Sheet based triply periodic minimal surface implants for promoting osseointegration and methods for producing same
Provided herein are implants and methods for producing implants. In at least one embodiment, the implants include sheet-based, triply periodic, minimal surface (TPMS) portions. According to one embodiment, the TPMS portions include a gyroid architecture that provides for improved osseointegration and mechanical performance over previous implants due to novel ratios of porosity to compressive strength, among other features. In one or more embodiments, the gyroid architecture is organized into unit cells that demonstrate anisotropic mechanical performance along an insertion direction. In various embodiments, the present methods include novel selective laser melting (SLM) techniques for forming the TPMS portions of implants in a manner that reduces defect formation, thereby improving compressive performance and other implant properties.
1. A 3D-printed implant comprising:
a top surface and a bottom surface;
a titanium frame comprising:
a perimeter portion; and
an interior portion bisecting the titanium frame, wherein the perimeter portion and the interior portion define a first void area and a second void area; and
a titanium sheet-based triply periodic minimal surface (TPMS) portion integrally formed with the titanium frame via SLM 3D printing extending from the top surface through the first void area and the second void area of the titanium frame to the bottom surface, the TPMS portion comprising:
a gyroid architecture;
a wall density greater than 99%;
unit cells with x and y sides of a first length and a z side of a second length;
a stiffness modulus of about 3-14 GPa;
a porosity of about 55-85%; and
an ultimate compression strength of about 50-230 MPa.
2. The 3D-printed implant of claim 1 , wherein the TPMS portion is free of nodes.
3. The 3D-printed implant of claim 2 , further comprising one or more teeth extending from the top surface or bottom surface.
4. The 3D-printed implant of claim 3 , wherein the one or more teeth extend from the top or bottom surface along a surface of the titanium frame.
5. The 3D-printed implant of claim 2 , wherein the interior portion defines a third void area free of TPMS structures.
6. The 3D-printed implant of claim 5 , wherein:
the TPMS portion comprises a wall thickness of about 0.25 mm;
the stiffness modulus is about 3 GPa;
the porosity is about 85%; and
the ultimate compression strength is about 50 MPa.
7. The 3D-printed implant of claim 5 , wherein:
the TPMS portion comprises a wall thickness of about 1.00 mm;
the stiffness modulus is about 14 GPa;
the porosity is about 55%; and
the ultimate compression strength is about 227 MPa.
8. The 3D-printed implant of claim 5 , wherein the second length is equal to the first length.
9. The 3D-printed implant of claim 5 , wherein the second length is smaller than the first length.
10. The 3D-printed implant of claim 9 , wherein:
the x and y sides are approximately 6.0 mm; and
the z side is approximately 3.0 mm.
11. The 3D-printed implant of claim 10 , wherein the 3D-printed implant is anisotropic in an insertion direction.
12. The 3D-printed implant of claim 11 , wherein the 3D-printed implant is a spinal cage.
13. The 3D-printed implant of claim 11 , wherein the 3D-printed implant is an osteotomy wedge.
14. The 3D-printed implant of claim 1 , wherein:
the perimeter portion comprises a proximal end and a distal end; and
the interior portion extends from the proximal end to the distal end, thereby bisecting the titanium frame.
15. The 3D-printed implant of claim 14 , wherein a volume of the first void area is substantially equal to a volume of the second void area.
16. A 3D-printed implant comprising:
a top surface and a bottom surface;
two titanium sheet based triply periodic minimal surface (TPMS) portions integrally formed with, and bounded by, a titanium frame extending from the top surface to the bottom surface and comprising:
a wall density greater than 99%;
unit cells with x and y sides of a first length and a z side of a second length;
a stiffness modulus of about 3-14 GPa;
a porosity of about 55-85%; and
an ultimate compression strength of about 50-230 MPa.
17. The 3D-printed implant of claim 16 , wherein the titanium frame comprises:
a perimeter portion; and
an interior portion bisecting the titanium frame, wherein the perimeter portion and the interior portion define areas comprising the two titanium TPMS portions.
18. The 3D-printed implant of claim 17 , wherein the two titanium TPMS portions comprise a gyroid architecture.
19. The 3D-printed implant of claim 18 , wherein the two titanium TPMS portions are free of nodes.
20. The 3D-printed implant of claim 19 , wherein the interior portion defines a third void area free of TPMS structures.
21. The 3D-printed implant of claim 20 , further comprising one or more teeth extending from the top surface or the bottom surface.
22. The 3D-printed implant of claim 21 , wherein the second is length smaller than the first length and the 3D-printed implant is anisotropic in an insertion direction.
23. The 3D-printed implant of claim 21 , wherein the second length is equal to the first length.
24. The 3D-printed implant of claim 23 , wherein the two titanium TPMS portions comprise a wall density of greater than 99%.