Tissue support structure

• US 7,718,109 B2
• Filed: 02/14/2006
• Issued: 05/18/2010
• Est. Priority Date: 02/14/2005
• Status: Expired due to Fees

• Current Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Original Assignee: Mayo Foundation For Medical Education And Research (Mayo Clinic)
• Inventors: Rajagopalan, Srinivasan, Robb, Richard A.
• Primary Examiner(s): Tucker; Philip C
• Assistant Examiner(s): Grun; Robert J
• Application Number:
  US11/351,860
• Publication Number:
  US 20060249875A1
• Time in Patent Office: 1,554 Days
• Field of Search: 264/308, 424/426
• US Class Current: 264/308
• CPC Class Codes: A61F 2/0077 Special surfaces of prostheses, e.g. for improving ingrowth A61F2/30767 takes precedence
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 50/00 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing

Abstract

Techniques for generating tissue support structure are presented. A curved minimal surface shape is determined as a template for generating a tissue support structure. The determined curved minimal surface shape is numerically or functionally defined to create data representing the shape. The data is exported to a rapid prototyping system to generate a plurality of tissue support structures having a curved minimal surface. The tissue support structure can have a pore sub-section and a non-pore sub-section divided by a non-intersecting two-sided surface. A number of characteristics of the tissue support structure can be modulated including porosity and mechanical strength.

Claims

1. A method of fabricating a reproducible tissue support structure, the method comprises:

using a non-stochastic, deterministic process to fabricate the reproducible tissue support structure, the non-stochastic deterministic process comprising;

determining a smooth and monolithic curved minimal surface shape as a template for the reproducible tissue support structure, wherein the smooth and monolithic curved minimal surface comprises a surface having a mean curvature of zero bounded by one or more pores, obtaining data indicative of the determined curved minimal surface shape; and

fabricating the repeatable and reproducible tissue support structure based on the obtained data, wherein the reproducible tissue support structure comprises repeated unit cells having the curved minimal surface shape which exhibits at least one structural characteristic selected from the group consisting of pore size, mechanical strength, or durataxicity, which are the same structural characteristics exhibited by the surface of the template.

2. The method of claim 1, further comprises fabricating a plurality of tissue support structures using a rapid prototyping technique.

3. The method of claim 2, wherein the rapid prototyping technique is solid freeform fabrication.

4. The method of claim 1, wherein fabricating the tissue support structure comprises creating a pore sub-space and a non-pore sub-space separated by a non-intersecting two-sided surface.

5. The method of claim 1, wherein determining the smooth and monolithic curved minimal surface shape comprises:

selecting a fundamental region; and

deforming for surface minimality a plane in the fundamental region to obtain a patch.

6. The method of claim 5, wherein obtaining the data comprises defining the smooth and monolithic curved minimal surface shape using a surface function generated using a numerical model, a functional representation or both.

7. The method of claim 6, wherein fabricating the tissue support structure comprises:

tessellating the patch to fabricate a unit cell having the smooth and monolithic curved minimal surface; and

tessellating the unit cell to generate the monolithic scaffold comprising the repeated unit cells having the smooth and monolithic curved minimal surface.

8. The method of claim 7, wherein the smooth and monolithic curved minimal surface is a triply periodic Schwartz minimal surface.

9. The method of claim 7, wherein the patch is a discrete patch represented by a variable number of triangles.

10. The method of claim 1, further comprises modulating a porosity of the tissue support structure based on a scaling factor that changes a size of each pore.

11. The method of claim 10, wherein the porosity is greater than fifty percent.

12. The method of claim 5, further comprises modulating a mechanical strength of the tissue support structure by evolving the patch to a non-zero constant mean curvature.

13. The method of claim 1, further comprises creating parallel seeding and feeding networks by embedding a constant mean curvature version of a Schwartz unit-cell within an optimally evolved Schwartz unit-cell.