Computer-aided-design of skeletal implants

• US 20060094951A1
• Filed: 12/09/2005
• Published: 05/04/2006
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: Osteoplastics, LLC
• Original Assignee: Case Western Reserve University
• Inventors: Min, Kyoung-June, Dean, David, Ratcheson, Robert A.
• Granted Patent: US 7,747,305 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61F 2/2875 Skull or cranium A61F2/2803 and A61F2/3099 take precedence
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: A61F 2002/30943 using mathematical models
• CPC Class Codes: A61F 2002/30952 using CAD-CAM techniques or NC-techniques
• 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
• CPC Class Codes: G05B 2219/45168 Bone prosthesis
• CPC Class Codes: G06T 17/10 Constructive solid geometry [CSG] using solid primitives, e.g. cylinders, cubes
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders
• CPC Class Codes: Y10S 623/901 Method of manufacturing prosthetic device

Abstract

The present invention is directed to a computer aided design method for producing an implant for a patient prior to operation comprising the steps of: generating data with a non-invasive 3D (3-dimensional) scan of the patient'"'"'s defect site that digitally represents the area that will receive the implant; designing and validating an implant on a computer based on digital data generated from a volume image of the patient; and fabricating the implant based solely on the implant design data generated on computer.

Claims

1. A computer aided design method for producing an implant for a patient prior to operation comprising the steps of:

generating data with a non-invasive 3D (3-dimensional) scan of the patient'"'"'s defect site that digitally represents the area that will receive the implant;

designing and validating an implant on a computer based on digital data generated from a volume image of the patient; and

fabricating the implant based solely on the implant design data generated on computer.

2. The method of claim 1 wherein the step of designing an implant based on the data generated from the 3D scan of a patient includes the steps of:

constructing a isurface image representing a patient'"'"'s defect site from 3D volume images.

3. The method of claim 2 wherein the step of generating data includes:

defining a contour, describing the external boundary of the patient'"'"'s defect site to receive the implant, on an surface image representing a patient'"'"'s defect site that is derived from the 3D volume images in an accurate 3D space.

4. The method of claim 2 wherein the step of designing an implant further includes the steps of:

determining a 3D region of interest that includes only the region of the isosurface image immediately adjacent to the defect site; and

clipping the 3D region of interest from the complete isosurface image.

5. The method of claim 4 wherein the step of designing an implant further includes the steps of:

placing a plurality of landmarks in order to seed the defect margin contour line on the isosurface image surrounding the defect margin.

6. The method of claim 5 wherein the step of designing an implant further includes the steps of:

determining 3D surface curvature and traversal cost factors; and

color mapping of the magnitude of the curvature at each 3D surface point.

7. The method of claim 6 including the step of:

redistributing the color values in an image referred to as a histogram over the entire intensity scale so as to make the contrast between low an high curvature regions visually useful.

8. The method of claim 6 including the step of:

measuring the thickness of the patient'"'"'s body structure underlying the defect margin crestline in order to determine its sufficiency for affixing the implant.

9. The method of claim 6 including the steps of:

resampling the defect-filling template surface to have uniformly shaped and spaced triangles;

the use of these resampled manifolds for the accurate partitioning of a defect filling template image; and

articulating the prototype implant surface while maintaining surface curvature continuity across the defect margin.

10. The method of claim 9 including the step of using an implant surface smoothing algorithm that removes slice edge artifact when volume image slices have larger inter-slice than pixel dimensions.

11. The method of claim 1 including the step of:

validating the prototype implant surface and taper fit with adjacent bone and soft tissue structures prior to fabricating the implant using Rapid Prototyping production.

12. The method of claim 1 wherein the step of constructing the implant based on the data generated the 3D volume scan includes the step of:

designing a full thickness 3D implant that articulates well with the defect site;

validating that this implant design does not intersect adjacent tissues in the defect site; and

designing an implant surface image that can be directly sent to a rapid prototyping device to print a full thickness implant from the data derived from the 3D scan and a template.

13. The method of claim 1 including the step of:

selecting the defect site from any portion of a person'"'"'s body that is defective and requires an implant wherein the portion of the person'"'"'s body is selected from the group comprising a skeletal element, a soft tissue organ, the external surface, and microscopic structures.

14. The method of claim 12 including the step of:

selecting a defect site from the skeletal element of a person'"'"'s head.

15. A computer aided design apparatus for producing an implant for a patient prior to operation comprising:

means for gathering surface data (i.e., digital data) of the patient'"'"'s defect site to receive the implant via non-invasive 3D volume imaging;

means for designing with a computer (computer aided design) an implant based on the data generated from a 3D volume scan of the patient; and

means for designing the implant based on the data generated by the 3D volume scan.

16. The computer aided design apparatus of claim 15 wherein the means for constructing the implant based on the data generated the 3D volume scan includes:

means for inputting the data of the 3D volume (e.g., 3D CT) scan directly to a rapid prototyping device to print a full thickness implant.

17. The computer aided design apparatus of claim 16 wherein the means for constructing an isosurface image representing a patient'"'"'s defect site is from 3D volumetric images.

18. The computer aided design apparatus of claim 17 further including:

means for determining a 3D region of interest that includes only a region of the isosurface image immediately adjacent to the defect site; and

means for clipping the 3D defect region of interest from the complete isosurface image.

19. The computer aided design apparatus of claim 18 further including:

means for measuring the thickness of the body structure found internal to the crestline.

20. The use of a two pass warp to match a right-left mirrored or average template to the defect site, including:

providing a two-pass warp, following an initial local positioning by least-squares fitting;

providing a first pass warp based on globally defined bilateral and midline landmarks; and

providing a second pass warp based on locally defined landmarks.