Sheet based triply periodic minimal surface implants for promoting osseointegration and methods for producing same
Inventors
MILLER, Andrew Todd • Rexrode, Matthew • Kelly, Cambre • Gall, Ken
Assignees
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Publication Number
US-10772732-B1
Publication Date
2020-09-15
Expiration Date
Abstract
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.
Core Innovation
The disclosure describes a 3D-printed implant comprising a titanium frame and a titanium sheet-based triply periodic minimal surface (TPMS) portion integrally formed with the frame. The TPMS portion exhibits a gyroid architecture extending from a top surface through two void areas defined by the frame to a bottom surface. Material characteristics include a wall density greater than 99%, a stiffness modulus of about 3–14 GPa, a porosity of about 55–85%, and an ultimate compression strength of about 50–230 MPa.
An alternative implant configuration provides two titanium sheet-based TPMS portions integrally formed with and bounded by a titanium frame extending between the top and bottom surfaces. The TPMS portions share specified ranges for wall density, stiffness modulus, porosity, and compressive strength. In addition, unit cells feature x and y sides of a first length and a z side of a second length, enabling direction-dependent mechanical properties in configurations such as wedge-shaped implants.
Claims Coverage
The independent claims cover two inventive features directed to 3D-printed titanium implants combining a titanium frame with one or more sheet-based TPMS portions and specified structural parameters.
Frame-integrated gyroid TPMS implant
Claim 1 covers a 3D-printed implant with a titanium frame comprising a perimeter portion and an interior portion that define first and second void areas. A titanium sheet-based TPMS portion with a gyroid architecture is integrally formed with the frame via SLM 3D printing and extends from the top surface through both void areas to the bottom surface. The TPMS portion has wall density greater than 99%, unit cells with x and y sides of a first length and a z side of a second length, stiffness modulus of about 3–14 GPa, porosity of about 55–85%, and ultimate compression strength of about 50–230 MPa.
Two TPMS portions bounded by a titanium frame
Claim 16 covers a 3D-printed implant with two titanium sheet-based TPMS portions integrally formed with and bounded by a titanium frame extending from the top surface to the bottom surface. The TPMS portions have wall density greater than 99%, unit cells with x and y sides of a first length and a z side of a second length, stiffness modulus of about 3–14 GPa, porosity of about 55–85%, and ultimate compression strength of about 50–230 MPa.
The independent claims cover a frame-integrated gyroid TPMS configuration and a dual-TPMS bounded configuration, both defining wall density, unit-cell dimensions, stiffness modulus, porosity, and ultimate compression strength.
Stated Advantages
Improved porosity-to-compressive-strength performance, including gyroid-sheet designs exhibiting greater compressive strength than literature examples at comparable porosity.
Bone-ingrowth potential.
Documented Applications
Spinal cages.
Osteotomy wedges, including wedge-shaped implants.
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