FUNCTIONALLY GRADED POLYMER KNEE IMPLANT FOR ENHANCED FIXATION, WEAR RESISTANCE, AND MECHANICAL PROPERTIES AND THE FABRICATION THEREOF

Abstract

The present invention comprises a polymeric based femoral and/or tibial component implant to be used in total knee replacement/arthroplasty procedures serving to provide increased wear resistance, enhanced physiological response at the bone/implant interface, and decreased stress-shielding. The implant can be made via additive manufacturing. The articulating surface of the implant may be implemented in without any additive or in a form containing an additive for improved tribological response. Further, the device disclosed herein contains an interfacial surface which is in contact with the native bone (i.e., bone/implant interface) which may exist in its pure form, containing a bioactive additive. The implant has a porous morphology on the bone/implant interface for improved biological response and improved fixation. The depth of the additives and the topographical morphology therein are controlled via techniques disclosed herein.

Claims

1. A polymeric-based knee implant comprising an articulating surface and a bone/implant interface; wherein the bone/implant interface is porous; and wherein the implant has a polymeric material comprising a PAEK species (PEEK, PEKK, PEKEKK, etc.) or a PE species (PE, HDPE, UHMWPE, XL-PE, Vit-E-PE).

2. The polymeric-based knee implant of claim 1, wherein the porous bone/implant interface has a pore size of from 0.1 mm to 10 mm.

3. The polymeric-based knee implant of claim 1, wherein the bone/implant interface comprises bioactive additives.

4. The polymeric-based knee implant of claim 1, wherein the articulating surface comprises a high wear resistant bioinert composition.

5. The polymeric-based knee implant of claim 1, wherein the implant further comprises fixation pegs.

6. The polymeric-based knee implant of claim 1, consisting of one or more components, wherein at least one component of the implant comprises a bioinert polymer.

7. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioactive additive.

8. The polymeric-based knee implant of claim 7, wherein the bioactive additive is a calcium phosphate derivative.

9. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a functionally graded layer of bioactive additive.

10. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer, a bioactive additive, an osteoconductive additive, or any combination or mixture thereof.

11. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer, wherein the bone/implant interface is porous.

12. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives.

13. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a functionally graded layer of wear-resistant additive.

14. The polymeric-based knee implant of claim 1, wherein the articulating surface comprises a functionally graded layer of wear-resistant additive.

15. The polymeric-based knee implant of claim 12, wherein the wear-resistant additive is carbon, glass, polymeric, ceramic, metallic, or any combination or mixture thereof.

16. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives, and wherein the bone/implant interface comprises a bioactive additive, an osteoconductive additive, or any combination or mixture thereof.

17. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives.

18. The polymeric-based knee implant of claim 1, wherein the one or more components comprises a bioinert polymer and a bioactive additive, wherein the articulating surface comprises wear-resistant additives.

19. The polymeric-based knee implant of claim 1, wherein the implant comprises a reinforcing additive.

20. The polymeric-based knee implant of claim 19, wherein the reinforcing additive is a fibrous material, particulate material, or any combination or mixture thereof.

21. The polymeric-based knee implant of claim 20, wherein the fibrous material is carbon-based, polymeric, glass, ceramic, or any combination or mixture thereof.

22. The polymeric-based knee implant of claim 21, wherein the carbon-based fibrous material is carbon fibers, pitch-derived carbon fibers, pan-derived carbon fibers, or any combination or mixture thereof.

23. The polymeric-based knee implant of claim 20, wherein the particulate material is polymeric, metallic, ceramic, or any combination or mixture thereof.

24. The polymeric-based knee implant as in claim 1, wherein the implant is fabricated through blending, compounding, extruding, injection molding, multi-component injection molding, co-injection molding, two-shot injection molding, injection-compression molding, compression molding, hot pressing, hot isotactic pressing, additive manufacturing, or a combination thereof.

25. The polymeric-based knee implant of claim 1, wherein the porosity is fabricated by abrasive blasting, salt-leaching, matrix dissolution, additive manufacturing, or a combination thereof.

26. The polymeric-based knee implant of claim 25, wherein the implant is fabricated by additive manufacturing after blending a bioinert polymer with a bioactive additive to form a blended material.

27. The polymeric-based knee implant of claim 26, wherein the fabrication of the blended material is achieved through twin-screw melt compounding into a filament.

28. The polymeric-based knee implant of claim 27, wherein the filament has a diameter between 1.5 mm and 3.25 mm.

29. The polymeric-based knee implant of claim 27, wherein said filament contains up to about 20 wt % of the bioactive additive.

30. The polymeric-based knee implant of claim 25, wherein the implant is printed via additive manufacturing with a print head temperature of between 380 C. and 440 C.

31. The polymeric-based knee implant of claim 25, wherein the implant is printed via additive manufacturing with a print bed temperature of between 110 C. and 160 C.

32. The polymeric-based knee implant of claim 25, wherein the implant is printed via additive manufacturing with a print speed of between 10 mm/sec and 40 mm/sec.

33. The polymeric-based knee implant as in claim 1, wherein the implant is thermally annealed.

34. The polymeric-based knee implant of claim 25, wherein said annealing is carried out at a temperature between 140 C. and 250 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Some exemplary embodiments of the disclosed invention are illustrated as examples but are not to be understood as limitations of the invention wherein:

[0020] FIG. 1 depicts a typical femoral knee implant showing the articulating surface 1 and the bone/implant interface surface 2.

[0021] FIG. 2 depicts a typical femoral knee implant showing the articulating face 1, the bone/implant interface surface 2, and pegs 3 which are commonly implemented to aid in primary implant fixation.

[0022] FIG. 3 depicts one platform where a porous bone/implant interface surface 4 is implemented to a controlled thickness 5 from the bone/implant interface surface.

[0023] FIG. 4 depicts one platform where a porous bone/implant interface surface containing bioactive additives 6 is implemented to a controlled thickness 7 from the bone/implant interface surface.

[0024] FIG. 5 depicts one platform where a wear-resistant composite articulating surface 8 is implemented to a controlled thickness 9 from the articulating surface.

[0025] FIG. 6 depicts one platform where a wear-resistant composite articulating surface 8 is implemented to a controlled thickness 9 from the articulating surface as well as a porous bone/implant interface surface 4 is implemented to a controlled thickness 5 from the bone/implant interface surface.

[0026] FIG. 7 depicts one platform where a wear-resistant composite articulating surface 8 is implemented to a controlled thickness 9 from the articulating surface as well as a porous bone/implant interface surface containing bioactive additives 6 is implemented to a controlled thickness 7 from the bone/implant interface surface.

[0027] FIG. 8 depicts a typical tibial baseplate implant showing the tibial tray platform 10, stabilizing fins 11, and stabilization post 12.

[0028] FIG. 9 depicts a typical tibial baseplate implant showing the tibial tray platform 10 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins 13 and a surface porous stabilizing post 14.

[0029] FIG. 10 depicts a typical tibial baseplate implant showing one platform of the herein disclosed invention comprising surface porous stabilizing fins 13, a surface porous stabilizing post 14, and the lower side of the tibial tray platform comprising surface porosity 15.

[0030] FIG. 11 depicts a typical tibial baseplate implant showing the tibial tray platform 10 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins containing bioactive additives 16 and a surface porous stabilizing post containing bioactive additives 17.

[0031] FIG. 12 depicts a typical tibial baseplate implant showing one platform of the herein disclosed invention comprising surface porous stabilizing fins containing bioactive additives 16, a surface porous stabilizing post containing bioactive additives 17, and the lower side of the tibial tray platform comprising surface porosity containing bioactive additives 18.

[0032] FIG. 13 depicts a typical tibial baseplate implant showing the stabilizing fins 11, and stabilization post 12, and a wear-reinforced composite tibial tray platform 19.

[0033] FIG. 14 depicts a typical tibial baseplate implant showing the wear-reinforced composite tibial tray platform 19 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins 13 and a surface porous stabilizing post 14.

[0034] FIG. 15 depicts a typical tibial baseplate implant showing the wear-reinforced composite tibial tray platform 19 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins 13, a surface porous stabilizing post 14, and the lower side of the tibial tray platform comprising surface porosity 15.

[0035] FIG. 16 depicts a typical tibial baseplate implant showing the wear-reinforced composite tibial tray platform 19 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins containing bioactive additives 16 and a surface porous stabilizing post containing bioactive additives 17.

[0036] FIG. 17 depicts a typical tibial baseplate implant showing the wear-reinforced composite tibial tray platform 19 as well as one platform of the herein disclosed invention comprising surface porous stabilizing fins containing bioactive additives 16, a surface porous stabilizing post containing bioactive additives 17, and the lower side of the tibial tray platform comprising surface porosity containing bioactive additives 18.

[0037] FIG. 18 depicts the stabilization insert that holds the tibial baseplate in place within the tibial bone showing the connection to the tibial baseplate 20 and the typical bone/implant interface surface 21.

[0038] FIG. 19 depicts the stabilization insert that holds the tibial baseplate in place within the tibial bone showing the connection to the tibial baseplate 20 and a surface porous bone/implant interface surface 22.

[0039] FIG. 20 depicts the stabilization insert that holds the tibial baseplate in place within the tibial bone showing the connection to the tibial baseplate 20 and a surface porous bone/implant interface surface containing bioactive additives 23.

[0040] FIGS. 21 A, B and C depicts compositional data of the polymer materials containing a bioactive additive. Thermogravimetric analysis shows that the bioactive additive comprises about 20% of the blended material by weight. The polymeric material shown is poly ether ether ketone while the bioactive additive is biphasic calcium phosphate (BCP)a calcium phosphate derivative.

[0041] FIG. 22 depicts the average pore sizes of the test specimens showing that small pores are within a range of about 0.35 mm to about 0.5 mm while large pores are defined as having an average size of about 0.55 mm to about 2 mm. Samples containing a gradient porosity are therefore a mix of small and large pores in a fashion with one layer of porosity existing below a second, dissimilar layer of porosity in a series.

[0042] FIG. 23 depicts the improvement in fixation found in a static loading pull-off force analysis when a porous surface is used at the bone-implant interface.

[0043] FIG. 24 depicts the increase in flexural response until failure when imparting a porous structure to the bone implant interface of the implant when tested under static compressive loads.

DETAILED DESCRIPTION

[0044] The terminology used herein is chosen for the purpose of describing particular embodiments of the invention but are not intended to impart limitations of the invention. Herein, the term and/or includes any and all combinations of one or more of the associated listed items. Further, the terms comprises and/or comprising is to be understood in the specification to specify the presence of stated features, procedures, components, elements, geometries, and/or other characteristics, but do not impede the presence and/or addition of one or more further features, procedures, components, elements, geometries, and/or other characteristics thereof.

[0045] Unless otherwise defined, all terms, including those scientific and/or technical in nature, are to be understood to have the same meanings as those commonly understood by one having ordinary skill in the art of the invention. Further, terms such as those of a common nature, should be interpreted as having a meaning that is consistent with their meaning in the scope of the relevant art and/or the present disclosure and shall not be interpreted in an overly formal sense without the term being expressly defined so herein.

[0046] In describing the herein disclosed invention, it will be understood that a number of techniques and/or steps are disclosed. Each of these stated techniques and/or steps has individual benefit and each can also be used in conjunction with one or more of the other herein disclosed techniques and/or steps. Therefore, this description will refrain from repeating all possible combinations of these individual steps in an unnecessary fashion for the sake of clarity but is not to be understood as limiting the possible techniques and/or steps that lie within the scope of the invention and claims.

[0047] A new device, preferred (but not limiting) embodiments, composite specifications, and methods for implementing the present invention are discussed herein. In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the present invention. It will be evident, however, to one skilled in the art that the present invention may be practiced without these specific details.

[0048] The disclosure herein is to be considered only as an exemplification of the invention and is not to be understood as a limitation of the invention to the specific embodiments which are illustrated by the descriptions and figures herein.

[0049] The present invention will now be described by referencing the appended figures representing preferred embodiments, but not limiting potential embodiments of the present invention.

[0050] FIG. 1 depicts a typical femoral knee implant depicting the articulating surface 1 and the bone/implant interface surface 2. FIG. 2 shows a second potential embodiment of a typical femoral implant with the articulating surface 1 and bone/implant interface 2 shown as well as fixation pegs 3 commonly used to aid in primary fixation of the implant. The articulation surface 1 in these embodiments typically undergoes the highest wear-rate in the implant as it articulates against an opposing tibial component during everyday activities. The bone/implant interface 2 generally is fixed to the distal femoral bone with the use of fixation pegs 3 and/or bone cement, typically PMMA. This fixation has adequate primary fixation, but it known to fail with long-term studies of the implants.

[0051] FIG. 3 depicts one possible embodiment of the present invention depicting the articulating surface 1 as well as a porous bone/implant interface 4 with a controlled thickness of porosity 5 measured from the bone/implant interface. The introduction of the porous bone/implant interface 4 may be capable of initiating more rapid bone ingrowth and subsequent long-term fixation without the use of pegs or bone cement thus removing potential stress-concentration zones and potential third-body wear particles, respectively. Further, the controlled thickness of porosity 5 allows for enhancing the physiological response from the native bone without affecting the articulating surface 1 and thus wear properties.

[0052] FIG. 4 further depicts a porous bone/implant interface containing bioactive additives 6 with a controlled thickness of porosity and bioactive additive penetration 7 measured from the bone/implant interface. The introduction of the porous bone/implant interface containing bioactive additives 6 may be capable of initiating more rapid bone ingrowth and subsequent long-term fixation without the use of pegs or bone cement thus removing potential stress-concentration zones and potential third-body wear particles, respectively. Further, the controlled thickness of porosity and bioactive additive penetration 7 allows for enhancing the physiological response from the native bone without affecting the articulating surface 1 and thus wear properties.

[0053] FIG. 5 depicts a modified typical femoral knee implant. In this particular embodiment, the bone/implant interface 2 remains as is found in typical femoral knee implants. The articulating surface, however, contains wear-resistant additives 8 to a controlled depth 9 as measured from the articulating surface. The presence of these wear-resistant additive may improve the wear-rate of the femoral knee implant articulating interface and lead to longer service life of the implant.

[0054] FIG. 6 depicts a femoral knee implant comprising a porous bone/implant interface 4 with a controlled depth of porosity 5 as well as a wear-resistant additive reinforced articulating surface 8 with a controlled depth of wear-resistant additive 9. This particular embodiment may aid in initial and long-term fixation of the implant due to the porous bone/implant interface 4 as well as increase the service-life of the implant due to the wear-resistant additives 8 at the articulating surface.

[0055] FIG. 7 depicts a further potential embodiment of the present invention comprising a porous bone/implant interface containing bioactive additives 6 with a controlled thickness of porosity and bioactive additive penetration 7 measured from the bone/implant interface. The introduction of the porous bone/implant interface containing bioactive additives 6 may be capable of initiating more rapid bone ingrowth and subsequent long-term fixation without the use of pegs or bone cement thus removing potential stress-concentration zones and potential third-body wear particles, respectively. Further, the addition of wear-resistant additives 8 at the articulating surface to a controlled depth 9 as measured from the articulating interface may lead to a more resistant wear-composite at the articulating surface. This particular embodiment may lead to superior bone response and wear-resistance and therefore give greatly enhanced implant survival rates compared to currently used technologies.

[0056] FIG. 8 depicts a typical tibial insert used in total knee replacement comprising the tibial baseplate 10, stabilizing fins 11, and a stabilizing post 12. The tibial plate 10 commonly serves to hold in place the material which the articulating surface of the femoral component articulates against.

[0057] FIG. 9 depicts another potential embodiment of the present application comprising a stabilizing fins with surface porosity 13 and a stabilizing post with surface porosity 14. Further, FIG. 10 indicates the bone/implant interface of the tibial plate with implemented surface porosity 15. The surface porosity found on the stabilizing fins 13, the stabilizing post 14, and the lower side of the tibial plate 15 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0058] FIG. 11 depicts another potential embodiment of the present application comprising a stabilizing fins with surface porosity containing bioactive additives 16 and a stabilizing post with surface porosity containing bioactive additives 17. Further, FIG. 12 indicates the bone/implant interface of the tibial plate with implemented surface porosity containing bioactive additives 18. The surface porosity and bioactive additives found on the stabilizing fins 16, the stabilizing post 17, and the lower side of the tibial plate 18 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0059] FIG. 13 depicts a typical tibial insert used in total knee replacement comprising stabilizing fins 11, and a stabilizing post 12. Further, the tibial baseplate containing wear-resistant additives 19 is introduced. Introduction of a tibial baseplate containing wear-resistant additives may promote greater wear-resistance to the tibial baseplate and lead to enhanced longevity of the implant.

[0060] FIG. 14 depicts another potential embodiment of the present application comprising a stabilizing fins with surface porosity 13, a stabilizing post with surface porosity 14, and a tibial baseplate containing wear-resistant additives. Further, FIG. 15 indicates the bone/implant interface of the tibial plate containing wear-resistant additives 19 with implemented surface porosity 15. The surface porosity found on the stabilizing fins 13, the stabilizing post 14, and the lower side of the tibial plate 15 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0061] FIG. 16 depicts another potential embodiment of the present application comprising a stabilizing fins with surface porosity containing bioactive additives 16, a stabilizing post with surface porosity containing bioactive additives 17, and a tibial baseplate containing wear-resistant additives. Further, FIG. 17 indicates the bone/implant interface of the tibial plate containing wear-resistant additives 19 with implemented surface porosity containing bioactive additives 18. The surface porosity and bioactive additives found on the stabilizing fins 16, the stabilizing post 17, and the lower side of the tibial plate 18 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0062] FIG. 18 depicts the tibial insert typically used to further stabilize the tibial baseplate with the connection to the tibial baseplate 27 the bone/implant interface surface 28.

[0063] FIG. 19 depicts a potential embodiment of the invention comprising the connection to the tibial baseplate 27 and a porous surface at the bone/implant interface 29. The surface porosity found on the bone/implant interface of the tibial insert 29 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0064] FIG. 20 depicts a potential embodiment of the invention comprising the connection to the tibial baseplate 27 and a porous surface containing bioactive additives at the bone/implant interface 30. The surface porosity and bioactive additives found on the bone/implant interface of the tibial insert 30 may initiate more efficient bone response when placed against the tibial bone upon implantation resulting in development of a stronger physiological bond and subsequent increased survival of the implant.

[0065] FIG. 21 depicts compositional data of the polymer materials containing a bioactive additive. Thermogravimetric analysis (FIG. 21A) shows that the bioactive additive comprises about 20% of the blended material by weight. The polymeric material shown is poly ether ether ketone while the bioactive additive is biphasic calcium phosphate (BCP)a calcium phosphate derivative. Relative amounts of the chemical constituents carbon, oxygen, calcium, and phosphate are also shown as a result of energy dispersive spectroscopy (FIG. 21B & FIG. 21C) to verify chemical composition and presence of bioactive additive BCP.

[0066] FIG. 22 depicts the average pore sizes of the test specimens showing that small pores are within a range of about 0.350 mm to about 0.500 mm while large pores are defined as having an average size of about 0.550 mm to about 2 mm. Samples containing a gradient porosity are therefore a mix of small and large pores in a fashion with one layer of porosity existing below a second, dissimilar layer of porosity.

[0067] FIG. 23 depicts the improvement in fixation found in a static loading pull-off force analysis when a porous surface is used at the bone-implant interface.

[0068] FIG. 24 depicts the increase in flexural response until failure when imparting a porous structure to the bone implant interface of the implant when tested under static compressive loads.

[0069] A polymeric-based knee implant comprising an articulating surface and a bone/implant interface. Preferably the implant further comprises fixation pegs.

[0070] The bone/implant interface is porous. The bone/implant interface has a pore size preferably of 0.1 mm to 10 mm, more preferably of 0.2 mm to 5 mm, and most preferably of 0.3 mm to 1 mm. Preferably the pore sizes are determined by electron microscopy (preferably SEM) or optical microscopy. Small pores are defined within a range of about 0.35 mm to about 0.5 mm while large pores are defined as having an average size of about 0.55 mm to about 2 mm.

[0071] Preferably the bone/implant interface has gradient pores. Preferably, gradient porosity is a mix of small and large pores, preferably in a fashion with one layer of porosity existing below a second, dissimilar layer of porosity in a series.

[0072] Preferably the articulating surface comprises a high wear resistant bioinert composition.

[0073] Preferably the implant consists of one or more components, preferably at least one component comprises a bioinert polymer. Preferably the at least one or more components comprises a bioactive additive.

[0074] Suitable bioinert polymers include but are not limited to PAEK species (PEEK, PEKK, PEKEKK, etc.) or a PE species (PE, HDPE, UHMWPE, XL-PE, Vit-E-PE).

[0075] Preferably the bioactive additive is a phosphate derivative, preferably apatites and calcium phosphates, more preferably the apatites comprise hydroxyapatites and fluorohydroxyapatites. The phosphates comprise preferably alpha and/or beta tri calcium phosphate. A bioactive additive can also include an osteoconductive additive. An osteoconductive additive is an additive that can promote bone growth.

[0076] Suitably, the bioactive material is a material which elicits a specific biological response at the interface of the material, which results in a formation of a bond between tissue and polymeric material.

[0077] Preferably the one or more components of the implant comprises a functionally graded layer of bioactive additive.

[0078] Preferably the one or more components of the implant comprises a bioinert polymer, a bioactive additive, an osteoconductive additive, or any combination or mixture thereof. Preferably the one or more components of the implant comprises a bioinert polymer, wherein the bone/implant interface is porous. Preferably the one or more components of the implant comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives.

[0079] Preferably the one or more components of the implant comprises a functionally graded layer of wear-resistant additive.

[0080] Preferably the articulating surface comprises a functionally graded layer of wear-resistant additive. Preferably the wear-resistant additive is carbon, glass, polymeric, ceramic, metallic, or any combination or mixture thereof.

[0081] Preferably the one or more components of the implant comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives, and wherein the bone/implant interface comprises a bioactive additive, an osteoconductive additive, or any combination or mixture thereof. Preferably the one or more components of the implant comprises a bioinert polymer, wherein the articulating surface comprises wear-resistant additives, and wherein the bone/implant interface is porous. Preferably the one or more components of the implant comprises a bioinert polymer and a bioactive additive, wherein the articulating surface comprises wear-resistant additives, and wherein the bone/implant interface is porous.

[0082] Preferably the implant comprises a reinforcing additive. Preferably the reinforcing additive is a fibrous material, particulate material, or any combination or mixture thereof.

[0083] Preferably the fibrous material is carbon-based. Preferably the fibrous material is carbon fibers, pitch-derived carbon fibers, pan-derived carbon fibers, or any combination or mixture thereof.

[0084] Preferably the fibrous material is polymeric, glass, ceramic, or any combination or mixture thereof. Preferably the particulate material is polymeric, metallic, ceramic, or any combination or mixture thereof.

[0085] Preferably the implant is fabricated through blending, compounding, extruding, injection molding, multi-component injection molding, co-injection molding, two-shot injection molding, injection-compression molding, compression molding, hot pressing, hot isotactic pressing, additive manufacturing, or a combination thereof.

[0086] Preferably the porosity of the porous knee implant is fabricated by abrasive blasting, salt-leaching, matrix dissolution, additive manufacturing, or a combination thereof, more preferably by additive manufacturing.

[0087] Preferably the implant is fabricated by additive manufacturing after blending a bioinert polymer with a bioactive additive to form a blended material.

[0088] Preferably said blended material is achieved through twin-screw melt compounding into a filament. Preferably the filament has a diameter between 1.5 mm and 3.25 mm. Preferably the filament contains up to about 20 wt % of said bioactive additive.

[0089] Preferably the polymeric-based knee implant is printed via additive manufacturing with a print head temperature of between 380 C. and 440 C. Preferably the implant is printed via additive manufacturing with a print bed temperature of between 110 C. and 160 C. Preferably the implant is printed via additive manufacturing with a print speed of between 10 mm/sec and 40 mm/sec.

[0090] Preferably the implant is thermally annealed, preferably the annealing is carried out at a temperature between 140 C. and 250 C.

[0091] In preferred embodiments, the polymeric material for the device would be one from polyaryletherketone (PAEK polymers, including but not limited to PEEK, PEKK, PEKEKK, and other polymerization species of the parent species of PAEKs consisting of a backbone of alternating ether and ketone bonds contacting, or not containing, crosslinked polymer chains), polyetheretherketone (PEEK, poly-ether-ether-ketone, and other embodiments of the parent polymer, PAEKs, containing, or not containing, crosslinked polymeric chains), polyethylene (PE, UHMWPE, crosslinked PE, Vitamin-E infused PE, and other embodiments and compounds of the parent polymer), and/or other biologically favorable and mechanically robust polymeric species.

[0092] In preferred embodiments, the polymeric species, including but not limited to polyaryletherketone (PAEK polymers, including but not limited to PEEK, PEKK, PEKEKK, and other polymerization species of the parent species of PAEKs consisting of a backbone of alternating ether and ketone bonds contacting, or not containing, crosslinked polymer chains), polyetheretherketone (PEEK, poly-ether-ether-ketone, and other embodiments of the parent polymer, PAEKs, containing, or not containing, crosslinked polymeric chains), polyethylene (PE, UHMWPE, crosslinked PE, Vitamin-E infused PE, and other embodiments and compounds of the parent polymer), and/or other biologically favorable and mechanically robust polymeric species, would exist as the main species in the device. Reinforcing fibers, including but not limited to carbon fibers (both pitch-based and PAN-based), glass fibers, polymeric fibers, and/or ceramic fibers may exist within the polymeric matrix of the device as a methods of reinforcement and enhancement biological response.

[0093] In preferred embodiments, the polymeric species, including but not limited to polyaryletherketone (PAEK polymers, including but not limited to PEEK, PEKK, PEKEKK, and other polymerization species of the parent species of PAEKs consisting of a backbone of alternating ether and ketone bonds contacting, or not containing, crosslinked polymer chains), polyetheretherketone (PEEK, poly-ether-ether-ketone, and other embodiments of the parent polymer, PAEKs, containing, or not containing, crosslinked polymeric chains), polyethylene (PE, UHMWPE, crosslinked PE, Vitamin-E infused PE, and other embodiments and compounds of the parent polymer), and other biologically favorable and mechanically robust polymeric species, would exist as the main component in the device. Reinforcing particulates, including but not limited to carbon particles (both pitch-based and PAN-based), glass particulates, metal particulates, ceramic particulates, and/or any combination therein may exist within the polymeric matrix of the device as a methods of enhancement of mechanical and wear properties as well as enhancing biological response.

[0094] Preferably the polymeric species does not contain any polaethylene (PE, UHMWPE, crosslinked PE, Vitamin-E infused PE, and other embodiments and compounds of the parent polymer).

[0095] In preferred embodiments, the device is one that has been manufactured via thermal method. These methods include, but are not limited to, compression molding, injection molding, additive manufacturing, or any combination therein. As an example, but not a fabrication limitation, the polymeric species, either neat/virgin or containing additives, may be forcibly injected into a design mold of the specific application geometry. Conversely, the polymeric species, either neat/virgin or containing additives, may be extruded or otherwise mixed thermally and forced through a die and the subsequent material melt placed into a mold and formed to shape.

[0096] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compositions, articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in C. or is at ambient temperature, and pressure is at or near atmospheric.

[0097] Example 1: The bioinert polymer (PEEK) was blended with a bioactive added calcium phosphate derivative known as biphasic calcium phosphate (BCP) through a dry blending procedure followed by thermal processing via twin-screw compounding. First, the respective materials were weighed out in powder form to comprise a total compositional ratio of 80 wt % polymer (80 g PEEK) and 20 wt % biphasic calcium phosphate (20 g BCP) using an inversion blender. The blended powders were then dried overnight at 80 C. After drying the powder blend was processed in a twin-screw compounder with temperature profiles between 250 C. and 410 C. The resultant extrudate was then drawn into a composite filament and collected for use in fused filament fabrication.

[0098] Example 2: Fused filament fabrication of the composite filament of EXAMPLE 1 was carried out as follows. The PEEK+20% BCP constructs were printed using the 3NTR A4v3 fused filament fabrication printer. The constructs were printed using a nozzle temperature of 410 C., a bed temperature of 135 C., and a chamber temperature of 75 C. The first layer of the construct was printed at a thickness of 0.4 mm while the rest of the part was printed at a layer height of 0.1 mm. A raft was used for each print to prevent the parts from warping and to better adhere to the build plate. This procedure was carried out to fabricate all testing samples with the variation existing only in the geometries of pore sizes as selected.

[0099] Example 3: As depicted in FIG. 23, fabricated samples of the blended composite material from EXAMPLES 1 and 2 were exposed to static loading in order to measure pull-off force after fixation to synthetic bone with poly(methyl methacrylate) (PMMA) bone cement until a pull-off force was achieved that caused the sample to separate from the PMMA/synthetic bone construct. The PMMA used was Stryker Simplex P at 20 C. with mixing done in a vacuum and the cement being added after approximately 5 minutes. Impaction of the testing construct was carried out using a surgical hammer and manual pressure to seat the implant. After 1 hour of setting time, the implant construct was affixed to a hydraulic actuator through a stud on a MTS Mini Bionix tensile tester. The synthetic bone construct was affixed to the lower side of the test area using a vice grip. Tests were carried out at a constant displacement rate of 0.008 mm/s and a data sampling rate of 100 Hz until the load reached 10% of peak load which was deemed to be after failure. The data demonstrates that the samples that contained small pores and gradient pores had a higher pull off force, thus a better anchoring effect than the samples with no pores and large pores. The sample with the best anchoring effect was the sample with the gradient pores.

[0100] Example 4: As depicted in FIG. 24, the no pores bone interface and porous bone interface constructs were printed as described in the above examples and exposed to static loading on the proximal end of the implant after affixing the distal end into an epoxy resin in order to measure the load required for failure of the implant in a bending environment. The implants were potted in a fixture filled with two part epoxy resin with an embedding height of 25 mm measured from bottom flat surface of the implant condyle to the top of the resin potting fixture. The potted implants were placed inside an oven at 40 C. for one hour, taken out of the oven and let to rest for an additional hour at room temperature to allow the resin to fully cure. The specimens were then tested using an Instron 3366B dual column frame in compression. Each implant was placed in between two compression platens with the top platen allowed to slide along the top surface of the implant's condyle. The compression test was then conducted until failure. The porous bone interface showed that it held more load, and showed greater extension before it failed than the no pore bone interface.

[0101] Example 5: As depicted in FIG. 21a, thermogravimetric analysis and energy dispersive spectroscopy (EDAX) was carried out on the composite filament to quantify weight percentage of the bioactive additive, biphasic calcium phosphate, in the composite material. Approximately 25 mg of sample material was placed into a TGA Q500 under an air atmosphere and exposed to a temperature profile as follows: equilibration at 25 C. for at least 5 minutes followed by a temperature ramp at 10 C./min up to 900 C. and then held isothermally for 5 minutes. The reported remaining mass was taken as the amount of bioactive additive within the composite material. EDAX results were gathered by use of a Hitachi TM3030 table-top SEM with an accelerating voltage of 15 kV. Relative amounts of chemical constituents of carbon, oxygen, calcium, and phosphate also were used to verify amount of biphasic calcium phosphate (FIG. 21c).