METHODS AND SYSTEMS FOR FORMING IMPLANTS WITH SELECTIVELY EXPOSED MESH FOR FIXATION AND RELATED IMPLANTS

• US 20080174043A1
• Filed: 01/18/2008
• Published: 07/24/2008
• Est. Priority Date: 01/19/2007
• Status: Active Grant

• Current Assignee: Mimedx Group Incorporated
• Original Assignee: SpineMedica Corporation
• Inventors: Denoziere, Guilhem, Ghodadra, Anish, Tomko, Daniel
• Granted Patent: US 7,879,100 B2
• Time in Patent Office: Days
• US Class Current: 264/232
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30014 differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2002/30016 differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2002/30028 differing in tissue ingrowth capacity, e.g. made from both ingrowth-promoting and ingrowth-preventing parts
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30075 swellable, e.g. when wetted
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30322 differing in surface structures
• CPC Class Codes: A61F 2002/30324 differing in thickness
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30672 temporary
• CPC Class Codes: A61F 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30899 Protrusions pierced with apertures
• CPC Class Codes: A61F 2002/30909 Nets
• CPC Class Codes: A61F 2002/30915 : made of a stack of bonded perforated sheets, grids or wire meshes
• CPC Class Codes: A61F 2002/30957 : using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30971 : Laminates, i.e. layered products
• CPC Class Codes: A61F 2002/4495 : having a fabric structure, e.g. made from wires or fibres
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2210/0061 : swellable
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2250/0018 : differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2250/0019 : differing in hardness, e.g. Vickers, Shore, Brinell
• CPC Class Codes: A61F 2250/0023 : differing in porosity
• CPC Class Codes: A61F 2250/0026 : differing in surface structures
• CPC Class Codes: A61F 2250/0036 : differing in thickness
• CPC Class Codes: A61F 2250/0051 : differing in tissue ingrowth capacity, e.g. made from both ingrowth-promoting and ingrowth-preventing parts
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00365 : Proteins; Polypeptides; Degradation products thereof

Abstract

Molded orthopaedic implants include at least one mesh substrate having opposing upper and lower primary surfaces. At least a major portion of the mesh substrate lower primary surface is integrally moldably attached to the molded implant body. The mesh substrate has at least one selectively exposed region devoid of molded material that exposes at least a portion of the mesh substrate upper surface to at least a partial thickness of the mesh substrate so as to allow for tissue in-growth in the at least one exposed region of the mesh substrate.

Claims

1. A molded orthopaedic implant comprising at least one mesh substrate having opposing upper and lower primary surfaces, wherein at least a major portion of the mesh substrate lower primary surface is integrally moldably attached to the molded implant body, wherein the mesh substrate has at least one selectively exposed region devoid of molded material that exposes at least a portion of the mesh substrate upper surface to at least a partial thickness of the mesh substrate so as to allow for tissue in-growth in the at least one exposed region of the mesh substrate.

2. An implant according to claim 1, wherein the at least one exposed region is a region that extends over at least a major portion of the upper surface of the mesh substrate and that extends into a partial thickness of the mesh substrate.

3. An implant according to claim 2, wherein the at least one exposed region has a gradient configuration whereby increasing amounts of molded material reside closer to the lower primary surface.

4. An implant according to claim 1, wherein the at least one exposed region is a plurality of discrete spaced apart exposed regions that extend through the upper primary surface and extend a partial thickness into the mesh substrate.

5. An implant according to claim 1, wherein the at least one exposed region is a plurality of discrete spaced apart exposed regions extending wholly through the mesh substrate.

6. An implant according to claim 1, further comprising an intermediate material layer residing between the lower primary surface of the mesh substrate and an upper portion of the molded body whereby the intermediate material layer resides proximate to the at least one exposed mesh substrate region.

7. An implant according to claim 6, wherein the intermediate layer comprises a second mesh substrate with a higher density than the mesh substrate with the at least one exposed region.

8. An implant according to claim 6, wherein the intermediate layer is a substantially impermeable film.

9. An implant according to claim 6, wherein the intermediate layer is resorbable.

10. An implant according to claim 1, further comprising at least one temporary material that resides on the upper primary surface of the mesh substrate and is removed prior to implantation or resorbed in situ to define the at least one exposed region.

11. An implant according to claim 10, wherein the molded implant comprises molded PVA hydrogel, and wherein the temporary material comprises moldable silicone that is peelably removable from the mesh substrate.

12. An implant according to claim 10, wherein the molded implant comprises molded PVA hydrogel, and wherein the temporary material is resorbable in situ.

13. An implant according to claim 1, wherein the molded implant comprises molded PVA hydrogel, wherein the implant further comprises at least one removable mesh peel layer residing on the upper primary surface of the mesh substrate, the mesh peel layer comprising a restorable biocompatible salt, and wherein the mesh peel layer is removable from the molded implant to expose the at least one exposed region in the mesh substrate.

14. An implant according to claim 1, wherein the implant molded material comprises crystalline PVA hydrogel.

15. An implant according to claim 1, wherein the mesh substrate has a thickness that is between about 0.5 mm to about 5 mm.

16. An implant according to claim 1, wherein the mesh substrate comprises a knitted polyester fabric.

17. An implant according to claim 1, wherein the mesh substrate is a polyester mesh.

18. An implant according to claim 1, wherein the implant is a spinal disc replacement implant that has a plateless, non-articulating unitary solid body of crystalline hydrogel, and wherein the at least one mesh substrate is at least three mesh substrates integrally molded to the implant, a first piece of mesh material disposed about an annulus outer surface of the body, a second piece of mesh material covering at least a portion of a superior surface of the body, and a third piece of mesh material covering at least a portion of an inferior surface of the body, wherein the second and third pieces have a lesser thickness than the annulus piece, and wherein the second and third pieces both comprise selectively exposed regions that allow for tissue in-growth.

19. A method of fabricating an implantable prosthesis, comprising:

placing an inferior mesh layer on a floor of a three-dimensional mold;

introducing moldable material into the mold;

placing a superior mesh layer on a top surface of the moldable material in the mold;

heating the mold with the moldable material to a desired temperature so that the mold is heated for a desired time;

then

forming a molded implant body formed by the heated moldable material whereby the mesh layers are integrally moldably attached to the molded body formed by the moldable material; and

selectively exposing at least one of the inferior and superior mesh layers so that at least one region is substantially devoid of the moldable material whereby the exposed region promotes tissue in-growth therein while at least a major portion of the mesh layers are integrally moldably attached to the molded body.

20. A method according to claim 19, wherein the selectively exposing step comprises placing a temporary mesh layer over at least a portion of at least one of an upper primary surface of the superior layer or a lower primary surface of the inferior mesh layer, then after the forming step, removing the temporary mesh layer to selectively expose the mesh of the superior and/or inferior mesh layers.

21. A method according to claim 19, wherein the selectively exposing step comprises placing a restorable material on selective regions of the inferior and superior mesh layers before the forming step.

22. A method according to claim 19, wherein the selectively exposing step comprises placing a temporary silicone layer over at least a portion of at least one of an upper primary surface of the superior layer or a lower primary surface of the inferior mesh layer to inhibit moldable material from entering at least a top portion of the superior mesh layer or a bottom portion of the inferior mesh layer, respectively, during the forming step, then after the forming step, removing the temporary silicone layer to selectively expose the mesh of the superior and/or inferior mesh layers.

23. A method according to claim 19, wherein the selectively exposing step comprises placing intermediate mesh segment layers having smaller areas than the inferior and superior mesh layers, between at least one of the superior layer or the inferior mesh layer and the moldable material to locally inhibit moldable material from entering selected regions of the superior mesh layer and the inferior mesh layer, respectively.

24. A method according to claim 19, wherein the selectively exposing step comprises placing an intermediate substantially impermeable layer between at least one of the superior layer or the inferior mesh layer and the moldable material to locally inhibit moldable material from entering selected regions of the superior mesh layer or the inferior mesh layer, respectively, during the forming step.

25. A method according to claim 19, wherein the selectively exposing step comprises inhibiting the moldable material from extending through localized regions of an upper portion of the superior mesh layer and a lower portion of the inferior mesh layer during the forming step.

26. A method according to claim 19, wherein the selectively exposing step comprises allowing the moldable material to enter the mesh superior and inferior layers while inhibiting the moldable material from extending through at least a major portion of an area of an upper portion of the superior mesh layer and a lower portion of the inferior mesh layer during the forming step.

27. A method according to claim 19, wherein the selectively exposing step comprises flowing PVA hydrogel moldable material into the inferior and superior mesh layers during the forming step whereby a density gradient of the hydrogel moldable material extends in the mesh substrate whereby a lesser density of moldable material resides on an outermost bounds of the implant body.

28. A method according to claim 19, wherein the selectively exposing step comprises placing a temporary mesh layer comprising calcium salt over at least a portion of at least one of an upper primary surface of the superior layer or a lower primary surface of the inferior mesh layer, then after the forming step, removing the temporary mesh layer to selectively expose the mesh of the superior and/or inferior mesh layers.

29. A method according to claim 19, wherein the selectively exposing step comprises directing pressurized liquid to remove material throughout a target localized region in at least one of the superior and inferior mesh layers.

30. A method according to claim 29, wherein the pressurized liquid is a jet stream of heated and pulsed sterile water or saline directed to expose a desired local area and/or volume of the superior and/or inferior mesh layers.

31. A method according to claim 19, wherein the selectively exposing step comprises further comprising at least one optically, chemically or mechanically removing molded material from at least one upper region of the superior layer and at least one lower region of the inferior mesh layer after the forming step

32. A method according to claim 19, wherein the selectively exposing step comprises shielding the molded implant body with the attached inferior and superior mesh layers while exposing at least one target exposure area, then immersing the shielded implant body in a solvent bath.

33. A method according to claim 19, further comprising closing the mold before the forming step, wherein the moldable material includes PVA crystals and a liquid irrigation solution that defines a PVA hydrogel, wherein the heating is carried out to heat the mold with the moldable material to between about 80-200°

C. for at least about 5 minutes to less than about 8 hours,

the method further comprising;

freezing and thawing the PVA hydrogel molded body a plurality of times after the heating to provide a crystalline implant body with a desired compressive modulus of elasticity.

34. A method according to claim 19, wherein the forming step forms a total disc replacement spinal disc.

35. A method according to claim 19, wherein the superior and inferior mesh layers comprise a polyester mesh material having a thickness that is between about 5 mm to about 0.5 mm.