CN-121971698-A - Functionally graded polymer knee implants for enhanced fixation, wear resistance and mechanical properties and their manufacture

Abstract

The present invention relates to functionally graded polymer knee implants for enhanced fixation, wear resistance and mechanical properties and their manufacture. The present invention includes a polymer-based femoral and/or tibial component implant for use in a total knee replacement/arthroplasty procedure for providing improved wear resistance, enhanced physiologic response at the bone/implant interface, and reduced stress shielding. The implant may be made via additive manufacturing. The articular surface of the implant may be embodied without any additives or in the form of additives for improving tribological response. In addition, the devices disclosed herein contain interface surfaces (i.e., bone/implant interfaces) that contact the natural bone, which may exist in their pure form, containing bioactive additives. The implant has a porous morphology at the bone/implant interface to improve biological response and improve fixation. Wherein the depth and morphology of the additives are controlled via the techniques disclosed herein.

Inventors

• B. cloth cloth
• A. WOOD
• M. Dade Setan
• KARAU ANDREAS
• S. Bandy
• K. ROSS
• M. Knebel

Assignees

• 赢创运营有限公司

Dates

Publication Date

20260505

Application Date

20190201

Priority Date

20180202

Claims (15)

1. 1. A method for preparing a polymer-based knee implant comprising a joint surface and a bone/implant interface, wherein the bone/implant interface is porous, and wherein the implant has a polymeric material consisting of PAEK species, preferably PEEK, PEKK, PEKEKK, Wherein the porous bone/implant interface has a pore size of 0.2 mm to 5mm, Wherein the bone/implant interface comprises a bioactive additive, Wherein the bioactive additive is a calcium phosphate derivative, Wherein the calcium phosphate derivative is biphasic calcium phosphate, Wherein biphasic calcium phosphate is contained in the polymeric material, and Wherein the bone/implant interface comprises gradient porosity, Wherein the preparing is performed by additive manufacturing after blending the biologically inert polymer with the bioactive additive to form a blended material.
2. 2. The method of claim 1, wherein the porous bone/implant interface has a pore size of preferably 0.3mm to 1 mm.
3. 3. The method of claim 1, wherein the gradient pores are a mixture of small pores and large pores.
4. 4. The method of claim 1, wherein one pore layer is present below a series of second, different pore layers.
5. 5. The method of claim 1, wherein the implant further comprises a fixation peg.
6. 6. The method of claim 1, consisting of one or more components, wherein at least one component of the implant comprises a biologically inert polymer.
7. 7. The method of claim 6, wherein the one or more components comprise a bio-inert polymer, wherein the articular surface comprises an abrasion resistant additive.
8. 8. The method of claim 7, wherein the wear additive is carbon, glass, a polymeric wear additive, a ceramic wear additive, a metallic wear additive, or any combination or mixture thereof.
9. 9. The method of claim 1, wherein one or more components of the implant comprise a biologically inert polymer and a bioactive additive, wherein the articular surface comprises an antiwear additive, and wherein the bone/implant interface is porous.
10. 10. The method of claim 1, wherein the manufacturing of the blended material is accomplished by twin screw melt compounding filaments.
11. 11. The method of claim 10, wherein the filaments have a diameter of 1.5 mm to 3.25 mm.
12. 12. The method of claim 10, wherein the filaments contain up to about 20wt% of the bioactive additive.
13. 13. The method of claim 1, wherein the implant is printed via additive manufacturing at a printhead temperature of 380 ℃ to 440 ℃.
14. 14. The method of claim 1, wherein the implant is printed via additive manufacturing at a printing speed of 10 mm/sec to 40 mm/sec.
15. 15. The method of any one of the preceding claims, wherein the implant is thermally annealed.

Description

Functionally graded polymer knee implants for enhanced fixation, wear resistance and mechanical properties and their manufacture The application is a divisional application of patent application with the application number 201980023197.1 and the application date 2019, 2 months and 1 day. Technical Field The present disclosure relates to instruments for orthopedic implant applications, with the objective of providing implants with higher wear resistance, enhanced bone/implant interface osseointegration, reduced third body abrasion potential, rapid post-operative healing, and more efficient load transfer from the implant to the native bone structure in an effort to reduce the detrimental effects of stress shielding on bone mineral density. The present invention is directed to improving the wear resistance of a knee implant assembly and inducing a physiologic bond at the interface between the knee implant and the natural ends of the distal femur and/or distal tibia. Background As the population ages, the need for artificial implants increases rapidly. Much of the focus in this area has been on developing new techniques or modifying the prior art, respectively, to provide improved materials and methods for large joint replacement/repair. Macrojoints, including those belonging to the shoulders, buttocks, knees and ankles, have been designed with unique systems for each macrojoint in an effort to provide beneficial instruments to replace damaged, diseased or dysfunctional natural structures. While metal and/or ceramic based implants provide the improved mechanical properties required for large joint implants, they also suffer from drawbacks that reduce their effectiveness, useful life, and may cause adverse biological reactions when subjected to activities in the patient's daily living (e.g., walking, squatting, etc.). For example, in total knee arthroplasty, coCr femoral knee implants (and other implants of metallic and/or ceramic materials) are commonly used because they are easily polished to a smooth surface, provide adequate fixation to natural bone, and provide reasonable wear resistance. While these metal and/or ceramic femoral knee implants dominate the overall knee replacement market (and most of the market in other large joint reconstruction areas), they have mechanical properties that introduce a way in which these materials may harm the patient's health in long term applications. While the mechanical properties and wear resistance of these types of materials are desirable, their mechanical properties are often of concern beyond those of natural bone. In particular, it has been shown that the improved mechanical properties of metal and/or ceramic based femoral knee implants consistently result in a loss of bone mineral density in the distal femur. According to the walf's law, if the natural bone is not loaded, it will remodel according to the newly applied load and regenerate the modified structure. In the case of metal and/or ceramic based femoral knee implants, the implant is subjected to loads that are typically applied to the distal femur, and thus the distal femur remodels accordingly, resulting in a reduction in bone mineral density. Subsequent concerns following such loss of bone mineral density include the likelihood of implant loosening, the occurrence of third body wear, increased difficulty in revision procedures, and/or implant failure, which must be addressed. Furthermore, these metal and/or ceramic based implants are problematic in that they are radiopaque, have the potential to cause allergic reactions in the patient, may release toxic sub-species into the patient, are prone to mechanically induced oxidation and corrosion, and have had a record of mechanical failure due to many of these reasons and their propensity to migrate away from the initial fixation site due to lack of long term fixation of the distal femur. Many of these factors have led to current trends toward the implementation of polymer-based materials in these particular applications. This transfer with respect to implant materials is due to the fact that the mechanical properties of many polymer-based materials can be tailored to closely mimic the mechanical properties of natural bone, as well as their ease of processing, radiopacity, non-induction of allergic reactions in patients, and elimination of the oxidation and corrosion potential of currently used metal-based implants. Furthermore, the particular species of polymeric material are biologically inert, thus eliminating the possibility of any adverse systemic effects upon implantation. Of particular interest, the development of thermoplastic polymer class Polyaryletherketones (PAEKs) and their derivatives (i.e., polyetheretherketone, polyetherketoneketone, polyetherketoneetherketone and other derivative polymers) has recently grown. While polyethylene and its derivatives (i.e., ultra-high molecular weight polyethylene, vitamin E infused polyethylene, and crosslinked p