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 spinal implant comprising:
a top surface, a bottom surface, a first side surface, a second side surface, a back surface, and a front surface;
a titanium, non-porous frame encompassing an outer perimeter of the top surface; and
a porous sheet based triply periodic minimal surface portion:
integrally formed with the titanium frame via powder bed fusion;
comprising part of the top surface and extending from the top surface to the bottom surface; and
defined by a plurality of unit cells, each unit cell comprising a base geometry defined by a base equation:
cos
x
sin
y
+
cos
y
sin
z
+
cos
z
sin
x
=
0
wherein:
at least one of the first side surface, the second side surface, the back surface and the front surface defines at least one opening for receiving instrumentation;
the porous sheet based triply periodic minimal surface portion is node and strut free;
the porous sheet based triply periodic minimal surface portion comprises a wall thickness of 0.25 mm to 1.0 mm;
the porous sheet based triply periodic minimal surface portion defines an opening devoid of any structure, the opening bisecting the porous sheet based triply periodic minimal surface portion; and
the porous sheet based triply periodic minimal surface portion defined by the base equation comprising the part of the top surface is configured to directly contact bone of a patient upon implantation.
2 . The 3D-printed implant of claim 1 , wherein the first side surface transitions to the back surface via a first rounded corner.
3 . The 3D-printed implant of claim 2 , wherein the second side surface transitions to the back surface via a second rounded corner.
4 . The 3D-printed implant of claim 3 , wherein the back surface is defined by a plane intersecting each of the rounded corners.
5 . The 3D-printed spinal implant of claim 4 , wherein the back surface at least partially comprises the porous sheet based triply periodic minimal surface portion.
6 . The 3D-printed spinal implant of claim 5 , wherein the porous sheet based triply periodic minimal surface portion is a gyroid portion.
7 . The 3D-printed implant of claim 6 , wherein the porous sheet based triply periodic minimal surface portion comprises a stiffness modulus of about 3.0-14.0 GPA.
8 . The 3D-printed implant of claim 7 , wherein the porous sheet based triply periodic minimal surface portion comprises an ultimate compression strength of about 50.0-230.0 MPa.
9 . The 3D-printed implant of claim 8 , wherein the porous sheet based triply periodic minimal surface portion comprises a wall density greater than of at least 99%.
10 . A 3D-printed spinal implant comprising:
a top surface, a bottom surface, a back surface, and a front surface; and
a porous sheet based triply periodic minimal surface portion:
integrally formed with a non-porous titanium frame via powder bed fusion;
comprising part of the top surface and extending from the top surface to the bottom surface; and
defined by a plurality of unit cells, each unit cell comprising a base geometry defined by a sinusoidal equation,
wherein:
the back surface at least partially comprises the porous sheet based triply periodic minimal surface portion;
the porous sheet based triply periodic minimal surface portion is node and strut free;
the porous sheet based triply periodic minimal surface portion comprises a wall thickness of 0.25 mm to 1.0 mm;
the porous sheet based triply periodic minimal surface portion defines an opening devoid of any structure, the opening bisecting the porous sheet based triply periodic minimal surface portion;
the porous sheet based triply periodic minimal surface portion defined by the sinusoidal equation comprising the part of the top surface is configured to directly contact bone of a patient upon implantation;
the porous sheet based triply periodic minimal surface portion comprises an ultimate compression strength of about 50.0-230.0 MPa; and
the top surface is bounded at an outer perimeter by the non-porous titanium frame.
11 . The 3D-printed spinal implant of claim 10 , wherein:
the first side surface transitions to the back surface via a first rounded corner; and
the second side surface transitions to the back surface via a second rounded corner.
12 . The 3D-printed spinal implant of claim 11 , wherein the back surface is defined by a plane intersecting with each of the rounded corners.
13 . The 3D-printed spinal implant of claim 12 , wherein the porous sheet based triply periodic minimal surface portion is a gyroid portion.
14 . The 3D-printed spinal implant of claim 13 , wherein the back surface defines at least one opening for receiving instrumentation.
15 . The 3D-printed spinal implant of claim 14 , wherein the back surface is devoid of ridges extending away from the back surface.
16 . The 3D-printed spinal implant of claim 15 , wherein the sinusoidal equation comprises:
cos
x
sin
y
+
cos
y
sin
z
+
cos
z
sin
x
=
0
17 . The 3D-printed implant of claim 16 , wherein the porous sheet based triply periodic minimal surface portion comprises a stiffness modulus of about 3.0-14.0 GPA.
18 . The 3D-printed implant of claim 17 , wherein the porous sheet based triply periodic minimal surface portion comprises a wall density greater than of at least 99%.