DEVICE FOR INTERFACING FILAMENTOUS OR FIBROUS STRUCTURES WITH A REAL OR SIMULATED BIOLOGICAL TISSUE

Abstract

A device for interfacing at least one filamentous structure, with real or simulated biological tissue and a system for regeneration, repair, replacement, or simulation of tendon and/or ligamentous tissue. The device comprises one or more bodies for anchoring a filamentous structure. The one or more bodies may include at least one capstan for wrapping the filamentous structure, and at least one porous portion having a trabecular structure. The system comprises the device and at least one filamentous structure having a plurality of nanofiber assemblies that are obtained by electrospinning. The plurality of assemblies may be arranged to form a single bundle, with the bundle being wrapped to the capstan.

Claims

1. A device for interfacing at least one filamentous structure, with real or simulated biological tissue, comprising at least one body for anchoring the filamentous structure, and said device comprising: at least one capstan configured for wrapping of the filamentous structure; and at least one porous portion having a trabecular structure and including at least a first porous zone having a porosity comprised between 1% and 98% and a pore size comprised between 0.1 μm and 800 μm and a second porous zone having a pore size comprised between 1 μm and 980 μm, wherein the difference between the first porous zone and the second porous zone being comprised between 1% and 98% and being such as to ensure a gradient of deformability at least between the first porous zone and the second porous zone.

2. A device for interfacing at least one filamentous structure, with real or simulated biological tissue, comprising: a first body for anchoring the filamentous structure, wherein said first body comprises: at least one capstan configured for wrapping of the filamentous structure, and at least one porous portion having a trabecular structure; and a second hollow body including at least one porous portion having a trabecular structure, wherein the first body for anchoring the filamentous structure is housed inside of the second hollow body; wherein the first body is conformed as a tweezer comprising a first flat arm and a second flat arm; wherein the at least one porous portion of the first body includes a porosity comprised between 1% and 98% and a pore size comprised between 0.1 μm and 800 μm; wherein the at least one porous portion of the second body includes a pore size comprised between 1 μm and 980 μm, and the difference of the porosity of at least one porous portion of the first body, and the porosity of the at least one porous portion of the second body being comprised between 1% and 98%, and being such as to ensure a gradient of deformability at least between the first body and the second body.

3. The device according to claim 1, wherein the structure of the at least one porous portion follows a Voronoi tessellation that is projected onto the surface of the body for anchoring the filamentous structure.

4. The device according to claim 1, wherein the body for the anchoring the filamentous structure is conformed as a tweezer comprising a first flat arm and a second flat arm, wherein said arms are joined to one another by means of the capstan.

5. The device according to claim 1, wherein the body has the shape of a plate provided with a plurality of capstans.

6. The device according to claim 2, wherein the at least one porous portion of the second body comprises a first porous zone and a second porous zone, wherein the pore size of said zones being comprised between 1 μm and 980 μm, and the difference between the porosity of the first porous zone and the porosity of the second porous zone being comprised between 1% and 98%.

7. The device according to claim 4, wherein said device includes a second hollow body including at least one porous portion having a trabecular structure, wherein the body for anchoring the filamentous structure is housed inside of the second body.

8. The device according to claim 7, wherein the body for anchoring the filamentous structure is embedded inside of the second body.

9. The device according to claim 7, wherein the second body has the shape of a threaded screw.

10. The device according to claim 7, wherein the at least one porous portion of the second body comprises a first porous zone and a second porous zone, and wherein the difference between the porosity of the first porous zone and the porosity of the second porous zone of the second body is between 1% and 98%.

11. The device according to claim 1, wherein at least one part of the device is made of at least one material selected from the group consisting of bioreabsorbable material, biocompatible material, inert material, and conductive material.

12. The device according to claim 11, wherein the at least one material is selected from the group consisting of: polyesters, polyurethanes, polyanhydrides, polycarbonates, polyamides, polyolefins, fluorinated polymers, polyester copolymers, polyurethane copolymers, polyanhydrides copolymers, polycarbonates copolymers, polyamide copolymers, polyolefin copolymers, fluorinated polymer copolymers, polysaccharides, proteins, polyesters, polypeptides, polysaccharide copolymers, protein copolymers, polyester copolymers, polypeptide copolymers, and metal and ceramic material.

13. A system for at least one of regeneration, repair, replacement, and simulation of tendon and/or ligament tissue, the system comprising: a device for interfacing at least one filamentous structure, having with real or simulated biological tissue, comprising at least one body for anchoring the filamentous structure having at least one capstan and having at least one porous portion; and at least one filamentous structure comprising a plurality of electrospun nanofiber groups; wherein said plurality of electrospun nanofiber groups are arranged to form a single bundle; and wherein said bundle is wrapped to the capstan.

14. The system according to claim 13, wherein the electrospun nanofiber bundle passes into the pores of the porous portion.

15. The system according to claim 14, wherein the system is configured to be used with at least one of a prosthetic actuator and a robotic system.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0021] The following description refers to the attached drawings, wherein:

[0022] FIG. 1 is a perspective view of the first embodiment of the device of the present invention;

[0023] FIG. 2a is a front view of the first embodiment of the device of the present invention;

[0024] FIG. 2b is a side view of the first embodiment of the device of the present invention;

[0025] FIG. 3a is a first perspective view of a detail comprising the second body of the second embodiment of the device of the present invention;

[0026] FIG. 3b is a second perspective view of a detail constituted by the second body of the second embodiment of the device of the present invention;

[0027] FIG. 4 is a longitudinal section of a particular constituted by the second body of the second embodiment of the device of the present invention;

[0028] FIG. 5a is a first longitudinal section of the second embodiment of the device of the present invention;

[0029] FIG. 5b is a second longitudinal section of the second embodiment of the device of the present invention, said second longitudinal section being in a plane orthogonal to that of the first longitudinal section;

[0030] FIG. 6 is a perspective view of the fourth embodiment of the device of the present invention;

[0031] FIG. 7a is a front view of the fourth embodiment of the device of the present invention;

[0032] FIG. 7b is a front rear view of the fourth embodiment of the device of the present invention;

[0033] FIG. 8 is an exemplary schematic of a Voronoi trabecular tessellation followed by the porous portions of the device of the present invention;

[0034] FIG. 9a is a side section of a normal stress diagram obtained with a finite element model of the first embodiment of the system of the present invention;

[0035] FIG. 9b is a front section of a diagram of the equivalent Von Mises stresses obtained with a finite element model of a part of the first embodiment of the system of the present invention, said part being constituted by the body for anchoring the filament structure;

[0036] FIG. 10a is side section of a strain diagram obtained with a finite element model of the first embodiment of the system of the present invention; and

[0037] FIG. 10b is a side section of a strain diagram obtained with a finite element model of a part of the first embodiment of the system of the present invention, said part being constituted by the body for anchoring the filamentous structure and a bundle of nanofibers anchored to said body.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Referring to FIGS. 1, 2a, 2b, 5b, 6, 7a, 7b, the device for interfacing at least one filamentous structure, with real or simulated biological tissue, of the present invention, comprises at least one body (10, 20) for anchoring the filamentous structure, said body (10, 20) comprising: [0039] at least one capstan (12, 22, 22′, 22′) configured for wrapping the filamentous structure; [0040] at least one portion (13, 13′, 24) porous having a trabecular structure (300).

[0041] In the center of the at least one capstan (12, 22, 22′, 22″) there may be a hole (11, 21, 21′, 21″).

[0042] Referring to FIGS. 1, 2a, 2b, and 8, in a first embodiment of the device of the present invention, the body (10) for the anchoring the filamentous structure is conformed as a tweezer (13,13′, 12,11) comprising a first flat arm (13) and a second flat arm (13′), said arms (13, 13′) being joined to each other by means of the capstan (12).

[0043] The porous portion (13, 13′), moreover, may comprise, at least a first porous zone and a second porous zone. The difference between the porosity of the first porous zone and the porosity of the second porous zone being such as to ensure a gradient of deformability. More specifically, the first porous zone, configured for the cartilage/tendon/ligament interface, has a porosity comprised between 1% and 98% and a pore size comprised between 0.1 μm and 800 μm, and a second porous zone, configured for the bone interface, has a pore size comprised between 1 μm and 980 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. However, the absolute porosity value and the pore size can vary according to the anatomical district wherein the device is directed to be implanted and according to the clinical characteristic of the patients (e.g. it is well known that the age can affect also greatly the porosity of the bone). The target application (i.e biological tissue or simulated tissue) can also influence the absolute porosity and the pore size values. In a preferred embodiment, the first porous zone (13,13′) has a porosity comprised between 2% and 95% and a pore size of 0.2 μm and 750 μm. In such preferred embodiment the pore size of the second zone is 5 μm and 950 μm. In another preferred embodiment, the first porous zone (13,13′) has a porosity comprised between 2% and 90% and a pore size of 0.5 μm and 700 μm. In such preferred embodiment the pore size of the second zone is 10 μm and 900 μm. The difference of porosity can be along the longitudinal axis (Y) of the arms (13,13′) and/or along a transversal direction (X), orthogonal to the longitudinal axis (Y) of the arms (13, 13′). The structure of the porous portion (13, 13′) follows a trabecular Voronoi tessellation (300) projected onto the surface of the arms (13, 13′) of the tweezer (10). The latter can be made of a bioresorbable and/or inert material, in case the device is used as a device for interfacing a filamentous structure with a real biological tissue (e.g., in vivo bone tissue), or made of an inert and/or conductive material, in case the device is used as a device for interfacing a filamentous structure with a simulated biological tissue (e.g., simulated tissue of a prosthesis actuator).

[0044] With reference to FIGS. 1, 2a, 2b, 3a, 3b, 4, 5a, 5b and 8, in a second embodiment thereof, the device of the present invention, comprises also a second hollow body (30) comprising at least one porous portion (33) having a trabecular structure (300), the body (10) for anchoring the filamentous structure being housed, and in particular embedded, within (30′) the second body (30). The trabecular structure of the second body (30) also follows a Voronoi trabecular tessellation (300) projected onto the surface of the body (30). The second body (30) is shaped like a threaded screw and has two porous portions (33, 33′) and two nonporous portions (34, 34′). Both porous portions (33,33′) of the screw (30) may also, like the porous portions (13,13′) of the tweezer (10), comprise a first porous zone for the cartilage/tendon/ligament interface and a second porous zone, for the bone interface, the difference between the porosity of the first porous zone and the porosity of the second porous zone being such that an adequate gradient of deformability is generated. More specifically, the first porous zone has a porosity comprised between 1% and 98%, and a pore size comprised between 0.1 μm and 800 μm, and the second porous zone has a pore size comprised between 1 μm and 980 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. The absolute porosity value and the pore size can vary according to the anatomical district wherein the device is directed to be implanted and according to the clinical characteristic of the patients (e.g. it is well known that the age can affect also greatly the porosity of the bone). The target application (i.e biological tissue or simulated tissue) can also influence the absolute porosity and the pore size values. In a preferred embodiment, the first porous zone has a porosity comprised between 2% and 95% and a pore size of 0.2 μm and 750 μm. In such preferred embodiment the pore size of the second zone is 5 μm and 950 μm. In another preferred embodiment, the first porous zone has a porosity comprised between 2% and 90% and a pore size of 0.5 μm and 700 μm. In such preferred embodiment the pore size of the second zone is 10 μm and 900 μm. The difference of porosity can be along the longitudinal axis (Y) of the screw (30) and/or along a transversal direction (X), orthogonal to the longitudinal axis (Y) of the screw (30). Finally, the porosity of the porous portions (33, 33′) of the screw (30) may be less in the area of the screw (30) in the proximity of the capstan (12) of the tweezer (10) than the porosity in the area of the screw (30) farthest from the capstan (12) and, that is, in the proximity of the tip of the screw (30) itself.

[0045] The screw (30) may also be made of a bioresorbable and/or inert material, or made of an inert and/or conductive material depending on the application, as already described above with respect to the first embodiment of the present device. Such materials may be in particular: polyesters, polyurethanes, polyanhydrides, polycarbonates, polyamides, polyolefins and fluorinated polymers and copolymers thereof, materials of natural origin, for example polysaccharides, proteins, polyesters, polypeptides, and copolymers thereof, and/or mixtures of these materials and/or metallic materials and/or ceramic materials or combinations thereof. Moreover, the material of the screw and/or of the deformable inner element may advantageously be loaded and/or functionalized with organic and/or inorganic components capable of performing a biological function and/or modifying the physical-chemical and/or mechanical properties of the screw and/or of the deformable inner element.

[0046] In a third embodiment of the device of the present invention the body (10) for anchoring the filamentous structure comprises the body (10) for the anchoring the filamentous structure is conformed as a tweezer (13, 13′, 12, 11) comprising a first flat arm (13) and a second flat arm (13′), said arms (13, 13′) being joined to each other by means of the capstan (12).

[0047] The device comprises also a second hollow body (30) comprising at least one porous portion (33) having a trabecular structure (300), the body (10) for anchoring the filamentous structure being housed, and in particular embedded, within (30′) the second body (30). The trabecular structure of the second body (30) also follows a Voronoi trabecular tessellation (300) projected onto the surface of the body (30). The second body (30) is shaped like a threaded screw and has two porous portions (33,33′) and two nonporous portions (34, 34′). Both the tweezer (10) and the screw (30) are each characterized by a homogeneous porosity, but have different porosity with respect to each other. In other words, the porous portions (33, 33′) of the screw (30) have a porosity that differs with the porosity of the tweezer (10) such that an appropriate gradient of deformability is generated. Specifically, the porosity of the first body (10), configured for the cartilage/tendon/ligament interface, can be comprised between 1% and 98% and the pore size between 0.1 μm and 800 μm. Preferably, the porosity of the first body can vary between 2% and 95% and the pore size between 0.2 μm and 750 μm. More preferably, the porosity of the first body can vary between 2% and 90% and the pore size between 0.5 μm and 700 μm. The porosity of the second body, configured for the bone interface, can vary between 1% and 98% with a pore size comprised in the range between 1 μm and 980 μm. Preferably, the porosity of the second body can vary between 2% and 95% and the pore size between 5 μm and 950 μm. More preferably, the porosity of the second body can be comprised between 2% and 90% and the pore size between 10 μm and 900 μm. The difference between the porosity of the first body (10) and the porosity of the second body (30) can vary between 1% and 98%. More preferably, the difference between the porosity of the first body (10) and the porosity of the second body (30) is comprised in the range between 2% and 90%.

[0048] In a fourth embodiment of the device of the present invention the body (10) for the anchoring the filamentous structure is conformed as a tweezer (13, 13′, 12, 11) comprising a first flat arm (13) and a second flat arm (13′), said arms (13, 13′) being joined to each other by means of the capstan (12).

[0049] The device comprises also a second hollow body (30) comprising at least one porous portion (33) having a trabecular structure (300), the body (10) for anchoring the filamentous structure being housed, and in particular embedded, within (30′) the second body (30). The trabecular structure of the second body (30) also follows a Voronoi trabecular tessellation (300) projected onto the surface of the body (30). The second body (30) is shaped like a threaded screw and has two porous portions (33,33′) and two nonporous portions (34, 34′). The tweezer (10) has a homogeneous porosity, that is comprised between 1% and 98% and a pore size comprised between 0.1 μm and 800 μm. Preferably, the porosity of the tweezer (10) is comprised between 2% and 95% and the pore size between 0.2 μm and 750 μm. More preferably, the porosity of the tweezer (10) can vary between 2% and 90% and the pore size between 0.5 μm and 700 μm. The porous portions (33, 33′) of the screw (30) comprise a first porous zone and a second porous zone, the difference between the porosity of the first porous zone and the porosity of the second porous zone being comprised between 1 and 98%. More specifically, the first porous zone of the screw has a porosity comprised between 1% and 98%, and a pore size comprised between 0.1 μm and 800 μm. The second porous zone has a pore size comprised between 1 μm and 980 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. In a preferred embodiment, the first porous zone has a porosity comprised between 2% and 95% and a pore size of 0.2 μm and 750 μm. In such preferred embodiment the pore size of the second zone is 5 μm and 950 μm. In another preferred embodiment, the first porous zone has a porosity comprised between 2% and 90% and a pore size of 0.5 μm and 700 μm. In such preferred embodiment the pore size of the second zone is 10 μm and 900 μm. The difference of porosity can be along the longitudinal axis (Y) of the screw (30) and/or along a transversal direction (X), orthogonal to the longitudinal axis (Y) of the screw (30).

[0050] In a fifth embodiment of the device of the present invention the body (10) for the anchoring the filamentous structure is conformed as a tweezer (13, 13′, 12, 11) comprising a first flat arm (13) and a second flat arm (13′), said arms (13, 13′) being joined to each other by means of the capstan (12).

[0051] The device comprises also a second hollow body (30) comprising at least one porous portion (33) having a trabecular structure (300), the body (10) for anchoring the filamentous structure being housed, and in particular embedded, within (30′) the second body (30). The trabecular structure of the second body (30) also follows a Voronoi trabecular tessellation (300) projected onto the surface of the body (30). The second body (30) is shaped like a threaded screw and has two porous portions (33,33′) and two nonporous portions (34,34′). The screw (30) has a homogeneous porosity, that is comprised between 1% and 98% and a pore size comprised between 1 μm and 980 μm. Preferably, the porosity of the screw (30) is comprised between 2% and 95% and the pore size between 5 μm and 950 μm. More preferably, the screw (30) has a porosity varying between 2% and 90% and a pore size varying between 10 μm and 900 μm. The porous portions (13, 13′) of the tweezer (10) comprise each a first porous zone and a second porous zone, the difference between the porosity of the first porous zone and the porosity of the second porous zone. More specifically, the first porous zone has a porosity comprised between 1% and 98% and a pore size comprised between 0.1 μm and 800 μm. The second porous zone has a pore size comprised between 1 μm and 980 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. In a preferred embodiment, the first porous zone has a porosity comprised between 2% and 95% and a pore size of 0.2 μm and 750 μm. In such preferred embodiment the pore size of the second zone is 5 μm and 950 μm. In another preferred embodiment, the first porous zone has a porosity comprised between 2% and 90% and a pore size of 0.5 μm and 700 μm. In such preferred embodiment the pore size of the second zone is 10 μm and 900 μm.

[0052] The absolute porosity value and the pore size can vary according to the anatomical district wherein the device is directed to be implanted and according to the clinical characteristic of the patients (e.g. it is well known that the age can affect also greatly the porosity of the bone). The difference of porosity can be along the longitudinal axis (Y) of the arms (13, 13′) and/or along a transversal direction (X), orthogonal to the longitudinal axis (Y) of the arms (13, 13′). With reference to FIGS. 6, 7a, 7b and 8, in a sixth embodiment thereof, the device of the present invention, has the form of a plate provided with a plurality of capstans (22, 22′, 22″). At the center of each capstan (22, 22′, 22″) there may be a hole (21, 21′, 21″). The porous portion (24) has a structure that follows a trabecular Voronoi tessellation (300) and comprises at least a first porous zone (24″) and a second porous zone (24′). The second porous zone (24′), which is located away from the capstan (22, 22′, 22″) has a higher porosity than the first porous zone (24″), which is located in the proximity of the capstan (22, 22′, 22″), and the difference between the porosity of the first porous zone (24″) and the porosity of the second porous zone (24′) is such that a gradient of deformability is provided.

[0053] More specifically, the first porous zone (24″), configured for the cartilage/tendon/ligament interface, has a porosity comprised between 1% and 98%, and a pore size comprised between 0.1 μm and 800 μm, and a second porous zone (24′), configured for the bone interface, has a pore size comprised between 1 μm and 980 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. More preferably, the first porous zone has a porosity comprised between 2% and 95%, and a pore size comprised between 0.2 μm and 750 μm, and the second porous zone has a pore size comprised between 5 μm and 950 μm, the difference between the first porous zone and the second porous zone being comprised between 1% and 98%. In a preferred embodiment, the first porous zone has a porosity comprised between 2% and 90% and a pore size of 0.5 μm and 700 μm. In such preferred embodiment the pore size of the second zone is 10 μm and 900 μm. The absolute porosity value and the pore size can vary according to the anatomical district wherein the device is directed to be implanted and according to the clinical characteristic of the patients (e.g. it is well known that the age can affect also greatly the porosity of the bone). The target application (i.e biological tissue or simulated tissue) can also influence the absolute porosity and the pore size values. The difference of porosity can be along the longitudinal axis (Y) of the plate (20) and/or along a transversal direction (X), orthogonal to the longitudinal axis (Y) of the plate (20).

[0054] The plate (20) may also be made of a bioresorbable and/or inert material or made of an inert and/or conductive material depending on the application.

[0055] With reference to FIGS. 1, 2a, 2b, 3a, 3b, 4, 5a, 5b and 8, a first embodiment of the system for regenerating, or repairing, or replacing, tendon and/or ligamentous tissue of the present invention comprises: [0056] the device of the present invention according to its second embodiment, namely, a tweezer (10)-screw (30) assembly as described above; [0057] at least one filamentary structure comprising a plurality of nanofiber assemblies obtained by electrospinning, said plurality of assemblies being arranged to form a single bundle.

[0058] The pass bundle is wrapped to the capstan (12) of the tweezer itself (10). Additional nanofiber bundles, in addition, may pass through the pores of the porous portion (13, 13′) of the tweezer (10) and, possibly, also through the pores of the porous portion (33, 33′) of the screw (30), as well as through the hole (11) in the center of the capstan (12). With reference to FIGS. 6, 7a, 7b and 8, a second embodiment of the system for regenerating, or repairing, or replacing, tendon and/or ligament tissue of the present invention comprises: [0059] the device of the present invention according to its sixth embodiment, namely, a plate (20) as described above; [0060] at least one filamentary structure comprising a plurality of nanofiber groups obtained by electrospinning, said plurality of groups being arranged to form a single bundle.

[0061] The bundle is wrapped at each capstan (22, 22′, 22″) of the plate (20). Additional nanofiber bundles, in addition, can pass through the pores of the porous portion (24) of the plate (24), as well as through the holes (21, 21′, 21″) in the center of the capstans (22, 22′, 22″)

[0062] Finally, both the first and second embodiments of the system of the present invention can be used to simulate tendon and/or ligamentous tissue and thus be part of a prosthetic actuator or robotic system.

Examples

[0063] Finite Element Simulation

[0064] In order to have a validation of the designed device and to study the gradient of deformability the tweezer-screw assembly, a finite element simulation was performed using Ansys Workbench 2019 R3 software. Geometric CAD models were imported from SolidWorks with some simplifications on the geometry. Due to the difficulties of the meshing operation, after verifying the condition of the screw as nearly unloaded, it was decided to neglect the trabecular model.

[0065] To load the tweezer-screw assembly as in an operational working condition, a tendon-inspired system was modeled as a simplified nylon bundle assembly. To simplify the model in this simulation, only the nylon side (the working part of the biphasic bundle attachment) was considered. The bundle assembly was modeled using a hyperelastic Nylon material. The geometry of the bundles was based on a cylinder having, at the end, a ring, which surrounds the tweezer inside the screw. The main section of the cylindrical bundle has a diameter of 3.80 mm before splitting into two half-bundles. In order to have a constant cross section for the entire bundle, the half-dashes were modeled as having an elliptical cross section with a minor and major semi-axis of 1.20 mm and 1.50 mm, respectively. The two half-dashes surround the tweezer and then join together in the main circular section.

[0066] In addition, a baseplate was introduced as a support for the assembly. PLA plastic (material present in the Ansys library, E=3.5 GPa and σY=54.1 MPa) was used as the material of the base and the tweezer in the simulation. Considering the absence of the trabecular model, reduced properties were assigned to the screw, to confer greater strain, with a Young's modulus of 2.4 GPa.

[0067] The baseplate was used as a fixed support to which the Voronoi porosity screw is attached, allowing, thus testing the thread resistance under load. A load was applied to the opposite side of the tweezer cross-section. To simplify the finite element simulation, a quarter of the CAD model was used. This simplification was done everywhere less than where the holes on the tweezer and the screw did not exhibit true symmetries. This assumption was imposed to significantly reduce the computational time.

[0068] The model was subjected to a “meshing” procedure using the Ansys Tetrahedra method. Tetrahedra with a maximum size of 0.40 mm were used for meshing the tweezer and the trabecular screw. To better study the trabecular surface subjected to higher loading, tetrahedral “meshes” with a maximum size of 0.25 mm were used for the tweezer. For the baseplate, tetrahedral “meshes” with a maximum dimension of 0.50 mm were used. The entire “mesh” of the model has 207402 nodes and 134632 elements, with a “meshing” quality of 0.82. Only linear elements were used.

[0069] Two different contacts were used to better simulate the interaction between the four parts: [0070] friction with a coefficient of friction=0.3, between the base and the screw in the threaded connection area, and, between the screw and the tweezer, to simulate interference conditions; [0071] friction with a coefficient of friction=0.4, between the tweezer and the bundle assembly, on the faces where wrapping occurred.

[0072] Contact between the trabecular screw and the tweezer was imposed in the area where the groove pitch provides axial clamping of the tweezer and between the inside of the screw and the top face of the tweezer. Lateral contact was imposed to prevent instability during compression of the tweezer arms. The model was clamped using a fixed support on the bottom face of the base. The load was applied as a force on the upper section of the bundle, simulating the force applied by the connected muscle-inspired bundle.

[0073] Simulation Results

[0074] The finite element simulation was performed in 2 hours and 24 minutes. Due to the risk of elastic instability for a fully trabecular tweezer, a partial trabecular tweezer was used in this simulation. This tweezer exhibited compressive loading but no signs of impending instability. The normal stress results are shown in FIG. 9a.

[0075] As imagined, the normal stress presents the highest value at the point where there is detachment between the bundle assembly and the capstan, due to a concentration of stresses. A normal stress concentration factor of 3.24 can be calculated.

[0076] The normal strain analysis presented a high strain of the bundle assembly, while the trabecular screw proved to be almost non-deformable. The tweezer, on the other hand, presented an average strain compared to that of the other two components (screw and bundle assembly), thus providing for the desired strain gradient of the bioinspired junction. The normal strains of the tweezer and the bundle assembly are shown in more detail in FIGS. 10a and 10b.