective femoral cavity.
[0079] FIG. 14 shows a front view of a reinforcing element 200 for a prosthesis with geometrical indications associated with the metal body 201 .
[0080] In particular, the conicity 213 of the side wall, as in the example of the reinforcing element 200, is between 6° and 10° overall, and more preferably equal to 8.5°.
[0081] As can be seen, the second cross-section at end 206 is further inclined in a second inclination direction in a plane transverse to the inclination direction of longitudinal axis 207. In that sense, metal body 201 has an inclination surface at end 206 that differs from the inclination surface at end 205, resulting in an overall asymmetry of reinforcing element 201, not only in the frontal inclination direction already considered, but also in the inclination direction transverse to the entire metal body 201, as can be seen in Figure 14.
[0082] Additionally, the pair of bicondylar supports 220a and 220b extend the same height 221 from the second end 206, thereby defining an asymmetric pair of bicondylar supports 220a and 220b.
[0083] In light of the overall asymmetry of the reinforcing 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 a reinforcing element 200 for a prosthesis with geometrical indications associated with the metal body 201 .
[0085] In the example of the reinforcing element 200, the front wall 208 is vertical and has a 0° inclination relative to the vertical. Generally, the inclination of the front wall 208 relative to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.
[0086] In the example of the reinforcing element 200, the rear wall 209 has an inclination 214 of 8.5° to the vertical. Generally, the inclination of the rear wall 209 to the longitudinal axis is comprised between 6° and 10°.
[0087] Figure 16 is , pu The first reinforcement element 300 for the prosthesis 2 of example The reinforcing element 300 in this example is an element for application to the tibia in combination with a knee prosthesis.
[0088] The reinforcing element 300 comprises a generally frusto-conical metal body 301 adapted to be inserted into the distal end of the tibia. Preferably, the metal body 301 is made of titanium or an alloy thereof for biomedical applications.
[0089] The metal body 301 has an outer surface including metal prism surfaces 302, which are preferably applied directly to the metal body 301 in an integral and seamless manner by a co-manufacturing procedure, for example by EBM (Electron Beam Machining) techniques.
[0090] The metal body 301 preferably comprises a smooth edge 303 on its outer surface surrounding the metal prism face 302 on one or more sides, preferably on all sides.
[0091] The metal body 301 is hollow with axially extending cavities 304 defining a plurality of generally annular cross sections, the construction of which will be further described.
[0092] In nature resemblance, the metal body 301 resembles a corolla shape with two opposing petals removed.
[0093] FIG. 17 shows a front view of a reinforcing element 300 for a prosthesis, showing the same two symmetrical side walls with the same slope and configuration.
[0094] FIG. 18 shows a side cross-sectional view of a reinforcing element 300 for a prosthesis, with reference to section XVIII-XVIII in FIG.
[0095] The metal body 301 is inclined in an oblique direction, in this case towards the right in the figure, to define an eccentricity between a first cross-section at a first end 305 of the axial through cavity 304 and a second cross-section at a second end 306 of the axial through cavity 304.
[0096] In particular, axial through cavity 304 has a longitudinal axis 307 that is inclined at an angle relative to the longitudinal axis of metal body 301. The longitudinal axis, which is not shown in the figures for simplicity, is perpendicular to one of the first or second transverse planes at end 305 or 306.
[0097] The metal body 301 includes a front wall 308 extending in the inclined direction, and a rear wall 309 facing the front wall 308 and extending away from the inclined direction.
[0098] The front wall 308 has a slope relative to the longitudinal axis that is less than the slope of the rear wall 309 .
[0099] In other words, the profile of the metal body 301 tapers towards the second end 306, and the frontal asymmetry is visible in cross section.
[0100] FIG. 19 shows a side view of a reinforcing element 300 for a prosthesis, in which some of the features already discussed in relation to FIG. 18 are pointed out.
[0101] For tibia applications, it can be seen that the first cross section at end 305 is larger in size than the second cross section at end 306 to facilitate insertion of the metal body into the distal end of the tibia.
[0102] The reinforcing element 300 further comprises a pair of notches 320 arranged side by side on the metal body 301 and opening from the first end 305 to an intermediate portion on the metal body 301 .
[0103] FIG. 20 shows a front cross-sectional view of a reinforcing element 300 for a prosthesis, according to section XX-XX of FIG.
[0104] Book example Now, considering the direction transverse to the tilt direction shown in FIG. 18, it can be seen how the longitudinal axis 307 of the axial through cavity 304 is instead not tilted relative to the longitudinal axis of the metal body 301.
[0105] FIG. 21 shows a front view of a reinforcing element 300 for a prosthesis with geometrical indications associated with the metal body 301.
[0106] Preferably, the metal body 301 has side walls 321 in the cutout 320, such side walls 321 having a curved and concave shape relative to the outside of the metal body 301, respectively, to replicate the anatomical structure of the medial / lateral and posterior bones.
[0107] In particular, the overall conicity 313 of the symmetrical side wall 321, measured relative to an imaginary line passing through the two edges of the metal body 301 at each of the first end 305 and the second end 306, is between 12° and 20° overall, and more preferably equal to 18°.
[0108] FIG. 22 shows a side view of a reinforcing element 300 for a prosthesis with geometrical indications associated with 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 with respect to the vertical equal to 2°. Generally, the inclination of the front wall 308 with respect to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.
[0110] In the example of the reinforcing 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 comprised between 15° and 20°.
[0111] Preferably, the posterior wall 309 also has a curved and concave shape relative to the exterior of the metal body 301 to replicate the anatomical structure of the posterior tibia.
[0112] FIG. 23 shows a plan view of a reinforcing element 300 for a prosthesis.
[0113] In this view, it can be seen that eccentricity 312 results between a first cross-section (in this case, circular) at the first end 305 of the axial through cavity 304 and a second cross-section (in this case, circular) at the second end 306.
[0114] Figure 24 is , pu The first reinforcement element 400 for the prosthesis 3 of example The reinforcing element 400 in this example is an element for application to the tibia in combination with a knee prosthesis.
[0115] The reinforcing element 400 comprises a generally frusto-conical metal body 401 adapted to be inserted into the distal end of the tibia. Preferably, the metal body 401 is made of titanium or an alloy thereof for biomedical applications.
[0116] The metal body 401 has an outer surface including metal prism surfaces 402, which are preferably applied directly to the metal body 401 by an integral and seamless co-manufacturing procedure, for example by EBM (electron beam machining) techniques.
[0117] The metal body 401 preferably comprises a smooth edge 403 on its outer surface surrounding the metal prism surface 402 on one or more sides, preferably on all sides.
[0118] The metal body 401 is hollow with axially extending cavities 404 defining a plurality of generally annular cross sections, the configuration of which will be further described.
[0119] FIG. 25 shows a front view of a reinforcing element 400 for a prosthesis, showing the same two symmetrical side walls 421 with the same slope and configuration.
[0120] FIG. 26 shows a side cross-sectional view of a reinforcing element 400 for a prosthesis, taken along section XVI-XVI of FIG.
[0121] The metal body 401 is inclined in an oblique direction, in this case towards the right in the figure, so as to define at least one eccentricity between a first cross-section at a first end 405 of the axial through cavity 404 and a second cross-section at a second end 406 of the axial through cavity 404.
[0122] In particular, axial through cavity 404 has a longitudinal axis 407 that is inclined at an angle relative to the longitudinal axis of metal body 401. The longitudinal axis, which is not shown in the figures for simplicity, is perpendicular to one of the first or second transverse planes at end 405 or 406, respectively.
[0123] The metal body 401 includes 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 relative to the longitudinal axis that is less than the inclination of the rear wall 409 .
[0125] In other words, the profile of the metal body 401 tapers towards the second end 406, and the frontal asymmetry is visible in cross section.
[0126] FIG. 27 shows a side view of a reinforcing element 400 for a prosthesis, in which some of the features already discussed in relation to FIG. 26 are pointed out.
[0127] For tibia applications, it can be seen that the first cross section at end 405 is larger in size than the second cross section at end 406 to facilitate insertion of the metal body into the distal end of the tibia.
[0128] The reinforcing element 400 further comprises a pair of notches 420 arranged side by side on the metal body 401 and opening from the first end 405 to an intermediate portion on the metal body 401 .
[0129] FIG. 28 shows a front cross-sectional view of a reinforcing element 400 for a prosthesis, with reference to section XXVIII-XXVIII in FIG.
[0130] Book example Now, considering the direction transverse to the tilt direction shown in FIG. 26, it can be seen how the longitudinal axis 407 of the axial through cavity 404 is instead not tilted relative to the longitudinal axis of the metal body 401.
[0131] FIG. 29 shows a plan view of a reinforcing element 400 for a prosthesis, where it can be seen that the first cross section at the end 405 is bilobed annular, whereby the outer surface of the metal body 401 tapers between the first and second cross sections, as can be seen best in FIG. 24.
[0132] In natural resemblance, the metal body 401 resembles a corolla shape with two opposing petals removed.
[0133] In this view, it is also possible to see that the double eccentricity 412 occurs between a first cross-section at the first end 405 of the axial through cavity 404 (in this case, bilobed and therefore having two circumferential centers to account for it) and a second cross-section at the second end 406 (in this case, circular with only one circumferential center).
[0134] FIG. 30 shows a front view of a reinforcing element 400 for a prosthesis with geometrical indications associated with the metal body 401.
[0135] Preferably, the metal body 401 has side walls 421 in the cutout 420, such side walls 421 having a curved and concave shape relative to the outside of the metal body 401, respectively, to replicate the anatomical structure of the medial / lateral and posterior bones.
[0136] In particular, the overall concavity 413 of the lateral symmetric wall 421 is configured to be between 45° and 55° overall, more preferably equal to 50°.
[0137] FIG. 31 shows a side view of a reinforcing element 400 for a prosthesis with geometrical indications associated with a metal body 401 .
[0138] In the example of the reinforcing element 400, the front wall 408 is close to vertical and has an inclination 415 equal to 2° relative to the vertical. Generally, the inclination of the front wall 408 relative to the longitudinal axis can be configured between 0° and 5°, more preferably between 0° and 2°.
[0139] In the example of the reinforcing 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 comprised between 15° and 20°.
[0140] Preferably, the posterior wall 409 also has a curved and concave shape relative to the exterior of the metal body 401 to replicate the posterior anatomical structure of the tibia.
[0141] 32 and 33 show respective perspective views of a variation of a reinforcing element 400' for a prosthesis.
[0142] In this variant, the reinforcing element 400' comprises a plurality of through slits 410 in the metal body, opening from the first end to the middle portion of the metal body. The plurality of through slits 410 are configured for radial compression of the metal body, causing a localized reduction in circumference upon insertion of the reinforcing element 400', increasing press-fit into the bone portion. Preferably, each of the through slits 410 terminates in a respective enlarged circular hole 411.
[0143] FIG. 34 shows an example of the application of a prosthetic reinforcing element 200 to the distal end of the femur.
[0144] FIG. 35 shows an example of the application of a prosthetic reinforcing element 300 to the distal 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 fortuitous needs.
[0146] In particular, the embodiment Or example Specific features described with reference to may also be applied to other embodiments described herein in their variations, without any technical prejudice in this regard.
[0147] Therefore, the above embodiment and examples should be understood as being provided for illustrative and non-limiting purposes.
Claims
1. A reinforcing element (100, 200, 300, 400) for a prosthesis, in particular a knee prosthesis, said reinforcing element (100, 200, 300, 400) comprising a substantially frusto-conical metal body (101, 201, 301, 401) adapted to be inserted into an epiphysis and having an outer surface including a metal trabecular surface (102, 202, 302, 402), the metal body (101, 201, 301, 401) is hollow having axially-through cavities (104, 204, 304, 404) defining a plurality of generally annular cross sections; a reinforcing element (100, 200, 300, 400) inclined in an oblique direction so as to define at least one eccentricity (112, 312, 412) between a first transverse plane at a first end (105, 205, 305, 405) of the axial through cavity (104, 204, 304, 404) and a second transverse plane at a second end (106, 206, 306, 406) of the axial through cavity (104, 204, 304, 404).
2. 2. The reinforcing element according to claim 1, wherein the axial through cavity (104, 204, 304, 404) has a longitudinal axis (107, 207, 307, 407) inclined in the oblique direction relative to the longitudinal axis of the metal body (101, 201, 301, 401), and the longitudinal axis (107, 207, 307, 407) is perpendicular to one of the first transverse plane or the second transverse plane.
3. 3. The reinforcing element according to claim 2, wherein the metal body (101, 201, 301, 401) comprises a front wall (108, 208, 308, 408) extending towards the inclined direction and a rear wall (109, 209, 309, 409) opposite the front wall (108, 208, 308, 408) and extending away from the inclined direction, the front wall (108, 208, 308, 408) having an inclination relative to the longitudinal axis, the inclination of the front wall being smaller than the inclination of the rear wall (109, 209, 309, 409).
4. 4. A reinforcing element according to claim 3, wherein the inclination of said front wall (108, 208, 308, 408) relative to said longitudinal axis is comprised between 0° and 5°, more preferably between 0° and 2°.
5. 5. A reinforcing element according to claim 4, wherein, for femoral application, the inclination of said rear wall (109, 209) relative to said longitudinal axis is comprised between 6° and 10°.
6. A reinforcing element according to claim 4, wherein, for tibia application, the inclination of said rear wall (309, 409) relative to said longitudinal axis is comprised between 15° and 20°.
7. The reinforcing element according to claim 6, wherein the rear wall (309, 409) further has a curved concave shape relative to the outside of the metal body (301, 401) in order to replicate the anatomical structure of the posterior tibia.
8. 8. The reinforcing element according to claim 1, further comprising a plurality of through slits (110, 210, 410) in the metal body (101, 201, 401), the through slits (110, 210, 410) being configured for radial compression of the metal body (101, 201, 401), causing a local reduction in the circumference of the substantially annular cross section upon insertion of the reinforcing element (100, 200, 300, 400) and increasing a press fit into the bone portion.
9. 9. A reinforcing element according to claim 8, wherein for application to a femur, the first transverse surface (105, 205) is smaller in size than the second transverse surface (106, 206) so as to facilitate insertion of the metal body (101, 201) into the distal end of the femur.
10. 9. The reinforcing element according to claim 8, wherein, for application to the tibia, the first transverse surface (305, 405) is larger in size than the second transverse surface (306, 406) so as to facilitate insertion of the metal body (301, 401) into the distal end of the tibia.
11. 11. The reinforcing element according to any one of claims 8 to 10, wherein each of the plurality of through slits (110, 210, 410) terminates in a respective enlarged circular hole (111, 211, 411) in the intermediate portion, the enlarged circular hole (111, 211, 411) being configured to improve the local mechanical resistance of the metal body (101, 201, 401).
12. 12. A reinforcing element according to any one of claims 1 to 11, for application to the femur, wherein the first transverse surface (205) is smaller in size than the second transverse surface (206), and wherein 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) comprising a tapered body projecting from the second transverse surface (206) and widening away from the metal body (201).
13. 13. A reinforcing element according to claim 12, wherein the bicondylar supports (220a, 220b) have an outer surface comprising a metal prismatic surface, made integral and seamless with the bicondylar supports (220a, 220b).
14. 14. A reinforcing element according to claim 12 or 13, wherein the second transverse surface (206) is inclined in a second oblique direction transverse to the oblique direction, and the pair of bicondylar supports (220a, 220b) extend the same height (221) from the second transverse surface (206), thereby defining an asymmetric pair of bicondylar supports (220a, 220b).
15. 12. A reinforcing element according to any one of claims 1 to 11, for application to the tibia, wherein the first transverse section (305, 405) is larger in size than the second transverse section (306, 406) and the metal body (301, 401) comprises side walls (321, 421) having a curved shape and a concave shape respectively towards the outside of the metal body (301, 401) in order to reproduce the anatomical structure of the medial / lateral and posterior bone.
16. 16. The reinforcing element (100, 200, 300, 400) according to claim 15, further comprising a pair of notches (320, 420) arranged in the side walls (321, 421) and opening from the first end (305, 405) to an intermediate portion on the metal body (301, 401).
17. 17. A reinforcing element according to claim 15 or 16, wherein the first transverse cross-section (405) is bilobal annular and the second transverse cross-section (406) is circular annular, and the outer surface of the metal body (401) tapers between the first transverse cross-section (405) and the second transverse cross-section (406).
18. A reinforcing element according to any one of the preceding claims, wherein the metal body (101, 201, 301, 401) comprises a smooth edge (103, 203, 303, 403) on the outer surface surrounding the metal prismatic surface (102, 202, 302, 402).
19. A reinforcing element according to any one of the preceding claims, wherein the metal prismatic surface (102, 202, 302, 402) is made integral and seamless with the metal body (101, 201, 301, 401).
20. A reinforcing element according to any one of the preceding claims, wherein the metal body (101, 201, 301, 401) comprises a wall (108, 208, 308, 408; 109, 209, 309, 409; 321, 421) having a substantially constant thickness.