Because of their unique geometry, characterization of wear damage in total disc replacement (TDR) is difficult. In the article, we developed and validated an automated damage calculation technique for explanted TDR components. Eight polyethylene cores implanted from 4.6 to 16.0 years were using cone-beam microCT imaging (SCANCO Medical, Switzerland). The nominal uniform voxel size for the implant under investigation was 18 mu m, however with a smaller sample size increased resolutions (10-mu m nominal voxel size) could be achieved using the same microCT imaging hardware. Nominal surface data for both sizes of TDR components we examined were obtained from manufacturer's drawings (Link, Germany) and converted to highly discretized triangular meshes. The damage calculation technique utilized an initial alignment phase, followed by a pointwise calculation of the linear damage at each 3D surface point. During the alignment phase, a three-dimensional surface of the undamaged component was automatically aligned with volumetric image data from the damaged component. The alignment algorithm maximized the contact area between undamaged portions of the implant and its nominal surface using an iterative optimization technique. Linear damage at each triangle on the nominal surface was computed by moving along the local normal of the surface both inward and outward direction for a distance much less than the size of the implant. For the retrieved components, the maximum damage occurred away from the central axis of the dome close to the rim. Penetrations of up to 0.8 mm were observed in this region. Lower magnitude penetrations were observed near the pole of the dome. In conclusion, we have developed an analytical method to automatically align and measure three-dimensional surface damage with both high resolution and accuracy on implants with complicated, nonparametric, surface geometry and used this technique to analyze eight implants. (C) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 94B: 312-317,2010.
Wear pattern observations from TDR retrievals using autoregistration of voxel data
Creators
Yakov P. Shkolnikov - Exponent
Anton Bowden - Brigham Young University
Daniel MacDonald - Drexel University
Steven M. Kurtz - Exponent (United States)
Publication Details
Journal of biomedical materials research. Part B, Applied biomaterials, v 94B(2), pp 312-317
Publisher
Wiley
Number of pages
6
Grant note
R01AR047904 / NATIONAL INSTITUTE OF ARTHRITIS AND MUSCULOSKELETAL AND SKIN DISEASES; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS)
R01 AR47904 / NIH; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA
Resource Type
Journal article
Language
English
Academic Unit
School of Biomedical Engineering, Science, and Health Systems
Web of Science ID
WOS:000280009900004
Scopus ID
2-s2.0-77955379607
Other Identifier
991019168135804721
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