Implant device
The present invention is directed to an implant device, in particular an implant device placed between bony, cartilaginous or soft tissues or between prosthetic surfaces to restore or create a gap. More particular the present invention is directed to an implant device made from polymeric material and having a stiffness gradient as well as a limited dimensional deformation, wherein the implant device has a stiffness gradient and a limited dimensional deformation and preferably is at least partially anisotropic.
1. An inter-condylar implant device comprising a body having a stiffness gradient with at least one minimum along the x-axis and/or along the y-axis, wherein the body has a limited dimensional deformation, limited by material properties of the implant body, in the direction of the x-axis and/or y-axis under maximum physiological load condition, wherein the relative dimensional deformation is below 10% in the direction corresponding to the x- and/or y-axis, based on the dimension under no load condition compared to the dimension under a maximum load condition in the z-direction ranging from 20 MPa to 200 MPa, and wherein the stiffness of the implant body is at least partially anisotropic.
2. The implant device according to claim 1 , wherein the stiffness gradient is continuous.
3. The implant device according to claim 1 , wherein the stiffness gradient is discontinuous.
4. The implant device according to claim 1 , wherein the body has a stiffness gradient with at least two minima along the x-axis and/or y-axis.
5. The implant device according to claim 1 , wherein the device is an interspace implant, in particular an inter-condylar implant or a spinal disc implant.
6. The implant device according to claim 1 , wherein the shape of the device conforms to the physiological situation upon implantation.
7. The implant device according to claim 1 , wherein the device is self-centering in the physiological space it is implanted in.
8. The implant device according to claim 1 , wherein the device has a stiffness corresponding to a Young modulus ranging from at least 0.1 to 100 MPa in each direction when the material is modeled as linear elastic.
9. The implant device according to claim 1 , wherein the device has a dynamic coefficient of friction below 0.1.
10. The implant device according to claim 1 , wherein the body is comprised of a polymer material.
11. The implant device according to claim 10 , wherein the polymer material is a hydrogel.
12. The implant device according to claim 10 , wherein the polymer material is biocompatible.
13. A method for manufacturing an inter-condylar implant device according to claim 1 , wherein the body is formed by a polymer material, and wherein the stiffness gradient and/or the partial anisotropy is created (a) through partly orienting the molten or semi-molten polymer material, or (b) through a layer-by-layer curing and/or crosslinking process, or (c) through introducing oriented or non-oriented fibre reinforcement into part of the polymer material.